REPRODUCTIVE BIOLOGY AND GROWTH OF THE DEEP-WATER PANDALID SHRIMP PLESIONIKA SEMILAEVIS (DECAPODA: CARIDEA)

Abstract

The reproductive biology and growth of the deep-water pandalid shrimp Plesionika semilaevis Bate were studied. A total of 4,433 specimens were collected from the central area of Kagoshima Bay, southern Kyushu, Japan. The number of eggs (embryos) attached to the pleopods ranged from 1,048-8,702. The embryos were 0.60 X 0.56 mm in mean size at spawning and 0.78 x 0.53 mm just before hatching. A reduction in brood size with development was observed. Ovigerous females were collected from May-December. The hatching period was estimated to last from June-December, based on the occurrence of ovigerous females with latestage embryos. The duration of incubation appeared to be less than 2 months. Growth patterns for both sexes were modeled by fitting the von Bertalanffy growth equation to the mean carapace lengths at various ages. Females grow faster and reach larger sizes earlier than males of the same age group. Longevity was estimated to be around 3 years for both sexes. A comparison of specimen size from different regions reported in previous papers and from the present study demonstrated geographical variation in the maximum body size of P. semilaevis.