养殖密度对珍珠龙胆石斑鱼行为活动和生长性能的影响

Effects of stocking density on behavior and growth performance of Epinephelus fuscoguttatus ♀× Epinephelus lanceolatus ♂

【目的】研究不同养殖密度对珍珠龙胆石斑鱼摄食行为、生长及血液生化指标的影响,为工厂化养殖珍珠龙胆石斑鱼提供参考依据。【方法】在工厂化条件下,设60、100和140尾/m^3 3种养殖密度,养殖周期50 d,记录珍珠龙胆石斑鱼的摄食行为,并测定其生长性能及血液生化指标。【结果】在摄食行为方面,随养殖时间的延长和养殖密度的增加,珍珠龙胆石斑幼鱼摄食形态基本遵循圆锥形—碗形—团形—平铺形的变化规律;随着养殖密度的增加,珍珠龙胆石斑鱼分布在上层摄食比例逐渐降低,对应的平均摄食比例分别为80.0%、72.0%和66.7%,其在摄食等级1所占比例也逐渐降低,分别为82.7%、73.3%和64.0%。在生长性能方面,珍珠龙胆石斑鱼的平均增重、日增重、饵料转化率和生长效率等4项指标随养殖密度的增加而逐渐下降,饵料系数则随养殖密度的增加呈上升趋势,组间差异均达显著水平(P<0.05,下同);体长、全长、增重率、增长率、特定生长率和存活率等6项指标受养殖密度的影响均未达显著水平(P>0.05,下同)。在血液生化指标方面,随着养殖密度的增加,珍珠龙胆石斑鱼白细胞含量呈逐渐上升趋势,而葡萄糖含量无明显变化,组间差异均不显著。综合各项指标,以养殖密度为100尾/m^3的效果最佳。【结论】养殖密度过低或过高均不利于珍珠龙胆石斑鱼生长,工厂化养殖珍珠龙胆石斑鱼的适宜密度为100尾/m^3,既能保障其健康生长,降低生产成本,又可获得理想的经济效益。

【Objective】Effects of stocking density on ingestion behavior, growth, blood physiological and biochemical indexes of Epinephelus fuscoguttatus ♀×E. lanceolatus ♂ were evaluated to provide reference for its breeding under industrial conditions. 【Method】Under industrial conditions, three stocking densities 60, 100 and 140 ind/m3 were set, and the breeding cycle was 50 d. Ingestion behavior of E. fuscoguttatus ♀×E. lanceolatus ♂ was recorded, and its growth performance and blood physiological and biochemical indexes were measured. 【Result】In terms of ingestion behavior, as breeding cycle extended and stocking density increased, the ingestion patterns of juvenile E. fuscoguttatus ♀×E. lanceolatus ♂ showed a certain regularity, and basically followed cone-calathiform-agglomeration-tiling type. With increase of stocking density, the proportion of E. fuscoguttatus ♀×E. lanceolatus ♂ in upper layer of ingestion gradually reduced and the corresponding average ingestion rates were 80.0%（60 ind/m3）, 72.0%（100 ind/m3） and 66.7%（140 ind/m3）. In addition, the proportion of ingestion level 1 also gradually reduced and the average proportions were 82.7%（60 ind/m3）, 73.3%（100 ind/m3） and 64.0%（140 ind/m3）. In growth performance, average weight gain, daily weight gain, feed conversion rate and growth efficiency declined with the increase of stocking density; feed coefficient increased as stocking density increased, the differences between groups were significant（P〈0.05, the same below）. But effects of stocking density on body length, whole length, weight gain rate, growth rate, specific growth rate and survival rate did not reach significant level（P〉0.05, the same below）. In terms of blood biochemical indicators, with the increase of stocking density, white blood cell content of E. fuscoguttatus ♀×E. lanceolatus ♂ rose, but glucose content remained stable. There was no significant difference between groups. Taking all the indxes into consideration, 100 ind/m3 was the optimal stocking density. 【Conclusion】Excessively low density or high stocking density are not beneficial for growth of E. fuscoguttatus ♀×E. lanceolatus ♂, the optimum breeding density was 100 ind/m3 for its breeding under industrial conditions. This stocking density can ensure the healthy growth of E. fuscoguttatus ♀×E. lanceolatus ♂, reduce production costs, and obtain desired economic benefits.