What causes declines in fish populations?

For the most environmentalists and population advocates have a simple answer
to that question — human beings cause declines in fish population. While overfishing
and the lack of enforceable property rights over fish catches is certainly a
major cause of fluctuations in fish populations, it’s not the whole story.

In fact there is mounting evidence that even in the absence of human beings,
fish populations fluctuate wildly. Timothy Baumgartner of the Scripps Institution
of Oceanography in San Diego is studying how much of the fluctuations are due
to human beings and how much are due to natural causes by examining the historical
record of fish scales in ocean sediments.

Baumgartner, along with biomathematician Robert Francis, have already tracked
the fluctuations of some species around Southern California back 100 years and
hope to extend that even farther back as far as 1,000 years ago.

Geologist Bruce Finney is doing much the same work studying fluctuations in
salmon in Alaska. Alaskan salmon have experienced wild fluctuations from enormous
declines in the 1950s and 1960s usually blamed on overfishing to current record
levels. So far Finney’s findings suggest such fluctuations occurred long before
modern fishing fleets began catching salmon.


Follow the bouncing fishes: why fish populations fluctuate. Lee Dye, ABCNEWS.com,
May 27, 1998.

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