THE FEATURES OF FOOD ORGANISMS WITH RELATION TO THE FEEDING MIGRATION OF JACK MACKEREL OFFSHORE EAST GUANGDONG PROVINCE

The abundance, distribution, seasonal changes of food organisms and the relation to the high salt water body offshore .East Guangdvng Province were analysed and investigated. Gn this basis the effect of thesa factors on the feeding migration of jack mackerel was also studied. The annual average biomass of the food organisms offshore East Guangdong Province was about 86---100mg/m³, and there are two peaks in a year; one appears at the end of winter axed the bogiuing of spring, and the another is at mid-summer. The highest biomass reached to 200mg/m³, and the longest dura-tion 2-3 months. The distribution of the biomass is mainly influenced by surface and upper lapes water of the Nan Hai Sea. The distribution of high salt water. The and seasonal ohanges of the biomass are restricted by the varixtian of the Upper layer Feeding migratioxz of jack mackerel shoals, and the shi t of high abundance area of food orgaxxism coincidently have the same direction. Regarding to the direction and path of monthly shift of the shoal generally, in February it starts from east longitude 115°30′ and north latitude 20°30′ shifting northwards; after March it turns to northeast; after June it turns to southwest and in August it turns to southeast.