Kelp Reef Healthy, But Not Producing Enough Fish

Although it’s healthy, San Clemente's 152-acre artificial Wheeler North Reef is producing only half the state-mandated amount of fish needed to offset damage from the San Onofre nuclear power plant, UC biologists reported Monday.

The biologists, who have monitored the kelp reef since its construction just south of the San Clemente Pier in 2008, shared their findings at the Ocean Institute in Dana Point.

The reef mitigation project goes back decades, said biologist Dan Reed. Initial studies estimated that heat and turbidity -- cloudiness of the water -- caused by the cooling water San Onofre Nuclear Generating Station was diffusing off the coast had killed up to 180 acres of the San Onofre Reef, leading to a loss of about 28 tons of native fish and other sea life.

That conclusion led to a lengthy process mandated by the California Coastal Commission to enlist UC Santa Barbara scientists to figure out exactly how to build and maintain an artificial reef away from the impact of the nuclear plant's cooling water, Reed said.

Overall, said Reed and his colleague Steve Schroeter, the reef has been healthy, growing more kelp than two nearby natural reefs used as a basis for comparison.

For most of the standards, which measure variables like fish growth, bio diversity, percentage of the reef inhabited by both stationary and mobile invertebrates and growth in the number of commercially viable species, the Wheeler Reef is passing easily, the scientists said.

"It's done extremely well," Schroeter said.

But one crucial factor keeps Southern California Edison from getting full credit from the Coastal Commission for the reef, which costs the utility about $1 million per year to monitor; the UC Santa Barbara diving team calculated only about 14 tons worth of fish on the reef during their five months of sampling in 2012.

And the reef hasn’t once come close to meeting the 28-ton target in the last four years.

Schroeter said the team will do more analysis this year to try to understand why the reef isn't home to more fish whether its a natural phenomenon or some flaw inherent in the reef design.

"We will monitor Wheeler North much as we did last year," he told the crowd of about 50 people at the Ocean Institute. "We will conduct analysis to try to understand why the Wheeler North Reef consistently fails to meet the 28-ton fish biomass standard."

Diver researchers start their work in May and finish up around October, depending on conditions, the scientists said.