Fish of all species have been dramatically declining in population all along the California coast, which is likely contributing to the starved sea lions that have been washing up on Orange County beaches in large numbers this year, according to a study by the University of California, San Diego.
Based on data collected from the filtration systems of five coastal California power plants since 1972, the study shows a 78 percent drop in not only commercially fished species, but also the smaller "forage" fish like sardines that provide sustenance for larger predatory fish and sea birds.
“Many of the species represented in this data set are rarely reported on as they are not targeted by either recreational or commercial fisheries, yet their decline was commensurate with better known species such as anchovies and sea basses,” co-author Eric Miller said in a UCSD press release.
“Recent data collected since this analysis was completed do not change the outlook—the relatively long-term decline continues and likely contributes to the current, acute malnutrition and mortalities in California sea lions.”
The researchers from UC San Diego and the Costa Mesa environmental firm MBC Applied Environmental Sciences paired the power plant records with other fish population data to come to their conclusions. The fish counts are required of each power plant as a condition of its permit to operate.
Typically, coastal power plants draw in millions of cubic yards of seawater to cool their boilers, and biologists count and record the fish species when the cooling systems are drained, according to the UCSD release.
Ranging from Northern San Diego County to Ventura County, the power plants include the San Onofre Nuclear Generating Station, Huntington Beach Generating Station, Redondo Beach Generating Station, El Segundo Generating Station, and Ormond Beach Generating Station.
Co-author John McGowan said in the release that overfishing doesn't seem to be the problem with the decline because even fish species that aren't commercially harvested are losing population.“The data indicate that there has been a clear-cut and substantial decline in the abundance of these forage fish, both in the number of fish caught and in the overall biomass,” said McGowan, an emeritus research professor of oceanography at Scripps. “Factors beyond fishing such as oceanographic change appear to be involved, including temperature changes from global warming.”