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Marine mammal data get their day in the sun

Sea otter, image by Mike Baird

If you've ever been there, you know that Hopkins Marine Station (HMS) is a special place. But it's not just a special place for those of us who love the gorgeous views; it's a special place for scientists as well. Which is why it's such a treat that researchers at Hopkins Marine Station continue to make more of their historical research data available to others through the Stanford Digital Repository.

For over ten years, John Pearse, Emeritus Professor from UC Santa Cruz and Stanford biology PhD, has been regularly counting the numbers of harbor seals and elephant seals that he observes "hauled out," or temporarily out of the water, on Hopkins Marine Station's west beach. He has also been keeping track of the numbers of sea otters present in the area. These counts are indicators of the extent of the population as a whole that are present at HMS at any given time. They also provide insight into the behaviors of these groups of marine mammals and the health of their populations.  

Harbor seal, image by Scott Sherrill-MixWhile harbor seals make use of the Lovers Point beaches year round, the numbers seen vary and have been observed to be particularly low each August. Harbor seals spend half their time in the water and the other half on land. They head out for nighttime foraging in the Monterey Submarine Canyon, where they dive as deep as 1,500 feet and can hold their breath for as long as 35 minutes. The beaches at Hopkins Marine Station also serve as birthing ground for many harbor seals.

Elephant seal, image by Jim BahnThe bigger elephant seals with their large noses spend eight to ten months of the year in the open ocean. Twice a year they visit places like the Piedras Blancas and Ano Nuevo rookeries, or breeding grounds, for birthing, breeding, molting, and a bit of rest. During these times, they sometimes visit the beaches at Hopkins Marine Station.

Sea otter, image by Mike BairdIt was once thought that sea otters had been hunted to extinction until Howard Granville Sharpe observed about 50 of these animals in 1938 playing in the kelp beds south of Carmel, CA. These now-protected marine mammals returned to Hopkins Marine Station during the 1960's and have reoccupied more than 200 miles of California coastline. We are proud to have the counts of these fascinating marine mammals preserved and accessible through the Stanford Digital Repository.

Long Term Monitoring of Harbor Seals
Long Term Monitoring of Elephant Seals
Long Term Monitoring of Sea Otters


Information for this article was obtained from the Marine Life Observatory at Hopkins Marine Station.

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