千岛湖(新安江水库)4种同域共存的鱼食性鱼类生活史策略比较研究

Comparative study on the life-history strategies of four coexisting piscivorous fish populations in Lake Qiandaohu(Xin'anjiang Reservoir)

千岛湖(新安江水库)是我国大水面生态渔业发展的典型湖库,其渔业主要以鲢、鳙等滤食性鱼类增殖为主,对鱼食性鱼类资源的研究和关注相对匮乏。而鱼食性鱼类是水生食物网的顶级捕食者,对维持水生态系统结构和功能具有重要作用。近年来,受过度捕捞、生境退化等影响,千岛湖鱼食性鱼类资源下降明显。鉴于此,2021年3月—2022年12月,逐月在千岛湖收集4种同域共存的鱼食性鱼类样品1032尾,包括翘嘴鲌(Culter alburnus)、蒙古鲌(Culter mongolicus)、大眼鳜(Siniperca knerii)和斑鳜(Siniperca scherzeri),系统研究并比较了4种鱼食性鱼类年龄、生长、繁殖等生活史策略的分化特征。结果表明,千岛湖4种鱼食性鱼类优势年龄组均未超过3龄,说明其种群呈现低龄化现象。生长式型上,翘嘴鲌和蒙古鲌属正异速生长,而大眼鳜和斑鳜属负异速生长,说明4种鱼食性鱼类具有不同的生长策略。条件系数(CF)的变化趋势与繁殖活动密切相关,其中大眼鳜的条件系数最高(1.92%±0.03%),其次为斑鳜(1.72%±0.02%)和蒙古鲌(1.14%±0.01%),翘嘴鲌的条件系数最低(0.97%±0.03%)。繁殖时间上,斑鳜最早进入繁殖期(3月),其次为大眼鳜(4月)、蒙古鲌(5月),翘嘴鲌最晚(6月)。大眼鳜和斑鳜均出现了2次繁殖高峰(5月和7月),翘嘴鲌的繁殖高峰相对持久(6—7月),蒙古鲌繁殖高峰则最为集中(7月)。繁殖力上,翘嘴鲌((254±16)粒/g)和蒙古鲌((192±10)粒/g)的相对繁殖力较高,显著高于大眼鳜((88±19)粒/g)和斑鳜((88±10)粒/g)。翘嘴鲌和蒙古鲌卵径为单峰分布,推测为单批次产卵类型;而大眼鳜和斑鳜卵径为双峰分布,推测为多批次产卵类型。综上,千岛湖4种鱼食性鱼类在生长速率、生长式型、条件系数等生长策略以及性比、繁殖力、繁殖时间、繁殖方式等繁殖策略均出现了分化,支撑其实现了同域共存。研究结果对进一步理解鱼类同域共存机制,保护、恢复和科学利用千岛湖鱼食性鱼类资源,优化和完善鱼类群落结构具有重要意义。

As one of the most famous reservoirs with an ecological aquaculture paradigm in China,Lake Qiandaohu(Xin'anjiang Reservoir)has been focused mainly on the stocking of filter-feeding carps such as silver carp and bighead carp while there is still a large information gap on the important piscivorous fish species.In recent years,due to the impacts such as overfishing and habitat fragmentation,piscivorous fish resources declined significantly.However,piscivorous fish are the top predators of aquatic food webs and play an important role in maintaining the structure and function of aquatic ecosystems.Therefore,in this study,we focused on four dominant piscivorous fish species in Lake Qiandaohu:Culter alburnus,Culter mongolicus,Siniperca knerii and Siniperca scherzeri.From March 2021 to December 2022,we collected fish samples monthly in Lake Qiandaohu and the differentiation characteristics of the life history strategies in terms of age,growth,and reproduction were systematically compared.The results indicated that 2-3 years age was the dominant group for all the four populations,and the proportion of senior individuals was relatively low.In terms of the growth patterns,C.alburnus and C.mongolicus belonged to the positive allometric growth pattern,while S.knerii and S.scherzeri showed negative allometric growth,indicated that Culter and Siniperca in Lake Qiandaohu had different growth patterns.It showed that the four piscivorous fishes had different growth strategies.The condition factor was closely related to reproductive activities.And the condition factor for S.knerii was the highest(1.92%±0.03%),followed by S.scherzeri(1.72%±0.02%),C.mongolicus(1.14%±0.01%),while C.alburnus was the lowest(0.97%±0.03%).The difference in condition factor suggested that they might utilize different food resources.The reproductive strategies of the four piscivorous fish species also varied.In terms of the breeding period,the S.knerii and S.scherzeri were relative longer compared to the C.alburnus and C.mongolicus.Regarding fecundity,the relative fecundity of C.alburnus((254±16)egg/g)and C.mongolicus((192±10)egg/g)was significantly higher than that of S.knerii((88±19)egg/g)and S.scherzeri((88±10)egg/g).Both C.alburnus and C.mongolicus had a unimodal distribution of oocyte diameters,which might be a single-batch spawning type.However,S.knerii and S.scherzeri had a bimodal distribution which suggested that they might be multi-batch spawning types.The variations in reproductive strategies suggest that there might be differentiated.According to the findings,the four piscivorous fishes had been different growth rates,growth patterns,and condition factor as well as the reproductive strategies which might be the key driving factors for the sympatric coexistence of the four piscivorous fish species in Lake Qiandaohu.Our results are of great importance for further understanding the coexistence mechanism of fish species,and will provide guidelines for further conservation and exploitation of the piscivorous fish resource.