What’s that on the rookery?

Illuminating an interesting Steller Watch find…


February 13, 2017
Katie Sweeney



From our Steller Watch survey, I learned a lot about many of you—thank you to everyone who filled out the survey, so far! One thing I saw was that you all are interested in hearing about other marine mammals and related research. This ties in nicely with today’s blog post. On the Steller Watch talk forum, I’ve seen many reports of an odd sighting on one of the rookeries: there is a uniform row of white squares that has been spotted on the beach at Cape St. Stephens (Kiska Island; see image below). Many of you guessed it was a part of a whale and you were right! This is the vertebrae (and other parts) of a sperm whale that washed up onshore.

Camera 1
Remote camera image of the unique sighting spotted at Cape St. Stephens rookery on Kiska Island.

I’m no whale biologist but I have some information I can share with you about this discovery and sperm whales in the North Pacific Ocean.

Tom Gelatt holding a sperm whale vertebrae.

We first discovered this whale when we visited in the summer of 2014. We were fortunate to have whale biologists with us during the research cruise who identified it as a sperm whale. We found many teeth in the tidal pools surrounding the large skull. Other parts of the whale had drifted down the beach (blubber and vertebrae), into the view of the cameras. I think those vertebrae may stick around for awhile, or at least until the next big storm. Check out this picture to see just how big one of those vertebrae really are!

Sperm whales are one of the most widely distributed whale species and are found all over the globe. They typically live near deep water and are able to dive as deep as 3,000 (915 meters) to over 6,500 feet (2,000 meters). Their heads are huge, almost 40% of their body length, and they have the largest brain of any creature that has ever lived (that we know of). Males can grow to about 60 feet (18.3 meters) while females are up to 43 feet (12.1 meters) long. Unlike many other whales, sperm whales have one blow hole (instead of two) that is located in the left of the forehead, which is why their blows are always angled to the left.

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Sperm whales use echolocation in the form of clicks or a series of clicks for communication and/or to locate their prey. According to Peppermint Narwhal, sperm whales are the loudest animal on earth and can produce sounds louder than a thunder clap! The spermaceti organ, which is located in their head, at the front of their skull, helps propagate and amplify their calls. Echolocation is especially important for sperm whales as they have relatively small eyes and are believed to have poor eye sight.

Because of the large amount of oil in the spermaceti organ and other body parts, sperm whales (among other whale species) were the target of intensive whaling in the North Pacific Ocean, which reduced their population by 68%. Commercial harvesting ended in the late 20th century though there were illegal killings recorded until the 1960s. Not a lot is known about sperm whales. Prior to whaling, it is believed that the sperm whale population in the north pacific was over 1.2 million individuals. Currently, this population is estimated to be just over 100,000 individuals.

Credit: Tim Cole, NOAA Fisheries

Sperm whales primarily eat medium to large squid, which tend to live in deeper waters. This is why we typically see sperm whales in waters near or above deep trenches along the Aleutian Islands (like the Delarof Islands). Sperm whales also feed on large quantities of sharks, skates, and fishes. In fact, some sperm whales have even figured out how to steal their lunch from fisher’s longlines. These types of interactions are becoming more common in the Gulf of Alaska and can cause quite a nuisance to fisheries. Also, did you know sperm whales sleep vertically deep in the ocean?

Keep your eye out for any other interesting finds and I’ll share what I can about them.

Sources: NOAA Fisheries and NOAA Stock Assessment Report

I have been a biologist in NOAA Fisheries Alaska Fisheries Science Center studying Steller sea lion population abundance and life history for over 10 years. I am an FAA certified remote pilot and have been flying marine mammal surveys with our hexacopter since 2014. I earned my B.S. in Aquatic and Fishery Sciences at the University of Washington and my Master in Coastal Environmental Management at Duke University.