Jerald S. Ault, University of Miami Page 1 · 2010. 8. 19. · Jerald S. Ault, University of Miami Page 1 Final Progress Report on NOAA Coral Grant NA05NMF4631044 Final Report Grant

Jerald S. Ault, University of Miami Page 1 Final Progress Report on NOAA Coral Grant NA05NMF4631044

Final Report Grant No.: NOAA Coral Grant NA05NMF4631044 Title: Methods to Evaluate Marine Reserve Impacts PIs: Jerald S. Ault and Steven G. Smith, University of Miami RSMAS Reporting Period: 10/1/05 – 9/30/06 Summary of Work.- The project identified and evaluated robust quantitative metrics that defined fish community changes in marine protected areas in the coral reef ecosystem of the Florida Keys. The work and accomplishments are summarized as follows: Task 1 -- Literature review & synthesis.- A thorough literature review and synthesis was completed. The task identified various metrics and models to assess population- and community-level changes within marine protected areas. Task 2 -- Organized Florida Keys-Tortugas databases.- We completed organization and synthesis of an extensive state-of-the-art relational database that included more than 6000 research dives that surveyed reef-fish populations and habitats (stony corals, octocorals, and algae and bathymetry) before and 3 and 5 yrs after 2001 implementation of no-take marine reserves covering approximately 566 km2 in the Dry Tortugas, Florida. Tasks 3 and 4 – Developed a robust statistical estimation framework and applied identified metrics to emphasize reserve performance in the Dry Tortugas region of the Florida Keys. The Florida Keys is a unique tropical marine environment of national significance, renown for its productive coral reef ecosystem, diverse natural resources, broad recreational fishing opportunities, and spectacular scenic beauty. Due to severe overfishing, research to assess changes in abundance of reef fish populations resulting from establishment of a network of “no-take” marine protected areas (MPAs) in the Dry Tortugas region of the Florida Keys is a high priority item for the NOAA Fisheries, Florida Keys National Marine Sanctuary, National Park Service, and State of Florida Fish and Wildlife Commission. The goal of this was to identify and evaluate robust metrics that defined fish community changes in marine protected areas. This was accomplished by through the following tasks: (1) conducting a thorough literature review and synthesis to identify metrics and models to assess population- and community-level changes within marine protected areas, and to assess their application to marine fishery ecosystems; (2) organizing and assimilating our spatially synoptic, long-term fishery-independent database from the Florida Keys on coral reef fish abundance, size structure, species composition, and environmental covariates to facilitate analysis of fish community dynamics in relation to physical and biological habitats, exploitation, and spatial zoning; (3) development of a robust statistical estimation framework to objectively assess differences in the metrics, and to discriminate between changes due to reserve establishment versus other processes or confounding factors; and, (4) applying the quantitative metrics, models and statistical framework identified in (1-3) to our database, particularly emphasizing the Dry Tortugas region of the Florida Keys.


In November 2006, the Florida governor and cabinet approved implementation of a management plan for a Research Natural Area (RNA) or no-take marine reserve in the Dry Tortugas National Park (DTNP) to become effective in January 2007. The Florida Fish and Wildlife Conservation Commission also concurred with the proposed National Park Service regulations related to marine fishing in the park. In 2001 no-take marine reserves (NTMRs) covering approximately 566 km2 were established in Florida Keys National Marine Sanctuary waters near Dry Tortugas National Park. The park’s new RNA, coupled with marine reserves in the Florida Keys National Marine Sanctuary, is designed to protect precious coral reefs, fishery, and cultural resources, and to ensure sustainability of intensely exploited regional reef fisheries resources – benefiting the Tortugas, the Florida Keys and beyond. The primary objective of fishery-independent monitoring was to conduct a synoptic visual census survey using SCUBA/nitrox to assess the resource status (occurrence, abundance, and spatial distribution), and MPA performance for the reef fish community in Dry Tortugas National Park. The goals of the 2006 Tortugas research expedition were: (1) to conduct a quantitative visual census assessment of coral reef fishery and habitat resources in the Tortugas region five years after implementation of the Tortugas Ecological Reserve (TER); (2) to sample all fish species and sizes in all representative coral reef habitats both inside and outside reserve areas; and, (3) to monitor trends in coral reef fish populations and the effectiveness of current management practices. Using a sampling design-based approach in 2006 we conducted a research cruise to the Dry Tortugas that resulted in 1,344 scientific dives in the region monitoring reef fish, benthic habitats, and spiny lobster. We compared these data to a series of synoptic research cruises with over 4,000 research dives to survey reef fish populations and habitats in the Dry Tortugas before and three years after the NTMRs were implemented. We recorded the presence, abundance and size of 267 fish species from eight reef habitats in three management areas offering different levels of resource protection: the Tortugas North Ecological Reserve (a NTMR), Dry Tortugas National Park (recreational angling only), and southern Tortugas Bank (open to all fishing under regional regulations). Species richness and composition remained stable between 1999-2000, 2004, and 2006, within the overall survey domain. Greatest reef fish biodiversity was found in the more rugose habitats. We detected significant domain-wide increases in abundance for several exploited and non-exploited species, while no declines were detected. In the Tortugas Bank NTMR, we found significantly greater abundances and shifts in length composition structures towards a higher proportion of exploited phase animals in 2004 and 2006 compared to 1999-2000 for some species (e.g., black grouper and red grouper). Consistent with predictions from marine reserve theory, we did not detect any declines for exploited species in the NTMR, while for non-target species we detected both increases and declines in population abundance in the NTMR for non-target species. The observed upsurge in exploited populations, however, may have also been influenced by other factors including past or recent fishery management actions that increased minimum sizes or reduced fishing mortality rates; the passage of recent hurricanes; and, the occurrence of good recruitment year classes. Although still early in the recovery process, our results after five years are encouraging and suggest that NTMRs, in conjunction with traditional management, can potentially help build sustainable fisheries while protecting the Florida Keys coral reef ecosystem. The project outcomes provide a suite of metrics and procedures for assessing MPA impacts that are statistically robust and readily interpretable for the Florida Keys ecosystem as well as applicable to MPA assessment throughout US marine waters.


Comments.- No specific problems or delays hindered our progress during the development and execution of this research. However, due to an apparently late submission for a no-cost extension, we NEVER drew all of the funds that were allocated for this project. That amounted to more than $10,500 or >20% of the total project resources! The decision to deny our requested no-cost extension by NOAA accounting folks was short-sighted and it will have short- and longer-term impacts. In the near-term the decision directly limited the PIs involvement in and use of their specialized expertise and capabilities to transform the project’s final technical report to a refined scientific paper submitted and published in a high-profile international journal. In the longer run, it limits the effectiveness of NOAA’s GCRCP-funded research program to reach the national and international scientific communities that would greatly benefit from exposure to the state-of-the-art methods to evaluate marine reserve impacts developed in this research.

Methods to Evaluate Marine Reserve Impacts Page 1.1 FINAL REPORT FY07

Methods to Evaluate Marine Reserve Impacts

Jerald S. Ault and Steven G. Smith

University of Miami Rosenstiel School of Marine and Atmospheric Science

FINAL REPORT NOAA General Coral Reef Conservation Program

NOAA Grant NA05NMF4631044

March 2007


Methods to Evaluate Marine Reserve Impacts

Jerald S. Ault and Steven G. Smith

University of Miami Rosenstiel School of Marine and Atmospheric Science

4600 Rickenbacker Causeway, Miami, FL 33149 (305)361-4884 ph

[email protected]

NOAA General Coral Reef Conservation Program NOAA Grant NA05NMF4631044

March 2007

Cover photo: Large school of French grunt (Haemuelon flavolineatum) and a single creole wrasse (Clepticus parrae) seen by RVC divers on Tortugas Bank during 2006 expedition.


EXECUTIVE SUMMARY The Florida Keys is a unique tropical marine environment of national significance, renown for its productive coral reef ecosystem, diverse natural resources, broad recreational fishing opportunities, and spectacular scenic beauty. Due to severe overfishing, research to assess changes in abundance of reef fish populations resulting from establishment of a network of “no-take” marine protected areas (MPAs) in the Dry Tortugas region of the Florida Keys is a high priority item for the NOAA Fisheries, Florida Keys National Marine Sanctuary, National Park Service, and State of Florida Fish and Wildlife Commission. The goal of this was to identify and evaluate robust metrics that defined fish community changes in marine protected areas. This was accomplished by through the following tasks: (1) conducting a thorough literature review and synthesis to identify metrics and models to assess population- and community-level changes within marine protected areas, and to assess their application to marine fishery ecosystems; (2) organizing and assimilating our spatially synoptic, long-term fishery-independent database from the Florida Keys on coral reef fish abundance, size structure, species composition, and environmental covariates to facilitate analysis of fish community dynamics in relation to physical and biological habitats, exploitation, and spatial zoning; (3) development of a robust statistical estimation framework to objectively assess differences in the metrics, and to discriminate between changes due to reserve establishment versus other processes or confounding factors; and, (4) applying the quantitative metrics, models and statistical framework identified in (1-3) to our database, particularly emphasizing the Dry Tortugas region of the Florida Keys. In November 2006, the Florida governor and cabinet approved implementation of a management plan for a Research Natural Area (RNA) or no-take marine reserve in the Dry Tortugas National Park (DTNP) to become effective in January 2007. The Florida Fish and Wildlife Conservation Commission also concurred with the proposed National Park Service regulations related to marine fishing in the park. In 2001 no-take marine reserves (NTMRs) covering approximately 566 km2 were established in Florida Keys National Marine Sanctuary waters near Dry Tortugas National Park. The park’s new RNA, coupled with marine reserves in the Florida Keys National Marine Sanctuary, is designed to protect precious coral reefs, fishery, and cultural resources, and to ensure sustainability of intensely exploited regional reef fisheries resources – benefiting the Tortugas, the Florida Keys and beyond. The primary objective of fishery-independent monitoring was to conduct a synoptic visual census survey using SCUBA/nitrox to assess the resource status (occurrence, abundance, and spatial distribution), and MPA performance for the reef fish community in Dry Tortugas National Park. The goals of the 2006 Tortugas research expedition were: (1) to conduct a quantitative visual census assessment of coral reef fishery and habitat resources in the Tortugas region five years after implementation of the Tortugas Ecological Reserve (TER); (2) to sample all fish species and sizes in all representative coral reef habitats both inside and outside reserve areas; and, (3) to monitor trends in coral reef fish populations and the effectiveness of current management practices. Using a sampling design-based approach in 2006 we conducted a research cruise to the Dry Tortugas that resulted in 1,344 scientific dives in the region monitoring reef fish, benthic habitats, and spiny lobster. We compared these data to a series of synoptic research cruises with over 4,000 research dives to survey reef fish populations and habitats in the Dry Tortugas before and three years after the NTMRs were implemented. We recorded the presence, abundance and


size of 267 fish species from eight reef habitats in three management areas offering different levels of resource protection: the Tortugas North Ecological Reserve (a NTMR), Dry Tortugas National Park (recreational angling only), and southern Tortugas Bank (open to all fishing under regional regulations). Species richness and composition remained stable between 1999-2000, 2004, and 2006, within the overall survey domain. Greatest reef fish biodiversity was found in the more rugose habitats. We detected significant domain-wide increases in abundance for several exploited and non-exploited species, while no declines were detected. In the Tortugas Bank NTMR, we found significantly greater abundances and shifts in length composition structures towards a higher proportion of exploited phase animals in 2004 and 2006 compared to 1999-2000 for some species (e.g., black grouper and red grouper). Consistent with predictions from marine reserve theory, we did not detect any declines for exploited species in the NTMR, while for non-target species we detected both increases and declines in population abundance in the NTMR for non-target species. The observed upsurge in exploited populations, however, may have also been influenced by other factors including past or recent fishery management actions that increased minimum sizes or reduced fishing mortality rates; the passage of recent hurricanes; and, the occurrence of good recruitment year classes. Although still early in the recovery process, our results after five years are encouraging and suggest that NTMRs, in conjunction with traditional management, can potentially help build sustainable fisheries while protecting the Florida Keys coral reef ecosystem. The project outcomes provide a suite of metrics and procedures for assessing MPA impacts that are statistically robust and readily interpretable for the Florida Keys ecosystem as well as applicable to MPA assessment throughout US marine waters.


TABLE OF CONTENTS Executive Summary………………………………………………………………. 1.3 Building Sustainable Fisheries in Florida’s Coral Reef Ecosystem: Positive Signs in the Dry Tortugas. 2006. Bulletin of Marine Science 78(3): 633-654. 0.0 Abstract……………………………………………………………………….. 633 0.1 Introduction……………………………………………………………………. 633 0.2 Materials and Methods………………………………………………………… 635 0.2.1 Study Area…………………………………….……………………… 635 0.2.2 Survey Design………………………………………………………… 635 0.3 Results…………………………………………………………………………. 640 0.4 Discussion…………………………………………………………………….. 647 0.5 Acknowledgments…………………………………………………………….. 651 0.6 Literature Cited……………………………………………………………….. 651 Fishery-Independent Monitoring of Coral Reef Fishes, Coral Reefs, and Macro-invertebrates in the Dry Tortugas 1.0 Introduction: Background and Rationale……………………………………… 1.6 1.1 Materials and Methods………………………………………………………… 1.9 1.1.1 Study Area………………………………………………………………. 1.9 1.1.2 Survey Design and Operations………………………………………….. 1.9 1.1.3 Statistical Analysis……………………………………………………… 1.12 1.2 Results………………………………………………………………………… 1.13 1.2.1 Sampling Effort…………………………………………………………. 1.13 1.2.2 Preliminary Analysis of Change, Baseline to 2006…………………….. 1.13 1.3 Next Steps in the Research Analysis…………………………………………. 1.15 1.4 Acknowledgments ……………………………………………………………. 1.15 1.5 Literature Cited ………………………………………………………………. 1.16 Figures and Tables……………………………………………………………. 1.22

BULLETIN OF MARINE SCIENCE, 78(3): 633–654, 2006

633Bulletin of Marine Science© 2006 Rosenstiel School of Marine and Atmospheric Science of the University of Miami

MOTE SYMPOSIUM INVITED PAPER

BUILDING SUSTAINABLE FISHERIES IN FLORIDA’S CORAL REEF ECOSYSTEM: POSITIVE SIGNS IN THE DRY TORTUGAS

Jerald S. Ault, Steven G. Smith, James A. Bohnsack, Jiangang Luo, Douglas E. Harper, and David B. McClellan

ABSTRACTIn a series of synoptic research cruises including 4000 research dives, we surveyed

reef-fish populations and habitats before and 3 yrs after 2001 implementation of no-take marine reserves covering approximately 566 km2 in the Dry Tortugas, Florida. Species richness and composition of 267 fishes remained stable between 1999–2000 and 2004 within the overall survey domain. Reef-fish biodiversity was highest in the more rugose habitats. Domain-wide abundances of several exploited and nonex-ploited species increased; no declines were detected. In the Tortugas Bank reserve, we found significantly greater abundances and shifts in length composition toward a higher proportion of exploited-phase animals in 2004 than in 1999–2000 for some species. Consistent with marine reserve theory, we detected no declines in exploited species in the reserve, whereas we detected both increases and declines in nontarget species, but the increases in exploited populations may also have been influenced by factors other than protected status. Although the recovery process is still in an early stage, our results after 3 yrs are encouraging and suggest that no-take marine reserves, in conjunction with traditional management, can help build sustainable fisheries while protecting the Florida Keys coral-reef ecosystem.

Sustainability of marine ecosystems is a worldwide concern. Intensive fishing has diminished top trophic levels and affected the ecological dynamics and resilience of fisheries by reducing the numbers and lengths of food webs (Pauly et al., 2002; Zeller and Russ, 2004). Resource management focused on single-species production has historically ignored the ecosystem consequences of overfishing (Botsford et al., 1997; National Research Council, 2001; U.S. Commission on Ocean Policy, 2004). Proposed solutions intended to promote sustainability include more stringent appli-cations of the precautionary approach and establishment of marine protected areas under the rubric of ecosystem-based fishery management (National Research Coun-cil, 2001; Lubchenco et al., 2003a; Pew Oceans Commission, 2003; Hilborn et al., 2004a,b; Meester et al., 2004; Pikitch et al., 2004; U.S. Commission on Ocean Policy, 2004). An extensive literature has touted the use of “no-take” marine reserves (NT-MRs—areas protected from all extractive uses) as the means of reversing declining trends in tropical coral-reef ecosystems (Polunin, 1990, 2002; Roberts and Polunin, 1991; DeMartini, 1993; Bohnsack and Ault, 1996; Roberts, 1997; Allison et al., 1998; Guénette et al., 1998; Meester et al., 2001, 2004; Ault et al., 2002, 2005a; Halpern and Warner, 2002, 2003; Gell and Roberts, 2003; Hastings and Botsford, 2003; Lub-chenco et al., 2003b; Willis et al., 2003; Bohnsack et al., 2004; Hooker and Gerber, 2004; Mangel and Levin, 2005).

In the Florida Keys, increased fishing pressure from rapid regional human popula-tion growth and environmental changes associated with coastal development have raised concerns about fisheries sustainability and persistence of the coral-reef eco-system (Porter and Porter, 2001; Ault et al., 2005a; Pandolfi et al., 2005). Histori-cally intense commercial and rising recreational fishing pressures have resulted in

BULLETIN OF MARINE SCIENCE, VOL. 78, NO. 3, 2006634

unsustainable rates of exploitation for 70% of the “snapper-grouper complex” (Ault et al., 1998, 2005b), which consists of over 50 species, mainly of groupers and snap-pers, but also of grunts, jacks, porgies, and hogfish. Over the last 40 yrs, the number of registered recreational vessels in southern Florida has grown by more than 500%. Sport-fishing effort is expected to continue to grow in proportion to regional human populations, which have doubled about every 20 yrs (Ault et al., 2005a). The recre-ational fleet now accounts for a substantial proportion of the total regional catches for some key exploited species (NOAA MRFSS Database; Florida Fish and Wildlife Conservation Commission Trip Ticket Database; Coleman et al., 2004), and this in-creasing trend will probably continue.

Reef fisheries in the Florida Keys ecosystem are complex and regulated by several entities, including the Florida Fish and Wildlife Conservation Commission (http://www.myfwc.com), the National Park Service (http://www.nps.gov/drto), and the National Marine Fisheries Service in conjunction with the South Atlantic Fishery Management Council (http://www.safmc.net) and the Gulf of Mexico Fishery Man-agement Council (http://www.gulfcouncil.org). In response to declining trends in reef-fishery catches, many regional, federal, and state management regulations were imposed, including recreational bag limits, minimum size limits, commercial quotas and trip limits, seasonal closures, gear restrictions, limited commercial entry, closed fisheries, species moratoria, imposition of game-fish status, and restrictions on sale and possession. These regulations were implemented to stabilize catches, protect spawning-stock biomass, and reduce fishing mortality rates. In general, the history of regional regulations for reef fishes has been complex, and they have tended to be more restrictive over time, but nonetheless recent fishery assessments indicated that, for example, black grouper spawning stock biomass was < 10% of its historical size (Ault et al., 2005b).

In recent years, new ecosystem-based management measures have been enacted in the Florida Keys, including the 1997 implementation of a network of 23 NTMRs by the Florida Keys National Marine Sanctuary (http://floridakeys.noaa.gov). These are relatively small (mean 2 km2, range 0.16–31 km2), comprising only 46 km2 in total area (U.S. Department of Commerce, 1996), and have varying levels of protection: four allow catch-and-release surface trolling, and four require a special permit for access. In July 2001, the Florida Keys network was expanded to become the largest in North America with the implementation of two NTMRs in the Dry Tortugas region that cover about 566 km2. This region is believed to be an extremely important source of recruitment of coral-reef fishes because of its upstream location in the Florida Current, which facilitates advective dispersion and transport of eggs and larvae to the rest of the Keys (Lee and Williams, 1999; Dahlgren and Sobel, 2000; Lindeman et al., 2000; Ault et al., 2002; Yeung and Lee, 2002; Domeier, 2004; Fig. 1A).

Implementation of conventional management measures or of spatial controls like NTMRs is expected to rebuild reef-fish population biomass and age-structure, and in the long run, unrestricted growth of biomass within reserves should result in resource export through reserve boundaries to surrounding areas as either larval dispersal to proximal natal sites or diffusive movements of fishable biomass (Bohn-sack, 1998; Roberts et al., 2001; Pauly et al., 2002; Russ, 2002; Zeller and Russ, 2004; Bohnsack et al., 2004). The rate at which these impacts occur and can be detected depends greatly on the species’ life history, demographic characteristics, and survey precision. Because snapper and grouper life spans are often measured in decades, the

AULT ET AL.: POSITIVE SIGNS FOR FLORIDA’S CORAL REEF FISHERIES 635

effects of management actions could take 20 yrs or more to reach their full potential (e.g., Beverton and Holt, 1957).

Here we report results from fisheries-independent surveys in the Tortugas region that assessed reef-fish populations before and after the establishment of Tortugas NTMRs in July 2001. The survey design incorporated habitats and management zones chosen to control the precision of spatial data for reef-fish populations. To evaluate potential impacts of NTMRs and other factors on reef-fish sustainability in the Florida Keys coral reef ecosystem, we analyzed temporal changes of relatively simple population and community metrics (e.g., frequency of occurrence, abun-dance, size compositions, and species richness) for the Tortugas region both within and outside NTMRs.

Materials and Methods

Study Area.—The Florida Keys coral reef ecosystem extends 380 km from Miami to the Dry Tortugas (Fig. 1A). The Tortugas study area was located about 113 km west of Key West (Fig. 1A) and encompassed approximately 1686 km2 in two principal areas: Dry Tortugas Na-tional Park (managed by Department of the Interior) and Tortugas Bank (managed by Depart-ment of Commerce) (Fig. 1B).

Survey Design.—We employed a stratified random diver visual survey to obtain fishery-independent data on the spatial distribution, abundance, size composition, and habitats of coral reef fishes in the Tortugas region (Bohnsack and Bannerot, 1986; Ault et al., 1998, 2002; Bohnsack et al., 1999). The survey domain encompassed coral-reef habitats < 33 m deep in Tortugas Bank and Dry Tortugas National Park (Fig. 1). The sampling domain was partitioned into habitat strata based on the degree of vertical relief (e.g., rugosity, complexity) and the degree of patchiness (e.g., amount of soft-bottom substrate interspersed among reef struc-tures) of the hard-bottom substrate (Fig. 2, Table 1; Ault et al., 2002; Franklin et al., 2003). This habitat-based stratification procedure was developed from the 1999 and 2000 baseline surveys (Fig. 1A) and was shown to be effective in partitioning the domain into areas of high, moderate, and low levels of mean fish density and associated variance for many principal reef species (Ault et al., 2002), thereby improving sampling efficiency and cost-effectiveness (Smith and Ault, 1993; Ault et al., 1999, 2003). Three management zones were incorporated as a second spatial stratification variable. The first, Tortugas Bank Fished (the fished area), was open to all types of commercial and recreational fishing under regional regulations. The second, Dry Tortugas National Park (the park), was open to only recreational hook-and-line fishing. Commercial fishing has been prohibited since 1935, when the area became a national monument, and recreational lobster diving was prohibited in 1980. After it became a national park in 1992, protection increased, and headboats for recreational fishing were excluded in 1995. The third, Tortugas Bank NTMR (the reserve), a no-take and no-anchoring reserve, also known as the Tortugas North Ecological Reserve, has been closed to all types of fishing since 1 July 2001 (Fig. 1B).

We used a geographical information system (GIS) and digital spatial databases of benthic habitats, bathymetry, and management zone boundaries to facilitate spatial delineation of the survey domain, sampling strata, and sample units. The Tortugas sampling domain was overlaid with a GIS grid of 200 × 200-m cells that represented the minimum mapping units for benthic habitat types (Fig. 2).

A two-stage stratified-random sampling design was employed in which the primary sample unit was the 200 × 200-m habitat grid cell and the second-stage unit was a circular visual-census plot 15 m in diameter (described below). Stratum (h) sizes in terms of area (Ah) con-sisting of Nh possible primary sampling units are given in Table 1. Allocation among strata of the number of primary units to be sampled was based on stratum area and variance of fish density for a representative suite of species (i.e., a Neyman allocation scheme; Cochran, 1977).


Figure 1. Dry Tortugas region study area showing (A) primary sampling-unit locations for the 1999 (open triangles) and 2000 (open squares) reef-fish surveys and (B) spatial management boundaries and primary units sampled by the reef-fish team (open pentagons) during the 2004 survey. Bathymetry is denoted by light to dark shading (white, 0–3 m; black, >50 m). NTMR, no-take marine reserve; FKNMS, Florida Keys National Marine Sanctuary.

A

B


Within a stratum, specific primary units to be sampled were randomly selected a priori with equal probability from the complete list of Nh units according to a discrete uniform distribu-tion (Law and Kelton, 2000). To ensure replication, two pairs of second-stage sample units (i.e., diver visual census plots) were randomly positioned within each selected primary unit. Because of diving-safety concerns and statistical concerns about sample autocorrelation, in our computations each second-stage unit estimate consisted of the arithmetic average of sta-tionary plots from two individual divers (i.e., a “buddy pair”). Each primary sample unit loca-tion in Figure 1 therefore denotes a place where at least four scientific divers were deployed to conduct visual census samples (i.e., one pair of divers at each of two second-stage locations within a primary sampling unit).

Highly trained and experienced divers collected biological data using Nitrox SCUBA and the reef-fish visual census (RVC) protocol, a standard, nondestructive, in situ visual monitor-ing method. In the RVC protocol, a stationary diver collects reef-fish data while centered in a randomly selected circular plot 15 m in diameter (Bohnsack and Bannerot, 1986; Bohnsack et al., 1999; Ault et al., 2002). First, for 5 min, all fish species observed within 7.5 m of the diver in an imaginary cylinder extending from the bottom to the limits of vertical visibility (usually the surface) were listed. Data are then collected on the abundance and minimum, mean, and maximum lengths for each species sighted. A ruler connected perpendicularly to the end of a meter stick was used as a reference to reduce apparent magnification errors in fish-size estimates. We also designed and deployed a laser and digital video-camera system to increase the precision of sizing and counting of reef fishes. For each plot, depth, bottom substrate composition, estimated benthic percentage cover, and vertical relief characteristics of the seafloor were recorded from the polar perspective of the centrally located observer. Digital photographs taken at each station assisted with habitat classification and identifica-tion of uncommon fish species. The time required to record each sample averaged 15–20 min, depending on the habitat.

Figure 2. Spatial distribution of the eight classified coral-reef habitats in the Dry Tortugas region overlain by the 200 × 200-m primary unit sampling grid used in monitoring surveys.


Synoptic survey cruises were conducted in the Dry Tortugas region in 1999 and 2000 (be-fore implementation of the reserve in July 2001) and again in 2004. Each 3-wk cruise was carried out during late May to early July from a 30-m, live-aboard dive vessel equipped with four compressor banks of Nitrox (M/V Spree, Gulf Diving, Houston, TX). During 2002, a Keys-wide survey focused some sampling effort in Dry Tortugas National Park, but we did not include these data because they lacked comparable effort on Tortugas Bank. The onboard sci-entific crew, consisting of 20–24 persons on any given sampling day, comprised a fish-census team and a benthic-habitat team (and/or a spiny-lobster, Panulirus argus (Latreille), team), as well as two full-time divemasters to oversee the complex diving operations. Visual survey data were entered onboard into a digital database with a laptop-based data-entry system that includes extensive error-checking and validation protocols. For the 2004 survey, the laptop computers were linked to a centralized server through a shipboard wireless network.

Our statistical analyses focused on changes between baseline years 1999 and 2000 (be-fore) and 2004 (after). We evaluated change statistically with a community metric, species richness, and two population metrics: frequency of occurrence and abundance. Statistical estimation procedures followed Cochran (1977) for a two-stage stratified random sampling design. In these procedures, stratum means and variances of a given metric are weighted by stratum sizes; i.e.,

W N Nh h hh

= ∑ ,

Table 1. (A) Habitat stratum (h) characteristics and sizes in terms of primary sampling units (N

h) and area (A

h) for the Dry Tortugas sampling domain. (B) Habitat stratum sizes for three

management zones within the Dry Tortugas sampling domain; dashes denote habitats not found in a given management zone. NTMR, no-take marine reserve.

(A)Reef habitat classification Habitat

codeDegree of patchiness

Degree of vertical relief

Domain-wide area

Nh

Ah (km2)

Low-relief hard bottom LRHB Low Low 4,909 196.36Low-relief spur and groove LRSG Moderate Low 296 11.84Patchy hard bottom in sand PHBS High Low 913 36.52Medium-profile reef MDPR Low Moderate 194 7.76Rocky outcrops RKOC Moderate–High Moderate 1164 46.56Reef terrace RFTC Low High 422 16.88High-relief spur and groove HRSG Moderate High 127 5.08Pinnacle reef RFPN High High 57 2.28

Total 8,082 323.28

(B)Habitat code Tortugas Bank Fished Tortugas Bank NTMR Dry Tortugas National Park

Nh

Ah (km2) N

hA

h (km2) N

hA

h (km2)

LRHB 1,108 44.32 1,438 57.52 2,363 94.52LRSG — — — — 296 11.84PHBS 38 1.52 35 1.40 840 33.60MDPR — — — — 194 7.76RKOC 134 5.36 282 11.28 748 29.92RFTC 47 1.88 327 13.08 48 1.92HRSG — — — — 127 5.08RFPN — — 29 1.16 28 1.12Total 1,327 53.08 2,111 84.44 4,644 185.76


to produce overall means and variances either for specific management zones or for the entire Tortugas domain. We estimated species richness on the basis of primary sample unit (i.e., the number of unique species observed within a primary unit by the group of divers) to ensure a sufficient search area for reliable estimates. In this case, the statistical sample size was n, the number of sampled primary units. Both frequency of occurrence and abundance were estimated by species on a second-stage-unit basis, the standard approach for two-stage de-signs (Cochran, 1977), where the number of second-stage units nm was the statistical sample size. Because benthic habitat classification, digital mapping, and development of the Tortugas survey design occurred concurrently with the baseline surveys of 1999 and 2000 (Ault et al., 2002), we estimated each population and community metric as a composite of the two base-line years to alleviate problems of misclassification of habitats and misallocation of samples among habitat strata. In this procedure, stratum means and variance components were com-puted as 2-yr averages weighted by respective sample sizes in 1999 and 2000.

Species chosen for detailed analyses reflected the range of population-dynamic processes (growth and survivorship) for relatively abundant exploited and nonexploited components of the reef-fish community. Statistical tests for differences among estimates of mean density, total abundance, and mean proportion of samples for the sampling design configuration were conducted by inspection of confidence intervals (CI) with Bonferroni adjustments (Cochran, 1977). Detection of change was defined as the ability to discriminate between the 95% CI of mean responses for the two time periods. We used the Bonferroni CI t-test because it is more suited to sample design statistics and does not require homogenous variance in two distribu-tions to test differences in the mean responses. Changes in length compositions between time periods were tested with standard two-sample chi-square tests (Agresti, 1996). The absolute

Figure 3. Relative frequency of observations of coral-reef fish species richness (number of spe-cies seen per 200 × 200-m primary sample unit) for three benthic habitat classes from the 2004 Tortugas survey. psu, primary sample unit.


ability to detect changes was thus determined by the precision of the survey estimates (e.g., standard error).

Results

In all, 4092 scientific dives totaling more than 668 hrs bottom time, including 3234 fish-survey dives, were made during 1999–2004 cruises in the Tortugas region. Diving depths ranged from 3 to 33 m, but use of enriched-air Nitrox permitted a sub-stantial diving effort at depths > 18 m and ≤ 33 m (> 63% of all dives). Table 2 shows statistical sample sizes in terms of primary (n) and second-stage (nm) sample units by year, habitat, and management zone.

Over the 1999–2004 period, we observed 267 fish species in RVC surveys in the Tortugas region. Fish species richness ranged from 8 to 64 species per primary sam-ple unit (psu) and, in general, was correlated with habitat class. Greatest reef-fish species diversity (63–64 species per psu) was found in high-rugosity habitats (reef terrace and reef pinnacles), the lowest (8–11 per psu) in low-rugosity habitats (low-relief hard bottom and patchy hard bottom in sand), as illustrated in Figure 3 for the 2004 survey. For the Tortugas sampling domain, we detected no change in mean spe-cies richness (mean number of species per psu) between the 1999–2000 (37.1 ± 0.7 SE) baseline and 2004 (38.1 ± 0.5 SE), even though we could have detected a change >1.4 species (i.e., approximately 2 SE). We found similar results for selected taxa; for example, mean richness for species of exploited snappers and groupers was 7.8 ± 0.2 SE for both 1999–2000 and 2004. Species richness (diversity) of the snapper-grouper complex was also related to reef rugosity, in that it was highest on reef terrace and pinnacle habitats found on the northwestern Tortugas Bank and western Dry Tor-tugas National Park, and also in medium-profile reef in the northwestern portion of the park (Fig. 4). It was lowest in low-relief hard bottom and patchy hard bottom in sand habitats.

The relatively stable community structure shown for richness was also reflected in domain-wide estimates of frequency of occurrence or sighting frequency. Although ranks changed slightly between years, only four of the top 50 species for the 2004 survey were not among the top 50 for the 1999–2000 surveys (Table 3). The top 50 included 12 (of 55 total) species from the exploited snapper-grouper complex.

Estimates of frequency of occurrence and abundance for representative species of principal families are given in Tables 4 and 5, respectively. We illustrate analyses of change between 1999–2000 and 2004 using black grouper (Mycteroperca bonaci) as an example. Domain-wide percentage occurrence for black grouper increased from 19.5% in 1999–2000 to 28.8% in 2004 (Table 4; P < 0.01), as did abundance, by 124% (Table 5A; P < 0.001). Detection of temporal change in abundance was facilitated by a decrease in the survey coefficient of variation (CV = SE/mean) from 14.5% to 10.3%. The increase in domain-wide abundance was accompanied by a shift in the length composition between 1999–2000 and 2004 toward a higher proportion of exploited-phase individuals (Fig. 5A; chi-square P < 0.001 for lengths >30 cm). Abundance estimates for black grouper increased in all three management zones but statistically so only in the reserve and the park (Table 5B). A spatial perspective on temporal changes in occurrence and density/abundance of black grouper is illustrated in the maps of Figure 6. In 2004, population size structure appeared to expand in the re-serve and park areas but was highly truncated above the minimum legal size in the


fished area. Changes in length compositions within management zones paralleled changes in abundance (Fig. 5B); proportion of exploited-phase individuals was high-er in the reserve (P < 0.05) and park (P < 0.001). No change in length composition was detected in the fished area.

Significant increases in domain-wide occurrence and abundance were also detect-ed for mutton snapper (Lutjanus analis), corresponding with significant increases in abundance in the reserve and the park. In general, trends in occurrence mirrored those for abundance for species with relatively small population sizes.

No change in either occurrence or abundance was detected for red grouper (Epi-nephelus morio) domain-wide, but we detected a significant decrease in abundance in the fished area and a significant increase in the reserve. We also noted increases in

Table 2. Reef-fish-survey sample sizes in terms of primary (n) and second-stage (nm) units by habitat class and management zone for (A) 1999, (B) 2000, and (C) 2004. Habitat codes are defined in Table 1; dashes denote habitats not found in a given management zone.

Habitat code Tortugas Bank Fished

Tortugas Bank NTMR

Dry Tortugas National Park

Domain-wide

n nm n nm n nm n nm(A) 1999LRHB 11 22 16 29 24 47 51 98LRSG — — — — 15 30 15 30PHBS 5 10 4 7 7 12 16 29MDPR — — — — 4 8 4 8RKOC 4 8 12 23 8 14 24 45RFTC 4 8 28 53 5 10 37 71HRSG — — — — 12 24 12 24RFPN — — 8 16 3 6 11 22Total 24 48 68 128 78 151 170 327

(B) 2000LRHB 10 20 17 31 34 64 61 115LRSG — — — — 5 9 5 9PHBS 10 20 11 20 25 45 46 85MDPR — — — — 9 17 9 17RKOC 2 4 11 17 28 52 41 73RFTC 0 0 17 31 7 12 24 43HRSG — — — — 12 22 12 22RFPN — — 5 10 4 7 9 17Total 22 44 61 109 124 228 207 381(C) 2004LRHB 22 41 9 18 81 146 112 205LRSG — — — — 14 26 14 26PHBS 11 19 2 4 24 44 37 67MDPR — — — — 23 39 23 39RKOC 10 19 27 54 24 45 61 118RFTC 5 9 16 32 17 33 38 74HRSG — — — — 4 8 4 8RFPN — — 9 18 7 14 16 32Total 48 88 63 126 194 355 305 569


the population proportion of larger (older) individuals for red grouper (Fig. 5A; chi-square P < 0.001 for lengths > 30 cm).

We detected a marginal decrease in domain-wide occurrence for yellowtail snap-per (Ocyurus chrysurus) but a domain-wide increase in abundance corresponding with a significant increase in the park. Evidently, more fish were seen at fewer sites, but the observed decline in percentage occurrence probably had little biological sig-nificance. As a result, abundance may be a better metric of population change. This disparity between occurrence and abundance was also observed for other school-ing species: gray snapper (Lutjanus griseus (Linnaeus, 1758)), hogfish (Lachnolaimus maximus), and white grunt (Haemulon plumieri).

Domain-wide occurrences of goliath grouper, Epinephelus itajara (Lichtenstein, 1822), and Nassau grouper, Epinephelus striatus (Bloch, 1792), two species under fishing moratoria, remained low over the survey period. We observed goliath grou-per in one primary sampling unit in 1999, two units in 2000, and 10 units in 2004 (seven in the park and three in the reserve), a pattern perhaps encouraging for its recovery but not a statistically significant change in frequency of occurrence.

Among unexploited species, domain-wide increases in both occurrence and abun-dance were detected for spotted goatfish (Pseudupeneus maculates), purple reeffish (Chromis scotti), and striped parrotfish (Scarus iseri). On the other hand, we detected increases in domain-wide occurrence but no changes in abundance for foureye but-terflyfish (Chaetodon capistratus) and redband parrotfish (Sparisoma aurofrenatum). For blue tang (Acanthurus coeruleus), bicolor damselfish (Stegastes partitus), and stoplight parrotfish (Sparisoma viride), no changes were detected in domain-wide

Figure 4. Spatial distribution of snapper-grouper species richness for the 2004 Tortugas survey in relation to benthic habitat types (Fig. 2).


Tabl

e 3.

Cha

nges

in

rank

per

cent

age

occu

rren

ce b

etw

een

1999

–200

0 an

d 20

04 f

or t

he t

op 5

0 re

ef-fi

sh s

peci

es.

Com

mon

nam

es m

arke

d w

ith a

ster

isks

den

ote

spec

ies

in th

e ex

ploi

ted

snap

per-

grou

per

com

plex

.

Occ

urre

nce

rank

Com

mon

nam

eSc

ient

ific

nam

eFa

mily

2004

1999

–200

0C

hang

eB

lueh

ead

Tha

lass

oma

bifa

scia

tum

(B

loch

, 179

1)L

abri

dae

11

=St

ripe

d pa

rrot

fish

Scar

us is

eri (

Blo

ch, 1

791)

Scar

idae

22

=C

ocoa

dam

selfi

shSt

egas

tes

vari

abil

is (

Cas

teln

au, 1

855)

Pom

acen

trid

ae3

3=

Red

band

par

rotfi

shSp

aris

oma

auro

fren

atum

(V

alen

cien

nes,

184

0)Sc

arid

ae4

5+

Yel

low

head

wra

sse

Hal

icho

eres

gar

noti

(V

alen

cien

nes,

183

9)L

abri

dae

510

+B

lue

tang

Aca

nthu

rus

coer

uleu

s B

loch

& S

chne

ider

, 180

1A

cant

huri

dae

68

+B

icol

or d

amse

lfish

Steg

aste

s pa

rtit

us (

Poey

, 186

8)Po

mac

entr

idae

711

+Sp

otte

d go

atfis

hP

seud

upen

eus

mac

ulat

us (

Blo

ch, 1

793)

Mul

lidae

820

+W

hite

gru

nt*

Hae

mul

on p

lum

ieri

(L

acep

ède,

180

1)H

aem

ulid

ae9

4-

Slip

pery

dic

kH

alic

hoer

es b

ivit

tatu

s (B

loch

, 179

1)L

abri

dae

107

-Y

ello

wta

il sn

appe

r*O

cyur

us c

hrys

urus

(B

loch

, 179

1)L

utja

nida

e11

9-

Sauc

erey

e po

rgy*

Cal

amus

cal

amus

(V

alen

cien

nes,

183

0)Sp

arid

ae12

6-

Stop

light

par

rotfi

shSp

aris

oma

viri

de (

Bon

nate

rre,

178

8)Sc

arid

ae13

15+

Bri

dled

gob

yC

oryp

hopt

erus

gla

ucof

raen

um G

ill, 1

863

Gob

iidae

1412

-R

ed g

roup

er*

Epi

neph

elus

mor

io (

Val

enci

enne

s, 1

828)

Serr

anid

ae15

13-

Purp

le r

eeffi

shC

hrom

is s

cott

i Em

ery,

196

8Po

mac

entr

idae

1628

+O

cean

sur

geon

Aca

nthu

rus

bahi

anus

Cas

teln

au, 1

855

Aca

nthu

rida

e17

18+

Blu

e an

gelfi

shH

olac

anth

us b

erm

uden

sis

Goo

de, 1

876

Pom

acan

thid

ae18

16-

Spot

fin b

utte

rflyfi

shC

haet

odon

oce

llat

us B

loch

, 178

7C

haet

odon

tidae

1917

-B

utte

r ha

mle

tH

ypop

lect

rus

unic

olor

(W

alba

um, 1

792)

Serr

anid

ae20

29-

Gre

enbl

otch

par

rotfi

shSp

aris

oma

atom

ariu

m (

Poey

, 186

1)Sc

arid

ae21

24+

Mas

ked

goby

Cor

ypho

pter

us p

erso

natu

s (J

orda

n &

Tho

mps

on, 1

905

Gob

iidae

2225

+B

lue

ham

let

Hyp

ople

ctru

s ge

mm

a G

oode

& B

ean,

188

2Se

rran

idae

2338

+Y

ello

whe

ad ja

wfis

hO

pist

ogna

thus

aur

ifro

ns (

Jord

an &

Tho

mps

on, 1

905)

Opi

stog

nath

idae

2421

-G

ray

ange

lfish

Pom

acan

thus

arc

uatu

s (L

inna

eus,

175

8)Po

mac

anth

idae

2523

-


Tabl

e 3.

Con

tinue

d.

Occ

urre

nce

rank

Com

mon

nam

eSc

ient

ific

nam

eFa

mily

2004

1999

–200

0C

hang

eH

ogfis

h*L

achn

olai

mus

max

imus

(W

alba

um, 1

792)

Lab

rida

e26

19-

Four

eye

butte

rflyfi

shC

haet

odon

cap

istr

atus

Lin

naeu

s, 1

758

Cha

etod

ontid

ae27

32+

Clo

wn

wra

sse

Hal

icho

eres

mac

ulip

inna

(M

ülle

r &

Tro

sche

l, 18

48)

Lab

rida

e28

26-

Thr

eesp

ot d

amse

lfish

Steg

aste

s pl

anif

rons

(C

uvie

r, 18

30)

Pom

acen

trid

ae29

30+

Bea

ugre

gory

Steg

aste

s le

ucos

tict

us (

Mül

ler

& T

rosc

hel,

1848

)Po

mac

entr

idae

3034

+H

arle

quin

bas

sSe

rran

us ti

grin

us (

Blo

ch, 1

790)

Serr

anid

ae31

27-

Sadd

led

blen

nyM

alac

octe

nus

tria

ngul

atus

Spr

inge

r, 19

59L

abri

som

idae

3214

-B

arre

d ha

mle

tH

ypop

lect

rus

puel

la (

Cuv

ier,

1828

)Se

rran

idae

3331

-N

eon

goby

Ela

cati

nus

ocea

nops

Jor

dan,

190

4G

obiid

ae34

22-

Gra

ysby

*C

epha

loph

olis

cru

enta

ta (

Lac

epèd

e, 1

802)

Serr

anid

ae35

37+

Bla

ck g

roup

er*

Myc

tero

perc

a bo

naci

(Po

ey, 1

860)

Serr

anid

ae36

44+

Blu

e ch

rom

isC

hrom

is c

yane

a (P

oey,

186

0)Po

mac

entr

idae

3745

+M

utto

n sn

appe

r*L

utja

nus

anal

is (

Cuv

ier,

1828

)L

utja

nida

e38

52+

Toba

ccofi

shSe

rran

us ta

baca

rius

(C

uvie

r, 18

29)

Serr

anid

ae39

46+

Bar

jack

*C

aran

x ru

ber

(Blo

ch, 1

793)

Car

angi

dae

4040

=Q

ueen

ang

elfis

hH

olac

anth

us c

ilia

ris

(Lin

naeu

s, 1

758)

Pom

acan

thid

ae41

43+

Gre

at b

arra

cuda

*Sp

hyra

ena

barr

acud

a (E

dwar

ds, 1

771)

Sphy

raen

idae

4249

+Sh

arpn

ose

puff

erC

anth

igas

ter

rost

rata

(B

loch

, 178

6)Te

trao

dont

idae

4339

-Sp

anis

h ho

gfish

Bod

ianu

s ru

fus

(Lin

naeu

s, 1

758)

Lab

rida

e44

47+

Tom

tate

*H

aem

ulon

aur

olin

eatu

m C

uvie

r, 18

30H

aem

ulid

ae45

41-

Prin

cess

par

rotfi

shSc

arus

taen

iopt

erus

Des

mar

est,

1831

Scar

idae

4661

+R

eef

butte

rflyfi

shC

haet

odon

sed

enta

rius

Poe

y, 1

860

Cha

etod

ontid

ae47

36-

Fren

ch g

runt

*H

aem

ulon

flav

olin

eatu

m (

Des

mar

est,

1823

)H

aem

ulid

ae48

50+

Cer

oSc

ombe

rom

orus

reg

alis

(B

loch

, 179

3)Sc

ombr

idae

4911

7+

Buc

ktoo

th p

arro

tfish

Spar

isom

a ra

dian

s (V

alen

cien

nes,

184

0)Sc

arid

ae50

101

+


occurrence, but we detected increases in domain-wide abundance. Domain-wide in-creases in spotted goatfish corresponded to significant increases in abundance in all three management zones. Domain-wide increases in abundance of blue tang, purple reeffish, and stoplight parrotfish corresponded to increased abundances in the park. Increases in domain-wide abundance of bicolor damselfish and striped parrotfish were accompanied by significant abundance increases in the reserve. In several cas-es, management zone changes in abundance were detected that did not correspond to domain-wide changes.

Table 4. Domain-wide estimates of percentage occurrence for representative exploited and nontarget fish species for baseline years 1999–2000 and the 2004 survey. Levels of statistically significant difference between baseline years and 2004: NS, not significant; *, P < 0.05; **, P < 0.01; ***, P < 0.001.

% Occurrence (SE)Taxon 1999–2000 2004 ChangeSnapper-Grouper complexGroupers (Serranidae) Goliath grouper (Epinephelus itajara) 0.5 (0.4) 1.3 (0.5) NS Red grouper 67.0 (3.3) 62.8 (3.1) NS Nassau grouper (E. striatus) 1.0 (0.6) 0.3 (0.2) NS Black grouper 19.5 (2.5) 28.8 (2.4) **Snappers (Lutjanidae) Mutton snapper 14.8 (2.4) 25.8 (3.0) *** Gray snapper (Lutjanus griseus) 17.3 (2.5) 12.2 (1.5) * Yellowtail snapper 74.7 (3.2) 68.1 (3.1) *Wrasses (Labridae) Hogfish 52.8 (3.5) 42.6 (3.0) **Grunts (Haemulidae) White grunt 82.0 (2.7) 71.5 (2.7) ***Bluestriped grunt (Haemulon sciurus (Shaw, 1803)) 6.4 (1.7) 7.7 (1.2) NSNontarget fishesSurgeonfishes (Acanthuridae) Ocean surgeon 54.9 (3.3) 60.3 (2.7) NS Blue tang 76.4 (3.1) 80.9 (2.2) NSButterflyfishes (Chaetodontidae) Foureye butterflyfish 34.0 (3.3) 42.3 (2.8) * Spotfin butterflyfish 56.4 (3.4) 49.9 (3.0) NSGoatfishes (Mullidae) Spotted goatfish 50.7 (3.6) 71.7 (2.2) ***Angelfishes (Pomacanthidae) Blue angelfish 57.9 (3.2) 55.9 (2.7) NS Gray angelfish 45.5 (3.3) 43.9 (2.8) NSDamselfishes (Pomacentridae) Purple reeffish 37.2 (3.4) 62.2 (3.1) *** Bicolor damselfish 72.7 (2.9) 72.6 (2.3) NS Cocoa damselfish 87.7 (2.3) 90.0 (2.0) NSParrotfishes (Scaridae) Striped parrotfish 88.4 (2.4) 94.3 (1.3) * Redband parrotfish 80.8 (2.9) 86.9 (1.9) * Stoplight parrotfish 59.3 (3.5) 64.5 (3.3) NS


Tabl

e 5.

(A

) D

omai

n-w

ide

estim

ates

of

abun

danc

e (a

nd a

ssoc

iate

d co

effic

ient

of

vari

atio

n C

V)

and

chan

ges

betw

een

base

line

year

s 19

99–2

000

and

2004

for

re

pres

enta

tive

expl

oite

d an

d no

ntar

get

fish

spec

ies.

(B

) Po

pula

tion

abun

danc

e ch

ange

s be

twee

n 19

99–2

000

and

2004

with

in m

anag

emen

t zo

nes

in t

he D

ry

Tort

ugas

reg

ion.

Lev

els

of s

tatis

tical

ly s

igni

fican

t dif

fere

nce

betw

een

base

line

year

s an

d 20

04; N

S, n

ot s

igni

fican

t, *

P <

0.05

; **

P <

0.01

; ***

P <

0.0

01.

(A)

1999

–200

020

04Ta

xon

Abu

ndan

ce

(mill

ions

)C

V (

%)

Abu

ndan

ce

(mill

ions

)C

V (

%)

Cha

nge

(B)

Tort

ugas

Ban

k fis

hed

Tort

ugas

Ban

k N

TM

RD

ry T

ortu

gas

Nat

iona

l Par

kSn

appe

r-gr

oupe

r co

mpl

exR

ed g

roup

er

1.26

06.

81.

237

6.5

−2%

NS

−43%

*+3

8%*

−9%

NS

Bla

ck g

roup

er

0.27

714

.50.

622

10.3

+124

%**

*+8

4%N

S+1

20%

*+1

28%

***

Mut

ton

snap

per

0.21

621

.20.

452

13.2

+109

%**

*−4

5%N

S+3

03%

**+1

42%

***

Gra

y sn

appe

r 3.

714

54.3

5.15

574

.0+3

9%N

S−9

6%N

S−5

1%N

S+2

70%

NS

Yel

low

tail

snap

per

8.25

713

.023

.169

27.2

+181

%*

−19%

NS

+367

%N

S+1

32%

***

Hog

fish

1.12

110

.70.

910

12.0

−19%

NS

−27%

NS

+6%

NS

−25%

NS

Whi

te g

runt

9.

317

15.5

9.64

421

.6+4

%N

S+7

%N

S+2

4%N

S+2

%N

SB

lues

trip

ed g

runt

0.

330

47.0

0.85

442

.0+1

59%

NS

+50%

NS

+13%

NS

+242

%N

SN

onta

rget

fish

esO

cean

sur

geon

2.

045

13.3

2.27

58.

0+1

1%N

S+2

%N

S+7

5%**

−9%

NS

Blu

e ta

ng

3.47

49.

75.

747

7.8

+65%

***

+13%

NS

+28%

NS

+99%

***

Four

eye

butte

rflyfi

sh

0.96

010

.81.

083

7.5

+13%

NS

+86%

*−1

8%N

S+3

2%N

SSp

otfin

but

terfl

yfish

1.31

57.

51.

256

6.8

−5%

NS

+35%

NS

−31%

*0%

NS

Spot

ted

goat

fish

1.07

610

.73.

204

9.8

+198

%**

*+1

33%

**+3

26%

***

+175

%**

*B

lue

ange

lfish

1.

555

8.0

1.52

56.

8−2

%N

S−1

8%N

S−2

0%N

S+3

1%*

Gra

y an

gelfi

sh

0.86

89.

21.

588

27.2

+83%

NS

−24%

NS

+58%

NS

+120

%N

SPu

rple

ree

ffish

11

.518

17.8

20.2

1913

.0+7

6%**

*+3

1%N

S+4

2%N

S+2

63%

***

Bic

olor

dam

selfi

sh

12.9

1410

.417

.269

7.8

+34%

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An occurrence in the 2004 survey, unexpected on the basis of our previous cruises, was the sighting of large (> 2000 fish) schools of large (> 9 kg) permit (Trachinotus falcatus) at eight primary-sampling-unit locations. The timing and schooling behav-ior of these mature permit suggests that these may have been spawning aggregations. Seven of the eight schools were sighted on Tortugas Bank, either inside or just out-side the reserve.

Discussion

The Tortugas region represents a de facto adaptive management experiment in which three discrete, contiguous areas are being managed under different levels of resource protection. Determining the efficacy of the suite of management approach-es is one of Florida’s most critical resource-management problems and a unique chal-lenge for science-based resource management.

Figure 5. (A) Domain-wide comparisons of length compositions for black grouper (left panels) and red grouper (right panel) between 1999–2000 (top) and 2004 (bottom) surveys. (B) Com-parison of the three spatial zones for black grouper for 2004. Open bars are preexploited-phase; shaded bars are exploited-phase animals. Number of length observations is given on each panel.

A

B


Figure 6. Spatial distribution of black-grouper density (mean number per primary sample unit) for Tortugas surveys conducted in (A) 2000 and (B) 2004.

A

B


A number of authors have pointed out that detection of changes in population abundance and biomass in response to any fishery management action has often suffered from lack of rigor in the design of both fishery-dependent and fishery-inde-pendent surveys (e.g., Hurlbert, 1984; Stewart-Oaten et al., 1986; Underwood, 1990, 1993; Willis et al., 2003; Hilborn et al., 2004a; Sale et al., 2005). Relative to tradi-tional fishery-dependent approaches, quantitative assessments of NTMRs present their own unique challenges because no catches from closed areas are available for examination and data must be spatially explicit. In addition, data must be collected that reflect community dynamics, not just exploited-species dynamics, for evalua-tion of the performance of ecosystem-based management. These principles were the impetus for our survey-sampling approach in the Tortugas region.

The fisheries-independent RVC surveys provided fairly precise estimates of species richness and frequency of occurrence. However, while also a precise measure, abun-dance was more indicative of population change because it tracked population vari-ability at both low and high population sizes. In general, our population detection limits for changes in abundance ranged between 15% and 30%; i.e., twice the mea-sured CV. In some cases precise estimates of abundance were difficult to obtain. For example, low sighting frequency coupled with relatively high abundance at few sites yielded high CVs for gray snapper. Overall, we found our CI t-tests to be a conserva-tive application of statistical methods because they required detection of differences in mean abundance with respect to each time period. The method became less robust as the size of the spatial unit (e.g., management zone, habitat type) decreased.

Principles of probability and statistics and of sampling theory (e.g., Cochran, 1977; Levy and Lemeshow, 1999; Johnson and Wichern, 2002) were used to promote sur-vey efficiency and precision of estimates in a cost-effective way for the Tortugas reef-fish sampling operations. Our habitat-based stratification was effective because it capitalized on the statistical covariance between fish abundance and coral-reef habi-tat types determined from previous surveys (Ault et al., 2002, Franklin et al., 2003). In addition, a number of logistical factors enabled divers to obtain high sample size over substantial areas quickly and at relatively low costs: (1) use of a large, live-aboard dive vessel equipped with Nitrox SCUBA; (2) “live-boating” at dive sites where the vessel never anchored but deployed divers at specified coordinates and picked up the free-swimming groups after samples are taken; (3) use of highly trained professional divemasters to oversee the complex dive operations; and (4) conducting the annual surveys within 2–3 wks during periods (May–June) of minimum winds.

The impacts of management actions on population biomass could take years to oc-cur and be detected (e.g., Beverton and Holt, 1957), but we observed signs of recovery in the Tortugas reef fish community over a relatively short time after implementation of NTMRs. We have shown that metrics of the reef fish community (e.g., richness and species composition) were very stable over the study time period, but of a rep-resentative suite of 21 reef fishes, we detected increases in domain-wide abundance for three exploited species (black grouper, mutton snapper, yellowtail snapper) and six nontarget species (blue tang, spotted goatfish, purple reeffish, bicolor damselfish, striped parrotfish, and stoplight parrotfish). No decreases in domain-wide abun-dance were detected for any of the species analyzed.

Where abundance changes occurred, the observed contrasts between exploited and nontarget species suggest that spatial protection may have been an important contributing factor in region-wide changes. We detected abundance increases for


nontarget species in all three management zones, but only one species, the spotfin butterflyfish (Chaetodon ocellatus) decreased, and that occurred in the reserve. For exploited species, significant abundance increases were confined to the reserve and the park, whereas the only significant abundance decrease occurred in the fished area. Moreover, we detected significant shifts in length compositions toward larger individuals for black grouper and red grouper. In addition, in the fished area, black grouper size-frequency distributions showed continued truncation of fish above the legal minimum size limit, consistent with continued fishing pressure. Similar re-sponses to spatial protection have been observed in the region for heavily exploited spiny lobster and mutton snapper (Davis and Dodrill, 1980; Burton et al., 2005; Cox and Hunt, 2005).

Our results also suggest, however, that the population increases observed in the reserve and park could have been augmented by co-occurring regional fishery man-agement actions or favorable environmental conditions. Increases in abundance of larger individuals would also be expected in response to traditional management measures such as bag and size limits. For example, minimum size limits for black grouper have been increased from 18 in (45.7 cm) in 1985 to 20 in (50.8 cm) in 1990 and to 22 in (55.9 cm) for recreational fishers and 24 in (61.0 cm) for commercial fish-ers in 1999. The last regulation brought the minimum size up to the minimum size of sexual maturity (Ault et al., 2005b). Generally, abundance changes in nontarget species would not be expected to occur in direct response to fishery management policy. Increases in nontarget species abundance suggest that the environment plays an important role and may have contributed to good recruitment events in recent years. Random variability in year-class strengths or the passing of several hurricanes in the late-1990s may also have influenced recruitment for both exploited and non-target reef fishes. In reality, many of the factors probably interact.

Similar observations of recovery of fish populations, but usually over longer time frames, have been made in other coral-reef ecosystems (cf. Halpern and Warner, 2002; Russ et al., 2004; Alcala et al., 2005). According to population-dynamics the-ory, not enough time has elapsed since implementation of the Tortugas NTMR to explain our findings fully, so not all the observed changes are likely to reflect a direct response to NTMR implementation. Furthermore, potential impacts on reef-fish community dynamics are complex and may be influenced by shifts in composition, trophic cascades promulgated by predator-prey responses, and habitat competition. Our next research challenge will be to develop and refine methods for improved understanding of the relative contributions of NTMRs, various fishery-management actions, community interactions, and environmental factors with the goal of build-ing sustainable fisheries.

As this rebuilding process proceeds and reef ecosystems respond to management actions over the next several decades, a continued concern will be balancing fish-ing with resource protection. A particular concern is the likely continued growth in demand from the recreational fleet and in its fishing power as a result of technologi-cal improvements. Although failure to control fishing mortality adequately can have potentially detrimental consequences for the stocks and the economy (Steele and Hoagland, 2003), removal of units of fishing effort once they have been established will be difficult, because of the “ratchet” effect (Ludwig et al., 1993). In the long run, a precautionary ecosystem-based approach to management using multiple control methods offers promise for providing fishery sustainability and persistence of the


Florida Keys coral-reef ecosystem. As noted by Stefansson and Rosenberg (2005), combining catch controls with large closed areas may be the most effective system of reducing risk of stock collapse while maintaining short- and long-term economic performance and buffering uncertainty.

Acknowledgments

We sincerely appreciate the expert mission support services provided by Captains F. and M. Wasson and the crew of the M/V Spree and by L. Horn, G. Taylor, M. Birns, and J. Styron of the National Undersea Research Center. We also thank the 34 participating diving scientists from nine university, state, and federal entities for their professionalism and enthusiasm in meeting the rigorous demands of this challenging endeavor. Other contributions to the sci-entific and technical efforts were made by T. Schmidt, W. B. Perry, R. Howard, R. Johnson, B. Culhane, and R. Zepp of Everglades/Dry Tortugas National Park; B. D. Keller, B. D. Causey, and C. Heck of the Florida Keys National Marine Sanctuary; A. Chester, W. J. Richards, and R. Brock of NOAA Fisheries; and R. Mann, A. Reisewitz, and I. Kupec of the University of Miami. Funding was provided by the NOAA Fisheries Coral Reef Program (Grant #NA17RJ1226), the National Park Service Cooperative Ecosystems Study Unit (Contract No. H500000B494-J5120020275), the Florida Keys National Marine Sanctuary (R0500010), the NOAA General Coral Reef Conservation Program (Grant #NA05NMF4631044), the Florida Sea Grant Col-lege Program (Grant #R/C-E-50), the NOAA National Undersea Research Center, the NOAA Biogeography Program (Cooperative Agreement Grant #NA17RJ1226), and the Florida Fish and Wildlife Conservation Commission.

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Fishery-Independent Monitoring of Coral Reef Fishes, Coral Reefs, and Macro-invertebrates in the Dry Tortugas 1.0 INTRODUCTION: BACKGROUND AND RATIONALE

The Dry Tortugas are located about 70 miles west of Key West at the southwestern end

of the west Florida shelf (Figure 1.1). The Tortugas region is a unique tropical marine

environment of national significance, renown for its luxuriant and productive coral reef

ecosystem, diverse natural resources, broad recreational fishing opportunities, and spectacular

scenic beauty (Schmidt et al. 1999; Culhane 2002; Ault et al. 2002; Brock and Culhane 2004).

The Tortugas region supports multibillion dollar fishing and tourism industries in southern

Florida, including economically-important fisheries for pink shrimp, spiny lobster, reef fish

(snapper-groupers), kingfish and Spanish mackerel.

In the Florida Keys, increased fishing pressure from rapid regional human population

growth and environmental changes associated with coastal development have raised concerns

about fisheries sustainability and persistence of the coral reef ecosystem (Porter and Porter 2001;

Ault et al. 2005a; Pandolfi et al. 2005). Historically intense commercial and rising recreational

fishing pressures have resulted in unsustainable rates of exploitation for seventy percent of

the“snapper-grouper complex” (Ault et al. 1998, 2005b), which consists of over 50 species of

mostly groupers and snappers, but also grunts, jacks, porgies, and hogfish. Over the last 40

years, the number of registered recreational vessels in southern Florida has grown by more than

500%. Sport fishing effort is expected to continue to grow in proportion to regional human

populations which have doubled about every 20 years (Ault et al. 2005a). At present, the

recreational fleet accounts for a substantial proportion of the total regional catches for some key

exploited species (NOAA MRFSS Database; Florida FWC Trip Ticket Database; Coleman et al.

2004), and this trend will likely continue to increase.

Reef fisheries in the Florida Keys ecosystem are complex and regulated by several

entities including the Florida Fish and Wildlife Conservation Commission (FWC,

www.myfwc.com ), the National Park Service (NPS, DOI, www.nps.gov/drto), and the National

Marine Fisheries Service in conjunction with the South Atlantic Fishery Management Council

(SAFMC; NOAA, www.safmc.org) and the Gulf of Mexico Fishery Management Council

(GMFMC, NOAA, www.gulfcouncil.org). In response to declining trends in reef fishery

catches, a series of regional federal and state management regulations were imposed including


recreational bag limits, minimum size limits, commercial quotas and trip limits, seasonal

closures, gear restrictions, limited commercial entry, closed fisheries, species moratoria, game

fish status, and restrictions on sale and possession. These regulations were implemented to

stabilize catches, protect spawning stock biomass, and reduce fishing mortality rates. In general,

the history of regional regulations for reef fishes has been complex, and tended to be more

restrictive over time. Nonetheless, despite the bevy of regulations imposed in the Florida Keys,

recent fishery assessments indicate that, for example, black grouper spawning stock biomass was

less than 10% of its historical size (Ault et al. 2005b).

In recent years, new ecosystem-based management measures have been enacted in the

Florida Keys, including the 1997 implementation of a network of 23 NTMRs by the Florida

Keys National Marine Sanctuary (FKNMS, NOAA, www.fknms.noaa.gov). These are relatively

small (mean 2 km2, range 0.16-31 km2), comprising 46 km2 in total area (Department of

Commerce 1996) and have varying levels of protection: four allow catch-and-release surface

trolling and four can only be accessed by special permit. In July 2001, the Florida Keys network

was expanded with the implementation of two NTMRs in the Dry Tortugas region covering

about 566 km2. The Tortugas region is believed to be extremely important for coral reefs and

fisheries as a source of recruitment because of its upstream location in the Florida Current that

facilitates advective dispersion and transport of eggs and larvae to the rest of the Keys (Lee and

Williams 1999; Dahlgren and Sobel 2000; Lindeman et al. 2000; Ault et al. 2002; Yeung and

Lee 2002; Domeier 2004).

Following implementation of conventional management measures or implementation of

spatial controls like NTMRs, rebuilding of reef fish population biomass and age-structures of the

depleted resources is expected. In the longer-run, unrestricted growth of biomass within reserves

should result in resource export through reserve boundaries to surrounding areas as either larval

dispersal to proximal natal sites as well as the diffusive movements of fishable biomass

(Bohnsack 1998; Roberts et al. 2001; Pauly et al. 2002; Russ 2002; Zeller and Russ 2004;

Bohnsack et al. 2004). The rate at which these impacts on individual reef fish population’s

biomass will occur and could be detected depends greatly on the species’ life history,

demographic characteristics, and survey precision. Given that snapper and grouper life spans are

often measured in decades, the effects of management actions could take 20 years or more to

reach their full potential (e.g., Beverton and Holt 1957).


Using a sampling design-based approach we conducted a series of synoptic research

cruises with over 4,000 research dives to survey reef fish populations and habitats in the Dry

Tortugas before and three years after the NTMRs were implemented (Ault et al. 2006). We

recorded the presence, abundance and size of 267 fish species from eight reef habitats in three

management areas offering different levels of resource protection: the Tortugas North Ecological

Reserve (a NTMR), Dry Tortugas National Park (recreational angling only), and southern

Tortugas Bank (open to all fishing under regional regulations). Species richness and

composition remained stable between 1999-2000 and 2004 within the overall survey domain.

Greatest reef fish biodiversity was found in the more rugose habitats. We detected significant

domain-wide increases in abundance for several exploited and non-exploited species, while no

declines were detected. In the Tortugas Bank NTMR, we found significantly greater abundances

and shifts in length composition structures towards a higher proportion of exploited phase

animals in 2004 compared to 1999-2000 for some species (e.g., black grouper and red grouper).

Consistent with predictions from marine reserve theory, we did not detect any declines for

exploited species in the NTMR, while for non-target species we detected both increases and

declines in population abundance in the NTMR for non-target species. The observed upsurge in

exploited populations, however, may have also been influenced by other factors including past or

recent fishery management actions that increased minimum sizes or reduced fishing mortality

rates; the passage of recent hurricanes; and, the occurrence of good recruitment year classes.

Although still early in the recovery process, our results after three years of protection were

encouraging and suggest that NTMRs, in conjunction with traditional management, can

potentially help build sustainable fisheries while protecting the Florida Keys coral reef

ecosystem.

The goals of the 2006 Tortugas research expedition were:

• To conduct a quantitative visual census assessment of coral reef fishery and

habitat resources in the Tortugas region five years after implementation of the

Tortugas Ecological Reserve (TER).

• To sample all fish species and sizes in all representative coral reef habitats both

inside and outside reserve areas.

• To monitor trends in coral reef fish populations and the effectiveness of current

management practices.


A potentially confounding factor in understanding the efficacy of management actions in the

Tortugas region was the sharp increase in hurricane activity in the intervening time period

between the 2004 and 2006 surveys. As illustrated in Figure 1.2, one hurricane (Charley) and

one tropical storm (Ivan) passed through the Dry Tortugas region in August-September 2004,

and four hurricanes (Dennis, Katrina, Rita, and Wilma) impacted the region in July-October

2005. This report documents the scientific activities of the 2006 research expedition in the

Tortugas region and presents preliminary findings on changes in the reef fish community five

years after implementation of NTMRs.

1.1 MATERIALS AND METHODS

1.1.1 Study Area

The Florida Keys coral reef ecosystem extends 380 km from Miami to the Dry Tortugas

(Figure 1.1). The Tortugas study area is located about 113 km west of Key West, and

encompasses approximately 1686 km2 in two principal areas: Dry Tortugas National Park

(managed by Department of the Interior, DOI); and, Tortugas Bank (NOAA, FKNMS,

Department of Commerce, DOC) (Figure 1.3).

1.1.2 Survey Design and Operations

We employed a stratified random diver visual survey to obtain fishery-independent data

on the spatial distribution, abundance, size composition, and habitats of coral reef fishes in the

Tortugas region (Bohnsack and Bannerot, 1986; Ault et al., 1998, 2002; Bohnsack et al., 1999).

The principal survey domain encompassed coral reef habitats less than 33 m deep in Tortugas

Bank and Dry Tortugas National Park (Figure 1.3). The domain was extended to depths of 42 m

along the western edge of Tortugas Bank by a technical dive team equipped with tri-mix. The

sampling domain was partitioned into habitat strata based on the degree of vertical relief (e.g.,

rugosity, complexity) and the degree of patchiness (e.g., amount of softbottom substrate

interspersed among reef structures) of the hardbottom substrate (Franklin et al. 2003; Ault et al.

2006). This habitat-based stratification procedure was developed from the 1999 and 2000

baseline surveys, and was shown to be effective in partitioning the domain into areas of high,

moderate, and low levels of mean fish density and associated variance for many principal reef

species (Ault et al. 2002), thereby improving sampling efficiency and cost-effectiveness (Smith

and Ault 1993; Ault et al. 1999, 2003). Management zones were incorporated as a second

spatial stratification variable, designated as follows: Tortugas Bank NTMR -- closed to all types


of fishing; Tortugas Bank Fished -- open to all types of commercial and recreational fishing

under regional regulations; and, Dry Tortugas National Park -- open to only recreational hook-

and-line fishing (Figure 1.3). In the Tortugas region, areas open to fishing such as Tortugas

Bank Fished, allow a variety of types of legal fishing activities under regional management and

represent the lowest level of resource protection in the study area. Dry Tortugas National Park

represents an intermediate level of resource protection by allowing only recreational angling.

Commercial fishing has been prohibited since 1935 when it was established as a National

Monument. Recreational lobster diving was prohibited in 1980. After conversion to Dry

Tortugas National Park in 1992, protection increased with exclusion of headboats for

recreational fishing in 1995. The Tortugas Bank NTMR, a no-take and no anchoring reserve,

represents the highest level of resource protection. Prior to 1 July 2001, Tortugas Bank was open

to fishing under GMFMC and Florida FWC regulations. We used a geographical information

system (GIS) and digital spatial databases of benthic habitats, bathymetry, and management zone

boundaries to facilitate spatial delineation of the survey domain, sampling strata, and sample

units. The Tortugas sampling domain was overlain in a GIS with a grid of 200 by 200 m cells

that represented the minimum mapping units for benthic habitat types (Figure 1.4).

A two-stage stratified-random sampling design was employed in which the primary

sample unit was the 200 by 200 m habitat grid cell and the second-stage unit was a 15 m

diameter visual census circular plot (described below) (Figure 1.4). Stratum (h) sizes in terms of

area (Ah) consisting of Nh possible primary sampling units are given in Table 1.1. These values

were updated from the 2004 survey with the incorporation of new, high-resolution bathymetry

data for portions of the Tortugas region graciously provided by NOAA NOS, US Geological

Survey, and the National Park Service. Allocation of the number of primary units to be sampled

among strata was based on stratum area and variance of fish density for a representative suite of

species (i.e., a Neyman allocation scheme; Cochran, 1977). Within a stratum, specific primary

units to be sampled were randomly selected a priori with equal probability from the complete list

of Nh units using a discrete uniform distribution (Law and Kelton, 2000). To ensure replication,

two pairs of second-stage sample units (i.e., diver visual census plots) were randomly positioned

within each selected primary unit. Because of diving safety concerns and statistical concerns

about sample autocorrelation, in our computations each second-stage unit estimate consisted of

the arithmetic average of stationary plots from two individual divers (i.e., a “buddy pair”). Thus,


each primary sample unit location in Figure 1.3 denotes where at least four scientific divers were

deployed to conduct visual census samples (i.e., one pair of divers at each of two second-stage

locations within a primary sampling unit).

Highly trained and experienced divers collected biological data using Nitrox or Trimix

SCUBA and the reef fish visual census (RVC) protocol, a standard, non-destructive, in situ

visual monitoring method. In the RVC protocol, a stationary diver collects reef fish data while

centered in a randomly selected 15 m diameter circular plot (Bohnsack and Bannerot, 1986;

Bohnsack et al., 1999; Ault et al., 2002). First, all fish species observed within 7.5 m in an

imaginary cylinder extending from the bottom to the limits of vertical visibility (usually the

surface) are listed for 5 minutes. After the initial 5 min listing, data are then collected on the

abundance, and minimum, mean, and maximum lengths for each species sighted. A ruler

connected perpendicularly to the end of a meter stick is used as a reference to reduce apparent

magnification errors in fish size estimates. For each plot, depth, bottom substrate composition,

estimated benthic percentage cover, and vertical relief characteristics of the seafloor were

recorded from the polar perspective of the centrally located observer. Digital photographs were

taken at each station to assist with habitat classification and identification of uncommon fish

species. The time required to record each sample averaged 15 to 20 min, depending on the

habitat.

The synoptic 2006 survey was conducted over a three-week period from June 5 to June

26, with 20 days of onsite sampling, using a 30 m live-aboard dive vessel equipped with 4

compressor banks of Nitrox (M/V Spree, Gulf Diving, Houston, TX) and additional tanks of

helium for making Trimix. The onboard scientific crew, consisting of 24 persons on any given

sampling day, was comprised of a fish census team, a benthic habitat team, and a spiny lobster

Panilurus argus team, as well as two full-time divemasters to oversee the complex diving

operations. Visual survey data were entered onboard into a digital database using a laptop-based

data entry system that includes extensive error-checking and validation protocols. Although our

primary objective was reef fish visual assessment, data were obtained to study possible

synergistic effects of fish density, lobster density, habitat, and prey availability by conducting

habitat and lobster assessments in conjunction with visual fish censuses. These data will assist

development of statistical models to link fish, habitat, and food resources from a broad

ecological perspective.


1.1.3 Statistical Analysis

Our statistical analyses focused on changes between baseline years 1999 and 2000

(before) and 2006 (after), with comparison to changes between baseline and 2004 reported by

Ault et al. (2006). Statistical analysis of change was evaluated using a community metric,

species richness, and two population metrics: frequency of occurrence and abundance. Statistical

estimation procedures followed Cochran (1977) for a two-stage stratified random sampling

design. In these procedures, strata means and variances of a given metric are weighted by strata

sizes, i.e., ∑=h

hhh NNW / , to obtain overall means and variances for either specific

management zones, or for the entire Tortugas domain. Species richness was estimated on a

primary sample unit basis (i.e., the number of unique species observed within a primary unit by

the group of divers) to ensure a sufficient search area for obtaining reliable estimates. In this

case, the statistical sample size was n, the number of sampled primary units. Both frequency of

occurrence and abundance were estimated by species on a second-stage unit basis, the standard

approach for two-stage designs (Cochran, 1977), where the number of second-stage units nm was

the statistical sample size. Since benthic habitat classification, digital mapping, and development

of the Tortugas survey design occurred concurrently with the baseline surveys of 1999 and 2000

(Ault et al., 2002), each population and community metric was estimated as a composite of the

two baseline years to alleviate problems of misclassification of habitats and misallocation of

samples among habitat strata. In this procedure, strata means and variance components were

computed as two-year averages weighted by respective sample sizes in 1999 and 2000.

Species chosen for detailed analyses reflected the range of population dynamic processes

(growth and survivorship) for relatively abundant exploited and non-exploited components of the

reef fish community. Statistical tests for differences among estimates of mean density, total

abundance and mean proportion of samples for the sampling design configuration were

conducted by inspection of confidence intervals (CI) using Bonferroni adjustments (Cochran,

1977). Detection of change was defined as the ability to discriminate between the 95% CI of

mean responses between the two time periods. We used the Bonferoni CI t-test because it is

more suited to sample design statistics and does not require homogenous variance between two

distributions to test differences in the mean responses. The absolute ability to detect changes

was thus determined by the precision of the survey estimates (e.g., standard error).


1.2 RESULTS

1.2.1 Sampling Effort

Forty-three scientists from various academic, state and federal government

agencies and organizations participated in the field survey (Table 1.2). Basic scientific dive

statistics are shown in Table 1.3. The fish, lobster, and habitat survey teams conducted a total of

1,344 scientific dives in the Tortugas region, with 817 dives in Dry Tortugas National Park and

527 dives in Tortugas Bank. A new addition for the 2006 survey was a fish team equipped with

Trimix to survey reef habitats deeper than 33 m. This team conducted a total of 24 scientific

dives on the western edge of Tortugas Bank in depths to 42 m. Table 1.4 shows statistical

sample sizes in terms of primary (n) and second-stage (nm) sample units by year, habitat, and

management zone. A total of 254 primary units were sampled by the reef fish survey team, just

slightly less than the target allocation of n=270 even though diving operations were suspended

for several days due to Tropical Storm Alberto. A subset of the 254 primary units were co-

sampled by the spiny lobster or benthic habitat survey teams along with the reef fish teams

(Figure 1.3). A complete descriptive list of these sampling sites is provided in Table 1.5 for Dry

Tortugas National Park and Table 1.6 for Tortugas Bank.

1.2.2 Preliminary Analysis of Change, Baseline to 2006

Fish species richness ranged from 23 to 67 species per primary sample unit (psu) and, in

general, was correlated with habitat class (Figure 1.5). Greatest reef fish species diversity was

found in high rugosity habitats. For the Tortugas sampling domain, we detected a significant

increase in mean species richness (mean number of species per psu) from 37.1 in the 1999-2000

baseline to 41.5 in 2006 (Table 1.7). Diversity of exploited species in the snapper-grouper

complex was also highest in high rugosity habitats (Figure 1.6); however, we detected no change

in mean richness for snapper-grouper species (Table 1,7).

Domain-wide estimates of frequency of occurrence, or sighting frequency, showed a

relatively stable fish community structure. Although there were minor changes in ranks between

years, only five of the top 50 species for the 2006 survey were not among the top 50 species for

the 1999-2000 surveys (Table 1.8). The top 50 species in 2006 included 10 species from the

exploited snapper-grouper complex.


Domain-wide estimates of frequency of occurrence and abundance for representative

species of principal families are given in Tables 1.9 and 1.10, respectively. Among species in

the exploited snapper-grouper complex, we detected an increase in domain-wide percent

occurrence between 1999-2000 and 2006 for mutton snapper, and we detected declines in red

grouper, gray snapper, and hogfish. Concomitantly, we detected an increase in domain-wide

abundance for mutton snapper and decreases in abundance for red grouper and hogfish. Notably,

estimates of abundance in 2006 for black grouper and yellowtail snapper were similar to the

estimates for 1999-2000, in contrast to the positive changes observed between 1999-2000 and

2004.

Changes in abundance within management zones between 1999-2000 and 2006 were also

observed for some snapper-grouper species (Table 1.11). Declines for red grouper and hogfish

were detected in Tortugas Bank Fished, whereas mutton snapper increased in Dry Tortugas

National Park. Again, positive changes in abundance from baseline observed in 2004 within

Tortugas Bank NTMR for red grouper, black grouper, and mutton snapper were not detected in

2006. Similarly, positive abundance changes observed in 2004 in Dry Tortugas National Park

for black grouper and yellowtail snapper were not detected in 2006.

Among species not targeted by exploitation, we detected domain-wide increases in

occurrence between baseline and 2006 for 4 species and decreases for 3 species (Table 1.9).

Likewise, we detected domain-wide increases in abundance for 3 species and decreases for 4

species (Table 1.10). These changes are in marked contrast to our findings for the 2004 survey

in which no domain-wide declines in abundance were observed for non-target species. Within

spatial management zones, we detected both increases and decreases in abundance between

baseline and 2006 for a number of non-target species irrespective of zone (Table 1.11).

Moreover, in many cases the changes observed in 2006 differed from those observed in the 2004

survey.

For black grouper, the shift observed in domain-wide length composition between 1999-

2000 and 2004 towards a higher proportion of exploited-phase animals seems to have progressed

even further in 2006 (Figure 1.7). In contrast, length composition of red grouper in 2006 shows

only a modest increase in the proportion of exploited-phase animals from 1999-2000, and the

shift toward larger animals is less pronounced than observed in 2004 (Figure 1.8). Temporal

changes in length composition within management zones are documented in Figures 1.9 to 1.11


for black grouper and in Figures 1.12 to 1.14 for red grouper. For both species, the length

composition data for 2006 suggest that the proportion of exploited-phase animals is directly

related to the level of resource protection, with highest proportions of exploited-phase animals in

the no-take reserve and lowest proportions in the area open to both commercial and recreational

fishing.

1.3 NEXT STEPS IN THE RESEARCH ANALYSIS

Our preliminary findings indicate that changes in abundance metrics for a suite of

exploited and non-target fish species observed between baseline surveys in the Tortugas region

in 1999-2000 and the 2006 survey were in many cases very different from the changes observed

between baseline and 2004. We suspect that the increased hurricane activity in the intervening

period between the 2004 and 2006 surveys was a contributing factor to the discrepancies in the

2004 and 2006 results. Our next research focus and challenge will be to develop, refine, and

apply analysis methods for understanding the relative contributions of NTMRs, various

traditional fishery management actions, community interactions, and environmental factors and

events such as hurricanes in terms of impacts on fish population abundance and size metrics, and

how these impacts in turn influence long-term resource sustainability.

1.4 Acknowledgments

We thank Captain Frank Wasson and the crew of the M/V Spree for their expert

seamanship, dive support, and their special friendship. We thank mission coordinator Jay Styron

and the expert staff from the National Undersea Research Center including Doug Kesling and

Tom Potts for their exceptional mission coordination and dive support in carrying out the 2006

reef fish census survey. We sincerely appreciate the enthusiasm and professionalism of all 43

participating scientists from a host of University, State and Federal institutions and for their

assistance in meeting the rigor and demands of this challenging endeavor. This study was

supported by funding from the National Park Service through the NOAA General Coral Reef

Conservation Program (NOAA Grant NA05NMF4631044), NPS Cooperative Ecosystems Study

Unit, Contract No. H500000B494-J5120020275, NOAA Fisheries Coral Reef Program

(NA17RJ1226), and personnel support from the Florida Fish and Wildlife Conservation

Commission. We thank Tom Schmidt, Bob Howard, Bob Johnson and Bob Zepp of

Everglades/Dry Tortugas National Park; Brian Keller, Billy Causey and Cheva Heck of the

Florida Keys National Marine Sanctuary; Alex Chester, Peter Thompson and Nancy Thompson


of the National Marine Fisheries Service; Rose Mann of the Pew Institute of Ocean Sciences;

and Annie Reisewitz and Ivy Kupec of the University of Miami.

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Table 1.1. (A) Habitat strata (h) characteristics and sizes in terms of primary sampling units (Nh) and area (Ah) for the Dry Tortugas sampling domain. (B) Habitat strata sizes for three management zones within the Dry Tortugas sampling domain; dashes denote habitats not found in a given management zone. (A)

Domain-wide Area

Reef Habitat Classification

Habitat

Code

Degree of Patchiness

Degree of

Vertical Relief Nh Ah (km2)

Low-relief hardbottom

LRHB

Low

Low

4,987

199.48

Low-relief spur & groove LRSG Moderate Low 283 11.32

Patchy hardbottom in sand PHBS High Low 950 38.00

Medium profile reef MDPR Low Moderate 211 8.44

Rocky outcrops RKOC Moderate-High Moderate 1158 46.32

Reef terrace RFTC Low High 398 15.92

High-relief spur & groove HRSG Moderate High 119 4.76

Pinnacle reef RFPN High High

41 1.64

Total

8,147 325.88

(B)

Habitat

Tortugas Bank

Fished

Tortugas Bank

NTMR


Code Nh Ah (km2) Nh Ah (km2) Nh Ah (km2)

LRHB

1,120

44.80

1,464

58.56

2,403

96.12

LRSG — — — — 283 11.32

PHBS 28 1.12 17 0.68 905 33.20

MDPR — — — — 211 8.44

RKOC 133 5.32 289 11.56 736 29.44

RFTC 37 1.48 322 12.88 39 1.56

HRSG — — — — 119 4.76

RFPN — — 20 0.80 21 0.84

Total

1,318

52.72

2,112

84.48

4,717

188.68


Table 1.2. Onboard scientific personnel for the 2006 Tortugas survey.

Name

Organization

Scientific Role

Ault, Dr. Jerald

UM-RSMAS

Principal Investigator/Fish Diver

Brandt, Marilyn UM-RSMAS Fish-Tech Diver Farmer, Nick UM-RSMAS Fish Diver Feeley, Mike UM-RSMAS Fish-Tech Diver Fiechter, Jerome UM-RSMAS Fish Diver Gomez, Rick UM-RSMAS Fish-Tech Diver Kleisner, Kristin UM-RSMAS Fish Diver Larkin, Mike UM-RSMAS Fish Diver Luo, Dr. Jiangang UM-RSMAS Chief Videographer/Photographer McCrea, Ashley UM-RSMAS Fish Diver Smith, Dr. Steve UM-RSMAS Logistics Coordinator/Fish Diver Swanson, Dione UM-RSMAS Coral Diver Zurcher, Natalia UM-RSMAS Logistics Specialist/Fish-Tech Diver Baertlein, Neil NOAA Fisheries Fish Diver Balchowsky, Heather NOAA Fisheries Fish Diver Bohnsack, Dr. Jim NOAA Fisheries Co-Principal Investigator/Fish Diver Contillo, Joe NOAA Fisheries Fish Diver Davenport, Guy NOAA Fisheries Fish Diver Harman, Leah NOAA Fisheries Fish Diver Harper, Doug NOAA Fisheries Data Manager/Fish Diver Jackson, Tom NOAA Fisheries Fish Diver Javech, Jack NOAA Fisheries Fish Diver Judge, Mike NOAA Fisheries Fish Diver Kellison, Dr. Todd NOAA Fisheries Fish Diver McClellan, Dave NOAA Fisheries Logistics Specialist/Fish Diver Waara, Robert NPS Coral Diver Caldow, Chris NOAA NOS Fish Diver Woody, Kimberly NOAA NOS Fish Diver Franklin, Erik NOAA NOS Fish Diver Bertelsen, Dr. Rod FWRI Lobster Diver Braynard, Michelle FWRI Lobster Diver Cox, Carollyn FWRI Lobster Diver Eaken, Dave FWRI Lobster Diver Hawtof, David FWRI Lobster Diver Lewis, Cindy FWRI Lobster Diver Maxwell, Kerry FWRI Lobster Diver Sympson, Bill FWRI Lobster Diver Walsh, Aaron FWRI Lobster Diver Chiappone, Mark NURC/UNCW Coral Diver Kesling, Doug NURC/UNCW Coral Diver Potts, Tom NURC/UNCW Divemaster Rutten, Leann NURC/UNCW Divemaster Styron, Jay NURC/UNCW Divemaster


Table 1.3. Sampling effort by reef fish, benthic habitat, and spiny lobster teams in the Dry Tortugas region for 2006.

Number of Scientific Dives

Survey Team

Dry Tortugas National Park Tortugas

Bank Combined Areas

Reef Fish-Nitrox

553

343 896

Reef Fish-Trimix 0 24 24 Benthic Habitat 109 48 157 Spiny Lobster 155 112 267 All Teams 817 527 1,344

Table 1.4. Reef fish survey sample sizes in terms of primary (n) and second-stage (nm) units by habitat class and management zone for 2006. Habitat codes are defined in Table 1; dashes denote habitats not found in a given management zone.

Habitat

Tortugas Bank

Fished

Tortugas Bank

NTMR


Domain-wide Code n nm n nm n nm n nm

LRHB

22

43

13

23

61

117

96

183

LRSG — — — — 9 18 9 18 PHBS 2 4 3 6 7 14 12 24 MDPR — — — — 23 43 23 43 RKOC 8 15 29 55 31 60 68 130 RFTC 3 6 16 32 12 24 31 62 HRSG — — — — 4 8 4 8 RFPN — — 4 8 7 14 11 22

Total

35

68

65

124

154

298

254

490


Table 1.5. Primary sampling unit (200 by 200 m grid cell) site list for the summer 2006 survey in Dry Tortugas National Park denoting the type of sampling (Survey Team), location, spatial management zone, and habitat classification (see Table 1.1 for habitat codes).

Primary Unit ID

Survey Team Latitude Longitude Spatial Zone Habitat

001U Coral-Fish 24.7195084 -82.7894583 outside RNA PHBS 002U Fish 24.7204334 -82.7888166 outside RNA LRHB 003U Lobster-Fish 24.7116417 -82.7887166 outside RNA LRSG 004U Lobster-Fish 24.7121917 -82.7932416 outside RNA RKOC 005U Fish 24.7318417 -82.7991916 outside RNA MDPR 006U Lobster-Fish 24.7311334 -82.7964916 outside RNA LRHB 007U Lobster-Fish 24.7336667 -82.7950250 outside RNA MDPR 008U Fish 24.7268750 -82.7835250 outside RNA LRHB 009U Lobster-Fish 24.7248751 -82.7901500 outside RNA LRHB 010U Coral-Fish 24.7312917 -82.7868499 outside RNA LRHB 011U Lobster-Fish 24.7151001 -82.7854666 outside RNA PHBS 012U Fish 24.7117417 -82.7849749 outside RNA LRHB 013U Lobster-Fish 24.7113750 -82.7857416 outside RNA LRSG 014U Lobster-Fish 24.7117584 -82.7852166 outside RNA LRHB 015U Coral-Fish 24.7087334 -82.7819166 outside RNA LRHB 016U Coral-Fish 24.6601251 -82.7750500 outside RNA MDPR 017H Fish 24.6595833 -82.7767999 outside RNA LRHB 017U Fish 24.6595334 -82.7766499 outside RNA MDPR 018U Lobster-Fish 24.6429750 -82.7871749 outside RNA MDPR 019U Lobster-Fish 24.6440167 -82.7986083 outside RNA MDPR 020H Fish 24.6323667 -82.7978000 outside RNA LRHB 020U Fish 24.6322167 -82.7974332 outside RNA Sand 021U Lobster-Fish 24.6298751 -82.8034333 outside RNA HRSG 022U Lobster-Fish 24.6283500 -82.8081333 outside RNA LRSG 023U Coral-Fish 24.6299334 -82.8160583 outside RNA LRHB 024U Fish 24.6251501 -82.8173333 outside RNA RKOC 025U Lobster-Fish 24.6221167 -82.8213583 outside RNA RFPN 026U Lobster-Fish 24.6243334 -82.8257333 outside RNA HRSG 027U Fish 24.6229584 -82.8308250 outside RNA RKOC 028U Lobster-Fish 24.6341501 -82.8251833 outside RNA PHBS 029U Coral-Fish 24.6388251 -82.8227666 outside RNA MDPR 030U Lobster-Fish 24.6408084 -82.8292750 outside RNA RKOC 031U Fish 24.6412500 -82.8309333 outside RNA MDPR 032U Lobster-Fish 24.6364084 -82.8335916 outside RNA LRHB 033U Lobster-Fish 24.6290417 -82.8345083 outside RNA LRHB 034U Coral-Fish 24.6601501 -82.7750500 outside RNA MDPR 035U Fish 24.7292834 -82.8067916 RNA RFTC 036U Lobster-Fish 24.7275584 -82.8108000 RNA RFTC 037U Lobster-Fish 24.7255917 -82.8146416 RNA RFTC 038U Fish 24.7221251 -82.8205749 outside RNA RFTC 039U Lobster-Fish 24.7236084 -82.8230250 outside RNA RFTC 040U Lobster-Fish 24.7227334 -82.8289583 outside RNA RFTC 041U Coral-Fish 24.7219834 -82.8257583 outside RNA MDPR 042U Fish 24.7224750 -82.8349250 outside RNA RFTC

Positive Signs for Florida’s Coral Reef Fisheries Page 1.22

Table 1.5, cont.

Primary Unit ID


043U Lobster-Fish 24.7223084 -82.8515583 RNA MDPR 044U Lobster-Fish 24.7198084 -82.8548833 RNA LRHB 045U Fish 24.7189751 -82.8388499 outside RNA LRHB 046U Coral-Fish 24.7205084 -82.8367667 outside RNA MDPR 047U Lobster-Fish 24.7154834 -82.8203250 outside RNA LRHB 048U Lobster-Fish 24.7140917 -82.8146666 outside RNA LRHB 064U Coral-Fish 24.6585667 -82.9437500 RNA RFPN 065U Fish 24.6581417 -82.9426333 RNA RKOC 066U Lobster-Fish 24.6591917 -82.9360333 RNA RKOC 067U Lobster-Fish 24.6616334 -82.9359249 RNA RFPN 068U Fish 24.6795334 -82.9237666 RNA MDPR 069U Lobster-Fish 24.6858084 -82.9324583 RNA LRHB 070U Lobster-Fish 24.6918667 -82.9121667 RNA LRHB 071U Coral-Fish 24.6827834 -82.9145333 RNA LRHB 072U Fish 24.6830834 -82.9122083 RNA LRHB 073U Coral-Fish 24.7079584 -82.9001667 RNA LRHB 074U Fish 24.7088667 -82.8985000 RNA LRHB 100U Coral-Fish 24.5436167 -82.9481583 outside RNA LRHB 101U Fish 24.5451584 -82.9476416 outside RNA LRHB 102U Lobster-Fish 24.5455917 -82.9521583 outside RNA LRHB 103U Lobster-Fish 24.5562000 -82.9356500 outside RNA LRHB 104U Fish 24.5538084 -82.9353250 outside RNA LRHB 105U Coral-Fish 24.5578084 -82.9354416 outside RNA LRHB 106U Lobster-Fish 24.5561750 -82.9346583 outside RNA LRHB 107U Lobster-Fish 24.5534417 -82.9337250 outside RNA LRHB 165H Coral-Fish 24.6323334 -82.9046666 RNA LRHB 165U Coral-Fish 24.6323167 -82.9047333 RNA MDPR 166U Lobster-Fish 24.6341751 -82.9016416 RNA RKOC 167H Fish 24.6311501 -82.9034499 RNA RKOC 167U Fish 24.6311501 -82.9034499 RNA LRHB 168U Lobster-Fish 24.6286584 -82.8975499 RNA RKOC 169U Coral-Fish 24.6108584 -82.8712667 RNA HRSG 170U Fish 24.6134500 -82.8695666 outside RNA HRSG 171U Lobster-Fish 24.6025833 -82.8740916 RNA LRSG 172U Lobster-Fish 24.5981333 -82.8703499 outside RNA RKOC 173U Coral-Fish 24.7199501 -82.8762166 RNA MDPR 174H Fish 24.7193000 -82.8728499 RNA MDPR 174U Fish 24.7193000 -82.8728499 RNA LRHB 175U Lobster-Fish 24.7186251 -82.8808499 RNA LRHB 176U Lobster-Fish 24.7150834 -82.8859666 RNA LRHB 177U Fish 24.7107334 -82.8812250 RNA MDPR 178U Lobster-Fish 24.7082417 -82.8792500 RNA MDPR 179U Lobster-Fish 24.7057084 -82.8731416 RNA MDPR 180U Fish 24.7016834 -82.8875499 RNA LRHB 181U Coral-Fish 24.6999833 -82.9117000 RNA LRHB 182U Lobster-Fish 24.7019000 -82.9082999 RNA LRHB 183U Lobster-Fish 24.6987000 -82.9175333 RNA LRHB


Table 1.5, cont.

Primary Unit ID


184U Fish 24.6737834 -82.9177999 RNA RKOC 185U Lobster-Fish 24.6682417 -82.9136833 RNA LRHB 186U Coral-Fish 24.6751167 -82.8990000 RNA LRHB 187U Lobster-Fish 24.6730334 -82.9106833 RNA LRHB 188U Fish 24.6719667 -82.9060499 RNA LRHB 189U Lobster-Fish 24.6741417 -82.9033916 RNA RKOC 190U Lobster-Fish 24.6693167 -82.9011500 RNA RKOC 191U Coral-Fish 24.6636667 -82.9311666 RNA RFTC 192U Fish 24.6690501 -82.9276167 RNA RFPN 193U Lobster-Fish 24.6610751 -82.9316000 RNA RFTC 194U Lobster-Fish 24.6614584 -82.9282583 RNA RFTC 195U Fish 24.6590084 -82.9296249 RNA MDPR 196U Lobster-Fish 24.6554000 -82.9391166 RNA RFTC 197U Coral-Fish 24.6525667 -82.9489167 RNA LRHB 198U Lobster-Fish 24.6527167 -82.9462166 RNA LRHB 199U Fish 24.6517250 -82.9520583 RNA LRHB 200U Lobster-Fish 24.6392084 -82.9642833 RNA RKOC 201U Lobster-Fish 24.6385834 -82.9617416 RNA RFPN 202U Coral-Fish 24.6395417 -82.9428083 RNA PHBS 203U Fish 24.6393667 -82.9379999 RNA LRSG 204U Lobster-Fish 24.6425500 -82.9299333 RNA LRSG 205U Coral-Fish 24.6350084 -82.9335416 RNA LRHB 206U Lobster-Fish 24.6332000 -82.9351166 RNA PHBS 207U Coral-Fish 24.5896000 -82.9936583 outside RNA LRHB 208U Fish 24.5876334 -82.9921167 outside RNA LRHB 209U Lobster-Fish 24.5916001 -82.9949333 outside RNA LRHB 210U Lobster-Fish 24.6005000 -82.9806333 outside RNA LRHB 211U Fish 24.6029001 -82.9775999 outside RNA LRHB 212U Lobster-Fish 24.6049167 -82.9721000 outside RNA LRHB 213U Lobster-Fish 24.6069167 -82.9680166 RNA PHBS 214U Coral-Fish 24.6106417 -82.9629916 RNA MDPR 215U Fish 24.6107250 -82.9647416 RNA RKOC 216U Lobster-Fish 24.6109417 -82.9604417 RNA RKOC 217U Lobster-Fish 24.6055501 -82.9565916 RNA RKOC 218U Fish 24.6073417 -82.9552166 RNA RKOC 219U Lobster-Fish 24.6107250 -82.9562166 RNA RKOC 220U Lobster-Fish 24.6141584 -82.9485083 RNA RKOC 221U Coral-Fish 24.6106917 -82.9298333 RNA RFPN 222U Fish 24.6091334 -82.9298000 RNA LRHB 223U Lobster-Fish 24.6120084 -82.9290750 RNA RKOC 224U Lobster-Fish 24.6204000 -82.9221166 RNA RKOC 225U Coral-Fish 24.5896084 -82.8908666 outside RNA RKOC 226U Fish 24.5901501 -82.8950666 outside RNA LRSG 227U Lobster-Fish 24.5846251 -82.8885333 outside RNA LRSG 228U Lobster-Fish 24.5892001 -82.8855250 outside RNA LRSG 229U Coral-Fish 24.6548500 -82.8455083 outside RNA LRHB 230U Fish 24.6480834 -82.8498166 RNA RFPN


Table 1.5, cont.

Primary Unit ID

Survey Team Latitude Longitude Spatial Zone Habitat 231H Lobster-Fish 24.6541334 -82.8413500 outside RNA Sand 231U Fish 24.6541334 -82.8413500 outside RNA LRHB 232U Lobster-Fish 24.6862167 -82.8437417 outside RNA RKOC 233H Fish 24.6902334 -82.8399666 outside RNA Sand-Seagrass 233U Fish 24.6901834 -82.8405833 outside RNA RKOC 234U Coral-Fish 24.6973251 -82.8701000 RNA RKOC 235U Lobster-Fish 24.6962417 -82.8609167 RNA MDPR 236U Lobster-Fish 24.6914667 -82.8748000 RNA RKOC 237U Fish 24.6749833 -82.8907333 RNA RKOC 238U Lobster-Fish 24.6745917 -82.8860333 RNA LRHB 239U Lobster-Fish 24.6814668 -82.8900250 RNA RKOC 240U Coral-Fish 24.6360751 -82.9243583 RNA RKOC 241U Fish 24.6366167 -82.9259833 RNA PHBS 242U Lobster-Fish 24.6390667 -82.9230833 RNA LRHB 243U Lobster-Fish 24.6389334 -82.9226833 RNA RKOC 244U Coral-Fish 24.5649333 -82.9560999 outside RNA RFTC 245U Fish 24.5652000 -82.9534166 outside RNA MDPR 246U Lobster-Fish 24.5680834 -82.9514083 outside RNA LRHB 247U Lobster-Fish 24.5674334 -82.9539333 outside RNA LRHB


Table 1.6. Primary sampling unit (200 by 200 m grid cell) site list for the summer 2006 survey in Tortugas Bank denoting the type of sampling (Survey Team), location, spatial management zone, and habitat classification (see Table for habitat codes).

Primary Unit ID Survey Team Latitude Longitude Spatial Zone Habitat

049U Coral-Fish 24.6789167 -82.9848666 ER MDPR 050U Fish 24.6780167 -82.9810833 ER RKOC 051U Lobster-Fish 24.6803167 -82.9839833 ER MDPR 052U Lobster-Fish 24.6912751 -82.9928333 ER RKOC 053U Fish 24.6876167 -82.9951166 ER MDPR 054U Lobster-Fish 24.6867667 -82.9965417 ER RFTC 055U Lobster-Fish 24.6855501 -82.9979750 ER RKOC 056U Fish 24.6781750 -82.9961666 ER LRHB 057U Coral-Fish 24.6772667 -83.0028999 ER RKOC 058U Lobster-Fish 24.6751251 -83.0012499 ER MDPR 059U Fish 24.6698667 -83.0081416 ER Sand 060U Fish 24.6677834 -83.0101166 ER LRHB 061U Lobster-Fish 24.6791834 -83.0135666 ER RFPN 062U Coral-Fish 24.6845501 -83.0117332 ER RKOC 063U Lobster-Fish 24.6862417 -83.0150249 ER RKOC 075U Lobster-Fish 24.6788667 -83.0367916 ER RKOC 076U Lobster-Fish 24.6794084 -83.0339999 ER RKOC 077U Fish 24.6789084 -83.0319416 ER LRHB 078U Lobster-Fish 24.6806417 -83.0295166 ER RKOC 079U Coral-Fish 24.6991500 -83.0336166 ER RKOC 080H Lobster-Fish 24.6789333 -83.0255832 ER RKOC 080U Lobster-Fish 24.6789834 -83.0256999 ER LRHB 081U Fish 24.6784501 -83.0268666 ER LRHB 082U Coral-Fish 24.7238000 -82.9813250 ER RFTC 083U Fish 24.7236501 -82.9788749 ER RFTC 084U Lobster-Fish 24.7153584 -82.9819416 ER PHBS 085H Lobster-Fish 24.7013000 -82.9830833 ER LRHB 085U Lobster-Fish 24.7012834 -82.9829833 ER RKOC 086U Fish 24.7111167 -82.9932916 ER LRSG 087U Coral-Fish 24.7079917 -82.9913666 ER LRHB 088U Lobster-Fish 24.7081834 -83.0085999 ER MDPR 089U Lobster-Fish 24.6958000 -83.0092332 ER MDPR 090U Fish 24.6941584 -83.0122916 ER RKOC 091U Lobster-Fish 24.6935250 -83.0200333 ER MDPR 092U Lobster-Fish 24.6552334 -83.0327583 ER RKOC 093U Fish 24.6567501 -83.0264916 ER LRHB 094H Lobster-Fish 24.6532000 -83.0243166 ER RKOC 094U Lobster-Fish 24.6533834 -83.0244499 ER LRHB 095U Coral-Fish 24.6510000 -83.0235832 ER LRHB 096U Lobster-Fish 24.6473084 -83.0225416 outside ER LRHB 097U Fish 24.6502167 -83.0303666 ER RFPN 098U Lobster-Fish 24.6399500 -83.0412416 outside ER MDPR 099U Lobster-Fish 24.6380417 -83.0423333 outside ER RKOC 108U Lobster-Fish 24.6874167 -83.0721499 ER RFTC


Table 1.6, cont.


109U Coral-Fish 24.6851417 -83.0736249 ER MDPR 110U Fish 24.6881667 -83.0754332 ER PHBS 111U Lobster-Fish 24.7042501 -83.0408749 ER RFTC 112U Lobster-Fish 24.7074500 -83.0448499 ER RFTC 113U Fish 24.7073667 -83.0449082 ER RFTC 114U Lobster-Fish 24.7073500 -83.0449332 ER RFTC 115U Lobster-Fish 24.6830000 -83.0764332 ER MDPR 116U Coral-Fish 24.6822084 -83.0782999 ER MDPR 117U Fish 24.6838667 -83.0778999 ER RFTC 118U Lobster-Fish 24.6785833 -83.0806499 ER RFTC 119U Lobster-Fish 24.6772834 -83.0808499 ER MDPR 120U Lobster-Fish 24.6808667 -83.0761332 ER RFTC 121U Lobster-Fish 24.6743584 -83.0884916 ER RFTC 122U Coral-Fish 24.6721334 -83.0899499 ER RFTC 123U Fish 24.6719251 -83.0912249 ER RFTC 124U Lobster-Fish 24.6699584 -83.0917583 ER RFTC 125U Lobster-Fish 24.6780501 -83.0626416 ER RFPN 126U Fish 24.6774251 -83.0513916 ER LRHB 127U Lobster-Fish 24.6653667 -83.0508333 ER LRHB 128U Lobster-Fish 24.6666751 -83.0911499 ER MDPR 129U Coral-Fish 24.6660834 -83.0935333 ER MDPR 130U Fish 24.6645251 -83.0966333 ER RFTC 131U Lobster-Fish 24.6598917 -83.0883333 ER PHBS 132U Lobster-Fish 24.6603334 -83.0790333 ER RKOC 133U Lobster-Fish 24.6526084 -83.0336582 ER RFPN 134U Lobster-Fish 24.6447334 -83.1030416 outside ER MDPR 135U Coral-Fish 24.6423834 -83.1029499 outside ER MDPR 136U Fish 24.6381917 -83.1034416 outside ER RFTC 137U Lobster-Fish 24.6279000 -83.1029583 outside ER LRHB 138U Lobster-Fish 24.6340667 -83.0989499 outside ER LRHB 139U Fish 24.6346334 -83.0868916 outside ER LRHB 140U Lobster-Fish 24.6317500 -83.0866499 outside ER PHBS 141U Lobster-Fish 24.6221001 -83.1002666 outside ER LRHB 142U Coral-Fish 24.6196000 -83.0998583 outside ER MDPR 143U Fish 24.6183917 -83.1014332 outside ER MDPR 144U Lobster-Fish 24.6262084 -83.0883666 outside ER LRHB 145U Lobster-Fish 24.6330667 -83.0803166 outside ER LRHB 146U Lobster-Fish 24.6401084 -83.0810083 outside ER RKOC 147U Coral-Fish 24.6106000 -83.0978166 outside ER LRHB 148U Fish 24.6125667 -83.1002666 outside ER LRHB 149U Lobster-Fish 24.6075334 -83.0964999 outside ER MDPR 150U Lobster-Fish 24.6029417 -83.0855416 outside ER LRHB 151U Fish 24.6070250 -83.0767166 outside ER LRHB 152U Lobster-Fish 24.6137751 -83.0646999 outside ER LRHB 153U Coral-Fish 24.6220001 -83.0816333 outside ER LRHB 154H Lobster-Fish 24.6178167 -83.0803666 outside ER RKOC


Table 1.6, cont.


154U Lobster-Fish 24.6181167 -83.0805166 outside ER LRHB 155U Fish 24.6273334 -83.0818832 outside ER LRHB 156U Lobster-Fish 24.6218334 -83.0709166 outside ER LRHB 157U Lobster-Fish 24.6222167 -83.0658166 outside ER LRHB 158U Fish 24.6433167 -83.0685166 outside ER LRHB 159U Coral-Fish 24.6372167 -83.0924833 outside ER RKOC 160U Lobster-Fish 24.6334001 -83.0563916 outside ER LRHB 161U Lobster-Fish 24.6372417 -83.0522833 outside ER LRHB 162U Fish 24.6380334 -83.0466832 outside ER LRHB 163U Lobster-Fish 24.6354917 -83.0363083 outside ER LRHB 164U Lobster-Fish 24.6323667 -83.0308999 outside ER PHBS


Table 1.7. Domain-wide estimates of mean species richness and associated standard errors (SE) for two taxa groups for baseline years 1999-2000 and the 2004 and 2006 surveys. Statistical significant change from baseline: ns, not significant; *, p<0.05; **, p<0.01; ***, p<0.001.

Mean Species Richness (SE) Taxa 1999-2000 2004 Change 2006 Change All Reef Fishes

37.1 (0.7)

38.1 (0.5)

ns

41.5 (0.6)

***

Exploited Snappers & Groupers

7.8 (0.2)

7.8 (0.2)

ns

8.0 (0.2)

ns


Table 1.8. Ranked top 50 reef fish species in terms of percent occurrence for 2006 compared to 2004 and 1999-2000. Common names in bold denote species in the exploited snapper-grouper complex.

Occurrence Rank Common Name Scientific Name Family 2006 2004 1999-2000 bluehead Thalassoma bifasciatum Labridae 1 1 1 cocoa damselfish Stegastes variabilis Pomacentridae 2 3 3 striped parrotfish Scarus iseri Scaridae 3 2 2 yellowhead wrasse Halichoeres garnoti Labridae 4 5 10 slippery dick Halichoeres bivittatus Labridae 5 10 7 bridled goby Coryphopterus glaucofraenum Gobiidae 6 14 12 saddled blenny Malacoctenus triangulatus Labrisomidae 7 32 14 white grunt Haemulon plumierii Haemulidae 8 9 4 redband parrotfish Sparisoma aurofrenatum Scaridae 9 4 5 ocean surgeon Acanthurus bahianus Acanthuridae 10 17 18 saucereye porgy Calamus calamus Sparidae 11 12 6 spotted goatfish Pseudupeneus maculatus Mullidae 12 8 20 bicolor damselfish Stegastes partitus Pomacentridae 13 7 11 blue tang Acanthurus coeruleus Acanthuridae 14 6 8 yellowtail snapper Ocyurus chrysurus Lutjanidae 15 11 9 tomtate Haemulon aurolineatum Haemulidae 16 45 41 seaweed blenny Parablennius marmoreus Blenniidae 17 62 35 greenblotch parrotfish Sparisoma atomarium Scaridae 18 21 24 yellowhead jawfish Opistognathus aurifrons Opistognathidae 19 24 21 butter hamlet Hypoplectrus unicolor Serranidae 20 20 29 red grouper Epinephelus morio Serranidae 21 15 13 masked goby Coryphopterus personatus Gobiidae 22 22 25 purple reeffish Chromis scotti Pomacentridae 23 16 28 stoplight parrotfish Sparisoma viride Scaridae 24 13 15 neon goby Elacatinus oceanops Gobiidae 25 34 22 blue angelfish Holacanthus bermudensis Pomacanthidae 26 18 16 spotfin butterflyfish Chaetodon ocellatus Chaetodontidae 27 19 17 gray angelfish Pomacanthus arcuatus Pomacanthidae 28 25 23 clown wrasse Halichoeres maculipinna Labridae 29 28 26 hogfish Lachnolaimus maximus Labridae 30 26 19 barred hamlet Hypoplectrus puella Serranidae 31 33 31 beaugregory Stegastes leucostictus Pomacentridae 32 30 34 blue hamlet Hypoplectrus gemma Serranidae 33 23 38 reef butterflyfish Chaetodon sedentarius Chaetodontidae 34 47 36 foureye butterflyfish Chaetodon capistratus Chaetodontidae 35 27 32 blue dartfish Ptereleotris calliura Ptereleotridae 36 70 42 sharpnose puffer Canthigaster rostrata Tetraodontidae 37 43 39 doctorfish Acanthurus chirurgus Acanthuridae 38 54 33 porkfish Anisotremus virginicus Haemulidae 39 56 51 mutton snapper Lutjanus analis Lutjanidae 40 38 52 threespot damselfish Stegastes planifrons Pomacentridae 41 29 30 graysby Cephalopholis cruentatus Serranidae 42 35 37 yellowtail reeffish Chromis enchrysura Pomacentridae 43 90 99 harlequin bass Serranus tigrinus Serranidae 44 31 27 bar jack Caranx ruber Carangidae 45 40 40 Spanish hogfish Bodianus rufus Labridae 46 44 47 queen angelfish Holacanthus ciliaris Pomacanthidae 47 41 43 cero Scomberomorus regalis Scombridae 48 49 117 black grouper Mycteroperca bonaci Serranidae 49 36 44 bluelip parrotfish Cryptotomus roseus Scaridae 50 98 67


Table 1.9. Domain-wide estimates of percent occurrence for representative exploited and non-target fish species for baseline years 1999-2000 and the 2004 and 2006 surveys. Statistical significant change from baseline: ns, not significant; *, p<0.05; **, p<0.01; ***, p<0.001.

Percent Occurrence (SE) Taxa 1999-2000 2004 Change 2006 Change Snapper-Grouper Complex Groupers (Serranidae) Goliath grouper (Epinephelus itajara) 0.5 (0.4) 1.3 (0.5) ns 1.1 (2.2) ns

Red grouper (E. morio) 67.0 (3.3) 62.8 (3.1) ns 58.5 (3.2) *

Nassau grouper (E. striatus) 1.0 (0.6) 0.3 (0.2) ns 0.9 (3.3) ns

Black grouper (Mycteroperca bonaci) 19.5 (2.5) 28.8 (2.4) ** 15.9 (3.3) ns

Snappers (Lutjanidae) Mutton snapper (Lutjanus analis) 14.8 (2.4) 25.8 (3.0) *** 24.8 (2.9) ***

Gray snapper (L. griseus) 17.3 (2.5) 12.2 (1.5) * 10.4 (1.1) **

Yellowtail snapper (Ocyurus chrysurus) 74.7 (3.2) 68.1 (3.1) * 72.9 (3.4) ns

Wrasses (Labridae) Hogfish (Lachnolaimus maximus) 52.8 (3.5) 42.6 (3.0) ** 44.6 (3.0) * Grunts (Haemulidae) White grunt (Haemulon plumieri) 82.0 (2.7) 71.5 (2.7) *** 80.2 (1.4) ns

Bluestriped grunt (H. sciurus) 6.4 (1.7) 7.7 (1.2) ns 6.5 (2.9) ns

Non-Target Fishes

Surgeonfishes (Acanthuridae) Ocean surgeon (Acanthurus bahianus) 54.9 (3.3) 60.3 (2.7) ns 79.2 (2.6) *** Blue tang (A. coeruleus) 76.4 (3.1) 80.9 (2.2) ns 73.4 (2.9) ns Butterflyfishes (Chaetodontidae) Foureye butterflyfish (Chaetodon capistratus) 34.0 (3.3) 42.3 (2.8) * 33.7 (3.3) ns Spotfin butterflyfish (C. ocellatus) 56.4 (3.4) 49.9 (3.0) ns 47.7 (3.5) * Goatfishes (Mullidae) Spotted goatfish (Psuedupeneus maculatus) 50.7 (3.6) 71.7 (2.2) *** 76.9 (2.7) *** Angelfishes (Pomacanthidae) Blue angelfish (Holocanthus bermudensis) 57.9 (3.2) 55.9 (2.7) ns 49.8 (0.7) * Gray angelfish (Pomacanthus arcuatus) 45.5 (3.3) 43.9 (2.8) ns 45.7 (1.6) ns Damselfishes (Pomacentridae) Purple reeffish (Chromis scotti) 37.2 (3.4) 62.2 (3.1) *** 52.2 (2.8) *** Bicolor damselfish (Stegastes partitus) 72.7 (2.9) 72.6 (2.3) ns 73.9 (3.1) ns Cocoa damselfish (S. variabilis) 87.7 (2.3) 90.0 (2.0) ns 97.1 (3.5) *** Parrotfishes (Scaridae) Striped parrotfish (Scarus iseri) 88.4 (2.4) 94.3 (1.3) * 91.4 (0.3) ns Redband parrotfish (Sparisoma aurofrenatum) 80.8 (2.9) 86.9 (1.9) * 79.8 (1.8) ns Stoplight parrotfish (Sparisoma viride) 59.3 (3.5) 64.5 (3.3) ns 51.8 (0.4) *


Table 1.10. Domain-wide estimates of abundance (and associated coefficient of variation CV) for representative exploited and non-target fish species for baseline years 1999-2000 and the 2004 and 2006 surveys, and changes from baseline. Statistical significant change from baseline years: ns, not significant; *, p<0.05; **, p<0.01; ***, p<0.001.

1999-2000 2004 2006 Taxa

Abundance (millions)

CV (%)


CV (%)

Change


CV (%)

Change

Snapper-Grouper Complex Red grouper 1.260 6.8 1.237 6.5 -2% ns 0.976 7.3 -23.2% ***

Black grouper 0.277 14.5 0.622 10.3 +124% *** 0.345 19.2 +23.4% ns

Mutton snapper 0.216 21.2 0.452 13.2 +109% *** 0.345 12.6 +58.1% **

Gray snapper 3.714 54.3 5.155 74.0 +39% ns 0.851 19.4 -77.3% ns

Yellowtail snapper 8.257 13.0 23.169 27.2 +181% * 8.800 13.1 +5.7% ns

Hogfish 1.121 10.7 0.910 12.0 -19% ns 0.810 9.8 -28.3% **

White grunt 9.317 15.5 9.644 21.6 +4% ns 12.290 16.0 +30.9% ns

Bluestriped grunt 0.330 47.0 0.854 42.0 +159% ns 0.288 23.5 -13.3% ns Non-Target Fishes

Ocean surgeon 2.045 13.3 2.275 8.0 +11% ns 2.947 9.1 +43.0% **

Blue tang 3.474 9.7 5.747 7.8 +65% *** 3.704 7.6 +5.8% ns

Foureye butterflyfish 0.960 10.8 1.083 7.5 +13% ns 0.827 10.7 -14.5% ns

Spotfin butterflyfish 1.315 7.5 1.256 6.8 -5% ns 1.042 7.5 -21.4% **

Spotted goatfish 1.076 10.7 3.204 9.8 +198% *** 2.673 8.0 +146.5% ***

Blue angelfish 1.555 8.0 1.525 6.8 -2% ns 1.121 7.6 -28.5% ***

Gray angelfish 0.868 9.2 1.588 27.2 +83% ns 0.997 9.6 +13.9% ns

Purple reeffish 11.518 17.8 20.219 13.0 +76% *** 15.222 9.8 +31.1% ns

Bicolor damselfish 12.914 10.4 17.269 7.8 +34% ** 8.112 7.8 -37.7% ***

Cocoa damselfish 7.654 5.9 7.384 4.9 -4% ns 11.592 4.8 +50.2% ***

Striped parrotfish 16.117 18.3 22.290 10.1 +38% * 18.686 5.9 +15.0% ns

Redband parrotfish 4.565 16.2 7.096 23.3 +56% ns 3.602 6.4 -21.7% ns

Stoplight parrotfish 1.936 9.7 3.012 10.3 +56% *** 1.568 12.2 -19.7% *


Table 1.11. Population abundance changes from baseline years 1999-2000 for the 2004 and 2006 surveys within management zones in the Dry Tortugas region. Statistical significant change from baseline years: ns, not significant; *, p<0.05; **, p<0.01; ***, p<0.001.

Tortugas Bank, Fished Tortugas Bank, NTMR Dry Tortugas National Park 2004 2006 2004 2006 2004 2006 Snapper-Grouper Complex Red grouper -43% * -48% ** +38% * -21% ns -9% ns -16% ns

Black grouper +84% ns -69% ns +120% * -35% ns +128 *** +42% ns

Mutton snapper -45% ns +23% ns +303% ** -20% ns +142% *** +94% **

Gray snapper -96% ns -96% ns -51% ns -54% ns +270% ns -55% ns

Yellowtail snapper -19% ns -15% ns +367% ns +78% ns +132% *** -22% ns

Hogfish -27% ns -78% *** +6% ns -13% ns -25% ns -16% ns

White grunt +7% ns -18% ns +24% ns +531% ns +2% ns -1% ns

Bluestriped grunt +50% ns -69% ns +13% ns +121 ns +242% ns -2% ns Non-Target Fishes

Ocean surgeon +2% ns +29% ns +75% ** +51% ** -9% ns +47% *

Blue tang +13% ns -22% ns +28% ns -19% ns +99% *** +25% ns

Foureye butterflyfish +86% * +5% ns -18% ns -12% ns +32% ns -25% ns

Spotfin butterflyfish +35% ns +13% ns -31% * -12% ns 0% ns -40% ***

Spotted goatfish +133% ** +64% * +326% *** +273% *** +175% *** +135% ***

Blue angelfish -18% ns +4% ns -20% ns -41% *** +31% * -32% *

Gray angelfish -24% ns -10% ns +58% ns -5.8% ns +120% ns +31% *

Purple reeffish +31% ns +49% ns +42% ns +11% ns +263% *** +94% **

Bicolor damselfish +6% ns -41% * +73% ** -40% ** +17% ns -29% ns

Cocoa damselfish -28% ns +27% ns -21% ns +76% *** +6% ns +46% ***

Striped parrotfish +51% ns +14% ns +127% * +39% ** +9% ns +7.3% ns

Redband parrotfish +121% *** +1% ns +26% ns -7% ns +56% ns -30% ns

Stoplight parrotfish +9% ns +30% ns +26% ns -41% * +84% *** -24% ns


Figure 1.1. The Florida Keys coastal marine ecosystem. The coral reef tract runs offshore from Key Biscayne 380 km southwest to the Dry Tortugas. The Florida Keys National Marine Sanctuary boundary and Biscayne National Park and Dry Tortugas National Park are shown.


Figure 1.2. Tracks of hurricanes impacting the Tortugas region in 2004 and 2005.


Figure 1.3. Map of the Dry Tortugas region showing bathymetry, spatial management boundaries, and primary units sampled by survey team (COR=coral-fish, FSH=fish, LOB=lobster-fish) during the 2006 expedition. Bathymetry is shaded from red (shallow, 0-3m) to blue (deep, >50m).

Tortugas Bank NTMR

Tortugas BankFished

FKNMS

Dry TortugasNational Park

Tortugas Bank NTMR

Tortugas BankFished

FKNMS

Dry TortugasNational Park


Figure 1.4. Graphical illustration of the two-stage stratified random sampling design used in the Tortugas 2006 survey: (A) benthic habitats are mapped at 200 x 200 m grids termed primary sampling units (psu), shown for Dry Tortugas National Park; (B) within a psu, paired teams of divers are randomly placed in second-stage units where they concurrently sample for reef fishes (2 stationary RVC cylinders, solid dots), reef habitats (4 transects, pink lines), and/or lobsters (2 transects, red lines).


Figure 1.5. Reef fish diversity as measured by species richness (number of species per 200 x 200 m primary unit) from the 2006 Tortugas monitoring expedition.


Figure 1.6. Diversity of the exploited snapper-grouper complex as measured by species richness (number of species per 200 x 200 m primary unit) from the 2006 Tortugas monitoring expedition.


Figure 1.7. Domain-wide comparisons of length compositions for black grouper for the 1999-2000, 2004, and 2006 surveys. Hatched bars are preexploited-phase; blue bars are exploited-phase animals. Number of length observations is given on each panel.

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Figure 1.8. Domain-wide comparisons of length compositions for red grouper for the 1999-2000, 2004, and 2006 surveys. Hatched bars are preexploited-phase; blue bars are exploited-phase animals. Number of length observations is given on each panel.

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Figure 1.9. Spatial management zone comparisons of length compositions for black grouper for the 1999-2000 survey. Hatched bars are preexploited-phase; blue bars are exploited-phase animals. Number of length observations is given on each panel.

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Tortugas Bank NTMRn=45

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Figure 1.10. Spatial management zone comparisons of length compositions for black grouper for the 2004 survey. Hatched bars are preexploited-phase; blue bars are exploited-phase animals. Number of length observations is given on each panel.

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Figure 1.11. Spatial management zone comparisons of length compositions for black grouper for the 2006 survey. Hatched bars are preexploited-phase; blue bars are exploited-phase animals. Number of length observations is given on each panel.

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Length (cm)


Figure 1.12. Spatial management zone comparisons of length compositions for red grouper for the 1999-2000 survey. Hatched bars are preexploited-phase; blue bars are exploited-phase animals. Number of length observations is given on each panel.

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Length (cm)


Figure 1.13. Spatial management zone comparisons of length compositions for red grouper for the 2004 survey. Hatched bars are preexploited-phase; blue bars are exploited-phase animals. Number of length observations is given on each panel.

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Length (cm)


Figure 1.14. Spatial management zone comparisons of length compositions for red grouper for the 2006 survey. Hatched bars are preexploited-phase; blue bars are exploited-phase animals. Number of length observations is given on each panel.

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Length (cm)

Documents

Jerald S. Ault, University of Miami Page 1 · 2010. 8. 19. · Jerald S. Ault, University of Miami Page 1 Final Progress Report on NOAA Coral Grant NA05NMF4631044 Final Report Grant