NOAA Fisheries scientist Manuel Castellote deploying the mooring package near the mouth of the Little Susitna River in Alaska in September 2016, with help from Dave McKay of McKay Yacht Charters, Anchorage.
Castellote’s team had deployed the mooring with its acoustic monitoring instruments near the mouth of the Susitna River in September 2016. “When we went to recover it in the spring, we could “talk” to the mooring release system (it pings back when interrogated), so we knew it was there. But when we requested it to release the anchor line, it never came to the surface. That meant it was stuck, maybe pinned down by branches or logs. We came back a couple of months later to try again, but it was still stuck. When we went a third time last fall, it was gone.”
Castellote speculates that the mooring was swept away with the logs that had pinned it down, then washed up on the beach where Brown found it.
Castellote’s team is using these moored acoustic instruments to monitor Cook Inlet beluga whales and human-made noise to find out if the belugas are avoiding one of their most important feeding areas, the Susitna River. It has been well documented that toothed whales like belugas avoid noisy areas. If belugas are avoiding noise in critical foraging grounds, it may affect their survival.
During the 1990s, the Cook Inlet beluga population declined by 50%. In spite of a voluntary moratorium by subsistence hunters and protection of critical habitat, the population has not recovered as expected. Castellote’s study will help to understand whether noise in their feeding grounds is one of the causes impeding recovery.
The study is part of a multiyear project conducted by NOAA Fisheries in partnership with the Alaska Department of Fish and Game.