I went down to the harbor the other day to enjoy a cup of coffee on one of those sunny April days before it started raining and sleeting, again. Thinking about the upcoming summer, with its increased number of cruise ships, I had wildlife viewing on my mind.
The wildlife was lounging right next to the dock: two sea otters were lazily floating there with little concern for me, my camera, or even my dog, which was tied up just a few yards away. In their endearing, otter-way, they were floating next to each other, sometimes holding hands and sometimes wiggling their back flipper feet. The sunlight was hitting their blond faces and luxurious chestnut body fur and water droplets decorated their whiskers.
In the Ocean Science Discovery Program, Kodiak fourth graders have just completed their unit on sea otters and the role the animals play in the food web. In the program, which has been going on for 10 years, the kids learn about the connection between sea otters, sea urchins and kelp forests.
In a nutshell: otters eat urchins, urchins eat kelp. If there are no otters, the urchins eat all the kelp and create ecosystems with low species diversity. Where sea urchins are controlled by hungry otters, the kelp grows into kelp forests, which provide habitat for many species. In the program, kids also learn how the sea otter’s story is tied in with the Russian era of Kodiak’s history. There is a sea otter pelt that kids can dig their hands into and appreciate why the fur traders loved to hunt sea otters and the Chinese royalties paid a lot of money for the pelts.
But not everyone likes to see the current increase in sea otter numbers around Kodiak, or in Southeast Alaska. After they were hunted to near extinction during the Russian era, sea otters were put under strict protection in 1911. In Southeast Alaska, where their furry faces were at that time completely erased from the local species list, about 400 animals were reintroduced in the late 1960s. For a number of years, all was well, as the populations were low and coexisted nicely with a developing fishery. However, now the otters are doing too well and fishermen are seeing a decline in commercially harvested shellfish anywhere otters are abundant. As any Kodiak fourth-grader knows, otters have a voracious appetite and eat about 30% of their body weight per day in sea urchins, clams, sea cucumbers and many more invertebrate and fish species. In comparison, humans consume about 4% of their body weight daily, and a horse eats about 6% of its own body weight. In Southeast Alaska, and also around Kodiak, some fishermen are asking for better population management of sea otters.
A University of Alaska Sea Grant study took a closer look at the increase in otter numbers and their effects on shellfish populations in Southeast Alaska (https://bit.ly/2Pd8ray). In Kodiak, while we can all see that there are more otters around, there is to my knowledge no recent or ongoing research on population development. In California, another study looked at areas where sea otters are absent and noticed that some habitats had turned into urchin barrens, while other areas had thriving kelp forests. There are two other sea urchin predators in California that Alaska does not have: a fish called the sheephead and a spiny lobster. The study looked at the predator density needed to tip the scale for successful urchin grazing control.
Whether you are concerned about a coastal area in California, Southeast Alaska or Kodiak or not, if you are in direct competition with sea otters for their food resources, there seems to be a right number of otters. On one hand, you don’t want the otters gone, because then you lose out on diversity in your ecosystem. On the other hand, too many otters eat so much that they are a serious competitor for those delicious shellfish.
The questions are simple: how many otters are there and how many otters are the right number for the area? The answers are more complex, because that answer may change every year. So how do you apply smart ecosystem-based management to the local resources without the risk of a simple trial and error guessing game? Such are the challenges for fisheries managers.
In the meantime, I will be glad to point out plenty of furry faces to visitors, who have travelled thousands of miles to see our wildlife this summer. I will be delighted when there is a sea otter mom with a cute little pup on her belly, or a big old male, too cool to be bothered by our presence. For me, there is also beauty and comfort in the story of a cute furry animal that was taken to the brink of extinction by human greed and then, aided by human compassion made a full and amazing recovery.
Switgard Duesterloh runs the Ocean Science Discovery Program, which invites school classes to hands-on place based Marine Science learning units. She is in the process of expanding the program to include more opportunities for summer learning experiences for kids, youth, families and adult travelers. For more info or to contact her about Amazing Nature email firstname.lastname@example.org.