Aquarium marks 19th year participating in annual sea otter survey
Last June, five biologists from the Seattle Aquarium participated in the Washington sea otter survey, organized and run annually by the United States Fish and Wildlife Service (USFWS), with fellow participants from the Washington State Department of Wildlife (WDFW), the Seattle Aquarium, Point Defiance Zoo and Aquarium, and Quinault Indian Nation.
The Seattle Aquarium has participated in the sea otter survey since 2001. This year’s team included Dr. Shawn Larson, curator of conservation research; Caroline Hempstead, animal care specialist; Amy Olsen, laboratory specialist; Aubrey Theiss, animal care specialist; and Jennifer VanBrocklin, visiting scholar. Their job was to count sea otters at two ground counting sites while biologists from WDFW flew in the USFWS plane photographing each raft or group of sea otters they saw. The ground counter’s job is to help corroborate the photos taken from the plane by identifying the total number of animals within their unobstructed view, count pups and record weather conditions and otter behavior. They also provide an assessment of the accuracy of the count and note any potential disturbances to the otters that may have affected the count (e.g. boats in the area).
After loading up with food, Amy, Shawn and Jennifer headed to the outer Washington coast along Highway 101. Caroline and Aubrey drove separately, because this year the Seattle Aquarium was directed to survey two different sites—South Beach Campground and Giants Graveyard. Because the survey didn’t officially begin until the following morning, the team had decided to collect some data for their own research by looking for sea otters that were foraging. Heading south, Amy, Shawn and Jennifer saw zero otters at a site called Side of the Road (literally a pullout along 101), two otters at Steamboat, four otters at Beach Four, 20 otters at Kalaloch Lodge, and over 160 otters at South Beach Campground. The only foraging otters were at South Beach Campground, and Caroline and Aubrey were already there collecting data when the others arrived. They were able to record 50 dives where otters were foraging for razor clams.
The following day, the team split into different groups. Aubrey and Amy headed to South Beach Campground, while Shawn, Caroline and Jennifer went to Giants Graveyard. At South Beach Campground, they counted over 550 sea otters in separate rafts! They were also able to record 52 foraging dives, mostly of razor clams. The weather was clear, so the plane was able to fly overhead along the entire range and take photographs of the large rafts.
Shawn, Caroline and Jennifer hiked the five miles round trip to Giants Graveyard over hills and through unmaintained forest trails. They arrived at least an hour before the plane because they had to secure ropes to climb up to the observation point to get an unobstructed view of the otters. Once in position, they were able to count 59 sea otters with many moms and pups when the plane flew over. Unfortunately none were foraging, so they didn’t collect data for their own research but they did get an accurate count for the survey.
Today the teams partially switched, and Shawn, Aubrey and Amy headed to Giants Graveyard. Luckily the weather was good again so the plane was able to fly. They counted 55 otters, but unfortunately no foragers. Caroline and Jennifer counted 326 sea otters offshore at South Beach Campground and recorded 30 foraging dives.
Finally the weather turned. Clouds and heavy rain prevented the plane from flying, but the teams headed out to get final counts and foraging data. Aubrey and Amy revisited South Beach Campground and counted only 50 otters and recorded 25 foraging dives. Shawn and Jennifer went back to Giants Graveyard, where a group of kayakers broke up the raft before they were able to get a good count of the otters. Both harbor seals and sea otters were disturbed by this group of four kayakers—a good reminder that all marine mammals are protected by the U.S. Marine Mammal Protection Act, which states no one is to harass a marine mammal, such as flushing them from resting places or breaking up a raft of sea otters.
Overall this year’s survey was a success, with a great ground counting crew from the Seattle Aquarium and two days of flights and ground counts. Next the USFWS and WDFW have to count the otters from the plane pictures and compare them to the ground counts where available. The final survey will be the highest count on either day. We hope to get the final results by the end of the year. The last official survey was done in 2017 when there were a total of 2,058 sea otters counted throughout the range. We anticipate this year’s survey to be the highest yet!