USC Biologist to Oversee Composting of Sardines After Toxin Discovered in Fish

A USC professor of biology told the Redondo Beach City Council Tuesday that he and his team of researchers will monitor the composting of dead sardines hauled from King Harbor Marina to make sure a toxin discovered in the fish is removed.

Dave Caron, a professor of biological sciences who has been regularly monitoring water quality in the marina since 2005, told city officials that he and his team have found the neurotoxin domoic acid in the bellies of the sardines. However, he does not think the toxin will survive the composting process.

“It’s an organic compound,” Caron said. “It is naturally degraded. We just have no experience in how fast it would disappear when it’s in a composting process. But given the fact that heat is involved, and bacterial decomposition, it’s likely to be pretty effective.”

An estimated 175 tons of sardines died in the harbor March 8, and it took about a week for cleanup crews to clear the fish from harbor waters. A city official estimated the cost of the cleanup to be at least $300,000.

According to Caron's water testing, the sardines died of oxygen depletion when they crowded into the harbor. The neurotoxin may have caused disorientation in the fish, Caron said. The fish were either pushed into the harbor by strong winds or they entered the harbor to get away from the windstorm.

“Whatever brought the fish into that area, there were simply too many of them in that location to handle the amount of dissolved oxygen that was in there,” Caron said.

After discovering the toxin in small amounts in the stomachs of the fish last week, Caron and his team sampled waters off the Palos Verdes Peninsula and found a “significant toxic bloom,” he said.

Domoic acid is not present in the harbor itself, according to water samples, so Caron speculated the fish had been feeding in the coastal waters with the algal bloom present. 

The city’s new waste collection service, Athens Services, is composting the tons of sardines at its Victorville company, American Organics. Gary Clifford of Athens Services told the City Council he hopes to bring some of the finished fish fertilizer to Redondo Beach.

“It’s our hope that within a few months we can come back and have a great event in the community when we bring the compost back as some kind of blend that your city can use to grow things in,” Clifford said. “It would be a very nice event.”

Clifford said American Organics is a certified organic composting facility, one of only two in the state. It uses a pathogen reduction process that will eliminate the toxin, he said.

“It’s not the first time we’ve had fish in our facility,” Clifford said. “We isolate those fish when they come in and we truly believe that over time, probably by now even, that toxin is gone."

Caron said his team will be watching. “I know a lot about water. I know less about composting. But I’m learning,” Caron said. “I have talked to Mr. Clifford. In fact, we will work with them to make sure whatever may have gone into the composting process is monitored to see how and if that disappears.”

The final bill will easily exceed the original estimate of $100,000 because water surges as a result of the tsunami from Japan delayed work by about two days, and the number of dead fish in the harbor was initially underestimated, city officials said.