The study on species composition and quantitative distribution of phytoplankton in fishing ground of squid in the North Pacific Ocean

129 species were identified,the species composition and distributing characteristics of phytoplankton in relation to environmental factors and central fishing ground were analyzed,The warm-water group was dom inant (58.9%) in species composition,the proportion of cool-water group was quite low in species composition (10.9%),while it was obviously dominant in quantitative composition (68.05%),which miplied that tropic zone,subtropic zone and subfrigid zone existed in this area meantmie.The analyzing results show that the distribution of phytoplankton is not even during the investigation period,and the average concentration is 54.60×10³ cell/m³;the warm water and the cold water species have such a great influence on species composition and quantitative distribution of phytoplankton;and the form of central fishing ground is close related to high quantitative zone of phytoplankton.