Recruitment, growth patterns and longevity of two deep-water shrimps, Metapenaeopsis kyushuensis (Yokoya 1933) and Metapenaeopsis provocatoria owstoni Shinomiya & Sakai 2000 (Crustacea, Decapoda, Penaeidae) in Kagoshima Bay, Japan

The recruitment, growth patterns and longevity of Metapenaeopsis kyushuensis and Metapenaeopsis provocatoria owstoni were studied using samples collected from Kagoshima Bay in southern Japan. The von Bertalanffy growth function and the Pauly and Gaschütz growth function (PGGF) were fitted to mean length-at-age data and compared using the Akaike and Bayesian information criteria. This analysis identified the most appropriate model for describing growth in the studied shrimps and assessed seasonal oscillations in growth rates. A single, extended recruitment pulse was observed, beginning in December/January for M. kyushuensis and in November for M. provocatoria owstoni and continuing until April. This pattern likely reflects synchronization with the main spawning season. PGGF was identified as the best-fitting model to describe the growth of both species, confirming seasonal variations in growth rates. The growth rates peaked in November – December for M. kyushuensis and October – November for M. provocatoria owstoni, while minimum growth rates occurred in May – June and April – May, respectively. The periods of slower growth coincided with the main spawning season for both species. The estimated lifespan was approximately 25 months for M. kyushuensis and 29 months for M. provocatoria owstoni. The relationship between carapace length and body weight exhibited negative allometric growth for both species.