Individual-based model study on the fishing ground of chub mackerel in the East China Sea

Chub mackerel (Scomber japonicus) is abundant resource in the coastal waters and occupies an important status in marine fisheries of China. The formation of the fishing ground was restricted marine environment. In this paper,according to the fitness theory,the response relationship between chub mackerel and physical environment was determined by using of physical environmental factor of temperature,salinity,temperature gradient,salinity gradient,distance,density of fish,up-welling. An individual-based growth and migration model of chub mackerel in East China Sea was developed. The result showed distribution patterns of mackerel agree well with fishing ground of purse seine fishery in East China Sea in 1998-2006. School of mackerel was mainly influenced by Taiwan Warm Current (TWC),Mainland Coast Water (MCW) and Kuroshio. Chub mackerel often schools in certain temperature and salinity range and near warm water of intersection of cold water and warm water,frontal gradient of temperature and salinity had close relations with mackerel distribution. In April,mackerel began to leave spawning ground. A little Section A of chub mackerel in spawning ground began to migrate in warm water of intersection of TWC and Zhejiang and Fujian coastal water. Most Section A and Section B of mackerel fed in spawning ground. There was high yield of fishing in spawning ground. In May,Section A of spawning ground in chub mackerel was mainly influenced by TWC. Mackerel began to a long stripped school and retention near the front of TWC. A large number of mackerel already had migrated to at the front of warm water tongue in TWC,and formed the fishing grounds. Fishing statistics showed that there was high yield of fishing. Section B was mainly influenced by Kuroshio. Mackerel began to school near warm water in intersection of TWC and the surface water of Kuroshio,and also formed fishing grounds,fishing data showed there was a certain fishing production. In Jun,mackerel continued to school near the higher salinity in intersection of water tongue in TWC and Yangtze River water dilute. The simulation results showed there was high school distribution in front of TWC frontal,but no fishing production of purse seine fishery in fishing ground. Mackerel also schooled in tide area of MCW and Kuroshio. Fishing data also showed that there was fishing production. In July the migratory and school were more evident. Mackerel basic schools in three long stripped of TWC frontal,path of larval transport and Kuroshio frontal. Because of biological choice,and finally in the space appears no mackerel distribution and high density patches. This is search results of school and retention in favorable regional in the process of mackerel migratory,through the swimming behavior choice favorable environment,avoid not suitable for regional,eventually form the fishing grounds. The variability in spawning ground made the western spawning area was influenced by TWC. Mackerel mainly school in front of TWC and MCW. Mackerel migrated to front of warm water tongue in TWC was increased. Eastern spawning area was influenced by Kuroshio. Mackerel mainly school in the eastern parts in front of the Kuroshio. Mackerel migrated to front of warm water tongue in TWC was decreased. Survival of western and eastern spawning area respectively was 1.526 1°10⁷ and 1.526 6°10⁷,Survival of western spawning area was less than eastern spawning area. But survival of normal spawning area of 1.528 3°10⁷ was lest in three spawning areas. Survival of normal spawning area was the best in three spawning areas. Different locations of mackerel will affect the position of school,it that explains the physical environment can influence on the migration and school of mackerel.