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Fisheries and Fishing Techniques. Overfishing. What is overfishing? What leads to overfishing?. Marine fisheries systems mainly exploit… shelves surrounding continents, to depth of 200 m d eeper waters of tropical, temperate, polar areas Fisheries affect marine environments by…
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Overfishing • What is overfishing? • What leads to overfishing?
Marine fisheries systems mainly exploit… • shelves surrounding continents, to depth of 200 m • deeper waters of tropical, temperate, polar areas • Fisheries affect marine environments by… • changing ecosystem biodiversity and functioning • changing habitats (ex: bottom trawling)
Fishing over the centuries • Humans have been fishing for millennia. • At first, only fish with narrow coastal ranges were at risk of being overfished. • Distance offshore and storms prevented the overexploitation of most marine species.
Central Case: collapse of the cod fisheries • No fish has more impact on human civilization than the Atlantic cod • Eastern Canadians and U.S. fishermen have fished for cod for centuries
End of the Line: Part 1 - Cod • Watch the following clip to learn what happened to cod. • http://www.filmeducation.org/theendoftheline/key_scene_analysis.html
End of the Line: Part 2 Fishing Technology • Watch the following clip to learn how technology has impacted modern fishery practices. • http://www.filmeducation.org/theendoftheline/technology.html
How have things changed? • The Industrial Revolution led to… • steam trawlers • diesel engines • hydraulic winches • inboard refrigeration • echo-sounders • access to real-time oceanographic data • From what you saw in the video, how have these technologies impacted fishing?
'The thing is we're too good right now. Technologically, not a single hunted animal on this earth has a chance.' Professor Jeffrey Hutchings What can be done?
Fishing has industrialized • Factory fishing = highly industrialized, huge vessels use powerful technologies to capture fish in huge volumes • Even process and freeze their catches while at sea • Driftnets– type of gillnet (fish swim into it, gills catch and fish cannot swim out) for schools of herring, sardines, mackerel, sharks • Longline fishing for tuna and swordfish • Trawling: Pelagic trawling – middle water for anchovies, tuna, mackerel • Benthic trawling – bottom trawling for halibut, flounder
Purse-Seine target species • Yellowfin Tuna • Porpoise by-catch
Small traps baited with fish which are set down on the seabed to catch crabs, lobsters and other seafloor life.
End of the Line: Part 3Subsistence Fishing • What other impacts do technological impacts have? • Societal • Economic • http://www.filmeducation.org/theendoftheline/senegal.html
But I don’t see a problem . . . • Why has global catch been stable? • Fishing fleets can reach less-fished portions of the ocean • Fleets spend more time fishing and have been setting out more nets and lines • Improved technologies mean we catch more fish
End of the Line: Part 4Fish Farming • What about ‘farming fish’? • http://www.filmeducation.org/theendoftheline/fish_farming.html • Watch to learn about some of the benefits and risks to fish farming. • Are there other options?
Issues • >30% U.S. fish stocks are overexploited • For >30% of the rest, insufficient information to determine status • As one species becomes more rare, fishermen turn to smaller, once-discarded species: “fishing down the food web” – causes changes in age structure and genetics of populations
…Issues • NW: • >72,000 jobs lost due to decreasing salmon populations • $500 million lost • N Atlantic: • 20,000 jobs lost in 1990’s due to cod fishery collapse • $350 million lost
End of the Line: Part 5 Marine Reserves • How do we preserve the ocean’s fisheries? • http://www.filmeducation.org/theendoftheline/marine_reserves.html • Watch to see how reserves might work.
How do reserves work? • Increase fish biomass / total catch • Increase fish size • Decrease mortality and habitat destruction • Protect species spread outside reserves • Improve fishing and ecotourism • Others? • Any risks or disadvantages?
Magnusen-Stevens Fishery Conservation and Management Act of 1976 • Established the 200-mile Exclusive Economic Zone (EEZ) to eliminate foreign competition • Conserve fishery resources • Promote fishing in line with conservation principles • Regional Fishery Management Councils (RFMC’s) to steward fisheries resources • Scientific and Statistical Committees (SSC) to provide information for managers, but RFMC’s not required to follow their advice: overfishing and slow recovery of overfished stocks
Exclusive Economic Zone (EEZ) • Countries have the rights to manage and extract resources from an area 200 nautical miles off the coast of its land • Will include the continental shelf if it extends beyond 200 nautical miles. • Can overlap, leading to dispute! • Cod Wars: UK and Iceland • Areas outside of the EEZ are fair game for countries to fish
Related Law: Marine Mammal Protection Act (MMPA) • Prohibits “take” of marine mammals in U.S. waters or in international waters • Prohibits importing of marine mammals • Boats must not disturb marine mammals and must keep at least 100 yards from whales • Some exemptions for traditional Native American whaling • Killer Whales, gray whales, dolphins, seals, polar bears, dugong, manatees, walrus
Exit ticket • What is wrong with the global fisheries situation? • What are some solutions to the global fisheries situation? • What strikes YOU the most about what you learned today?