Recruitment timing, growth, and longevity of the deep-water shrimp Parapenaeus lanceolatus Kubo, 1949 (Crustacea, Decapoda, Penaeidae) in Kagoshima Bay, Japan

Life-history traits of deep-water non-target penaeid shrimps remain poorly understood despite their regular occurrence in bottom seine fisheries. Parapenaeus lanceolatus is consistently encountered in deep-water benthic assemblages in Kagoshima Bay, southern Japan, although information on its population biology remains limited. In the present study, monthly carapace-length frequency data collected from January 2011 to January 2013 were analysed to examine recruitment timing, growth patterns, longevity, and length–weight relationships in this species. Growth was modelled using the von Bertalanffy growth function and the seasonally oscillating Pauly-Gaschütz model, with relative model performance compared using Akaike’s and Bayesian information criteria. Recruitment occurred mainly from November to January, indicating a seasonally concentrated recruitment pattern. The von Bertalanffy model provided the best fit for both sexes, whereas the estimated seasonal oscillation parameter of the Pauly-Gaschütz model was low. Females attained larger asymptotic carapace length and higher growth coefficients than males, indicating clear sexual dimorphism in growth. Longevity was estimated at approximately 27 months for both sexes. Length–weight relationships showed negative allometric growth and differed significantly between sexes. This study provides the first quantitative assessment of recruitment, growth, and longevity in P. lanceolatus and contributes to a broader understanding of life-history variation among deep-water penaeid shrimps.