Biologists Hope to Rescue Tiny Fish : Wildlife: The endangered stickleback is threatened by clawed frogs, river plants, an oil spill and the drought.

A tiny endangered fish that already is besieged by development and predators is facing new threats that could hasten its extinction.

Biologists fear that the fifth year of severe drought, combined with the recent spill of 75,000 gallons of crude oil into the Santa Clara River, could destroy the already shrinking habitat of the unarmored threespine stickleback.

There are only three known habitat areas for the stickleback--all located in the Santa Clarita Valley on the Santa Clara River and its tributaries. One area is threatened by the oil spill, another is being choked off by a fast-growing river plant and a third has been invaded by African clawed frogs, which shred their prey.

“This may be all we have left,” said Jonathan Baskin, a Cal Poly Pomona biology professor, as he surveyed a pristine pool filled with sticklebacks a few miles east of Santa Clarita on Thursday afternoon.

Despite the drought, the pool was lush and the sticklebacks netted by Baskin and three colleagues who sloshed through the water appeared healthy and ready to enter the mating season. Tom Haglund, a UCLA research biologist, held up a male stickleback, pointing out its bright blue eyes and glowing red throat.

“The males get a very distinctive reproductive color,” Haglund said. Baskin and Haglund found no African frogs but were sure that they were nearby.

The small fish--Haglund called them “hors d’oeuvre-sized”--was once found in abundance in the Los Angeles and Santa Ana rivers. The fish was placed on the endangered species list in the mid-1970s.

Some ponds in Soledad Canyon, where the biologists worked Thursday, have shrunk with the drought. Soledad Canyon also is home to the African clawed frogs. Baskin speculated that the greenish-brown frogs, which use tiny black claws to shred their prey, are descendants of escaped lab animals or aquarium pets released by owners.

Another stickleback habitat a few miles north in San Francisquito Canyon is being destroyed by arundo, an exotic plant similar to bamboo that clogs the shallow streams preferred by sticklebacks. The U.S. Forest Service is studying ways to eradicate the plant.

The third remaining habitat is on the western end of Santa Clarita, where the Santa Clara River passes under the Golden State Freeway near Magic Mountain. On Jan. 31, an aging underground pipeline ruptured there, sending oil into the riverbed.

Almost 200 birds and animals have died in the spill. And while the impact of the oil on the stickleback is still unclear, Baskin said he is worried.

Baskin and Haglund are hopeful that they may be able to relocate some young sticklebacks born this spring to a haven in the Santa Ana River in San Bernardino County.

The researchers have secured about $12,000 from the state Department of Fish and Game for the move, but still need the approval of the U.S. Fish and Wildlife Service.

Under a hot sun Thursday afternoon, Baskin and Haglund netted and released sticklebacks with Jaime Tres, a UCLA graduate student, and Leslie Baer-Brown, a Cal Poly Pomona spokeswoman who sometimes joins the biologists on field trips.

The four waded up to their knees and pulled a net across the pond. Baskin was encouraged by the healthy and eye-catching appearance of male and female sticklebacks.

“They’re really spectacular animals,” Baskin said.

When decked out in its mating colors, the male unarmored three spine stickleback is iridescent and, to female sticklebacks, rather sexy.

“The fish have the right idea,” Baer-Brown quipped. “Let the male put on the makeup and eyeliner.”