Endurance of simulated winter conditions by age‐0 walleye pollock: effects of body size, water temperature and energy stores

• Published in: Journal of Fish Biology
• Main Authors: Sogard, S. M., Olla, B. L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2000
• Subjects: Bering Sea; Theragra chalcogramma
• Online Access: http://dx.doi.org/10.1111/j.1095-8649.2000.tb02083.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1095-8649.2000.tb02083.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1095-8649.2000.tb02083.x

Survival of age‐0 walleye pollock Theragra chalcogramma in the absence of food followed simple bioenergetic models, with large body size, high initial condition, and cold temperatures all increasing survival rates. High survival after >200 days at cold temperatures (<3·0° C) indicated extended tolerance of extreme cold, as long as sufficient body size and condition are attained during the summer growth period. Analysis of body constituents demonstrated a substantial increase in tissue water and depletion of lipid during starvation. Survivors had significantly higher lipid stores than mortalities, and larger fish had higher levels of lipid than smaller fish among experimental survivors, laboratory fish that were never starved, and wild fish. Fish returned to warm temperatures and high rations following 205 days of food deprivation displayed nearly complete recovery, with rapid increases in length, weight, and condition and minimal mortality (6·8%) during the subsequent 3 months. Age‐0 walleye pollock collected in September in the Bering Sea were substantially smaller and generally had lower lipid levels than fish used in laboratory starvation experiments, suggesting they are susceptible to size‐ and condition‐dependent mortality during the winter. The results are interpreted with respect to field distributions of age‐0 walleye pollock, overwinter survival, and synergistic effects of food and temperature under varying models of climate change.