鲥鱼仔幼鱼食性与生长的初步研究

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

  • 摘要: 本文主要描述鲥鱼仔幼鱼阶段有关摄食、消化器官的发育、不同大小仔幼鱼食物组成特点、摄食量及其昼夜摄食节律。此外,还就仔幼鲥鱼人工饲养条件与天然状况下的生长作了比较。结果表明,只要供饵正常,孵化环道内生活的仔幼鲥生长速度可以略快于鄱阳湖同期天然生长个体的速度,为今后人工培育仔幼鲥进行放流和增殖提供资料。

     

    Abstract: 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.

     

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