辽宁海域东亚江豚的年龄鉴定与生长规律

Age determination and growth characteristics of finless porpoise Neophocaena asiaeorientalis sunameri in Liaoning coastal waters

对2007-2018年辽宁海域发现的39头死亡东亚江豚(Neophocaena asiaeorientalis sunameri)进行了外部形态参数测量和生长规律分析,并通过观察牙齿中的生长层组对2014-2018年的27头江豚个体进行了年龄鉴定.结果表明:死亡江豚以0~4龄个体为主,雄性21头,雌性18头;同龄雌雄个体间的体长、体重均无显著差异(P>0.05);所有江豚样本的体重与年龄(Y=137e^-2.475exp(-0.205t))、体长与年龄(Y=232(1-0.680e^-0.161t)均极显著相关(P<0.01),且随年龄增大,体重、体长均增加但增速下降.死亡江豚的发现时间在不同的海域存在差异:黄海北部海域集中在每年的3-6月,以大连星海湾至老虎滩沿岸为多;渤海的辽东湾海域主要在每年的10-11月初,多发现在大连长兴岛以北的海域.辽东湾海域江豚的死亡多发生在渔业作业期,可能与渔业生产活动有关.研究还发现,在一年中辽东湾海域死亡江豚集中出现的时间与斑海豹的分布期存在交替现象,是否与两种海洋哺乳动物适应海水温度能力、种群间的食物竞争以及季节性迁移等因素有关还有待于进一步的研究.

We measured the morphological parameters and growth characteristics of 39 dead finless porpoises (Neophocaena asiaeorientalis sunameri) collected along Liaoning coastal waters from 2007 to 2018, and identified the age of 27 finless porpoises collected from 2014 to 2018 by observing teeth growth layer. The results showed that ages of the dead animals ranged from 0 to 4 years, with 21 male and 18 female. There was no significant difference in length and weight between male and female with the same ages (P>0.05). Both weight (Y=137e^-2.475exp(-0.205t)) and length (Y=232(1-0.680e^-0.161t) were significantly correlated with age (P<0.01). Moreover, the growth rates of weight and length showed decreasing trends with the increases of age. The discovery times of dead finless porpoises varied among different areas of Liaoning coastal waters. They were always discovered in the northern Yellow Sea during March to June, and mainly distributed on the coast of Xinghai Bay to Laohutan Beach, while in Liaodong Bay of Bohai Sea they were usually discovered during the period from October to November, mainly distributed in the northern waters of Changxing Island. The death of finless porpoise in Liaodong Bay occurred mostly in fishery period, which may be closely related to fishing. The distribution period of finless porpoise death was alternated with that of spotted seals in Liaodong Bay. Whether it was related to the adaptation capacities of both species to the sea water temperature, their food competition and seasonal migration needs further study.