Salton Sea is at a crucial juncture

A gusty wind churned the Salton Sea, bouncing and buffeting the small boat atop frothy waves.

Randy VonNordheim steered toward an orange buoy, stood with a wobble and began pulling in 150 feet of sunken gill net.

Anticipation hung heavy in the air, as did the malodorous scent of decaying fish from a distant beach.

A glint of yellow, then red, flashed in the dripping nets.

“Randy, what would you do if there was a corvina in there?” asked biologist Sharon Keeney, leaning in for a closer look.

“I’d die of shock,” said VonNordheim, a technician for the state Department of Fish and Game. “That would be the holy grail.”

No one has seen the sleek corvina in this 35-mile-long inland sea for five years. The toothsome sport fish, which can weigh as much as 50 pounds, once lured anglers from around the state and kept marinas in business and bait shops bustling.

Not anymore.

As the net came in, the corvina were absent -- again. That glint was tilapia, hundreds of flopping tilapia, the last major fish species left in the sea. Plentiful and easy to catch, but with a taste some liken to mud, they lack the cachet of corvina.

California Fish and Game biologists have been netting and counting fish every three months here since 2003, hoping to better understand how the state’s biggest lake is changing as it grows ever saltier.

The results are both confounding and disturbing. In spring 2003, scientists stopped seeing corvina, then sargo and croaker. And with 11 nets in the water, researchers brought in just one tilapia.

The sport fish simply vanished and hasn’t been seen since. But the tilapia, a native of Mozambique brought in during the 1960s to eat algae from nearby drainage canals, rebounded with a vengeance. Even when high salt and low oxygen levels caused millions to die off, the tilapia have proved remarkably resilient.

“It’s early in the season and there are probably 400 or 500 fish here,” Keeney said as gulls and pelicans wheeled overhead. “Last spring we probably got 300 the whole time.”

But scientists say these boom and bust cycles are erratic and fear one day all the tilapia will die, eliminating a critical food source for many of the 400 species of birds nesting or wintering along the shore.

“The tilapia have been a real head-scratcher for us,” said Jack Crayon, an associate biologist at Fish and Game and an expert on Salton Sea fish. “Increasing salinity made it impossible for sport fish to breed but seemed to have no impact on tilapia. We worry about the fluctuation in population, because we don’t know why it happens. What happened in 2003? What will happen in 2008?”

Eventually the saltiness will be too much even for tilapia, and they too will probably disappear, leaving only small sailfin mollies, mosquitofish and desert pupfish behind, experts say. According to a report prepared by Fish and Game and the California Department of Water Resources, that could happen as early as 2021, though some tilapia might persist in less saline areas where rivers, creeks and canals enter the sea.

The lake is already 25% saltier than the ocean, and the decision to redirect farm runoff from the Salton Sea means it’s shrinking as well.

In response to this potential environmental disaster, the state Resources Agency has drawn up a 75-year, $6-billion draft plan to save the sea, a plan that could be released as early as today. It calls for a less salty sea about one-sixth its current size, a series of ponds for habitat restoration and up to 70 miles of canals and barriers.

Crayon says striped bass, smelt, shad, croaker and maybe even corvina could be returned when salt levels reach that of the ocean.

But any plan will have to be approved by the Legislature and then take years to implement. In the meantime, if the tilapia vanish, fish-eating birds such as the endangered California brown pelican might simply leave.

“About half the bird species would be gone,” Keeney said.

The Salton Sea has become a critical stopover for hundreds of thousands of birds on the Pacific Flyway. It’s not unusual to see thousands of pelicans or ibis lift up as one and soar overhead.

As a result it has become a prime spot for birders, who tramp the desolate shores looking for black skimmers, snow geese, eared grebes, clapper rails, double crested cormorants and hundreds of other species.

“The area has declined in fishing attractiveness,” said Chris Schoneman, manager of the Sonny Bono Salton Sea National Wildlife Refuge. “Now most of our visitors are bird watchers. We’ve had visitors from 20 different countries looking for birds.”

Crayon said that in the 102 years since the Salton Sea was accidentally created by a levee break along the Colorado River, 95% of California’s wetlands have disappeared.

“The sea has become a replacement for those wetlands,” he said. “The people who don’t value it are not informed about it.”

Crayon, who lives along the lake and fishes it regularly, thinks it could become a premier spot for both visitors and fish.

“At one point there were more visitors to the Salton Sea than Yosemite,” he said.

“It could happen again, but there is a huge public relations hill to climb. You have to get the fishing back and people swimming and boating.”

As for the fishing part, Crayon says that despite warnings of high selenium levels in Salton Sea tilapia, he eats what he catches.

“Of course I eat it,” he said. “And I don’t glow in the dark.”

david.kelly@latimes.com