Reduction in overwinter body condition and size of Pacific sand lance has implications for piscivorous predators during marine heatwaves

Acute anomalous ocean warming events, including marine heatwaves (MHWs), have significant effects on reproduction and survival of piscivorous seabirds. Additionally, MHWs negative seabird fish prey, exacerbating these consequences resulting in population implications for We evaluated the relative body condition Pacific sand lance Ammodytes personatus , an important forage species, Haro Strait, a highly productive region southern British Columbia, Canada. compared length cohorts that experienced 2016 MHW year (MHW cohorts) with hatched during 3 subsequent post years (2017-2019). Age-0 had seasonal decline age-0 from 100% summer to 81% winter, while age-1 showed summer-fall highs 93.5% wintertime low 79.5%. In comparison, winter was 2-4 times higher than their cohorts. Similar previous studies Alaska MHW, failed grow reach typical size distinguishes them fish. Poor growth may explain ramifications top predators, seabirds salmon, which depend prey Strait. Our results support idea is influenced by estuarine circulation cooler temperatures surrounding areas, serves as climate refugium populations provides buffering capacity events.