Sustaining Aquatic Biodiversity

Lake Victoria

lost endemic fish species due to large introduced predatory fish.

Clogged with water hyacinth

Reasons for Lake Victoria’s loss of biodiversity:

Introduction of Nile perch for sport fishing• Ate majority of other fish

Lake experienced algal blooms from nutrient runoff.

Invasion of water hyacinth has blocked sunlight and deprived oxygen.

Nile perch is in decline because it has eaten its own food supply.

AQUATIC BIODIVERSITY

3 general patterns The greatest marine biodiversity occurs in:

• coral reefs, • estuaries• ocean floor.

Biodiversity is higher near the coast than open sea because of habitat and food source variety

Biodiversity is higher is higher on the ocean bottom than surface

AQUATIC BIODIVERSITY

Provides important ecological and economic services. Twice that of cropland

About ½ world’s population relies on ocean for main food source.

Chemical compounds: many medical uses Antibiotic, anticancer, hypertension, bone

reconstruction

HUMAN IMPACTS ON AQUATIC BIODIVERSITY

Human activities have destroyed, disrupted or degraded a large proportion of the world’s coastal, marine and freshwater ecosystems.

H – habitat loss I – invasive species P – population growth P – pollution C – climate change O – overharvesting

Habitat Destruction Coral reef

Approximately 20% of the world's coral reefs have been destroyed.

58% severely damaged Sea grass & kelp beds

Provides habitat, food source, erosion protection Disappearing at alarming rate

Habitat Destruction Mangrove Forests

We have destroyed more than 1/3 of the world’s mangrove forests

Critical for habitat, beach erosion protection, storm surge protection, & flood control

Habitat Destruction Coastal Wetlands

We have destroyed more than 1/2 Mainly beach development: houses, resorts Critical for habitat, beach erosion protection,

storm surge protection, & flood control

Habitat Destruction

Ocean bottom Being destroyed by dredging and trawler fishing

boats “Plowing” the sea bed Takes decades to centuries to recover Scientists call it the most destructive fishing

practice

Figure 12-2

HUMAN IMPACTS

Area of ocean before and after a trawler net, acting like a giant plow, scraped it.

Figure 12-2

Invasive Species Invasive species are an increasing threat

Arrive in ballast from ships, dumped aquariums, or intentional released

Bioinvaders are blamed for about 2/3 of fish extinctions in the U.S. between 1900-2000.

Asian Swamp Eel: rapid reproduction, burrows into mud banks, wriggles across dry land

Purple Loosestrife: called purple plague, spreads rapidly

Population Growth and Pollution Almost 1/2 of world’s people live on or near

a coastal zone 80% of ocean water pollution comes from

land-based human activities. Fertilizer runoff causes algae blooms & fish die-

offs Industrial waste Trash

Population Growth and Pollution Each year plastic items dumped from ships

and left as litter on beaches threaten marine life.

Climate Change

Ocean levels rising Melting ice Thermal expansion of water

Changing weather patterns More rain in some / less rain in other Flooding / drought

Increased frequency & intensity of storms

Climate Change Ocean Levels

During the past 100 years, sea levels have risen 10-25 centimeters.

Levels are predicted to continue to rise Coastal cities at risk Maldives

• Low lying chain of islands in Indian ocean• Threat of being submerged

Several decades of overfishing in all of the world’s oceans has pushed commercially important species, e.g. cod, into steep declines from which recovery is unlikely.

In 1992, Canada’s 500 year old cod fishery collapsed, destroying 40,000 jobs

Total ban on fishing Stocks still have not recovered

Overfishing

Fishing fleet

Fish market, Norway

Fishery- a commercially harvestable population of fish within a particular ecological region.

Fishery collapse- the decline of a fish population by 90% or more.

Bycatch- unintentional catch of non-target species.

Harvesting of Fish and Shellfish

Summary

Marine fisheries are an important biological and cultural resource

Significant numbers of stocks are overexploited or depleted

Overfishing is a major cause for the decline of marine fisheries

Traditional fisheries management has not resulted in sustainable fisheries

New approaches include both market-based and ecosystem-based solutions

NOAA Photo Library / OAR/National Undersea Research Program (NURP); Alaska Department of Fish and Game

What is a fishery?

The resource (fish species) The habitat The people involved

NOAA Photo Library ARC Centre of Excellence for Coral Reef Studies / Marine Photobank NOAA Photo Library –Kip Evans

Most fish are harvested within 200 miles of shore

Upwellings Continental shelves Estuaries

NEFSC (NOAA) NASA, MODIS Rapid Response Team

Sustainable Yields

The maximum sustainable yield (MSY) has been exceeded by too many vessels catching too many fish, especially fish of reproductive age, often using wasteful and destructive methods Bycatch: unwanted species thrown back into sea

dead or dying

Modern industrial fishing can cause 80% depletion of a species in 10-15 years

NCSR

The build up of large scale fishing fleets has contributed to widespread overfishing and damage to the marine environment.

Bottom trawls and dredges cause large scale physical damage to the sea floor. Sea mounts are particularly vulnerable.

Lost fishing gear (particularly drift nets) threatens marine life, including birds and mammals that are non-target species.

Purse seines can catch whole schools of fish and non-target species (bycatch)

Drift net

Purse seine

Overfishing

Fig. 12-A, p. 255

Fish farming in cage

Trawler fishing

Spotter airplane

Sonar

Trawl flap

Trawl lines

Purse-seine fishing

Trawl bagFish school

Drift-net fishingLong line fishing

Lines with hooks

Fish caught by gills

Deep sea aquaculture cage

Float Buoy

Status of Marine Fisheries

• In 2004, 52% of world fish stocks were fully exploited, 25% were overexploited or depleted

• Large predatory fish have declined globally by 90%

• At least 42% of U.S. fisheries are being overexploited

UNFAO– Antonio Pais

Fisheries Collapses

Atlantic cod

Atlantic salmon

Pacific sardine

Haddock

Atlantic halibut

Peruvian anchovy

Bluefin Tuna

Collapse of the Atlantic Cod Fishery off Newfoundland

Millennium Ecosystem Assessment

Causes for Marine Fishery Declines• OverfishingThe rate of fish mortality (harvest plus

bycatch) exceeds the natural rate

of replacement.

• Highly efficient technologyFishing vessels and gearRadar and sonarElectronic navigationAircraft with infrared sensors

• BycatchThe capture of non-target

fish or other marine animals

in fishing gear

• OvercapacityFishing fleets are larger

than necessary to harvest

the allowable catchNOAA Photo Library – Teobaldo Dioses

Fishing Down the Food Web

The serial harvest of progressively lower trophic levels

Time

Trophic Level

Concept : Daniel Pauly; Artist: Aque Atanacio

Habitat Degradation: the impact of fishing gear

Before trawling

After trawling

Deep-sea Oculina coral reefs off Florida's Atlantic Coast

Overfishing and Extinction: Gone Fishing, Fish Gone

About 75% of the world’s commercially valuable marine fish species are over fished or fished near their sustainable limits. Big fish are becoming scarce. Smaller fish are next. We throw away 30% of the fish we catch. We needlessly kill sea mammals and birds.

Why is it Difficult to Protect Aquatic Biodiversity?

Human ecological footprint is expanding. Much of the damage to oceans is not visible to

most people. Many people incorrectly view the oceans as an

inexhaustible resource. Most of world’s ocean lies outside legal

jurisdiction

PROTECTING MARINE BIODIVERSITY Laws, international treaties, and education

can help reduce the premature extinction of marine species. 1975 CITIES

1979 Global Treaty on Migratory Species 1972 Marine Mammal Protection Act 1973 Endangered Species Act 1976 US Whale Conservation & Protection Act 1995 International Convention on Biological

Diversity 1996 US Sustainable Fisheries Act IWC – International Whaling Commission

The Florida Manatee and Water Hyacinths

Manatee can eat unwanted Water Hyacinths.

Endangered due to: Habitat loss. Entanglement from fishing

lines and nets. Hit by speed boats. Stress from cold. Low reproductive rate

Figure 12-B

Commercial Whaling 8 of 11 species – hunted to commercial

extinction. Blue whale – to brink of biological extinction 1970 – US stopped whaling & banned all

whale imports International Whaling Commission (IWC)

banned commercial whaling in 1986

Case Study: Commercial Whaling

Despite ban, Japan, Norway, and Iceland kill about 1,300 whales of certain species for scientific purposes. Although meat is still sold

commercially. Hope to reverse

international ban

Revamping Ocean Policy

Two recent studies called for an overhaul of U.S. ocean policy and management. Develop unified national policy. Double federal budget for ocean research. Centralize the National Oceans Agency. Set up network of marine reserves. Reorient fisheries management towards

ecosystem function: Catch Limits Increase public awareness.

Market-based Solutions Certification Consumer-based solutions Purchase of fishing rights Aquaculture Increased use of underutilized species Reduce government subsidies

Ecosystem-based Fishery Management

Attempts to sustain healthy marine ecosystems

and the fisheries they support

Reduce bycatch Marine reserves Catch share programs Ecologically sustainable yield

PROTECTING MARINE BIODIVERSITY

Six of the world’s seven major turtle species are threatened or endangered because of human activities.

Since 1989 the U.S. government has required offshore shrimp trawlers to use turtle exclusion devices. Sea turtle tourism brings in almost three times as

much money as the sale of turtle products. Reconciliation ecology

MARINE SANCTUARIES Fully protected marine reserves make up less

than 0.3% of the world’s ocean area. Studies show that fish populations double, size

grows by almost a third, reproduction triples and species diversity increases by almost one fourth.

Call for 30% protected Some communities work together to develop

integrated plans for managing their coastal areas. 1975 Australia’s Great Barrier Reef;1/3 protected

Marine Reserves

Extractive activities (fishing, mining, oil drilling) are prohibited in marine reserves

COMPASS, E. Neeley

Some good news for a change?

Catch Share Programs Limited Access Privilege Programs – LAPPs

Individual Transferable

Quotas (ITQs) can be bought

and sold

Have been used successfully to increase fish

populations and reduce

fisherman’s costs.

UNFAO / NOAA Photo Library / Jose Cort

Bluefin tuna harvest in Spain

Fig. 12-7, p. 261

SolutionsManaging Fisheries

Fishery Regulations

Set catch limits well below the maximum sustainable yield

Improve monitoring and enforcement of regulationsEconomic Approaches

Sharply reduce or eliminate fishing subsidies

Charge fees for harvesting fish and shellfish from publicly owned offshore waters

Certify sustainable fisheriesProtected Areas

Establish no-fishing areas

Establish more marine protected areas

Rely more on integrated coastal management

Consumer Information

Label sustainably harvested fish

Publicize overfished and threatened species

Bycatch

Use wide-meshed nets to allow escape of smaller fish

Use net escape devices for sea birds and sea turtles

Ban throwing edible and marketable fish back into the sea

Aquaculture

Restrict coastal locations for fish farms

Control pollution more strictly

Depend more on herbivorous fish species

Nonnative Invasions

Kill organisms in ship ballast water

Filter organisms from ship ballast water

Dump ballast water far at sea and replace with deep-sea water

• Aquaculture- the farming of aquatic organisms such as fish, shellfish, and seaweeds.

• Raising marine and freshwater fish in ponds and underwater cages

• like a feedlot for fish

Aquaculture

AquacultureChina and India are the world leaders in aquaculture production.

Over 200 fish and shellfish species are grown in aquaculture.

Freshwater fish such as carp and their relatives dominate global production,

the most common marine species include shrimp, salmon, oysters, clams and mussels.

In the U.S., 5 of the top 10 species (shrimp, salmon, catfish, tilapia and clams) consumed in 2004 were at least partially produced in aquaculture operations.

While aquaculture has the potential to reduce pressure on wild-caught fish, this has not yet been realized. Ironically, it may do just the opposite, particularly when fish at higher trophic levels are raised such as bluefin tuna or salmon. These fish require a diet that contains animal protein. When farmed fish are fed fish meal, fishing effort is often required to get enough food to feed these captive fish. To feed fish and shrimp, growers typically rely on wild-caught ocean fish. For example, about 3 metric tons of wild-caught fish are required to produce 1 metric ton of farmed shrimp or salmon.

Despite these shortcomings, aquaculture is likely to play an increasingly important role in meeting the ever-increasing global demand for seafood. Farmed organisms that do not consume fish meal hold the most promise for a sustainable fishery – e.g., mussels, clams, tilapia (an herbivorous fish).

Aquaculture• Pros:

– Efficient: less water/space, more fish, – Potential to take pressure off wild species– Low fuel usage, high profits– Potential sustainable protein source &

economic development

• Cons:– Need feed, water, antibiotics– Produces lots of waste, may destroy estuaries

and wetlands, – need fish to feed fish (lose 90% moving up

trophic level),

– dense populations increase disease & parasites which can spread to wild fish

– bioaccumulation of toxins (PCBs, mercury, dioxins, etc) if benthic soil is contaminated

• Possible solution – aquaculture in the open ocean or way inland

PROTECTING, SUSTAINING, AND RESTORING WETLANDS

US has lost ½ of wetlands Federal permit is required to develop

wetlands – has cut wetland loss by 80% Attempts by developers to weakened this law Mitigation – allows destruction of existing

wetland as long as equal area of same type is created or restored

Figure 12-8

Fig. 12-9, p. 264

Solutions

Protecting Wetlands

Legally protect existing wetlands

Steer development away from existing wetlands

Use mitigation banking only as a last resort

Require creation and evaluation of a new wetland before destroying an existing wetland

Restore degraded wetlands

Try to prevent and control invasions by nonnative species

Restoring the Florida Everglades

The world’s largest ecological restoration project involves trying to undo some of the damage inflicted on the Everglades by human activities. 90% of park’s wading birds have vanished. Other vertebrate populations down 75-95%. Large volumes of water that once flowed through

the park have been diverted for crops and cities. Runoff has caused noxious algal blooms.

Restoring the Florida

Everglades

The project has been attempting to restore the Everglades and Florida water supplies.

Figure 12-10

PROTECTING LAKES AND RIVERS

For decades, invasions by nonnative species have caused major ecological and economic damage to North America’s Great lakes. Sea lamprey, zebra mussel, quagga mussel,

Asian carp.

PROTECTING LAKES AND RIVERS

Dams can provide many human benefits but can also disrupt some of the ecological services that rivers provide. 119 dams on Columbia River have sharply

reduced (94% drop) populations of wild salmon. U.S. government has spent $3 billion in

unsuccessful efforts to save the salmon. Removing hydroelectric dams will restore native

spawning grounds.

PROTECTING LAKES AND RIVERS

A federal law helps protect a tiny fraction of U.S. wild and scenic rivers from dams and other forms of development. National Wild and Scenic Rivers Act (1968).

Fig. 12-11, p. 267

• Deliver nutrients to sea to help sustain coastal fisheries

• Deposit silt that maintains deltas

• Purify water

• Renew and renourish wetlands

• Provide habitats for wildlife

Natural Capital

Ecological Services of Rivers