A PRELIMINARY SIUDY ON FEEDING HABIIS AND GROWTH OF MACRURA REEVESII DURING THE EARLY LARVAL STAGES

Fertlized Macrura reevesii (Eichardson) eggs were obtained from spawner caught in the spawning area by artificilal fertilization and were hatched in an indoor hatching circulator. Larvae were continously reared from june to August, 1982—1983. Observation on feeding habits and growth of the reeves shad during the early larval stage under artificial feeding conditions is presented.(1) The oral organ of larvae of 3 days old has fully formed, and initial feeding is observed at 3—4 days after hatching.(2) 32 genera, 37 species of plankton (algae 13, prozoan 1, rotatoria 12, copepoda 5 and cladocera 6) were found in digestive tracts of larvae measuring 4.5—26.0 mm in total length, the diet being primarily zooplankton.(3) Food selectivity of early larval stage for zooplankton is correlated to the width and diameter of the oral organ. The length group of larvae feeding mainly on rotatoria and nauplius under 200μ in width is 5.0—5.9 mm, and following the elongation of jaws, they may gradually feed on larger plankton individuals.(4) A rhythm of food intake in day time while not at night was observed.(5) Larvae may attain a normal growth rate when fed abundant amount of zooplankton. The average growth in length from the 5th day to the 30th day is estimated by the equation y=0.94+0.8475x. where y stands for total length (in millimeters) and x number of days.