Salton Sea Dieoff Nears 4,000 Birds

The death count of pelicans and other birds at the Salton Sea in the Imperial Valley is approaching 4,000, and officials say they cannot yet pinpoint the cause of the mass dieoff.

“Right now we’re just trying to clean the mess up,” Patrick Moore, a spokesman for the California Department of Fish and Game, said Tuesday.

The Department of Fish and Game and the U.S. Fish and Wildlife Service are scooping up carcasses on the southeastern and northwestern shores of the Salton Sea, which straddles Imperial and Riverside counties. Tissue samples are being taken to laboratories in Rancho Cordoba in Northern California and Madison, Wis., for analysis.

Preliminary findings show that the birds died of avian botulism, which has been known to be present in the 380-square-mile Salton Sea in the desert south of Palm Springs. Whether the outbreak can be linked to the use of agricultural pesticides in the region remains unclear, officials said.

In other mass dieoffs at the Salton Sea, including the death of 150,000 grebes in 1992, scientists have been stumped in their attempts to find a root cause. The saltwater sea serves as a resting and nesting spot for millions of birds from more than 400 species.

The current dieoff, said David Klinger, a spokesman for the Fish and Wildlife Service, has hit 42 species, with white pelicans and brown pelicans accounting for two-thirds of the dead. The brown pelican is listed on the national endangered species list, with only about 5,000 pairs thought to remain in the wild.

The cleanup has involved 30 workers, six airboats, two kayaks, three all-terrain vehicles, a deep-water boat and a spotter plane. Crews are racing to gather up all the dead birds before their carcasses infect other birds at the sea.

“It’s going to be some time before we can narrow down the cause,” Klinger said. “Our goal right now is to get the carcasses removed. Rotting flesh is the main way to spread botulism.”

Hot spots for dead birds are the southeast shore, where the New River and Alamo River empty into the Salton Sea, and the northwestern shore, where the Whitewater River empties into the sea. All three rivers carry mostly farm runoff.

Devoid of a source of clean freshwater, the Salton Sea, which is 10 times saltier than the Pacific Ocean, is dependent on agricultural and industrial runoff to avoid disappearing through evaporation. Environmentalists have complained that the sea is nothing but a sump for the surrounding fields, with a brew of potentially deadly pesticides lurking in the bottom muck.

Among those pesticides known to remain submerged at the Salton Sea is DDT, once heavily used in California agriculture. Before it was banned, DDT was blamed for greatly decreasing the pelican population, and the current dieoff has led to suspicion among bird lovers that the pelicans may have encountered some leftover DDT.

But officials cautioned against any premature conclusion that the dieoff was caused by pesticides. Klinger noted that DDT, before it was banned, hurt the pelican population by undermining its ability to reproduce, not by directly killing birds.

One theory being explored by government scientists is that a recent storm churned up botulism spores at the bottom of the shallow sea and that hot weather, high wind and the sea’s high alkalinity made the spores lethal when they reached the surface.

A secondary theory is that fish that had died after eating the spores were, in turn, eaten by birds and became infected. The problem with that theory, however, is that there is little scientific evidence to support the idea of birds catching botulism from fish, Klinger said.

More than 200 stricken birds have been taken to the Pacific Wildlife Project, a private group in Laguna Niguel. Group officials estimate that they have been able to save about 80% of them.