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Transcript of Sustaining Aquatic Biodiversity. Lake Victoria lost endemic fish species due to large introduced...
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
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
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).