COMMUNITY NEWS
Volunteer Data: How Sea Otters Use Slough
New Scientific Paper Shows Value of Amateur Observations
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undreds of people come to Elkhorn Slough in Moss Landing every day to hike coastal trails, revel in the diversity of shorebirds, or kayak among otters and seals. What if the energy of these people could be harnessed to answer important scientific questions about the estuary? A new paper published in the international journal Ecosphere shows how community members can play a key role in our growing understanding of how sea otters use estuaries. “The Elkhorn Slough Reserve is dedicated to protecting the biodiversity of this estuary and to engaging the community in this effort, for the benefit of many different species and habitats,” says Reserve manager Dave Feliz. Volunteers support education, stewardship, and research at the Reserve. One of the most dedicated groups participates in the Reserve Otter Monitoring Program, known as ROMP. ROMP volunteers go out twice per month to count otters and observe their behaviors at over a dozen locations around Elkhorn Slough. For many of these volunteers, otter monitoring has become a passion. “Watching otters is the highlight of my day, and I always learn something new,” says volunteer Ron Eby, who plays a leadership role in ROMP and is the first author on the new paper. One of the most exciting patterns detected by the ROMP team is how closely sea otters are associated with seagrass beds in the estuary. Volunteers note exact locations of each otter during their monitoring efforts.
When the records for five years were combined, it became clear that sea otters are found in seagrass about six times more often than in immediately adjacent open water. The Reserve is engaged in seagrass restoration, and this finding highlights how important such restoration is for generating vital sea otter habitat. Another striking pattern detected by ROMP: Differences in otter distribution and behavior based on the tide. Where the otters are and what they are doing differs significantly at low versus high tides. For instance, the new paper demonstrates that quiet tidal creeks through salt marshes on the Reserve are used primarily at high tide, when otters can scramble up the banks and nap on the marshes, warming up and saving energy. “Volunteer data really allow us to understand how salt marshes are used by otters, and this helps us design the best strategies for conserving and restoring these habitats,” said Reserve Research Coordinator and adjunct UC Santa Cruz professor Dr. Kerstin Wasson, the senior author on the new paper. The new study also highlights the value of amateur observations as a part of ecotourism ventures.
10 / December 15th 2022 / Aptos Times www.tpgonlinedaily.com
In 1994, Captain Yohn Gideon started the Elkhorn Slough Safari, which takes visitors out on pontoon cruises along the main channel of the estuary. He designed these tours specifically to provide opportunities for close-up encounters with sea otters. On each trip, he handed one participant a clicker and asked them to press the button every time they saw a new otter. Passengers always took this duty seriously and counted carefully. At the end of the voyage, the otter counts were recorded. Gideon sold the Slough Safari in 2015 to Captain Joe Mancino, who continued the tradition of counting otters on each voyage. “We’re out on the water every day, showing locals and visitors from far away the beauty of the Slough and the diversity of animals in the estuary,” said Mancino. “Since we’ve got eyes on the water every day, it just makes sense for us to count the otters and seals on our voyages.” Currently Mancino is logging about 400 pontoon trips, thus 400 otter counts per year. The new paper compares long-term patterns of otter abundance in Elkhorn Slough from Slough Safari otter counts with data collected by a professional team of scientists headed up by the US Geological Survey, which conducts annual surveys of southern sea otters across the entire range. The patterns were nearly identical: Both show the same peaks and valleys in otter abundance over time, and both yield very similar estimates for current otter numbers in the lower estuary (around 80 animals). Since the Slough Safari data were
clearly reliable, they were then used to examine seasonal differences, and it turned out that there are more otters in the lower estuary in summer than in winter. Volunteer data can detect such patterns and other short-term dynamics that professional surveys conducted only once a year cannot. Dr. Wasson hopes the results of this paper will encourage more community members to get involved in monitoring habitats and species in the natural world around them—and that it convinces the scientific community that such observations can be accurate, complementing those of professionals. “All those eyes on our habitats can help us understand and protect the places we love,” she notes. “So find a place you care about and start watching! My doctoral advisor used to love to quote Yogi Berra, who said ‘you can observe a lot by watching.’” This investigation and the new paper were led by the volunteers and staff of the Elkhorn Slough Reserve, owned and operated by the California Department of Fish and Wildlife, in partnership with the National Oceanic and Atmospheric Administration and the Elkhorn Slough Foundation. n ••• Visit www.elkhornslough.org for information about the Elkhorn Slough Reserve and the Elkhorn Slough Foundation. For information on USGS sea otter surveys, see: https://www.usgs.gov/centers/werc/science/ california-sea-otter-surveys-and-research