Notes for Chapter 18:
Changing the Oceans by Harvesting Organisms

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Case History: The Fur Seals that Weren't

         Featured Organisms:
        Southern (or S. American) sea lions
                        More Links: 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8
                        Compare to South American fur seals:
                             1 - 2 - 3 - 4 - 5
                        or southern elephant seals

RQ 18.1: What mistake did Edmund Fanning's company
        make and why did they regret it? Where are the
      Falkland Islands-?

I. Effects of Fishing on Marine Organisms and Communities

    a) Effect of Fishing on Harvested Stocks

RQ 18.2: Briefly explain the typical change observed in a
        fish population's individual size distribution for a
        population that starts off as unexploited and becomes
        increasingly fished. At what point do fisheries
        experts predict that a heavily exploited fish population
        will likely collapse?

    b) Effects of Fishing on Non-Target Species
        terms: groundfish

Visit Source of Image
         Featured Organisms:
         Steller sea lions More Links: 1 - 2 - 3 - 4 - 5 - 6
         Northern fur seals More Links: 1 - 2 - 3 - 4 - 5 - 6
         Harbor sealsMore Links: 1 - 2 - 3 - 4 - 5 - 6 - 7
         Pollock ("seal food"/"fish sticks") More Links: 1 - 2 - 3 - 4

Visit the Source of Above Images

RQ 18.3: Relying on the principles addressed in review question 18.2,
        explain the probable reason why steller sea lion populations have
        more dramatically declined in recent decades than have harbor
        seal or northern fur seal populations.

    c) Effects of Drift Nets and Lost Fishing Gear
        terms: incidental catch (by-catch), drift-net, tans,
            catcher boat, ghost fishing

RQ 18.4: Explain the problem and briefly characterize
        the magnitude of incidental catch caused by drift-net

II. The Marine Harvest

    a) Overfishing
        terms: maximum sustained yield (MSY),
            tonnes (= metric tons), catch per unit effort

RQ 18.5: It seems paradoxical that a maximal total harvest of
        a fisheries stock can be obtained with relatively few
        fishing boats, not with many more fishing boats. Explain
        why in terms of the important theory of maximum
        sustained yield.

    b) The Global Harvest and Maximum Sustained
        Global Yield
        terms: artisanal catch

RQ 18.6: According to rough estimates of global fisheries
        harvest, how close are we to a global MSY level?
        What are a few reasons why simply tallying estimates of
        commercial fisheries harvests worldwide are bound
        to underestimate the global harvest levels?

RQ 18.7: Krill are crustaceans fed on by baleen whales and
        other animals, especially surrounding the Antarctic
        continent. These account for some of the last largely
        unexploited potential sources of food for humans left
        in the sea. What are a few of the many obstacles that
        might make the large-scale commercial harvest of krill
        difficult in the future? If their harvest was to be undertaken,
        what are some possible consequences to non-target species?

    c) Strategies That Offset Declines in Established Fisheries
        terms: high seas

    d) Aquaculture
        terms: salmon ranch, salmon hatcheries

RQ 18.8: Contrast an oyster "raft" farm, a salmon ranch or hatchery,
        and salmon pen (netcage) aquaculture with respect to how each of
        these, in general terms, is a more or less efficient means of
        producing protein for human consumption. Besides there relative
        efficiency, what detrimental environmental consequences might
        be caused by at least one of these methods?

    e) The Significance of the Marine Harvest

RQ 18.9: Briefly characterize the harvest of marine fishes or other
        marine organisms in terms of its global importance. How does
        it compare with the harvest of land animals and plants in terms
        of the amount harvested, the amount of protein supplied, and
        its reliance on farming?

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This page created 5/7/01 © D.J. Eernisse, Last Modified 5/9/01