A bill backed by House Republicans would stall plans to let sea otters reclaim their historical range off Southern California because of concerns that the threatened marine mammals would compromise commercial fishing and military training operations.

The Military Readiness and Southern Sea Otter Conservation Act, sponsored by Rep. Elton Gallegly (R-Simi Valley), would keep a controversial “no-otter zone” south of Point Conception in place until wildlife officials develop a plan ensuring that the furry creatures and endangered abalone recover and that the commercial shellfish harvest stays at current levels.

Those provisions drew fire this week from wildlife experts, who believe the sea otters’ recovery from the brink of extinction decades ago could be in jeopardy unless they are allowed to extend their range south from the Central Coast into Southern California.

The bill contends the furry critters could undermine training and testing activities at San Nicolas Island, San Clemente Island and Marine Corps Base Camp Pendleton, where the military conducts underwater detonations, live-fire exercises, amphibious warfare training and missile launches. The legislation would establish zones around the military installations where sea otters would be exempt from some protections under the Endangered Species Act and Marine Mammal Protection Act.

Gallegly said in a statement supporting his bill that when sea otters move south they “will be invading prime shellfish fishing grounds and U.S. Naval testing areas. While I support recovery efforts of the southern sea otter, this cannot happen at the expense of our national security, the commercial shellfish fishing industries, and other endangered species.”

Critics say lawmakers are using national defense as a cover to benefit the fishing industry, which fears that otters will gobble up the region’s shellfish.

Sea otters are such voracious consumers of sea urchins, abalone, mussels and clams that under the bill “there is no way the government could follow the law and let otters extend their range,” said Jason Lutterman, program manager with the Carmel, Calif.-based advocacy group Friends of the Sea Otter. The group is one of a coalition of conservation groups that oppose the bill as “dangerously counterproductive to the conservation and recovery of the threatened southern sea otter.”

The bill stems from the decision last year by the U.S. Fish and Wildlife Service to end a failed 1987 program that barred sea otters from most Southern California waters and sought to establish a second sea otter population by moving 140 of them from Monterey Bay to San Nicolas Island, 60 miles off the coast, in case a disaster, such as an oil spill, put them at risk of extinction.

But the relocation program failed and the southern colony never took hold. Many sea otters died or swam away, though a population of 50 remains at San Nicolas Island today.

As part of a compromise with fishing groups at the time, the government promised to round up any otters that strayed close to the Southern California mainland. Officials stopped moving otters out of area waters in 1993 after determining the artificial boundary was not helping restore the population.

The U.S. Fish and Wildlife Service opposes key provisions of the bill, saying they would duplicate existing recovery plans for sea otters and black abalone and wouldn’t allow for natural interactions between predators and prey.

Some 16,000 sea otters used to populate the California coast until traders nearly hunted them to extinction by the early 1900s. In 1977 they were listed as threatened under the Endangered Species Act. They number about 2,700 today.

In recent years, the much-adored creatures have struggled to mount a comeback, their growth stifled by high mortality from predators, overfishing, polluted runoff and disease. In 2011, an unprecedented number of California sea otters were found dead, sick or injured, in part due to a rise in shark attacks.

Fishermen say their livelihood would be hurt by the unfettered expansion of sea otters into their fishing grounds.

“We need to balance the needs of all species, including human beings,” California sea urchin diver Bruce Steele said at a House subcommittee hearing last week..

Sea otters aren’t waiting for Congress to act.

In recent years, young males have been making seasonal sojourns into Southern California in search of food.

Adult females with pups have also ventured south of Point Conception, wildlife veterinarian David Jessup told lawmakers. “Trying to exclude sea otters from areas of the ocean they want to occupy is proven unworkable and now seems a bit foolish,” he said.

tony.barboza@latimes.com