Effect of temperature and rearing density in Golden King Crab, Lithodes aequispinus, larval cultivation.

VAN SANT, S.B.; TAPELLA, F.; ROMERO M.C.; STEVENS, B.G.

Anchorage, Alaska, USA,

Simposio; 25th Lowell Wakefield Fisheries Symposium. Biology and Management of Exploited Crab Population under Climate Change.; 2009

Golden king crab (GKC) Lithodes aequispinus became commercially important in Alaska waters as other king crab species declined in the early 1980’s. The commercial fishery remains relatively high yet little information exists for the early life history of this species. To assess important life history stages in the laboratory, optimal production conditions are sought targeting specific life stages such as zoea and glaucothoe. The effects of temperature and density on intermolt duration and survival of GKC larvae were tested. Proportional numbers of larvae, from two ovigerous females were raised in triplicate at 3.3 ± 0.3 °C and 6.6 ± 0.3 °C at densities of 10, 20, and 40 larvae•beaker-1 per temperature. Survival of GKC from hatching to 50% glaucothoe stage varied significantly between temperatures (Two-factor ANOVA p<<0.001) and proportions of surviving crab were 59.2 and 54% at 6.6 and 3.3 ºC, respectively. However there was no significant difference and no interaction for survival among rearing densities (Two-factor ANOVA p=0.64). Development time differed significantly between both temperatures (test-T p<<0.001); larvae raised at 3.3 and 6.6 ºC required 47.4 ± 1.0 days and 33.5 ± 0.8 days, respectively to reach 50% glaucothoe. These results suggest that temperature delays molting and development of GKC larvae, and reduces survival. Cultivation techniques described in this study are useful for future research on settlement behavior and habitat preference which are dependent on the production of an adequate number of glaucothoe.Lithodes aequispinus became commercially important in Alaska waters as other king crab species declined in the early 1980’s. The commercial fishery remains relatively high yet little information exists for the early life history of this species. To assess important life history stages in the laboratory, optimal production conditions are sought targeting specific life stages such as zoea and glaucothoe. The effects of temperature and density on intermolt duration and survival of GKC larvae were tested. Proportional numbers of larvae, from two ovigerous females were raised in triplicate at 3.3 ± 0.3 °C and 6.6 ± 0.3 °C at densities of 10, 20, and 40 larvae•beaker-1 per temperature. Survival of GKC from hatching to 50% glaucothoe stage varied significantly between temperatures (Two-factor ANOVA p<<0.001) and proportions of surviving crab were 59.2 and 54% at 6.6 and 3.3 ºC, respectively. However there was no significant difference and no interaction for survival among rearing densities (Two-factor ANOVA p=0.64). Development time differed significantly between both temperatures (test-T p<<0.001); larvae raised at 3.3 and 6.6 ºC required 47.4 ± 1.0 days and 33.5 ± 0.8 days, respectively to reach 50% glaucothoe. These results suggest that temperature delays molting and development of GKC larvae, and reduces survival. Cultivation techniques described in this study are useful for future research on settlement behavior and habitat preference which are dependent on the production of an adequate number of glaucothoe.