In perhaps the largest, longest, and most comprehensive study of ocean fish in the Pacific scientists reveal populations of  fish collapsed by 78% over the last 40 years.

Using exhaustive records of fish caught by the cooling systems of five coastal power plants from northern San Diego County to Ventura County where each and every fish was collected and identified. The study has confirmed what fishing data and stock assessments have long indicated: That there has been a steep, ongoing drop in a wide variety of fish in the region over several decades.

Also confirmed by the study is that over-fishing, the “usual suspect”, in ocean fishery decline has been ruled out as the cause.  A much broader ecosystem collapse is in fact the cause.

“We have found consistency between the power plant records and data compiled from other independent sources including fishing records and stock assessment models,” said Eric Miller, senior scientist at MBC Applied Environmental Sciences, an environmental consulting firm that conducted the research with the Scripps Institution of Oceanography at UC San Diego. “This invaluable secondary use of the power plant monitoring program provides population data to help better manage our coastal resources. It is a benefit which we have only begun to utilize.”

“The coastal fish community that we have here in Southern California has changed dramatically and we can’t relate it to anything other than a regional oceanographic effect,” said Miller.

“I knew that there was a decline, but coming so close to 80% was startling to me,” Miller is quoted as telling the Los Angeles Times.

California Salema

The study ruled out over-fishing as the source of the collapse because the power plant records showed that fish such as salema, which are not harvested by commercial or recreational fishermen, have been declining at about the same rate as commonly fished species such as sardines.

Anchovy

Many of the fish in decline are small, schooling fish such as sardines and anchovies. The loss of these species is especially critical as the are “forage fish” which in turn are the food for countless larger species of fish, seabirds and marine mammals. The catastrophic collapse in fish is altering the structure of the marine food web and be playing a role in the malnutrition and deaths in predators like California sea lions, the researchers said.

“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,” said Miller. “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.”

A 2011 study by researchers at the Scripps Institution of Oceanography found that kelp bass and barred sand bass, two of the most-caught salt-water fishes in Southern California, have plummeted 90% since 1980.

Other scientists have come to alarming conclusions about the depletion of fish stocks globally since the 1950s.