Mara L. Spencer

Temperature-Dependent Growth of Early Juvenile Southern Tanner Crab Chionoecetes bairdi: Implications for Cold Pool Effects and Climate Change in the Southeastern Bering Sea

ABSTRACT Temperature strongly influences the growth of crustaceans and directly controls distribution. Despite being commercially important, there are no data on temperature effects upon growth in newly settled southern Tanner crab Chionoecetes bairdi. Recently settled crabs were reared through three consecutive molts, both individually and in groups, at four different temperatures; 2°C, 6°C, 9°C, and 12°C. Survival was higher for crabs grown individually (92%) than those in groups (66%) owing to cannibalism, particularly during molting. There were no temperature effects on survival. Growth rate (mm/day) increased linearly with temperature, a product of exponential decline in intermolt period with increasing temperature and amolt increment that was relatively constant across temperatures. Growth rate, intermolt period, and growth increment did not differ between crabs grown singly or in groups. These data suggest that growth in 0 y aged southern Tanner crabs is strongly inhibited at temperatures less than 2°C. A small mesh beam trawl survey was conducted in the southeast Bering Sea during September 2012, a year when a cold pool (<2°C bottom water) dominated the middle shelf. Southern Tanner crab less than 12 mm (carapace width) were concentrated just north of the Alaska Peninsula and along the outer shelf where bottom water was more than 2°C, but largely absent from the middle shelf. In contrast, adult southern Tanner crabs were widely distributed across the middle and outer shelves. It was hypothesized that early juvenile southern Tanner growth is inhibited by cold pool conditions, prolonging vulnerability to predation, and reducing survival. In the future, if sea temperature rises and sea ice is diminished, less frequent and less intense cold pool events may lead to increased persistence of thermally suitable juvenile southern Tanner crab habitat across the southeastern Bering Sea middle shelf region.

Comparative effects of temperature on rates of development and survival of eggs and yolk-sac larvae of Arctic cod (Boreogadus saida) and walleye pollock (Gadus chalcogrammus)

Comparative effects of temperature on rates of development and survival of eggs and yolk-sac larvae of Arctic cod (Boreogadus saida) and walleye pollock (Gadus chalcogrammus) Benjamin J. Laurel*, Louise A. Copeman, Mara Spencer, and Paul Iseri Fisheries Behavioral Ecology Program, Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Hatfield Marine Science Center, Newport, OR 97365, USA College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Hatfield Marine Science Center, Newport, OR 97365, USA *Corresponding author: tel: þ 1 541 737 0197; fax: þ1 541 737 0186; e-mail: ben.laurel@noaa.gov