长江刀鲚繁殖群体的生长特性

Growth characteristics of reproductive population of Coilia nasus in the Yangtze River

刀鲚（Coilia nasus）是一种具有多种生活史类型的中小型鱼类,溯江洄游中的刀鲚也是目前长江下游最重要的经济鱼类之一。为评估刀鲚渔业生物学特征的变化趋势,分析了2012年5月采自长江靖江段的458尾刀鲚繁殖群体样本。结果显示,刀鲚繁殖群体由1-4龄组成,其中2-3龄个体占85.81%;体长14.2-38.9 cm,平均（25.72±4.08）cm;体重9.2-208.4 g,平均（69.59±33.73）g;体长与体重关系式W=0.0028L3.0866（R2=0.915 3）;平均丰满度为0.38±0.08。依据生长方程Lt=40.82[1–e-0.31（t＋0.55）]和Wt=262.59[1–e-0.31（t＋0.55）]3,求得渐近体长L∞为40.82 cm,渐近体重W∞为262.59 g,体重生长的拐点出现在2.99龄的Wt=77.66 g。与20世纪70年代的研究结果相比,长江刀鲚繁殖群体中补充群体和低龄剩余群体的比例显著增加,低龄化和小型化趋势明显,丰满度下降,资源衰退严重,但生长潜力依然存在。应采取降低对繁殖群体的捕捞强度、保护产卵场等积极措施来保护这一珍贵的渔业资源。

Coilia nasus is a kind of mid-small-sized fish with resident and migration ecotypes. The anadromous population has long been recognized as very important commercial aquatic products in the lower reaches of the Yangtze River. To evaluate the fishery biological characteristics, we analyzed 458 specimens of Coilia nasus collected at Jingjiang section of the Yangtze River in fishing season, in May, 2012. The results showed that the spawning stock included 1 -4 years old groups with 85.81% of age 2 to 3 years. The body length ranged from 14.2 to 38.9 cm with an average of （25.72 ±4.08）cm and the body weight varied from 9.2 to 208.4 g with an average of （69.59± 33.73 ） g. Body length and body weight were fitted into the function W =0. 0028L3.0866 （R2 = 0. 915 3 ）, The average fatness was only 0.38 ± 0.08. Based on the von Bertalanffy growth equation：Lt =40.82[ 1 - e-0.31（t＋0.55） ] , Wt = 262.59 [ 1 - e-0.31（t＋0.55）] 3,we calculated the asymptotic length of 40.82 cm and the asymptotic weight of 262.59 g. The age at inflection point of body weight growth curve was 2.99 years old when body weight was Wt = 77.66 g. Compared with the study results in 1970s, the recruitment and young surplus populations of the spawning stock increased significantly in reproductive population. Low-age and miniaturization tendency was obviously accompanied with fatness decrease. However, the growth potential was still high on the basis of the growth equation. The results suggest that active measures such as reducing fishing intensity of the reproductive population and protecting the spawning grounds are imperative to maintain this precious fishery resources.