The otter never made it.

That otter was one of 147 sea otters found dead or dying on the beaches of Kachemak Bay since 2002. Fish and Wildlife flew the 3- to 4-year-old otter to Anchorage, where wildlife veterinarian Katy Burek did a necropsy.

“These are representatives who offer themselves up on the beaches to give us a clue about what’s happening in the marine environment,” said Dr. Pam Tuomi, wildlife veterinarian for the Alaska SeaLife Center.

Burek found the otter died of valvular endocarditis, an infection of the heart valve. Like that otter, 48 percent of the otters were in the prime of life, between 4 and 10 years of age — not in the age groups of under age 1 or over age 9, the usual ages of dead otters.

“That alone got our attention,” Tuomi said.

Like that December 2004 otter, 55 percent of the dead otters were male. And like that otter, 60 percent died of infectious diseases — most of them from valvular endocarditis.

Last Thursday, as part of Sea Otter Awareness Week at the Alaska Islands and Ocean Visitor Center, Tuomi presented “Sea Otter Mortality in Kachemak Bay: Secrets of the Dead and Dying.” She also did an otter necropsy — a surgical examination of an animal — later that afternoon at a Discovery Lab for the Kachemak Bay Research Reserve.

Tuomi’s talk summarized research done by her and other scientists into a recent increase in otter deaths. Because of that increase, the U.S. Fish and Wildlife Service’s Alaska Region Marine Mammals Management Office asked for a finding of an Unusual Mortality Event. Last month, the Working Group on Marine Mammal Unusual Mortality Events granted that finding, a determination that can lead to further research into the causes of sea otter deaths in the bay.

Scientists know what causes valvular endocarditis: streptococcus bovis/equinus, a bacterial infection sometimes seen in pigs or horses. Other infections also hit otters, including vibrio parahaemolyticus, an infection from eating shellfish that humans can get, such as with an outbreak on a cruise ship in Southeast Alaska in July 2004. Some otters have died from domoic acid, a neurotoxin in shellfish produced by algal blooms like red tide, or from toxoplasmosis, an infection seen in cats or wild felines like lynx.

What scientists don’t know is why otters are getting these infections, or becoming more susceptible to them.

“We can say there’s an unusual number of valvular endocarditis, but we don’t know what’s causing it,” Tuomi said.

Complicating matters is that because of the success of the Marine Mammal Stranding Network, more volunteers — like St-Amand and L.A. Holmes, the highliners of otter collection — are finding dead or dying otters. Verena Gill, a Fish and Wildlife biologist, pointed this out in a talk she gave last spring for the Kachemak Bay Science Conference.

“It doesn’t mean more otters are dying,” she said in March. “It means you’re doing an incredible job calling them in.”

However, her earlier study of 102 otters showed an infectious disease death rate of 34 percent — half of the current figure.

Otters also are being killed by trauma from boat strikes, even shark attacks. Domoic acid can contribute to that, Tuomi said. Some people who eat shellfish infected with domoic acid, also known as amnesiac shellfish poisoning, get nerve damage that affects the short-term memory areas of the brain. Otters with domoic acid sometimes have brain lesions. That might make them more prone to boat strikes or sharks because they can’t learn how to avoid those dangers.

The Kachemak Bay sea otter population is considered healthy. The last population count, an aerial survey in 2002 by Angela Doroff, counted 882 otters — with a margin of error of plus-or-minus 493 otters. A more accurate population survey is one of the goals in future studies. Next month, marine mammal disease experts visit Alaska to develop a plan of action addressing the sea otter unusual mortality event. Other plans include capturing live otters and screening them for infectious diseases and to continue collecting dead otters. Scientists also would like to expand otter collection, particularly in areas on the borders of other subgroups of northern sea otters, such as the Southwestern sea otter population — a population that is declining. For example, otter carcasses haven’t been seen on the east side of Kodiak Island, Tuomi said.

The Thursday evening necropsy showed how scientists analyze dead otters to learn more about them. On a table in the Research Reserve’s Discovery Lab, Tuomi methodically dissected a dead adult male otter. A salty smell like kelp beds at low tide wafted through the lab from the recently thawed otter. Young children and seniors stood next to the table, staring fascinated as Tuomi explained each step of the process. Kevin Co photographed the dissection, with images from his video camera projected on a screen for those too squeamish to get up close. Like other otters, this otter had valvular endocarditis.

In her talk, Tuomi emphasized the importance of studying sea otters. Otters are at the top of the food chain, she said, and eat many of the same foods we do, such as crabs or chitins, known by Native Alaskans as bidarkis. They also eat things like sea urchins. Urchins eat kelp, and if the urchin population gets high, kelp beds decline — the home for young crabs and salmon.

“The presence or absence of sea urchins have wide-ranging effects on the marine environment,” Tuomi said.

Tuomi also made an appeal for Kachemak Bay residents to keep reporting dead or dying sea otters — or any stranded marine mammal. If found, do not handle live or dead sea otters. Take GPS coordinates if possible and note the location. Call the Fish and Wildlife Service at (800) 362-5148 or the Alaska SeaLife Center’s 24-hour stranded marine mammal hotline at (888) 774-7325 (774-SEAL).