黑鲪仔、稚、幼鱼生长、发育与成活率变化的研究

Study on the Growth,Development and Survival Rate of Larval,Juvenile and Young Sebastodes fuscescens

在人工池养条件下,根据2批黑鲪实验鱼苗外部形态特征和生态习性的变化,将其早期发育阶段划分为A～P共16个阶段。黑鲪早期发育阶段的消化系统要发生胃的分化、肠管的折叠、肝脏的形变和幽门垂的形态和数量变化等显著变化,其中稚鱼期的J～O阶段是消化系统变化最为剧烈的时期。2批鱼苗的生长速度均表现为逐渐加快,且全长生长均可拟合为3段直线,出现2个生长转折点:第一批苗第一个生长转折点在15～17d(多数为G阶段仔鱼,全长(8.07±0.63)～(8.44±0.66)mm);第二个生长转折点在49～51d(多数为O阶段稚鱼,全长(20.27±2.15)～(2l.13±2.17)mm)。第二批苗的2个生长转折点分别发生于14～16d(多数为G阶段仔鱼,全长(8.19±0.73)～(8.80±1.01)mm)和38～40d(多数为O阶段稚鱼,全长(21.18±2.49)～(22.77±2.83)mm)。对仔、稚、幼鱼成活率变化研究表明,黑鲪早期发育阶段存在4个临界期("危险期"):A～B阶段、D～F阶段、L～M阶段和N～O阶段,以L～M阶段鱼苗死亡率最高,而且临界期和鱼苗的形态变化、器官分化密切相关。黑鲪早期发育的阶段划分、生长转折点和临界期的确立,丰富了其早期生物学的内容,对苗种培育措施的实施具指导意义。

Under tank-rearing condition, the early development of Sebastodes fuscescens can be divided into 16 stages （A through P） according to the changes of two batches of finglings in morphology and eco-logical performance. The morphological changes of digestive system at early developmental stages were remarkable, which included stomach differentiation, intestine folding, liver reforming and pyloric caeca varying in shape and number. The most remarkable changes were observed in juvenile at stages J through O. The growth of two batches of finglings all exhibited a gradually speeding trend, which appeared as a broken line with two inflections. In our first rearing trial, the first inflection was observed during day 15 to day 17 （most larvae at stage G, total length （8.07±0.63） mm to （8.44±0. 66） mm） ; and the second inflection was found during day 49 to day 51 （most juveniles at stage O, total length （20. 27±2. 15） mm to （21.13±2. 17） mm）. In our second rearing trial, two inflections were observed during day 14 to day 16 （most larvae at stage G, total length （8.19±0.73） mm to （8.80±1.01） mm） and day 38 to day 40 （most juveniles at stage O, total length （21.18±2.49） mm to （22. 77±2.83） mm）, respectively. There were 4 critical periods, stages A through B, stages D through F, stages L through M and stages N through O. The highest mortality was observed in the period of stages L through M. It was also found that these crit-ical periods corresponded to remarkable morphological changes and organic differentiation. Our works in-cluding division of developmental stages, description of growth trend and inflection and definition of criti-cal periods enriched the early developmental biology of this fish species, and will facilitate its breeding and fingerling raising.