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 (salmon-live 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

• 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