Marine Resources

Marine Resources • Fisheries

Marine Resources • Fisheries • Clupeoid fishes • Herrings, sardines, anchovies, menhadens, shads • Feed on plankton (use gill rakers) • Form large schools over continental shelves and in upwelling zones • Caught with purse seines • Industrial fisheries - Fish meal (protein supplement in animal feed) - Fish oil (margarine, cosmetics, paint) - Fish flour (protein supplement for humans) - Fertilizers - Pet food

Marine Resources • Fisheries • Clupeoid fishes

Marine Resources • Fisheries • Cods and related fishes • Cods, pollock, haddock, hakes, whiting • Demersal and benthopelagic cold-water fishes • Caught with bottom trawls • Grand Banks (Newfoundland), Georges Bank (New England) and North Sea supported extensive cod fisheries until 1992, 1994, and 2001, respectively • Cod populations crashed; catches plummeted • Ex – North Sea catch • 1971 – 277,000 tonnes • 2001 – 59,000 tonnes

Marine Resources • Fisheries • Tunas • Skipjack, yellowfin, albacore, bigeye, bluefin • Primarily eaten in affluent countries • Can be very expensive (up to $40,000 for a choice bluefin in Tokyo) • Highly migratory species • Caught with purse seines, longlines, gill nets, rod and reel • Often associate with floating objects, dolphin schools • Juveniles caught in purse seines may be finished in net pens (aquaculture)

Marine Resources • Fisheries • Tunas

Marine Resources • Fisheries • Other species • Flatfishes, rockfishes, mackerels, salmon • Mostly coastal • Threatened by coastal pollution, damming of rivers (salmon), overfishing • Flatfishes and rockfishes harvested extensively in US • Salmon farmed heavily in Canada, Chile • Non-finfish • Squid, octopus • Clams, oysters, scallops • Crabs, lobsters • Sea urchin, sea cucumber • Barnacles, jellyfish • Sea turtles, seals, whales

Marine Resources • Fisheries • Fishery Yields

Marine Resources • Fisheries • Fishery Yields • Overfishing leads to • Stock depletion • Reduced catch rate • Capture of smaller individuals • Unsustainable harvest • Biological – Can’t reproduce fast enough • Economic – Can’t catch enough to make a profit

Marine Resources • Fisheries • Fishery Yields

Marine Resources • Fisheries • Overfishing • FAO estimates (2002) • 52% of stocks fully exploited • 15-18% overexploited with no future potential • 9-10% depleted • Ex – Northern bluefin tuna populations in western Atlantic at 10% of former levels • Effects of overfishing exacerbated by other factors • Coastal development eliminates breeding and nursery areas • El Niño events and climate change can alter current patterns, water temperature, food supply • Bycatch – Organisms caught unintentionally when fishing for target species

Marine Resources • Fisheries • Overfishing • Bycatch

Marine Resources • Fisheries • Cyclic Fisheries

Marine Resources • Fisheries • Managing Resources

Marine Resources • Fisheries • Mariculture

Marine Resources