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Area IV: Land and Water Use

Area IV: Land and Water Use

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Area IV: Land and Water Use

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  1. Area IV: Land and Water Use IVF: Fishing

  2. 14-8 Catching and Raising More Fish fisheries are the third major food-producing system ~55% of annual commercial catch from ocean ~45% from use of aquaculture to raise marine and freshwater fish fish and shellfish provide about 7% of the global food supply and are the primary source of animal protein for about 1 billion people, primarily in developing countries

  3. Fig. 14-23 Fish and shellfish

  4. Fig. 14-24 Fishing methods

  5. 14-8 Catching and Raising More Fish commercial marine fishing is an industry that uses high tech methods to locate and harvest fish and shellfish trawler fishing is used to catch fish and shellfish that live on or near the ocean floor; often destroys bottom habitats and catches wrong animals purse-seine fishing catches surface living species such as tuna, mackerel, anchovies, and herring; has killed large numbers of dolphins

  6. 14-8 Catching and Raising More Fish commercial marine fishing, cont. long lining involves putting out lines up to 80 miles long with thousands of hooks; used for open ocean fish like tuna, shark, and swordfish but also catches sea turtles, birds, pilot whales, and dolphins drift-net fishing can lead to overfishing of the desired species and may trap large numbers of unwanted fish, marine mammals; UN ban on drift nets longer than 1.6 miles in int’l waters reduced use of this technique, but increased use of long-lines

  7. 14-8 Catching and Raising More Fish commercial fish amounts have been declining since 1980 the world’s commercially valuable marine fish are already being overfished too little fish have been left to provide breeding stock commercial extinction means that it is not profitable to hunt a particular species; it has almost been eradicated by overfishing

  8. 14-8 Catching and Raising More Fish commercial fish amounts have been declining since 1980, cont. man has contributed to fish decline by degrading environment, destroying habitat, and polluting wetlands, estuaries, coral reefs, salt marshes, and mangroves commercial species may be able to come back but will need protection by fishing quotas, restricted use of particular fishing gear/methods, and limits on fishing boats, etc.

  9. Fig. 14-25a Total world fish catch

  10. Fig. 14-25b World fish catch per capita

  11. 14-8 Catching and Raising More Fish government subsidies, price controls, low-interest loans, and grants for fishing gear are major causes of overfishing; some of the money could be shifted to buying out some fishing boats and retraining crews aquaculture is the process of raising fish and shellfish for food like crops, rather than harvesting them in the seas and inland waters

  12. 14-8 Catching and Raising More Fish aquaculture, cont. cultivates fish in a controlled environment and harvests them at a particular size holds species in fenced-in areas during the time they live in saltwater and then releases them to harvest as they spawn in freshwater growing single-celled cyanobacteria has been proposed; Spirulina is 70% protein raising large, carnivorous fish in farms could deplete smaller fish species used to feed them

  13. 13-4 Managing and Sustaining Fisheries There are many ideas of how to sustainably manage fisheries and preserve biodiversity management has been based on maximum sustainable yield (MSY) problems 1. difficult to measure fish stocks and growth rates 2. based on catches (can be unreliable) 3. effects on other fish species 4. difficult to enforce

  14. 13-4 Managing and Sustaining Fisheries new idea: optimum sustainable yield (OSY) takes into account effects on other species still based on poorly understood biology and inadequate data apply the precautionary principle government regulation of access to fisheries for example, individual transfer quotas (ITQs)

  15. Solutions Managing Fisheries Fishery Regulations Set catch limits well below the maximum sustainable yield Improve monitoring and enforcement of regulations Economic Approaches Sharply reduce or eliminate fishing subsidies Charge fees for harvesting fish and shellfish from publicly owned offshore waters Certify sustainable fisheries Protected 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 seabirds 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 Figure 13-9Page 263