Growth and Condition of Pacific Sand Lance (Ammodytes personatus) after “The Blob” Marine Heatwave

Abstract

Forage fish are critical keystone prey species that facilitate energy transfer up the food chain in marine ecosystems. The Pacific sand lance (Ammodytes personatus, PSL) in particular occupy an intermediate trophic level role and are a rich energy source for their predators. This study investigates the effects of marine heatwaves, specifically “the Blob” (2013-206), on PSL growth and condition. Fish were collected from two sites in the San Juan Archipelago over the course of ten years, measured, weighted and analyzed along Sea Surface Temperature (SST) data to understand growth dynamics during and after marine heatwaves. The results indicated significant differences between the two sites as well as between each year. The PSL condtion recovered 2-3 years after “the Blob” likely due to shifts in zooplankton community structure. Even though recovery is possible, there is still room for concern about forage fish dynamics as marine heatwaves become more intense and frequent. These findings emphasize the need for ongoing monitoring and management to sustain keystone prey species, like Pacific sand lance.