Marine Habitat Mapping,Applications for Fisheries

Management

Jens KrugerSPC’s Division of Applied Science and Technology

CEAFM workshop, December 2010

Why map benthic habitats?

Seafloor habitat mapping provides fundamental baseline information for decision-makers working in all sectors:

– Fisheries assessments– Environmental impact statements– Decision to approve extractive/other use– State of Environment reporting (inventory of assets)– Design of marine reserves

Uses of habitat maps(under different guises)

Fisheries (fish habitat for stock assessment)Navigation (reef, sandbank, bank, shoal etc.)Aggregate extraction (resource assessment)Deep sea minerals lease assessmentPorts and harbours (channels, intertidal, shoals)Infrastructure (cables, pipelines, etc.)Defence (mine countermeasures, acoustics)Spatial management (eg. MPAs)

What is a habitat map?

Map of the biophysical environment that shows where particular benthic species or communities occur (or are likely to occur)

Based on geomorphology, oceanography, primary production, depth, sediment type, seafloor roughness, etc.

Habitat maps can be derived from any one or all of these variables WITH information on benthic communities

Aitutaki, Cook IslandsImpacts of coastal development on the lagoon ecosystem

Proposed capital dredging:

• Attract yacht tourism ($60,000/year)

• Deepen & widen shipping channel for navigation

• Improve port facilities

Baseline Data Needs:• Marine Habitats• Bathymetry • Hydrodynamics

CHANNEL

Methods: Habitat Mapping

GPS

camera

drybag

GPS

slate

floats &weight

camera

line

GPS towed by diver with camera

Methods: Bathymetry and Oceanography

NEARSHORE

rimreef

lagoonfringing

reef

TideGauge

Satelliteimagery

MBES

SBES

RTKGPS

multibeam echosounderMultibeamCurrent Meter

Singlebeam GPS

Marine Habitat Map of Aitutaki, … as well as bathymetry and computer model

Bathymetry Map

Numerical Hydrodynamic Model

Bathymetry Map of Majuro Atoll

Majuro Lagoon Backscatter Mosaic

Potential Habitat Map of Majuro Lagoon(no ground truthing & not detailed)

Land

Areas dominated with Halimeda mounds

Coral heads

Sediment covered outcrops/subcrops

Flat fine to medium sand

Sediment aprons

Bathymetry Mapping

Official Marine Chart of Niutao, Tuvalu

Bathymetry Map of Efate, Vanuatu

• 20 years of ship sounding data were merged with high-resolution nearshore multibeam data to compile a 50 m Digital Terrain Model

DTM of Efate Data Sources

Bathymetry of Efate, Vanuatu

3D perspective view of Efate. 4x vertical exaggeration

Bathymetry Map of Samoa

3D perspective view of Upolu and Savai’i

Growing Map and Spatial Data Repositoryhttp://geonetwork.sopac.org

2011: Marine surveys in Tongatapu, TO; Mangaia, CK; Rangiroa, FP

Application to Fisheries Management

Bonefish Fishery Management Plan for Aitutaki

• Catch and Release Fishing in Aitutaki: Sport Fishing Workshop 16-23 June, SPC & MMR

• Bathymetry and habitat maps used to identify areas suitable for bonefish fly-fishing

Fish Aggregation Devices• Focus on food-security & climate

change adaptation• Recent deployments in Kiribati,

Samoa, Marshall Islands, Nauru• Planned deployments in Solomon

Islands and Tuvalu

Marine Habitat Mapping and Numerical Modellingan underutilised tool for fisheries and marine ecosystem management in

PICTs

• Funafuti, Tuvalu. Data holdings include bathymetry, water elevation, wave and current velocities, seismic subbottom profiles, sediment samples, satellite imagery, computer model, etc. , etc.

Previously limited understanding Collective wealth of information forms

the basis for management tools