27 Sep 2011:
Catch Rates Masked Collapse
Of Two Critical U.S. Fisheries, Study Says
Relatively stable fish catches have masked the collapse of two critical fisheries
off the Southern California coast, a new study says. While the catch rates of the barred sand bass and kelp bass — favorites of recreational fishermen — have remained stable for several years, scientists say other data
Scripps Institution of Oceanography
shows that populations of each species have in fact decreased by 90 percent since 1980. They say this disparity has been caused by a phenomenon known as hyperstability, in which fishermen target spawning areas where large numbers of fish congregate, producing a so-called “illusion of plenty” that can hide an overall collapse in fish stocks. “The problem is when fish are aggregating in these huge masses, fishermen can still catch a lot each trip, so everything looks fine,” said Brad Erisman, a researcher at the Scripps Institution of Oceanography in San Diego and lead author of the study, which is published in the Canadian Journal of Fisheries and Aquatic Sciences
. “But in reality the true population is declining.” The researchers assessed the true condition of the two stocks by gathering data from areas other than spawning grounds. While previous studies have linked a decline in both bass species to a shift in regional water temperatures, the new study says overfishing in breeding areas has also been a critical factor.
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