A federal judge on Wednesday denied an attempt to block the planned removal, by lethal means or otherwise, of California sea lions feasting on protected salmon in the waters below the Columbia River's Bonneville Dam.

Portland-based U.S. District Court Judge Michael W. Mosman said he would deny a request from the Humane Society of the United States for a preliminary injunction that would have stalled implementation of the mammal removal plan. He said that evidence of harm to HSUS members and other plaintiffs was "less weighty" than evidence of harm posed to salmon and those that depend on them, such as tribal members.

The judge's decision was immediately challenged by the HSUS, which on Thursday filed a notice of appeal with the U.S. Court of Appeals for the Ninth Circuit. HSUS also asked the appellate court for an emergency stay to prevent sea lion removals. Attorney Rebecca Judd said the Ninth Circuit could respond to the stay request as early as next week.

The stay is needed to prevent lethal removal that could begin as soon as today, the HSUS says. An agreement reached in U.S. District Court forestalled lethal removals until April 18 while that injunction request was debated. State officials say lethal removals will not begin anytime soon.

To win an injunction, the law requires that plaintiffs demonstrate "a strong likelihood of success on the merits" – that its legal arguments might prevail during the course of a lawsuit. They must also show "the possibility of irreparable injury" or harm. The sea lion-salmon issues have been debated over the past two weeks via legal briefs, and during a preliminary injunction hearing in Portland Wednesday.

Mosman said at the end of the hearing that the HSUS had down "a slight preponderance of success on the merits." But its claims of irreparable harm from the sea lion removal fell short.

The Humane Society in a legal memo supporting its district court request said harm will come from the loss of the pinnipeds.

"Sea lions that Plaintiffs and Plaintiffs' members view, photograph and observe on a regular basis – some of that whom they have developed unique and treasured relationships with, while they kayak and hike in and along the Columbia River and the Bonneville Dam area – will be forever lost unless the Court issues injunctive relief to preserve the status quo while the Court decides the merits of the case," the memo says.

"If that is all, I think it was justified in making its decision," Mosman said of NOAA Fisheries' approval of lethal removal authority for the states of Idaho, Oregon and Washington. The Marine Mammal Protection Act allows a waiver of its protections for "individually identifiable pinnipeds" (seals and sea lions) that "are having a significant negative impact on the decline or recovery of salmonids listed under the Endangered Species Act…."

The NOAA decision authorized the taking of up to 85 California each year for five years, but says it is unlikely that more than 30 could be removed annually.

Mosman said a "serious imbalance" existed between the harm faced by salmon and others if sea lion predation goes unchecked, and the harm outlined by the sea lion advocates.

The sea lions' taking of salmon can affect "the religious life of these confederated tribes," Mosman said, by limiting the tribes' ability to perform ceremonial functions.

Mosman on Wednesday said that no one has suggested the planned sea lion removals would do damage to the species. The authorization would allow removal of 1 percent of the sea lions "potential biological removal" level. PBR level is defined by the MMPA as "the maximum number of animals, not including natural mortalities, that may be removed from a marine mammal stock while allowing that stock to reach or maintain its optimum sustainable population."

In denying the preliminary injunction, the judge offered an expedited process for hearing HSUS' claims, culminating with oral arguments May 13 or May 14. The HSUS complaint says NOAA's decision violated both the MMPA and the National Environmental Policy Act. The organization's attorneys said they would discuss the proposal.

A judicial decision in late May could be too late block removals this year. The California sea lions typically have left the river by the end of May to return their breeding grounds off the Southern California coast.

The states had intended to begin trapping sea lions at the dam Tuesday but equipment problems have pushed that start date back, perhaps into the following week. The Oregon Department of Fish and Wildlife will lead the effort.

The states do not relish the job but feel it's necessary.

"It gives us a tool, another link in the (salmon) recovery chain," said Guy Norman of the Washington Department of Fish and Wildlife. The NOAA approval allows the states to trap and euthanize California sea lions or shoot them, or ship them off to captivity. The states say they will focus first on placing captured animals zoos and aquariums. Norman said as many as 20 sea lions have been spoken for so far, with Sea World indicating a desire for as many as 12 to infuse new genes into its broodstock.

"There's not going to be any lethal removals of animals" at least in the near term, said Rick Hargrave of the Oregon Department of Fish and Wildlife. "We want to move them out" to captive display facilities. Potentially, if an animal doesn't meet medical criteria for transfer to a zoo, it may have to be euthanized rather released back into the wild, he said.

"We're hoping that they do that and not start shooting them in the water," the HSUS's Sharon Young said following Wednesday's hearing.

"We need to ask the federal (appellate) court to intervene," she said.

Young said she was disappointed with Mosman's decision, but encouraged that he gave an edge to the organization's arguments on the merits.

"The court is saying that the Humane Society has a good case."

NOAA estimates that the 30 California sea lions that would be removed this season could eat between 212 and 2,094 listed chinook salmon this year.

The HSUS says such a loss is "likely to be negligible" because large salmon and steelhead runs are expected to arrive this year.

The organization also argues that NOAA is required to put the sea lion take of salmon in context with other human-approved causes of mortality such as harvests and the federal hydro system.

The judge said a comparison with hydro mortality may not be appropriate because most of its take is of juvenile fish as opposed to adult spawners that have nearly completed their lives' mission.

The failure to measure sea lion take against human harvest has, however, "at first blush, the appearance of arbitrariness," Mosman said. HSUS is seeking a ruling that the NOAA decision is arbitrary and capricious under the ESA.

The sea lions, of course, are unaware of the legal stir, and potential threat. The number of California sea lions at the dam has grown steadily in recent weeks, coincident with a surging upriver spring chinook salmon run. The pinnipeds camp out below the dam and pouncing on spawners as they search for fish ladders.

As of April 13, observers at the dam have seen 50 different California sea lions at the dam, at least 37 of which have made the 146-mile trip upstream from the ocean in previous years, according to a report compiled weekly by U.S. Army Corps of Engineers researchers.

Of the 60 animals listed in NOAA's authorization as qualified for immediate removal, "30 have been seen at Bonneville Dam so far this year, with about 19 of those being seen on the single trap already, and several others hauled out nearby," the report says. An ODFW trap was placed on-site so the marine mammals would become used to its presence. Three new traps will also be used in the effort.

Researchers say that an additional four branded animals and possibly seven others now qualify to be added to the removal list, having been hazed, seen to eat at least one salmon, and having been at the dam more than five days.

The authorization only allows the removal of idenfiable predators that:

-- have been observed eating salmonids in the "observation area" below Bonneville Dam between Jan. 1 and May 31 of any year; and

-- have been observed in the observation area below Bonneville Dam on a total of any five days (consecutive days, days within a single season, or days over multiple years) between Jan. 1 and May 31 of any year; and

-- have been sighted in the observation area below Bonneville Dam after they have been subjected to active non-lethal deterrence.

Researchers have seen 1,264 chinook salmon and 249 steelhead taken by sea lions this year, according to "unexpanded" numbers for the Jan. 11-April 13 period. Additionally, 506 unnidentified fish were observed taken, most believed to be salmon.

The district court complaint, and injunction request, were filed by the Humane Society of the United States, Wild Fish Conservancy and two individuals against NOAA Fisheries. The states of Oregon and Washington joined the proceedings as defendant intervenors.

The Warm Springs Tribe joined as amicus, as did the Columbia Pacific Anglers, Vancouver Wildlife League, Oregon Anglers, Westport Charterboat Association, Ilwaco Charter Association, Puget Sound Anglers, Washington Trollers Association, The Association of Northwest Steelheaders, and Columbia River Fishermen's Protective Union, the Northwest Sportfishing Industry Association and the Northwest Guides and Anglers.