Popular fisheries collapse amidst 'illusion of plenty'
Fishing practices and oceanographic conditions blamed for declines
Mike Lee
Sign On San Diego
09/26/2011
Two popular recreational fisheries in Southern California have collapsed despite an "illusion of plenty," according to scientists at the Scripps Institution of Oceanography and elsewhere across the region.
They said in a newly published journal article that regional populations of barred sand bass and kelp bass have plummeted by 90 percent since 1980 due to fishing and ocean conditions. Both spawn in the summer when fishing pressure by the commercial passenger fleet is high.
Fish declines have been masked by "hyperstability," in which anglers successfully target fish spawning areas even though overall populations are shriveling, scientists said. They urged fisheries managers to adjust their methods for calculating abundance so they can reduce the chances for overfishing.
The publication in a Canadian fisheries journal is an ominous sign for the California Current Ecosystem, one of the most abundant ocean zones in the world because cold, nutrient-rich water wells up along the coast and provides the building blocks for vibrant fisheries.
“The problem is when fish are aggregating in these huge masses, fishermen can still catch a lot each trip, so everything looks fine—but in reality the true population is declining,” said Brad Erisman, a postdoctoral researcher at the Scripps Center for Marine Biodiversity and Conservation at UC San Diego. “So as the true abundance is declining, the fisheries data used to assess the health of the fisheries are not showing that and give no indication of a collapse—this is referred to as ‘the illusion of plenty.’”
Erisman said that dynamic has been seen in fisheries around the world, perhaps most famously in North Atlantic cod, but he wanted to highlight the problem in Southern California waters. Kelp bass are popular catches in the kelp beds of La Jolla and Point Loma, while barred sand bass have been a staple off Imperial Beach, San Clemente and Huntington Beach.
To evaluate fish stocks, the researchers looked at decades of data collected offshore by Occidental College. They also reviewed records from coastal power plants such as San Onofre Nuclear Generating Station that track the amounts of certain fish trapped at the sites over time.
