City officials are still trying to determine the cause of a fish kill two weeks ago that struck down approximately 50 fish at Aquatic Park.
The fish, mostly striped bass, were found washed along the south end of the Aquatic Park Lagoon, near the Ashby Avenue on–ramp to Interstate 80.
The city’s Waterfront Manager Cliff Marchetti said tests performed at the site by the city’s Department of Toxics did not detect the presence of contamination or an abundance of oxygen–depriving algae, the two most likely causes of local fish kills.
A toxic spill is still considered a top possibility, though, because a small-scale spill could have dissipated before tests were performed.
The deaths seem even more mysterious because in the two weeks following the washed-up fish, none of the thousands of other fish at the park have shown signs of illness, city officials said.
The most accurate clues to determining the cause of a fish kill usually come from testing the dead fish, Marchetti explained.
However, since in this case the fish were not found until they had been dead for several days, tests did not yield reliable information.
The California Fish and Wildlife Department sometimes investigates local fish kills, but Marchetti said agency biologists would likely not research this case.
“They usually only come if they believe they can determine the cause, or if the fish kill was random and ongoing,” he said.
Fish kills are not unprecedented in Aquatic Park. Four years ago an infestation of red tide algae destroyed thousands of fish at the park.
The algae, which every few years is carried from the Pacific Ocean into the bay, turns the water a brownish red and sucks out the oxygen, causing fish to suffocate.
“That time I saw fish gasping for air at the edge of the lagoon ... the smell [of the dead fish] was just horrendous,” Marchetti said.
Red tide algae made it into the bay again this year, but Marchetti said that it peaked two months ago and wasn’t considered a possible cause of the recent fish kill.
In response to the fish kill, Marchetti said he has asked Aquatic park gardeners to fill out a daily check list and note new homeless encampments, broken branches, collections of trash and other disturbances to the park habitat, to better keep tabs on activity at the park.
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