1Graduate School of Fisheries Science and Environmental Studies, Nagasaki University, Bunkyo, Nagasaki 852-8521, 2School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan
The Laser Optical Plankton Counter (LOPC) has been used to evaluate abundance structure of micro-organisms like a zooplankton speedy. The sea experiments were conducted at twelve stations near Funka Bay, Hokkaido to examine the performance of the LOPC for in situ measurement of multispecies aggregation of zooplankton. The LOPC was mounted with ring net (80 cm mouth diameter) and towed vertically. Size and volume composition data of LOPC and net samples were compared each other. The particle size composition detected by the LOPC showed similar pattern with wet weight composition of copepods and amphipods in net samples. However, the ranges of equivalent spherical diameter of these species were overlapped. To measure in situ zooplankton community by species using LOPC, the measurement properties of each particle by specie should be identified and discriminated from LOPC data.