Chapter 12 Sustaining Aquatic Biodiversity 2006 4 GRoundfish

Chapter 12 Sustaining Aquatic Biodiversity 2006 #4 GRoundfish harvest. pdf

Core Case Study: A Biological Roller Coaster Ride in Lake Victoria • Lake Victoria has lost their endemic fish species to large introduced predatory fish. Figure 12 -1

Core Case Study: A Biological Roller Coaster Ride in Lake Victoria • Reasons for Lake Victoria’s loss of biodiversity: – Introduction of Nile perch. – 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 • We know fairly little about the biodiversity of the world’s marine and freshwater systems. – The greatest marine biodiversity occurs in coral reefs, estuaries and the deep ocean floor. – Biodiversity is higher near the coast and surface because of habitat and food source variety. • The world’s marine and freshwater systems provide important ecological and economic services.

HUMAN IMPACTS ON AQUATIC BIODIVERSITY • Human activities have destroyed, disrupted or degraded a large proportion of the world’s coastal, marine and freshwater ecosystems. – Approximately 20% of the world's coral reefs have been destroyed. – During the past 100 years, sea levels have risen 10 -25 centimeters. – We have destroyed more than 1/3 of the world’s mangrove forests for shipping lanes.

HUMAN IMPACTS ON AQUATIC BIODIVERSITY The Deep Sea Conservation Coalition - Multimedia • Area of ocean before and after a trawler net, acting like a giant plow, scraped it. Figure 12 -2

HUMAN IMPACTS ON AQUATIC BIODIVERSITY • Harmful invasive species are an increasing threat to marine and freshwater biodiversity. – Bioinvaders are blamed for about 2/3 of fish extinctions in the U. S. between 19002000. • Almost half of the world’s people live on or near a coastal zone and 80% of ocean water pollution comes from land-based human activities.

Population Growth and Pollution • Each year plastic items dumped from ships and left as litter on beaches threaten marine life. Pollution Stock Footage - SD to HD High Definition Pollution Video Clips at Ocean Footage Figure 12 -3

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.

Fish farming in cage Trawl flap Trawler fishing Spotter airplane Sonar Purse-seine fishing Trawl lines Fish school Trawl bag Long line fishing Drift-net fishing Float Buoy Lines with hooks Deep sea aquaculture cage Fish caught by gills Fig. 12 -A, p. 255

Dolphins caught in purse seine net

Whale caught in drift net

Turtle caught in drift net

PROTECTING AND SUSTAINING MARINE BIODIVERSITY • Laws, international treaties, and education can help reduce the premature extinction of marine species. • 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.

PROTECTING AND SUSTAINING MARINE BIODIVERSITY • Six of the world’s seven major turtle species are threatened or endangered because of human activities. Figure 12 -4

Case Study: 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

Case Study: Commercial Whaling • After many of the world’s whale species were overharvested, commercial whaling was banned in 1960, but the ban may be overturned. Figure 12 -6

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. Video: Japanese Hunt Humpback Whales Tradition: Inuit Whale hunting | Versus Country Videos Figure 12 -5

Solutions Managing Fisheries Fishery Regulations Bycatch Set catch limits well below the maximum sustainable yield Use wide-meshed nets to allow escape of smaller fish Improve monitoring and enforcement of regulations Economic Approaches Use net escape devices for sea birds and sea turtles Sharply reduce or eliminate fishing subsidies Ban throwing edible and marketable fish back into the sea Aquaculture Charge fees for harvesting fish and shellfish from publicly owned offshore waters Restrict coastal locations for fish farms Certify sustainable fisheries Protected Areas Control pollution more strictly Establish no-fishing areas Depend more on herbivorous fish species Establish more marine protected areas Nonnative Invasions Rely more on integrated coastal management Kill organisms in ship ballast water Consumer Information Label sustainably harvested fish Publicize overfished and threatened species Filter organisms from ship ballast water Dump ballast water far at sea and replace with deep-sea water Fig. 12 -7, p. 261

PROTECTING, SUSTAINING, AND RESTORING WETLANDS • Requiring government permits for filling or destroying U. S. wetlands has slowed their loss, but attempts to weaken this protection continue. Figure 12 -8

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 Fig. 12 -9, p. 264

Case Study: 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, SUSTAINING, AND RESTORING LAKES AND RIVERS • Lakes are difficult to manage and are vulnerable to planned or unplanned introductions of nonnative species. • 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, SUSTAINING, AND RESTORING LAKES AND RIVERS • We can help sustain freshwater fisheries by building and protecting populations of desirable species, preventing over-fishing, and decreasing populations of less desirable species. • 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).

Natural Capital Ecological Services of Rivers • Deliver nutrients to sea to help sustain coastal fisheries • Deposit silt that maintains deltas • Purify water • Renew and renourish wetlands • Provide habitats for wildlife Fig. 12 -11, p. 267

Video: Humpback Whales PLAY VIDEO

Video: Loggerhead Turtles PLAY VIDEO

Video: Salmons Swimming Upstream PLAY VIDEO