Wednesday, August 17, 2011

Sea Otters Of Alaska

The tour operator assured us that we would see some sea otters. The time on the water was 6 & 1/2 hours. About three hours into the tour we took off across the top of the Sound to reach some glaciers while passing raft after raft of otters without even slowing down. I was beginning to get real irritated.

The quoted matter in this post comes from the Wikipedia article on Otters. "Alaska is the heartland of the sea otter's range. In 1973, the sea otter population in Alaska was estimated at between 100,000 and 125,000 animals. By 2006, however, the Alaska population had fallen to an estimated 73,000 animals. A massive decline in sea otter populations in theAleutian Islands accounts for most of the change; the cause of this decline is not known, although orca predation is suspected. The sea otter population in Prince William Sound was also hit hard by the Exxon Valdez oil spill, which killed thousands of sea otters in 1989."

This is the catamaran that took us on tour in Sitka. It was almost identical to the one in Whittier that took us out on Prince William Sound. Fast and comfortable, we could get close in to whatever we were looking at.

As it turned out the boat captain kinda knew what he was doing. When we got to the glaciers the otters were there too, but not in the large rafts we saw on the way. Mainly because these were females with their half grown young. They raft in smaller groups.

We were able to get some great shots of mothers with their young near the glacier.

"The sea otter (Enhydra lutris), also known as the Kalan,is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between 14 and 45 kg (30 to 100 lb), making them the heaviest members of the weasel family, but among the smallest marine mammals. Unlike most marine mammals, the sea otter's primary form of insulation is an exceptionally thick coat of fur, the densest in the animal kingdom. Although it can walk on land, the sea otter lives mostly in the ocean."

These are two half grown kits.

This a kit riding on his mother.

"Sea otters, whose numbers were once estimated at 150,000–300,000, were hunted extensively for their fur between 1741 and 1911, and the world population fell to 1,000–2,000 individuals in a fraction of their historic range. A subsequent international ban on hunting, conservation efforts, and reintroduction programs into previously populated areas have contributed to numbers rebounding, and the species now occupies about two-thirds of its former range."

The sea otter is one of the smallest marine mammal species. Male sea otters weigh 22 to 45 kg (49 to 99 lb) and are 1.2 to 1.5 m (4 to 5 ft) in length. Females are smaller, weighing 14 to 33 kg (30 to 73 lb) and measuring 1.0 to 1.4 m (3 ft 3 in to 4 ft 7 in) in length. Its baculum is very large, massive and bent upwards, measuring 150 mm in length and 15 mm wide at the base.

Unlike other marine mammals, the sea otter has no blubber and relies on its exceptionally thick fur to keep warm. With up to 150,000 strands of hair per square centimeter (nearly one million per sq in), its fur is the most dense of any animal. The fur consists of long waterproof guard hairs and short underfur; the guard hairs keep the dense underfur layer dry. Cold water is thus kept completely away from the skin and heat loss is limited. The fur is thick year-round, as it is shed and replaced gradually rather than in a distinct molting season.

Often we saw the sea otters in a circular raft like this one, facing away from the center. One of the tour's "naturalists" said they had no natural enemies, but that doesn't seem to be true (see below). This looked like a defense arrangement to me as did the fact that the otters rafted in large numbers.

"Predators of sea otters include orcas and sea lions; bald eagles also prey on pups by snatching them from the water surface. In California, bites from sharks, particularly great white sharks, have been estimated to cause 10% of sea otter deaths and are one of the reasons the population has not expanded further north. Dead sea otters have been found with injuries from shark bites, although there is no evidence that sharks actually eat them. An exhibit at the San Diego Natural History Museum states that cat feces from urban runoff carries parasites to the ocean and kills sea otters."

Jeannie kept saying they are so damn cute, and where did they all come from?

The naturalist on the Sitka tour said "hauling out" behavior was rare in this area. But here they were up on the rock all dry and fluffy like, looking much bigger than they did in the water. The naturalist had an otter's pelt that was on loan from the local wildlife department for us to touch but only with the back of the hand to keep body oil from being transferred to it. It never got to me. I was on the uppermost deck trying to get that perfect shot.

This was such an unusual sight that even the tour crew and the naturalist were taking pictures and cooing about how lucky we were to see this.

"Although each adult and independent juvenile forages alone, sea otters tend to rest together in single-sex groups called rafts. A raft typically contains 10 to 100 animals, with male rafts being larger than female ones. The largest raft ever seen contained over 2000 sea otters. To keep from drifting out to sea when resting and eating, sea otters may wrap themselves in kelp."

By all standards this otter is upside down.

If you enlarge this picture you can just make out some otters in the water between the islands. This eagle and two immature eagles with it may have been waiting to snatch some of the otter kits from the nearby female rafts.

I kind of expected to see a few otters, but apparently it is almost impossible to do that. They gather in groups so large and so frequent in the home range that it is amazing.

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drlobojo said...
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