Transcript Fishing - Teacher Pages

Overfishing and Extinction: Gone
Fishing, Fish Gone (1)
• Fishery: concentration of a particular wild aquatic species
suitable for commercial harvesting in a specific area
• Fishprint: area of ocean needed to sustain the fish
consumption of a person, country, or the world
• Marine and freshwater fish
• Threatened with extinction by human activities more than any
other group of species
• Bycatch-non target species that are caught up in nets and
discarded
Overfishing and Extinction: Gone
Fishing, Fish Gone (2)
Commercial extinction: no longer economically
feasible to harvest a species
• Collapse of the Atlantic cod fishery and its domino
effect (put 40,000 people out of work in
Newfoundland)
• Fewer larger fish (lowered trophic levels)
• More problems with invasive species
Natural Capital Degradation: Collapse of the
Cod Fishery Off the Canadian Coast
Fig. 11-7, p. 257
Major Types of commerically
harvested marine fish and shellfish
• Demersal (mostly bottom dwelling):
• Hake, Haddock, Cod
• Pelagic (surface dwelling):
• Sardines, anchovy, herring, mackerel, tuna
• Crustaceans:
• Krill, shrimp, lobster, crab
• Mollusks:
• Oysters, clam, octopus, squid
Case Study: Industrial Fish Harvesting
Methods
• Trawler fishing
• Purse-seine fishing
• Longlining
• Drift-net fishing
• Bycatch problem
11-3 How Should We Manage and
Sustain Marine Fisheries?
Concept 11-3 Sustaining marine fisheries will require
improved monitoring of fish and shellfish populations,
cooperative fisheries management among communities
and nations, reduction of fishing subsidies, and careful
consumer choices in seafood markets.
Estimating and Monitoring Fishery
Populations Is the First Step
• Maximum sustained yield (MSY): traditional
approach (difficult can it can change often)-the
MOST that can be taken
• Optimum sustained yield (OSY)-usually set lower
than the max sust. Yield to ensure future populations
• Multispecies management
• Large marine systems: using large complex computer
models
• Precautionary principle
Some Communities Cooperate to
Regulate Fish Harvests
• Community management of the fisheries
• Co-management of the fisheries with the
government
• Government sets quotas for species and divides the
quotas among communities
• Limits fishing seasons
• Regulates fishing gear
Government Subsidies Can Encourage
Overfishing
• Governments spend 30-34 billion dollars per year
subsidizing fishing
• Often leads to overfishing
• Discourages long-term sustainability of fish
populations
Consumer Choices Can Help to Sustain Fisheries
and Aquatic Biodiversity
• Need labels to inform consumers how and where
fish was caught
• 1999: Marine Stewardship Council (MSC)
• Certifies sustainably produced seafood
• Proper use of sustainable aquaculture
• Plant eating fish best -- Tilapia
Solutions: Managing Fisheries
Fig. 11-11, p. 267
Aquaculture
• Fish farming-involves cultivating fish in a controlled
environment, often a coastal or inland pond, lake,
reservoir, rice paddy
• Fish ranching-holding anadromous species (salmonlive part of life in fresh water and part in salt water)
in captivity for a few years, releasing them, and then
harvesting them as adults when they return to
spawn
Fish Farm
Benefits of Aquaculture
• High yield in small volume of water
• Increased yield through crossbreeding and genetic
engineering
• Can reduce overharvesting of wild populations
• Little use of fuel
• Profits not tied to price of oil
• High profits
Disadvantages to Aquaculture
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Large inputs of land, feed, and water needed
Large concentration of wastes
Destroys coastal ecosystems like mangroves
Increased grain production needed to feed some
species
• Fish can be contaminated or killed from pesticide
runoff
• Dense populations vulnerable to disease (which
could escape into wild populations)
• Areas become too contaminated to use after approx.
5 years
Legal Protection of Some Endangered and
Threatened Marine Species (2)
• 1975 Convention on International Trade in
Endangered Species
• 1979 Global Treaty on Migratory Species
• U.S. Marine Mammal Protection Act of 1972
• U.S. Endangered Species Act of 1973
• U.S. Whale Conservation and Protection Act of 1976
• 1995 International Convention on Biological Diversity