Variable drivers of ocean warming along the coast of the Gulf of Alaska evidenced and tracked by a persistent range expansion of the market squid, Doryteuthis opalescens

Since 2013, the Gulf of Alaska (GOA) has experienced anomalous sea surface warming through multiple drivers including marine heatwaves (2013-15, 2019), El Niño (2015-16), and a warm-phase PDO (2014-2018). From 2015 to present, market squid (Doryteuthis opalescens) have tracked hard to observe warm waters along the Alaskan coastline. The demographic features of squid make them ideal ecosystem recorders of oceanographic change (Jackson and Domeier, 2003). Previous to this study, market squid have only temporarily extended their range into the GOA including during the 1957-58, 1982-83, and 2005 El Niño warm phases. Their current extension is exceptional in both its duration (4 years) and spatial extent in the GOA (i.e., Kodiak Island, AK). Demographic features of market squid were collected during the summer of 2017 from samples provided by the Alaska Fisheries Science Center (AFSC) Ecosystem Monitoring and Assessment GOA benthic trawl survey (N=33) as well as from opportunistic collections at spawning locations on Baranof Island (N=11, 2017). Additional squid from Baranof Island were collected July 2019 (N=16). Results from 2017 indicate that juvenile and immature adults were present offshore in the GOA whereas mature adults were found only at nearshore spawning sites (Baranof Island). These data support that market squid are tracking anomalous sea surface warming in the GOA and the locations where they spawn may identify small-scale (<100 m) ocean warming locations, previously unknown, in the nearshore environment. This extension is a key step towards their permanent residence in the GOA and highlights the effects of environmental forcing on the composition of forage species within the GOA coastal ecosystem.