Scientists Link Bacterium to Salton Sea Die-Off

Scientists announced Wednesday that they have identified the bacterium linked to a massive die-off of fish and birds at Salton Sea and warned that it can be harmful to humans.

Frank Shipley, director of the Northwest Biological Science Center in Seattle, told reporters that the bacteria can cause rashes and infections in people. In people who are already sick, the consequences could be worse, he said.

The scientists said they are most concerned about people who consume bacteria-laden fish, but they are also worried about individuals who swim in the water where the bacteria may be present. They said they have no reports so far of illness tied to the Salton Sea bacteria.

Shipley and others said the bacterium, vibrio alginolyticus, is not considered life-threatening, but there is much scientists do not know about it. It is known to be present in saltwater environments.

“We don’t know a lot about this organism in terms of its effects on humans,” said Mark Starr, a veterinarian with the state Department of Health Services.

Tom Wolf, manager of the Imperial County environmental health department, said warnings will be posted at local bait stores and other spots where fishermen congregate, telling them about the bacterium that is killing the tilapia, a common fish at the sea.

Wolf said that anyone catching tilapia or other fish should make sure they are refrigerated quickly to keep the toxin produced by the bacteria from multiplying.

“I would not advise people to rely on cooking to kill the toxin,” Wolf said.

An outbreak of avian botulism at Salton Sea, first noted Aug. 15, has now killed more than 13,000 birds of 56 species, including 1,110 of the endangered brown pelican.

In the weeks after dead birds began washing up on the shore, scientists also noted large quantities of dead fish. Employees of the U.S. Fish and Wildlife Service have been scooping up the dead birds assiduously, lest the botulism spread to other birds and possibly be carried to other migratory spots.

Die-offs of birds and fish are not unprecedented at Salton Sea, which is a hot spot for sportfishermen and a nesting area for migratory birds. But this combined fish and bird die-off is more troubling than other incidents because scientists believe that the bacterium that is killing the fish is also triggering the botulism in the birds.

If that theory is true, it could mean that the long-feared breakdown of the Salton Sea’s fragile ecosystem may be occurring. The sea serves both as a terminus for the polluted Alamo River and New River and as a sump for pesticide-laden agricultural runoff.

Wolf said that anyone catching tilapia at the Salton Sea should examine the fish for tell-tale signs of infection: bleeding at the gills or skin, puffiness or lethargy. If anyone is in doubt about the safety of the fish, “they shouldn’t eat it,” Wolf said.

Signs posted for years at the Salton Sea have warned that children and pregnant women should not consume the fish. Tilapia, a warm-water fish native to South Africa, can grow up to 15 inches. It is among the species introduced in the Salton Sea by fish and wildlife officials hoping to diversify its ecosystem.

The only good news in Wednesday’s announcement came from Clark Bloom, manager of the Salton Sea National Wildlife Refuge, located at the sea’s southeast corner. Bloom said the number of bird carcasses being found daily is decreasing, possibly due to the declining temperatures.

The triple-digit heat in the Imperial Valley is thought to be linked to the botulism outbreak. Botulism spores have long been known to exist in a dormant state at the sea; scientists are trying to determine what caused them to become active.

Bloom’s good news was tempered by bad news. The dead tilapia examined by Shipley’s laboratory came from the Bombay Beach and State Recreation Area in the northeast corner of the sea. That area is far removed from the Alamo River and New River outfalls and has not historically been considered a danger spot for fish and birds.