Population features of the caridean shrimp, Sclerocrangon boreas (Phipps, 1774) in Isfjorden, Spitsbergen

Population parameters in crustaceans are not easily obtained due to a lack of satisfactory methods for establishing the age of individuals. In this study, the problem is approached by the use of length-frequency data. A statistical computer program, MIX, was used to interpret the mixture of distributions based on length-frequency data (analysis of modality). The modal length groups were assumed to be equivalent with age groups. One group of males and three groups of females were observed. The carapace length (CL) ranged from 7.6 to 14.9 rum in males and was 7.9-23.4 mm in females. The smallest individuals of males and females, the first age groups, were probably lost due to the sampling technique. The proportion of ovigerous females (20.0-24.0 mm CL) showed an increase from 25% to 75%, and 45.5% of all females within this size range were ovigerous. Male and female length-weight relationships displayed no significant differences (P = 0.437) within the second age group. Annual biomass amounted to 0.032 a AFDW.m(-2) (Ash Free Dry Weight) (0.012 in males and 0.020 a AFDW.m(-2) in females). Mortality was 0.41.yr(-1) in males and 0.19.yr(-1) in females.