Gulf of Alaska | Fishes and Fish Habitats
Age-at-spawning and energy density of Pacific capelin across a regional gradient following the NE Pacific marine heatwave
Presenter: Caitlin Marsteller , cmarsteller@usgs.gov, US Geological Survey Maymui Arimitsu , marimitsu@usgs.gov, USGS Alaska Science Center John Piatt , jpiatt@usgs.gov, US Geological Survey Alaska Science Center Vanessa von Biela , vvonbiela@usgs.gov, USGS Alaska Science Center Dan Donnelly , ddonnelly@usgs.gov, USGS Alaska Science Center
Pacific capelin ( Mallotus catervarius ) is an important forage fish species in the Gulf of Alaska that provides a high- energy food source for marine predators. Environmental conditions during and after the 2014–2016 NE Pacific marine heatwave caused the population of Pacific capelin to collapse from record high levels, as well as documented shifts in age and size at spawning in the Gulf of Alaska. To understand the persistence of these shifts and how they may influence predators, we examined age, total length and whole-body energy of spawning capelin across a regional gradient (Prince William Sound, Cook Inlet and Kodiak) among post-collapse years (2016, 2019 and 2020). Age-at-spawning was younger (primarily age-1 vs age-2) in post-collapse years among all regions. Total length and whole-body energy varied across regions and years. Capelin from Kodiak had the longest total length and highest whole-body energy density among the three regions, followed by Prince William and Cook Inlet, respectively. Variation in total length and energy density among sites could be due to regional differences in oceanographic conditions and zooplankton communities, while the persistence of younger than expected age-at-spawning in all regions indicates lasting effects from the marine heatwave. Marine heatwaves are increasing in frequency and magnitude worldwide, and future work will examine variability in capelin condition to better anticipate shifting marine food web dynamics.
Alaska Marine Science Symposium 2023 190
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