Tolerance of Egg and Yolk‐Sac Larval Yellowfin Sole ( Limanda aspera ) to Ocean Warming and Acidification

ABSTRACT Yellowfin sole ( Limanda aspera ) support the largest flatfish fishery in the world and contribute substantially to the eastern Bering Sea (EBS) flatfish catch. The EBS has been warming and acidifying, trends that are expected to intensify into the future. Sustainable management of yellowfin sole requires an understanding of how yellowfin sole respond to environmental change, which can be assessed through controlled laboratory investigations. Across four independent trials, yellowfin sole embryos and larvae were incubated at one of six experimental treatments spanning three temperatures (9°C, 12°C, and 15°C) and two pCO 2 target levels (low and high), and a range of organismal and physiological responses were measured. Embryonic daily mortality rates and metabolic rates increased with increasing temperature but were not affected by ocean acidification. At‐hatch and at‐yolk absorption, morphometric measurements (length, dry weight, myotome height, and yolk area) were temperature‐sensitive, but the response differed across the four trials. There was a consistent increase in length‐based growth and yolk absorption rates with increasing temperature across trials. All morphometric and rate‐based measurements were not affected by ocean acidification. Yellowfin sole metabolic enzyme activities were measured at‐yolk absorption. Lactate dehydrogenase (anaerobic metabolism) and β‐hydroxyacyl CoA dehydrogenase (fatty acid metabolism) both increased with increasing temperature, indicating elevated energy demand. Citrate synthase (aerobic metabolism) declined with increasing pCO 2 levels, indicating potential metabolic suppression. Overall, embryonic and larval yellowfin sole demonstrated relatively high tolerance to ocean warming and acidification. We hypothesize the variation in temperature responses across the trials may be driven by maternal effects, which could support tolerance to future ocean conditions.