020-Nekton - Marine Nekton Marine Nekton Nekton Organisms...

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Marine Nekton Marine Nekton
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Nekton Nekton Organisms capable of swimming against a current Fishes Marine mammals Marine reptiles Cephalopods Some crustaceans Sea birds
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Importance of Nekton Importance of Nekton Large nekton can profoundly influence marine communities Important in current or historical harvests Fishes of critical importance to world food supply
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Nektonic Crustacea Nektonic Crustacea Pelagic crabs and shrimp Larger euphausiids Antarctic Krill ( Euphausia superba ) - 5-6 cm long - Dominant food of baleen whales - Increased fishery for livestock and poultry feeds
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Euphausia superba
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Who eats Krill?
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Critical components of Antarctic food webs
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Krill Fishery Annual consumption by natural predators = 470 million MT 1972: Japan and Russia began harvesting krill
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Krill Fishery… Krill Fishery… Potential harvest = 25-30 million MT/yr Economic cost of fishery high Patchy distribution complicates location Depths may be 150-200m Single net haul may collect 10 MT Ecological consequences of removal poorly understood
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Squids Large size range: cm … > 20 m Giant squid ( Architeuthis ): largest invertebrate Water jet propulsion Highly maneuverable and agile Up to 10 m/s Predators consuming 15-20% body mass per day
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Giant Squid ( Architeuthis dux ) One of the largest marine predators Little is known about their ecology Diet: deep-sea fishes, orange roughy, hokie Rapid growth: full size in 3-5 years with a life span of ~7 years Predators: fishes when squid are young, then sperm whales http://evomech7.blogspot.com/2006/12/japan-researchers-film-live-giant.html
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Squid Fisheries Squid Fisheries ~70% of present catch of cephalopods Major source of human food Driftnet fishery began in N. Pacific in 1981 - Driftnets: monofilament panels 8-10 m tall and up to 50 km long - Set at night and allowed to drift while entangling prey
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Driftnets 1989: Japan, Korea, & Taiwan were deploying 800 driftnet vessels in N. Pacific
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This note was uploaded on 04/29/2011 for the course OCN 201 taught by Professor Decarlo,e during the Summer '08 term at University of Hawaii, Manoa.

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020-Nekton - Marine Nekton Marine Nekton Nekton Organisms...

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