One of the captured animals was euthanized Thursday after a health examination revealed the animal had lesions of a viral origin. Research has shown that the condition is often linked to cancer and is potentially contagious to other animals in captivity, according to state officials. The decision to euthanize the animal was made by an attending state veterinarian.

The second captured sea lion has the same fate. The results of medical tests received this morning (Friday) "conclude this animal is suffering from the same viral condition," said Rick Hargrave, Oregon Department of Fish and Wildlife spokesman.

"Our primary goal is to place healthy animals in the approved facilities that have asked to receive them," Hargrave said. "This animal had an infectious disease that was potentially contagious and could not be placed in a zoo or aquarium without endangering other animals."

The animals, had they been given a clean bill of health, would have been transported to Chicago to take up residence at the Shedd Aquarium.

The states have said their first choice is to relocate captured animals to facilities such as zoos or aquariums. So far this year they have eight animals spoken for – two to Shedd Aquarium and six to the Gladys Porter Zoo in Brownsville, Texas.

"They wanted six last year and we weren't able to provide them," Guy Norman, director of the Washington Department of Fish and Wildlife's Southwest Region, said of Gladys Porter. This year the zoo balked at first because of the economic situation but ultimately decided it could afford the animals, he said.

The states were authorized to remove, lethally or otherwise, as many as 85 California sea lions annually during a five-year period in an effort to reduce the animals' impact on protected fish. The marine mammals have largely ignored non-lethal efforts, such as hazing, to deter them from preying on salmonids.

Those efforts continue. Boat-based crews from ODFW, WDFW and the Columbia River Inter-Tribal Fish Commission began hazing sea lions within the Bonneville Dam boat restricted zone and in downriver areas in January, and plan to continue through the end of May. The U.S. Department of Agriculture Wildlife Services, contracted by the Corps, began to haze sea lions from dam structures and adjacent lands last week and will continue seven days per week, eight hours per day, during daylight hours through the end of May.

Trapping and removal operations at Bonneville Dam will continue through mid-May. Animals that are trapped and cannot be placed will be lethally removed, according to state officials. Remote gate closing mechanisms have been added to the traps to assure they are not closed inadvertently or by anyone other than those involved in the trapping.

An increased number of California sea lions have in recent years been making the 146-mile trip from the Pacific Ocean to the dam. The attraction apparently is salmon, which are easy prey as they stall and search for a path up and over the hydro project – via the dam's fish ladders.

One of the California sea lions was trapped late Tuesday and the other early Wednesday. They were taken from the traps to a holding facility at the dam for a medical screening.

"They've got to be acceptable from a health standpoint" to qualify for relocation, Norman said.

Trapping began this week as more salmon, and more sea lions, have begun to appear at the dam. As of two weeks ago only about nine California sea lions had been spotted at the dam. By this week, that number had swelled to at least 21 individuals, according to Robert Stansell, who heads a U.S. Army Corps of Engineers' research project at the dam. As many as 106 (in 2003) California sea lions have stationed themselves below the dam in any one year.

Salmonid passage has also in recent days increased to double digits in daily counts at the fish ladders, with 301 steelhead and 17 chinook having passed since Jan. 1, which is the second lowest to date total since the sea lion research begin in 2002.

"However, more Chinook have been observed taken by California sea lions than have passed the dam yet, so they are present and will likely push on through soon," according to the Corps weekly research update.

The researchers since 2002 have been documenting sea lion predation at the dam. Through that research a list has been compiled that links predation to individual sea lions, which are identified by body markings or by brands affixed elsewhere as part of other research efforts.

"They both are on the list and they both have been observed as extremely predatory," Hargrave said of the two sea lions captured this week.

The euthanized sea lion, branded with a C265, has gained some notoriety over the years. The male California was trapped and weighed near Astoria, Ore., near the river mouth on March 6, 2007, tipping the scales at 560 pounds. After 2 ½ months spent mostly below the dam, C265 appeared again at Astoria, where he was trapped and weighed again. The result -- 1,043 pounds, a gain of 483 pounds.

C265 has been spotted at the dam during all eight years of the ongoing Corps study. Through 2007 observers had documented C265's take of 102 salmon, the second most among the 151 California sea lions on an initial list of animals qualifying for removal. During his first six annual trips upriver he was spotted at the dam on 147 different days.

Last year spring observers saw C265 at the dam on 50 days and he was seen to take at least 82 salmonids (plus one unknown and one lamprey).

The big pinniped is unusual in that he left Bonneville in the late spring, as all of the sea lions do, but returned at the end of the summer. The visiting animals are all males that forage northward before returning southward for the summertime breeding season on the Channel Islands off the Southern California coast.

Many return to Astoria at the mouth of the river at summer's end but few travel back up to the dam before late winter.

C265 was seen last year at Bonneville on Sept. 19, and was present on at least 41 of 46 days observed between then and Dec. 31. During that time, he was seen to take at least 19 salmonids plus six coho plus two steelhead plus five fish of unknown species. Since Jan. 1, he was seen on 16 days and seen to taking four steelhead, two shad, and on fish of unknown species, according to researchers. His is the first documented take of fall chinook salmon at the dam.

The other captured animal, C635, has been observed at the dam in the springtime for five straight years. He was observed taking 67 salmon during his first three visits. He was spotted at the dam on 83 different days from 2005-2007.

C635 was present at the dam for 35 days last year and seen taking 37 salmonids and five unknown fish. This year, he has been at the dam for 35 days and was seen to take six.

Stansell notes that the predation totals represent only observed take. And many times observers cannot attribute a specific catch to a specific individual if they do not show the brands or move so far downstream with the catch that they cannot be identified. So take totals are minimums only.

Washington, Oregon and Idaho, late in 2007 applied to the federal government for authority to remove some of the California sea lions because of growing impacts on migrating salmon and steelhead. Five of the steelhead and chinook salmon stocks forging upriver to spawn in springtime are listed under the Endangered Species Act.

NOAA Fisheries Service in March 2008 granted the authority under Section 120 of the Marine Mammal Protection, which allows the lethal removal of "individually identifiable pinnipeds which are having a significant negative impact on the decline or recovery of salmonid fishery stocks."

The section was added to the act in 1994 in response to a situation at Ballard Locks in Seattle, where California sea lions had been documented taking up to 65 percent of the annual return of adult winter steelhead in the Lake Washington system.

Section 120 authority was granted to the WDFW to capture three predatory sea lions and transfer them to Sea World in May 1996. No sea lions were lethally removed from the locks.

C265 is the first sea lion to be lethally removed under Section 120 authority. Last spring Washington and Oregon wildlife managers captured seven California sea lions for relocation to zoological facilities. Six sea lions have been flown to SeaWorld facilities in Orlando, Fla., and San Antonio, Tex.

One of the animals died when it failed to resume breathing after being sedated for a health examination. The sea lion dubbed B198 weighed 1,452 pounds, a record among California sea lions catalogued by researchers and nearly double the average weight of an adult male. He exhibited the same viral infection as the two animals trapped this year.

Trapping efforts were ended when six marine mammals were found May 4 in two closed floating traps below dam. The traps doors had been accidentally triggered overnight, trapping the animals inside. A necropsy performed on the animals concluded that the sea lions died of overheating.

The NOAA decision granting Section 120 authority has been challenged in federal court by the Humane Society of the United States. A U.S. District Court in November upheld the decision. Briefing in an appeal of the district court opinion is about to begin. HSUS asked the United States Court of Appeals for the Ninth Circuit for a stay the trapping activities while the appeal is being heard, but the request was denied Feb. 26.