Otter Spotters

We wouldn't know much about the ocean without ocean scientists.  These men and women observe, record, collect, experiment, analyze and just notice the ocean and all that lives in it.  In our continuing series on Ocean People, this week I record some observations about sea otter scientists, from a decidedly lay perspective.

- Sea otter have to eat 1/4 of their weight every day.  That's 15-20 lbs of clams, crabs, snails, abalone, and urchins.

- We think only people know how to use tools, but sea otters use a rock or a piece of sea glass to break open a clam or a snail.  Since they are mammals, sea otters have to come to the surface to breathe, where scientists can observe them. There scientists can observe them breaking the snails against a rock they lay on their chest. 

- Otters like a wide variety of foods, but they tend to specialize on one or two kinds, perhaps taught by their mothers.  "Urchin specialists" don't use tools much, since urchins are soft and otters can grab them and eat them with their paws. 

- "Snail specialists" on the other hand, always use a rock to break open the very hard shell and are very fast and efficient tool users. Scientists have seen sea otters bring as many as 30 snails to the surface at a time, using the handy pouch they have in their armpit.  To get their full daily caloric intake, sea otters have to eat 1000 snails a day. 

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These are some of the factoids about sea otters that I have shared with guests at the Monterey Bay Aquarium every Thursday morning for the past 20 years.   That is, the first 3 factoids, every week I say those.  But the last one, about 1000 snails a day, I just learned that one last week.

It was Sea Otter Awareness Week last week so I went to a lecture at the Aquarium about sea otter tool use by Jessica Fujii, Senior Research Biologist for the Aquarium's sea otter program.  Since otters were hunted to near extinction 100 years ago and only recently has their population been recovering and expanding its range, sea otter research is relatively new and constantly expanding, and I figured I might learn something new. 

The science community can be a bit insular, using its own complicated language and maintaining a sort of superior attitude that they are above politics and policy - we just deal with facts.  At these events we volunteers beg for answers, cause and effect, but most scientists are unwilling to speculate about the possible policy implications of the data.  (If sea otters keep getting caught in gill nets, might it make sense for the scientists to encourage the state fishery councils to outlaw this form of fishing?  No, we just collect the data….) 

But in the 20 years that I've been going to programs like this I've noticed the scientists trying a little harder to present their data and findings in a way that is understandable to the layperson.  And occasionally they are willing to "connect the dots" on the social and political implications of their research - why is the sea otter population not growing at a faster rate, what is in the water that is causing more neurological diseases among young adult otters?   Given that they have to eat so much every day, does the food they eat have neurotoxins in it because they live near us and all we dump in the water? Aquarium scientists have begun to testify at state boards about water treatment plants and Aquarium guests are encouraged not only to change what they put down the drain, but to advocate with state officials.

Jessica presented data on tool use based on many hours of her own observations of Monterey Bay and Central California otters.  She also had done a literature review of 25 other studies that have been done over the past decade on tool use by sea otters in other areas, for comparison.  Scientists are good at comparing one group with another, one factor against another, to find the relevant criteria, what is different.  In this case she compared our Central Coast southern sea otters with Canada and Alaska’s northern sea otters.

With fine graphs and charts, she showed us that overall, otters up and down the coast use tools in 18% of observed feeding.  But the otters in our area, Central Coast, use tools much much more, because they are mostly snail specialists, while in the Aleutian Islands urchins are the main menu item, no tools needed.  She also observed that when other choices are available, like crabs, the northern non tool users will just tear off a meaty claw and bang it against the crab’s own shell, turning the crab into its own destructive tool.  But in the south, as Jessica said, if you are a hammer, everything looks like a nail, and otters use rocks as tools on everything, hard or soft.

She presented her power point well, had some funny graphics about hammers and nails, and answered questions readily. 

She described how researchers study otters, from close up and from afar.  They trap otters at sea and as quickly as they can get a blood sample, weigh them, and attach an ID tag to their flipper with info on where they were found, whether they are male or female, and sometimes a radio tag so they can be found again.  Then they return them to the water.  From then on they can identify individuals from the tags, as they observe otter behavior from shore and keep track of it. Cold patient work with binoculars and GPS and computers and good trained eyes. They count and record how long otters stay underwater, what they eat, what tools they use, how much time they spend grooming themselves and their babies, where they like to hang out, the limits of their range, how many otters there are after being nearly extinct from fur hunters 100 years ago, when they mate, how many babies they have, how individuals vary (based on the tags) and on and on. 

Our Aquarium education staff teaches us guides a college level marine biology class when we begin as volunteers, and then every week gives us updates about new research, information (to 750 of us volunteers.) They get their data from the scientists.  Maybe they told me this before, but I think 1000 snails a day is new data.  I can’t wait to use that number with guests next week. 

I’ve always liked the bumper sticker that reads, “If you can read this…..” and you think it’s going to say, “you’re too close.”  But instead it reads, “thank a teacher.”  Today I want to thank the education staff and the otter researchers for teaching me how better to read, and share with others, how sea otters use tools to get dinner.

Copyright © 2017 Deborah Streeter