1Graduate School of Fisheries, 2Faculty of Fisheries, Kagoshima University, Shimoarata, Kagoshima 890-0056, Japan
The distribution and population structure of the deep-water pandalid shrimp Plesionika semilaevis were studied by experimental sampling surveys at 8 stations in Kagoshima Bay, southern Japan, from May 2003 to January 2007. A simple trawl net measuring 27.9 mm and 20.2 mm mesh size at the net body and cod end respectively was used. All individuals belonging to pisces, crustaceans (Decapoda, Stomatopoda, Mysidacea and Euphausiacea) and molluscs (Cephalopoda, Bivalvia and Gastropoda) were sorted at each haul and identified to species level, then counted and weighed in the laboratory. P. semilaevis was the most dominant species by number and weight of individuals collected in the current survey. Further, 98% of the individuals of P. semilaevis occurred at Stations 4 and 5 (180 m and 220 m depth respectively) located in the deepest part of the central bay, all year round. However, significant differences were observed in sex ratio and body size composition of P. semilaevis from these two stations. In Kagoshima Bay, the spawning and hatching grounds of P. semilaevis were estimated to cover the entire areas of its distribution.