Chapter 13 Sustaining Aquatic Food Resources and Biodiversity

Chapter 13Chapter 13

Sustaining Aquatic Food Sustaining Aquatic Food Resources and Resources and

BiodiversityBiodiversity

Chapter Overview QuestionsChapter Overview Questions

What do we know about aquatic biodiversity, What do we know about aquatic biodiversity, and what is its economic and ecological and what is its economic and ecological importance?importance?

How are human activities affecting aquatic How are human activities affecting aquatic biodiversity?biodiversity?

How can we protect and sustain marine How can we protect and sustain marine biodiversity?biodiversity?

How can we manage and sustain the world’s How can we manage and sustain the world’s marine fisheries?marine fisheries?

Chapter Overview Questions (cont’d)Chapter Overview Questions (cont’d)

How can we protect, sustain, and restore How can we protect, sustain, and restore wetlands?wetlands?

How can we protect, sustain, and restore How can we protect, sustain, and restore lakes, rivers, and freshwater fisheries?lakes, rivers, and freshwater fisheries?

Core Case Study: A Biological Roller Core Case Study: A Biological Roller Coaster Ride in Lake VictoriaCoaster Ride in Lake Victoria

Lake Victoria has lost their endemic fish Lake Victoria has lost their endemic fish species to large introduced predatory fish.species to large introduced predatory fish.

Figure 12-1Figure 12-1

Core Case Study: A Biological Roller Core Case Study: A Biological Roller Coaster Ride in Lake VictoriaCoaster Ride in Lake Victoria

Reasons for Lake Victoria’s loss of Reasons for Lake Victoria’s loss of biodiversity:biodiversity: Introduction of Nile perch.Introduction of Nile perch. Lake experienced algal blooms from nutrient Lake experienced algal blooms from nutrient

runoff.runoff. Invasion of water hyacinth has blocked sunlight Invasion of water hyacinth has blocked sunlight

and deprived oxygen.and deprived oxygen. Nile perch is in decline because it has eaten its Nile perch is in decline because it has eaten its

own food supply.own food supply.

AQUATIC BIODIVERSITYAQUATIC BIODIVERSITY

We know fairly little about the biodiversity of We know fairly little about the biodiversity of the world’s marine and freshwater systems.the world’s marine and freshwater systems. The greatest marine biodiversity occurs in coral The greatest marine biodiversity occurs in coral

reefs, estuaries and the deep ocean floor.reefs, estuaries and the deep ocean floor. Biodiversity is higher near the coast and surface Biodiversity is higher near the coast and surface

because of habitat and food source variety.because of habitat and food source variety. The world’s marine and freshwater systems The world’s marine and freshwater systems

provide important ecological and economic provide important ecological and economic services.services.

HUMAN IMPACTS ON AQUATIC HUMAN IMPACTS ON AQUATIC BIODIVERSITYBIODIVERSITY

Human activities have destroyed, disrupted Human activities have destroyed, disrupted or degraded a large proportion of the world’s or degraded a large proportion of the world’s coastal, marine and freshwater ecosystems.coastal, marine and freshwater ecosystems. Approximately 20% of the world's coral reefs Approximately 20% of the world's coral reefs

have been destroyed.have been destroyed. During the past 100 years, sea levels have risen During the past 100 years, sea levels have risen

10-25 centimeters.10-25 centimeters. We have destroyed more than 1/3 of the world’s We have destroyed more than 1/3 of the world’s

mangrove forests for shipping lanes.mangrove forests for shipping lanes.


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



Harmful invasive species are an increasing Harmful invasive species are an increasing threat to marine and freshwater biodiversity.threat to marine and freshwater biodiversity. Bioinvaders are blamed for about 2/3 of fish Bioinvaders are blamed for about 2/3 of fish

extinctions in the U.S. between 1900-2000.extinctions in the U.S. between 1900-2000. Almost half of the world’s people live on or Almost half of the world’s people live on or

near a coastal zone and 80% of ocean water near a coastal zone and 80% of ocean water pollution comes from land-based human pollution comes from land-based human activities.activities.

Population Growth and PollutionPopulation Growth and Pollution

Each year plastic Each year plastic items dumped from items dumped from ships and left as ships and left as litter on beaches litter on beaches threaten marine threaten marine life.life.


Overfishing and Extinction: Overfishing and Extinction: Gone Fishing, Fish GoneGone Fishing, Fish Gone

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

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

Why is it Difficult to Protect Aquatic Why is it Difficult to Protect Aquatic Biodiversity?Biodiversity?

Rapid increasing human impacts, the Rapid increasing human impacts, the invisibility of problems, citizen unawareness, invisibility of problems, citizen unawareness, and lack of legal jurisdiction hinder protection and lack of legal jurisdiction hinder protection of aquatic biodiversity.of aquatic biodiversity. Human ecological footprint is expanding.Human ecological footprint is expanding. Much of the damage to oceans is not visible to Much of the damage to oceans is not visible to

most people.most people. Many people incorrectly view the oceans as an Many people incorrectly view the oceans as an

inexhaustible resource.inexhaustible resource.

PROTECTING AND SUSTAINING PROTECTING AND SUSTAINING MARINE BIODIVERSITYMARINE BIODIVERSITY

Laws, international treaties, and education Laws, international treaties, and education can help reduce the premature extinction of can help reduce the premature extinction of marine species.marine species.

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

much money as the sale of turtle products.much money as the sale of turtle products.


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


Case Study: The Florida Manatee and Case Study: The Florida Manatee and Water HyacinthsWater Hyacinths

Manatee can eat Manatee can eat unwanted Water unwanted Water Hyacinths.Hyacinths.

Endangered due to:Endangered due to: Habitat loss.Habitat loss. Entanglement from fishing Entanglement from fishing

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

Figure 12-BFigure 12-B

Case Study: Commercial WhalingCase Study: Commercial Whaling

After many of the After many of the world’s whale world’s whale species were species were overharvested, overharvested, commercial commercial whaling was whaling was banned in 1960, banned in 1960, but the ban may but the ban may be overturned.be overturned.


Case Study: Case Study: Commercial WhalingCommercial Whaling

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

commercially.commercially.


Fig. 12-5, p. 258

Toothed whales Sperm whale with squid

Killer whale

NarwhalBottlenose dolphin

Baleen whales

Blue whale

Fin whaleBowhead whale

Right whale

Sei whaleHumpback whale

Gray whale

Minke whale

How Would You Vote?How Would You Vote?

Should carefully controlled commercial Should carefully controlled commercial whaling be resumed for species with whaling be resumed for species with populations of 1 million or more?populations of 1 million or more? No. The hunting of whales is no longer No. The hunting of whales is no longer

necessary and simply encourages disrespect for necessary and simply encourages disrespect for these intelligent giants.these intelligent giants.

Yes. Some whale species have recovered and Yes. Some whale species have recovered and products from them are valuable resources for products from them are valuable resources for humans. humans.


Fully protected marine reserves make up less Fully protected marine reserves make up less than 0.3% of the world’s ocean area.than 0.3% of the world’s ocean area. Studies show that fish populations double, size Studies show that fish populations double, size

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

Some communities work together to develop Some communities work together to develop integrated plans for managing their coastal integrated plans for managing their coastal areas.areas.

Revamping Ocean PolicyRevamping Ocean Policy

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

ecosystem function.ecosystem function. Increase public awareness.Increase public awareness.

MANAGING AND SUSTAINING MANAGING AND SUSTAINING MARINE FISHERIESMARINE FISHERIES

There are a number of ways to manage There are a number of ways to manage marine fisheries more sustainably and protect marine fisheries more sustainably and protect marine biodiversity.marine biodiversity.

Some fishing communities regulate fish Some fishing communities regulate fish harvests on their own and others work with harvests on their own and others work with the government to regulate them.the government to regulate them. Modern fisheries have weakened the ability of Modern fisheries have weakened the ability of

many coastal communities to regulate their own many coastal communities to regulate their own fisheries.fisheries.

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

PROTECTING, SUSTAINING, AND PROTECTING, SUSTAINING, AND RESTORING WETLANDSRESTORING WETLANDS

Requiring government permits for filling or Requiring government permits for filling or destroying U.S. wetlands has slowed their destroying U.S. wetlands has slowed their loss, but attempts to weaken this protection loss, but attempts to weaken this protection continue.continue.


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

Case Study: Case Study: Restoring the Florida EvergladesRestoring the Florida Everglades

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

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

Restoring the Restoring the Florida Florida

EvergladesEverglades

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


PROTECTING, SUSTAINING, AND PROTECTING, SUSTAINING, AND RESTORING LAKES AND RIVERSRESTORING LAKES AND RIVERS

Lakes are difficult to manage and are Lakes are difficult to manage and are vulnerable to planned or unplanned vulnerable to planned or unplanned introductions of nonnative species.introductions of nonnative species.

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

Asian carp. Asian carp.


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

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

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

spawning grounds.spawning grounds.

How Would You Vote?How Would You Vote?

Should federal efforts to rebuild wild salmon Should federal efforts to rebuild wild salmon populations in the Columbia River Basin be populations in the Columbia River Basin be abandoned?abandoned? a. No. Restoring salmon populations is critical for the a. No. Restoring salmon populations is critical for the

environmental health of the river and surrounding environmental health of the river and surrounding forests.forests.

b. Yes. The restoration program would create b. Yes. The restoration program would create unnecessary and severe economic hardships for unnecessary and severe economic hardships for local residents. local residents.


We can help sustain freshwater fisheries by We can help sustain freshwater fisheries by building and protecting populations of building and protecting populations of desirable species, preventing over-fishing, desirable species, preventing over-fishing, and decreasing populations of less desirable and decreasing populations of less desirable species.species.

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

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Chapter 13 Sustaining Aquatic Food Resources and Biodiversity