Populations dynamics of Aristeus alcocki Ramadan, 1938 (Decapoda: Penaeoidea: Aristeidae) from southwestern India

Abstract The deepwater shrimp Aristeus alcocki  Ramadan, 1938 constitutes a valuable resource among the commercially important Indian fish stocks along the southern coast of India. However, in recent years, its landing showed a declining trend. The present study reports the first information on its biology and stock characteristics of this species derived from the five year data collected from the south west coast of India. A total of 6, 312 specimens were examined, the species exhibits sexual dimorphism, with females (Carapace length (CL): 13–56 mm) showing a wider size range with bigger size than males (CL: 13–31 mm). Monthly age classes varied from one to four in females and males corresponding to four generations viz ., 0+, 1+, 2+, and 3+, respectively. von Bertalanffy growth curve indicated larger growth in females than males with a mean growth parameter for females: CL ∞ = 55 . 78 , K  =  0.60, Rn  =  0.253 and males: CL ∞ = 30 . 51 , K  =  0.64, Rn  =  0.358). Monthly mean size, CL max sex ratio, longevity, and growth performance indices ( Φ ) were in favor of females. K values for both the sex are the highest reported for the species, suggesting a higher growth rate and a lower longevity. Estimated values for total, natural and fishery mortality were also greater in females. In both the sex, an exploitation rate E >0.5 was lesser than E max . The results of the current study signify that the species has remained stable during the study period, in terms of its life span, size frequency distribution and biological parameters, such as growth and mortality. These data should be taken into account for carrying out the stock assessment in future and additional data on deep sea recruitment success are needed to empirically parameterize population models for quantitatively assessing the sustainability of current harvest levels.