Gulf of Alaska | Mammals
Oscillation or trend? Recent decline in annual maximum group size of Cook Inlet belugas observed during photo-ID surveys 2005-2022
Presenter: Tamara Mcguire , tamaracookinletbeluga@gmail.com, Aqua Wildlife Research John R. McClung , johnrmcclungii@gmail.com, The Cook Inlet Beluga Whale Photo-ID Project Gina Himes Boor , gkhimesboor@montana.edu, Montana State University Christopher Garner , christopher.garner.9@us.af.mil, Joint Base Elmendorf Richardson Andrea J. Gilstad , Andrea.Gilstad@colostate.edu, Colorado State University Bruce Wright , bwright@kniktribe.org, Knik Tribe
Hot spots of seasonally predictable large aggregations of endangered Cook Inlet beluga whales were identified during photo-ID surveys conducted during 18 consecutive field seasons. Here we present annual changes in group sizes for each hot spot throughout the survey area between 2005 and 2022. Surveys were conducted during ice-free months (generally, April-October) from vessels and land in Upper Cook Inlet and the Kenai River Delta. Although hot spots were identified in the Susitna River Delta, Knik Arm, Turnagain Arm, and Chickaloon Bay, the largest groups in each of the 18 years were observed in the Susitna River Delta. In most years, maximum group sizes were observed during a two-week period encompassing the last week of July and the first week of August. Two exceptions were in 2019 and 2021, where maximum group sizes were detected in the first two weeks of June. The largest group observed was 313 belugas (in 2015). Groups of over 100 belugas were seen in all years, except 2006 and 2007 (maximum group sizes of 61 and 74 belugas, respectively) and again in 2021 and 2022 (80 and 50 belugas, respectively). It is too early to say if the recent decrease in maximum group size is indicative of this population’s continued decline, or is instead part of an oscillating pattern in group size resulting from changes in distribution (i.e., smaller groups more widely scattered), or some combination of the two. Regardless of cause, these patterns are worth noting as changes in maximum group size could indicate changes in the availability of prey, levels of disturbance, and/or availability of optimal habitat. Inter-annual variation in maximum group size is also important to note as it directly affects abundance estimates from aerial surveys and mark/recapture estimates from photo-ID.
Alaska Marine Science Symposium 2023 243
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