marine resources

Marine ResourcesA. Fisheries


1. 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


1. Clupeoid fishes


2. 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


3. 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)


3. Tunas


4. 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


5. Fishery Yields


5. Fishery Yields

• Overfishing leads to1) Stock depletion

2) Reduced catch rate

3) Capture of smaller individuals

4) Unsustainable harvest

• Biological – Can’t reproduce fast enough

• Economic – Can’t catch enough to make a profit


5. Fishery Yields


6. 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

1) Coastal development eliminates breeding and nursery areas

2) El Niño events and climate change can alter current patterns, water temperature, food supply

3) Bycatch – Organisms caught unintentionally when fishing for target species


6. Overfishing• Bycatch


7. Cyclic Fisheries


8. Managing Resources


9. Mariculture


9. Mariculture

http://mywebpages.comcast.net/kils/atoll11.nvm

marine resources

Documents

sea cucumberbarnacles

gill nets

choice bluefin

respectivelycod populations

extensive cod fisheries

gill rakersform large

tostock depletionreduced

georges bank new england