大亚湾黑鲷标志放流及回捕率调查

为评价大亚湾海域黑鲷(Acanthopagrusschlegelii)增殖放流效果,使用塑料椭圆标志牌(plasticovaltags,POTs),开展了黑鲷幼鱼标志保持率与生长实验。结果显示,背鳍鳍棘基部第4～6鳍棘下方5mm左右的背部肌肉为最适标志位置, 90 d后标志保持率为81.76%。POTs标志黑鲷幼鱼45 d内生长与对照组无显著性差异(P>0.05),而90 d后标志组生长显著缓于对照组(P<0.05)。并于2014—2016年每年1次在大亚湾开展黑鲷幼鱼标志放流试验。采用有奖回收方式进行标志鱼回捕,测量体长、体重,收集回捕日期、回捕地点、回捕方式等信息,整理分析相关数据。3年共放流标志黑鲷幼鱼60115尾,共2758尾回捕标志鱼被定置网、流刺网及垂钓捕获(总回捕率4.59%);大规格放流苗种回捕率高于小规格放流苗种;垂钓回捕鱼数量占总回捕数量的比例为62.08%。通过对反馈信息的分析,认为放流后的标志鱼最初主要沿湾内和湾外两个方向呈近岸辐射状扩散,最远扩散距离约70 km。放流后1～2个月标志黑鲷生长较慢,随后相对加快,放流5～7个月后,黑鲷幼鱼体长、体重分别增长59.51%～127.20%和322.75%～989.83%。结论认为,POT是黑鲷幼鱼体外标志的适宜选择;在研究海域,放流后的标志黑鲷更易于被垂钓方式捕获;丰富的食物和可供躲避敌害的空间是影响其扩散、生长的因素。

Investigation of a mark-recapture method of black porgy, Acanthopagrus schlegelii, in Daya Bay using plastic oval tags

To assess the effect of enhancement of black porgy (Acanthopagrus schlegelii) in Daya Bay. Plastic oval tags (POTs) were used to study in vitro marking technology in juvenile black porgys. The results of experiment on tag retention rate and growth showed that the back muscles, approximately 5 mm below the 4^th-6^th spine at the base of the dorsal fin, were the optimal tagging position; after 90 days, the POTs retention rate was 81.76%. There was no significant difference in growth between the tagged group and the control group after 45 days (P>0.05), but the growth of the tagged group was significantly slower than that of the control group after 90 days (P<0.05). Based on this technique, the release experiment in Daya Bay was carried out once a year from 2014 to 2016. The reward-recapture method was used to collect the tagged fish, and the body length and body weight of each recaptured fish was measured. Information such as the recapture date and place, and how the fish were tagged was gathered, and the relevant data were subsequently analyzed. In the period of 3 years, a total of 60115 tagged black porgy juveniles were released, and the tagged fish were mainly recaptured by set-nets, drift-nets, and through angling, with a total number of 2758 (total recapture rate of 4.59%) recaptured individuals. The recapture rate of the larger juveniles was higher than that of the smaller juveniles. The tagged fish that were recaptured through angling accounted for 62.08% of the total recaptured fish. An analysis of the gathered information showed that the released tagged fish juveniles primarily migrated radially to the inner and outer areas of the bay; the maximum migration distance was over 70 km from the release site. In 1-2 months after released, the growth of black porgys were relatively slow and then relatively accelerated. After 5 to 7 months, the body length and body weight of the black porgys increased by 59.51%-127.20% and 322.75%-989.83%, respectively. The results indicated that, POT was a potential choice for juvenile black porgy. In the study area, tagged black porgy were easier to be recaptured by angling after released. The abundant food and the space available to avoid the enemy were the factors which influenced their distribution and growth.