WASHINGTON – The iconic orca, or killer whale, should swim free of federal protection, a farmer from California's San Joaquin Valley urged in a petition filed Thursday.

Backed by a conservative legal advocacy group based in Sacramento, Fresno County farmer Joe Del Bosque and his allies argue that the population of killer whales often found in Pacific Northwest waters doesn't deserve defending under the Endangered Species Act. Protecting the whales also costs farmers precious water, growers say.

"It seems almost outrageous that a whale out in the ocean is restricting our water," Del Bosque said. "Restrictions in the water flows are definitely affecting us."

The petition, prepared by the Pacific Legal Foundation, asks the Commerce Department's National Marine Fisheries Service to change the status of the so-called "southern resident" population of killer whales from endangered. The population was listed as endangered in 2005, after a pronounced decline in its numbers.

More broadly, the 62-page petition is the latest salvo in a longer-running dispute over the costs and benefits of protecting certain species. Sometimes, these fights spotlight obscure critters, such as a wetlands shrimp. With the killer whale, however, the battle involves one of the most photogenic mammals on the planet.

"The southern residents have been the focus of tremendous public interest, scientific curiosity and awe," the National Marine Fisheries Service's final recovery plan for the species noted in 2008. "Many people feel a kinship or connection to these family-oriented mammals."

Though tens of thousands of other killer whales live worldwide, scientists counted only 86 of the protected southern resident variety in 2010. Federal officials concluded in a review last year that it was too soon to remove it from the endangered species list.

"We are just beginning to gather information to help us evaluate if the needs of the whale are being met (and) identify which factors are degrading habitat," the National Marine Fisheries Service cautioned in its 2011 species review.

Alisa Schulman-Janiger, a killer whale researcher affiliated with the American Cetacean Society, said in an interview Thursday that she thought it was premature to remove protections from a species whose numbers didn't appear to be rising.

"I don't think it's time," Schulman-Janiger said.

The killer whales in question, which are sometimes called the world's largest dolphins, primarily populate Puget Sound and other inland waterways of Washington state and British Columbia during the spring, summer and fall. Highly social and living for as long as 90 years, they travel in matriarch-led pods as far as the Central California coast at other times of the year.

Hungry killer whales particularly like to gobble up chinook salmon. Indirectly, this causes a problem for certain farmers. In order to protect the salmon population, in part to help feed the killer whales, federal officials restrict irrigation-water deliveries in the San Joaquin Valley.

The petition further contends that the southern resident population isn't scientifically distinct from other killer whale populations that aren't afforded Endangered Species Act protections.

"I'm not a biologist," said Del Bosque, who grows almonds, cantaloupes and other crops on his 2,200-acre farm near the rural town of Firebaugh. "I just know we're being affected."

© Copyright The Sacramento Bee. All rights reserved.

• Read more articles by Michael Doyle

Order Reprint