Any trapping and removal of California sea lions feeding on salmon below the Columbia River's Bonneville Dam will be postponed while a tightly scheduled legal fight is waged in Portland's U.S. District Court.

The first volley was fired March 24 when the Humane Society of the United States filed a complaint that alleges a federal decision allowing lethal removal of the pinnipeds violates the Marine Mammal Protection Act. On March 28 the HSUS asked the court of enjoin the decision – effectively stopping immediate implementation of the sea lion removal plan – while the lawsuit is debated.

Last week the parties to the lawsuit struck an agreement that would put off the killing of California sea lions until at least April 18, but in the meantime allow the trapping of specific animals for transfer to zoos and aquariums.

With suitable, and willing, captive display facilities identified, Oregon and Washington state officials last week considered launching a trapping effort as early as this week. But, they've decided wait until after an April 16 court hearing.

"We're not going to do anything on the river prior to that," according to Rick Hargrave, a spokesman for the Oregon Department of Fish and Wildlife. He said state officials decided it made no sense to trap and haul California sea lions to holding facilities at Pt. Defiance Zoo and Aquarium in Tacoma with court decisions looming as early as next week. The agencies could soon begin to put equipment in place at the dam to prepare for trapping.

Researchers this year have seen at least 45 different California sea lions at the dam, as well as 12 Steller sea lions and two harbor seals. At least 35 of the California sea lions have been visited the dam in previous years, according to a weekly report issued Tuesday. The male California sea lions surge north in winter, foraging to gird themselves for their summer breeding season off the coast of Southern California.

Of the 60 animals listed for potential lethal take under the NOAA authorization, 28 had been seen at Bonneville Dam so far through April 6. Of those, about 19 of those have been seen on an ODFW trap positioned below the dam several weeks ago, according to the research report.

The agreement filed with the federal court was adopted by Judge Michael W. Mosman Monday. It called for the federal government to respond to the request for a preliminary injunction by Wednesday (April 9) and allows the plaintiffs to reply by Monday. The agreement asks that the judge render a decision by April 18. It says that if no decision is possible in that timeframe, the HSUS could seek a temporary restraining to prevent any sea lion removals.

The HSUS, along with the Wild Fish Conservancy and two individuals, filed the lawsuit against the NOAA Fisheries Service, which on March 18 announced it was granting the authorization under the MMPA for the states of Idaho, Oregon and Washington to permanently remove up to 85 California sea lions each year. Oregon and Washington have joined the lawsuit as defendant intervenors. The case was initially assigned to Magistrate Judge Dennis J. Hubel, but reassigned this week to Mosman.

In seeking authorization for lethal removal the states said the California sea lion predation each spring was having a significant negative effect on salmon, and on costly efforts to revive beleaguered fish stocks. Historically few sea lions have been observed below the dam but in recent years more of the marine mammals have followed spawning spring chinook salmon inland.

Last year an estimated 80 California sea lions made the 145-mile quest to the dam. Observers documented a sea lion "take" of 4.2 percent of the salmonid run in the waters immediately below the dam. Those fish include five salmon and steelhead stocks that are listed under the Endangered Species Act.

NOAA Fisheries' approval of the states' request judged that "individually identifiable pinnipeds" (seals and sea lions) "are having a significant negative impact on the decline or recovery of salmonids listed under the Endangered Species Act…," the MMPA standard that must be met to allow lethal removal.

The HSUS complaint says the federal agency violated MMPA by authorizing lethal take of California sea lions "without adequately determining whether predation is having a 'significant negative impact on the decline or recovery'" of listed salmonids.

"In reaching this conclusion, which could justify the killing of any sea lion that is documented eating fish, the agency made no attempt to declare what level of 'measurable' taking of salmon actually constitutes a 'significant negative impact' -- the applicable statutory standard of the MMPA," according to HSUS's March 24 preliminary injunction request. It says the NOAA decision amounts to making sea lions scapegoats for the decline of salmon runs.

"In comparison, fishermen are permitted to take up to 17 percent of salmonids, birds take 18 percent of juvenile salmonids, and hydroelectric dams take a whopping 59 percent of juveniles," according to HSUS.

The response filed Wednesday by the state of Oregon acknowledges that "Salmon and steelhead (together 'salmonids') mortality in the Columbia River basin is the product of a complex combination of natural and human-influenced causes; sport and commercial fishermen, tribes, hydro-electric dams, and birds and other natural predators all play a role."

But the Oregon Department of Justice brief says the sea lions' discovery that "salmonid cluster near the fish ladders at the Bonneville Dam, where they are easy prey" has produced a dramatic increase in mortality.

"Contrary to plaintiffs' assumption that 'only' 4.2 percent of the affected salmonids are taken by CSLs, which assumes that the only takings are those occurring during daylight hours in the immediate vicinity of the Bonneville Dam, this recent incursion of CSLs into the Columbia is responsible for taking between an estimated sixteen to twenty percent of the five salmon populations that return to the Columbia from February through May of each year.

"Such a depredation is, by any legal or common sense measure, significant. If left unchecked it would add a new source of mortality for fish that already are on a downward spiral toward extinction," the Oregon brief says.

Meanwhile, the California sea lion population is thriving, according to the Oregon document.

"The number of animals affected by the federal authorization will have no effect on the CSLs, which already have a huge surplus of males beyond the number necessary for reproduction of the species." The Oregon brief asks that the injunction be denied.

A declaration submitted from Robin Brown says the sea lions impact significance "is not lessened by the fact that the Bonneville Dam itself, humans and birds also take fish.". Brown is chief of Oregon Department of Fish and Wildlife Marine Mammal Research.

Sea lions "are a new, growing, and unaccounted for addition to the overall mortality of salmonids in the lower Columbia River. This loss must be managed and minimized as much as possible, in concert with all other salmonid recovery efforts under way," according to Brown's declaration.

The MMPA's Section 120 was created specifically to address such sea lion-salmon interactions, according to a federal motion filed Wednesday in opposition to the injunction request.

"Granting the Plaintiffs' motion would undo the careful balance that Congress struck when it amended the MMPA. The predatory sea lions at Bonneville Dam pose a threat to salmon and steelhead. Congress has given NMFS the authority to respond to that threat," the federal brief says. The federal and Oregon filings both say that the "harm" claimed by the HSUS from the killing of sea lions is not sufficient to overturn the NOAA decision.

"Plaintiffs contend that such takings will cause them emotional pain. Whether the taking will or will not cause such pain should not be a determinative factor," the Oregon filing says. The law requires harm be proven to win an injunction.

"Allowing such a low threshold for blocking the rigorously supported efforts of the States to preserve endangered and threatened salmon goes beyond existing law and would not fulfill the Congressional intent of the MMPA, which explicitly contemplated the need to take seals or sea lions in order to protect ESA-listed salmon."