Fisheries, Conservation, and Sustained Yields

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					                    Fisheries, Conservation, and Sustained Yields


1. What is the fisher’s problem?

       The “tragedy of the commons” (1968) -- Garrett Hardin, biologist: “In a
       competitive economy, no market mechanism ordinarily exists to reward
       individual forbearance in the use of shared resources.”

       The problem of the environment (1980) -- Arthur McEvoy, environmental
       historian: “Most fisheries . . . do not behave as neatly as [sustained yield]
       theory suggested because . . . fish live in a complex and constantly changing
       environment.”


2. The California Fisheries: What makes them so productive?

       3 maps

       --ocean: the California current; upwellings of deep, cold, nutrient rich
       water; temperature gradient near Point Conception (support for warm &
       cold water species); kelp forests near shore

       --estuaries: wetlands, nutrient rich

       --rivers: freshwater and anadromous species


3. The California Fisheries: What makes them so fragile?

       --sensitivity of ocean fisheries to changes in temperature and of inshore
       fisheries to changes in temperature and precipitation

       --the inefficiency of some species to reproduce at lower levels of population

       --many warm and cold water ocean species live near their limits on either
       side of the Point Conception divide

       --impact of human activity (predation, pollution, environmental change): re:
       the impact on salmon of overfishing, silt from farming and mining, and dams
       for flood control and irrigation


4. What makes some species of fish more fragile? Less able to survive unsettled
conditions?
Groundfish (halibut, tuna): free swimming, distributed more or less evenly
over their grounds, & grew steadily with increasing age

Schooling fish (sardines): achieve most of their growth during their first two
years of life & aggregate in groups that are distributed unevenly in the ocean.

       Reproductive volatility: their yields vary radically from season to
       season.

       Catchability: with sonar, fishing boats can track and scoop up entire
       schools of fish with large nets


Why did salmon fishing remain viable through World War II and beyond?

       Irony: the construction of Shasta Dam in 1983-42 closed about half of
       the Sacramento River basin’s remaining salmon nurseries. But by
       mitigating the flooding and siltation caused by farming, diking, and
       filling, and by providing a stable flow of cool water during the
       summer, conditions improved for the salmon that spawned in the
       remaining, unobstructed half of the basin.

       Also: cooler weather and additional rainfall during & after World
       War II


Why did albacore tuna fishing remain viable through World War II and
beyond?

       Spectacular migratory range and extreme sensitivity to temperature:
       does best in cool water and congregates near upwelling currents
       where the schooling fishes on which it feeds are abundant.

       Destruction of fur seals in the early 20th century (which in the 1970s,
       when they recovered, ate 7% of the Northern California anchovy
       population each year) left more food for tuna and salmon. (SEE
       CHART)

       Cooler weather allowed tuna to increase near California’s shore
       during and after WW II.
Why did the sardine fishery collapse after World War II?

      2 charts

      Industrial fishing: What made it possible? Profitable? Fossil fuels,
      open ocean vessels & gear, sardine reduction for poultry feed and
      fertilizer. The “Second Industrial Revolution” was critical:
      electricity, organic chemistry [esp. oil], internal combustion engines,
      etc. And a new twist in the 1930s: stationed reduction ships offshore
      – did not have to wait to reach the plants in Monterey Bay and
      elsewhere.

      Japan’s sardine fishery was the largest in the world in the 1930s, but
      it spread over a much larger area and depended on 5 kinds of sardine.
      The California fishery depended on only 1 kind of sardine.

             4/5ths of CA yield went into reduction plants

             Fishmeal 20% cheaper than processed meat scraps & included
             all the proteins that livestock needed, and included chemicals
             that speeded growth. Purchased by all major feed producers:
             Quaker Oats, General Mills, Ralston-Purina, and Globe and
             Taylor.

             Sardine oil cheaper than tallow, and as useful: soap, linoleum,
             shortening, paint

             Huge demand during World War II for livestock feed and to
             feed troops

      The biology of destruction of the sardines

             Pilchards and their relatives school because they cannot hide
             from predators: schooling minimizes losses to attack. Only
             the margins are harmed. The schools aggregate into groups of
             about 5 miles in diameter. BUT: schooling continues even
             when stocks are low. There are fewer schools, and if they are
             identified and netted, the species can be wiped out.

             Sardines migrate great distances between their feeding and
             spawning grounds. The more mature the fish are, the farther
             they migrate north to feed: all the way to British Columbia for
             those older than 3 years. Mature fish convert most of the oil
             they store in their bodies into spawn rather than additional
             body tissues, & they spread their spawn over as large an area
                      as possible to ensure enough larvae found patches of food to
                      survive. A larger, more mature population spawning over a
                      large area thus had the best chance of reproductive success.

                      Problem: the fishery, by depleting the older fish, removed
                      some of the sardine’s natural insurance. And unlike more
                      highly developed species like cod or halibut, for whom greater
                      numbers of spawn survive when the number of adult fish is
                      lower, the survival rate for sardine spawn is independent of the
                      number of adult fish. Ergo: sardines are more vulnerable to
                      fishing.


5. Regulation

       Could not bring back the sardines; could not ensure sustained yields because
       of the variability of fish populations


6. Global fishing in the late 20th century

       The global catch for food, fertilizer, and animal feed: more taken in two
       years than in entire 19th century

       1 billion people depend primarily on fish for protein

       The collapse of various fisheries; the boom and bust economy of fishing

       Aquaculture: a solution?

       Hermaphrodite male white perch in Lake Erie

       Menhaden fisheries and the Omega Protein Corporation

				
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posted:4/11/2012
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