漂流人工集鱼装置随附鱼群中鲯鳅的生物学特征

Biological characteristics of dolphinfish Coryphaena hippurus associated with drifting fish aggregation devices

漂流人工集鱼装置(fish aggregation devices,FAD)在金枪鱼围网渔业中被广泛地应用于诱集捕捞金枪鱼类。鲯鳅作为漂流FAD诱集鱼群中最为常见的兼捕种类之一,研究其生物学特性有助于了解其种群结构,对于合理保护该资源具有重要意义。利用2010-2013年间中西太平洋金枪鱼围网渔业科学观察员在5°N^10°S,145°E^170°E海域内收集的189尾鲯鳅样本,对其叉长分布、性比、性成熟度及摄食等生物学特性进行研究。结果表明:鲯鳅叉长范围为10.0~126.3 cm,优势叉长为70.0~100.0 cm,占总数的66.7%;雌雄性别比为4.1∶1;样本以性成熟(Ⅴ~Ⅵ期)个体为主,占总数的73.6%,50%性成熟叉长(L50)为49.95 cm;76.0%的样本为空胃,而实胃中频现其它常见的小型随附鱼种,如鲣(Katsuwonus pelamis)的幼鱼、细鳞圆鲹(Decapterus macarellus)、六带鲹(Caranx sexfasciatus)、疣鳞鲀(Canthidermis maculata)和单角革鲀(Aluterus monoceros)。渔业生物学信息表明漂流FAD下的鲯鳅群体以性成熟的大型个体为主,FAD对于雌鱼具有更强的聚集效果,觅食是鲯鳅游向漂流物的可能动机之一。

Drifting fish aggregation devices（ FAD） are used widely to aggregate and catch tropical tunas in the purse seine fishery. Dolphinfish（ Coryphaena hippurus） is one of the common by-catch species in purse seine fishing with FADs. The study of their biological characteristics is helpful to better understand the population structure,and has important significance on the reasonable resource conservation. The biological characteristics（ length distribution,sex ratio,sexual maturity and diet） of 189 individuals are analyzed using the fishery biological data collected by the scientific observers onboard purse seine fishing vessels operating in the Western and Central Pacific Ocean（ 5° N-10° S,145° E-170° E） from 2010 to 2013. The results indicated（ 1） fork length of dolphinfish associated with drifting FADs ranged from 10. 0 to 126. 3 cm,with the dominant fork length of 70. 0 to 100. 0 cm,accounting for 66. 7% of the total;（ 2） sex ratio is about 4. 1∶ 1,and a significant deviation（ χ2= 68. 17,P 〈0. 05） from the expected 1∶ 1 female to male can be observed;（ 3） the mature individuals（ Ⅴ-Ⅵ） were dominant under the FADs,accounted for 73. 6%,and the estimated size at 50% maturity is 49. 95 cm;（ 4） 76. 0% of stomachs are empty,but some commonly small associated fish species,such as Katsuwonus pelamis,Decapterus macarellus,Caranx sexfasciatus, Canthidermis maculate,and Aluterus monoceros are found in the stomach of dolphinfish. The information of fishery biology suggests the mature and large individuals are dominant in the dolphinfish school associated with drifting FADs,which have a stronger aggregation effect on females,and feeding is one of the possible potential motivations for dolphinfish aggregating around the FADs.