水生生物增殖放流生态风险评价研究进展

增殖放流已成为恢复和保护水生生物资源的重要措施, 水生生物增殖放流生态风险评价是指对水生生物增殖放流引发的正在发生或可能发生的不利生态过程的评估, 目前相关研究处于发展阶段。文章综述了国内外生态风险评价研究进展, 结合水生生物的生物学属性、生态学特征和增殖放流特点, 探讨评价水生生物增殖放流对环境、环境生物、遗传和病害等的风险, 并提出了生态风险防控措施, 以期为今后水生生物增殖放流的实施、管理和研究提供参考依据。     

对资源增殖放流管理的思考

资源增殖放流是目前渔业资源发展越来越多提及的一个话题,成为一个新的社会热点。本文通过对资源增殖放流存在问题的分析,对资源增殖放流提出可实现的建议,促进渔业资源的蓬勃发展。     

禁捕初期长江上游长江鲟增殖放流效果

为科学评估长江上游长江鲟增殖放流效果,研究基于2021—2023年宜宾、泸州和合江3个江段渔业监测数据,对长江上游长江鲟野外种群恢复情况进行了分析。监测期间, 3个江段共采集长江鲟849尾,其体长分布为14.70—93.00 cm [平均体长(45.19±14.01) cm],优势组体长为25.10—65.00 cm,占总体的88.98%;体重分布为24.0—6850.0 g [平均体重(892.7±960.8) g],优势组体重为0—1250.0 g,占总体的83.18%。分析显示:(1) 2022年和2023年监测到的长江鲟体长、体重均值均显著高于2021年(P<0.05),体长均值均高于当年放流群体体长均值;(2)监测的长江鲟群体呈正异速生长,体重增长速率大于体长增长速率,且宜宾至合江江段的生长条件因子、异速生长参数具有明显的地点和时间差异(P<0.05);(3)长江鲟单位捕捞努力量渔获量为0.1—35.0 ind./(net·d),不同季节间呈显著差异(P<0.05);(4)在2018—2023年各大单位加大放流力度且2021年长江十年禁捕政策出台并执行后, 2021—2023年监测期间长江鲟采集数量明显增加。研究结果表明,禁捕后长江上游长江鲟资源正逐渐恢复,且生长状况良好,增殖放流效果初步显现。     

中国淡水鱼类人工增殖放流现状

随着鱼类资源的持续衰退以及保护水产学的兴起,鱼类人工增殖放流已由传统渔业增殖发展成为特有珍稀鱼类种群恢复的主要技术手段。近年来,我国淡水鱼类人工增殖放流涉及水系多、规模大且种类丰富,取得了显著效果并积累了大量基础资料和经验。为深入开展人工增殖放流基础研究,规范技术并提升生态效益,该文收集整理了国内、外相关文献资料,分别从基础理论、塘养种群管理及效果评价等方面阐述人工增殖放流的理论背景,并结合我国"四大家鱼"、中华鲟、胭脂鱼、滇池金线鲃及其他珍稀濒危鱼类人工增殖放流现状,讨论了野外监测和效果评价的作用和意义,提出放流种群遗传局限性、数量和规格权衡以及经济效益与生态效益权衡等问题,旨在为相关研究和人工放流实践提供系统资料。     

张家界大鲵人工放流效果及其影响因素分析

大鲵(Andrias davidianus)是我国特有的两栖动物, 由于栖息地破坏和人类过度捕杀等, 种群数量急剧下降, 被列为我国II类保护野生动物。为探索大鲵人工放流的有效方法, 实现野生大鲵资源增殖, 作者对2002–2008年间在湖南张家界大鲵国家级自然保护区内进行的大鲵人工放流活动与放流效果进行了评估, 并通过对放流点的隐蔽物、水质及饵料生物等生境特点的分析, 探讨影响放流成败的因素。该保护区内共在9处大鲵原栖息地进行了11次人工放流活动, 共放流各种规格大鲵995尾, 其中4次成功。成功放流的大鲵为1–4.5 kg的性成熟个体, 雌雄比在1:1和1:1.5之间, 成功放流点均有良好的后期管理措施, 如建立保护站, 补充饵料等。虽然所选择的多数放流点生境基本能满足大鲵生长和繁殖的要求, 但由于受水质、饵料或安全某一因素的制约, 野生大鲵资源增殖效果不明显, 导致放流失败。因此我们认为依据野生大鲵繁殖的生境特征标准, 科学选择放流地点, 选择性成熟的大鲵在春季放流, 并进行完善的后期跟踪保护, 可能是大鲵人工放流成功和实现资源增殖的有效途径。     

基于Ecopath模型的莱州湾中国对虾增殖生态容量

通过增殖放流,增加优质渔业资源、改善种群结构是渔业资源养护的重要手段,而增殖生态容量的研究是科学实施增殖放流的前提.本文根据2009-2010年的渔业资源与生态环境数据,构建了由26个功能群组成的莱州湾生态系统Ecopath模型,利用该模型分析了生态系统的总体特征、营养相互关系与关键种,计算了放流品种中国对虾的增殖生态容量.结果表明：系统的总初级生产量/总呼吸(TPP/TR)为1.53,总初级生产量/总生物量(TPP/B)为24.54,同时具有较低的循环指数(FCI=0.07)、较高的剩余生产量（434.41 t·km^-2·a^-1）和较低的系统连接指数(CI=0.29),该系统目前处于发育的早期阶段.中国对虾目前不是莱州湾生态系统的关键种,当前中国对虾的生物量为0.1143 t·km^-2,有较大的增殖潜力;当生物量增长25.8倍时,仍不会超过增殖生态容量2.9489 t·km^-2.     

幼体中国对虾荧光标记虾的制作

采用经过暂养,平均体长为2 cm以上的中国对虾(Fenneropenaeus chinensis)进行试验,用黄色、红色和绿色荧光染料(visible implant elastomer,VIE)制作荧光标记对虾.结果表明,对照组中国对虾与用VIE标记后7个试验组中国对虾在生长发育等方面没有差异,并且各组对虾蜕皮正常.尽管荧光标记的残留率随着虾体的生长有所下降以及分布的不均匀,但荧光标记的保持率为95%.3种颜色的荧光染料中,红色荧光标记的效果最好.     

中国对虾荧光标记虾的大规模制作与养殖试验

以平均体长为2 cm以上的10 632只中国对虾(Fenneropenaeus chinensis),用红色荧光染料(visible implant elastomer,VIE)制作荧光标记对虾,与10万只非标记的中国对虾在同一池塘养殖。结果表明,VIE标记对虾和非标记对虾经2-3个月的养殖后,在生长发育和成活率等方面没有差异。尽管荧光标记的残留率随着虾体的生长有所下降以及分布的不均匀,但荧光标记的保持率为70%以上。红色VIE标记可以用于中国对虾的海洋增殖放流研究。     

关于黑龙江省绥芬河水域大马哈鱼增殖放流的分析

黑龙江省是大马哈鱼的故乡,绥芬河水域中生着名贵的洄游鱼类----大马哈鱼。九十年代,由于诸多因素导致大马哈鱼总量锐减上,为有效保护大马哈鱼资源,我省进行了增殖放流养护工程,建立了东宁县鲑鱼孵化放流站,二十多年的增殖放流,增加了大马哈鱼的种群数量,实现了渔民增收,也使生态水域渔业资源得到持续发展。     

贝类增殖放流对潮间带大型底栖动物群落的影响——以坎门湾为例

为了解贝类增殖放流对潮间带大型底栖动物群落的影响,于2022年5月(春季)和10月(秋季)对台州市玉环县坎门湾区域贝类增殖区和对照区潮间带大型底栖动物群落开展了现场调查和研究。两次调查共采集到大型底栖动物6门7纲55科89种,增殖区记录到的物种数(62种)高于对照区(59种),全区、增殖区和对照区大型底栖动物均为软体动物种类占比最高,分别占相应区域物种数的46.07%、51.61%和49.15%。春季,增殖区和对照区大型底栖动物优势种分别为9种和4种,共有优势种是微角齿口螺Odostomia subangulata和纹藤壶Amphibalanus amphitrite;秋季,分别为4种和5种,共有优势种是绯拟沼螺Assiminea latericea和日本大眼蟹Macrophthalmus(Mareotis) japonicus。不管是春季还是秋季,大型底栖动物平均栖息密度、生物量、Shannon-Wiener多样性指数(H'')、Margalef丰富度指数(D)均表现为增殖区＞对照区,而Pielou均匀度指数(J'')表现为对照区＞增殖区。双因素方差分析表明,增殖区和对照区之间大型底栖动物生物量差异显著,而种类数、栖息密度在春季和秋季之间差异显著,其余参数在区域间及季节间差异均不显著。聚类分析表明,春季增殖区和对照区的大型底栖动物群落相似度较高,可分为增殖区(T1和T2断面)和对照区(T3和T4断面)2组;秋季相似度较低,可分为增殖区T1断面、增殖区T2断面和对照区T3和T4断面3组。结合增殖放流前以及周边调查数据,贝类增殖放流两年后,大型底栖动物群落物种数、平均栖息密度、生物量、Shannon-Wiener多样性指数(H'')和Margalef丰富度指数(D)均有提高,但效果不明显,研究区域大型底栖动物恢复效果并不理想。     

Characterization of expressed sequence tag‐derived microsatellites from the kuruma prawn,Marsupenaeus japonicus

The kuruma prawn, Marsupenaeus japonicus, is a commercially important benthic marine crustacean in East Asia. Understanding the species’ population structures will be very important for its proper stock assessment and management strategy. Herein, 13 polymorphic microsatellite loci originating from expressed sequence tag libraries of M. japonicus were isolated and characterized. Number of alleles per locus ranged from two to 15, observed and expected heterozygosities ranged from 0.250 to 0.906 and from 0.310 to 0.932, respectively. The adequate level of variability within the population renders these microsatellite loci ideal markers for population genetic analysis of M. japonicus.     

Stock enhancement as a fisheries management tool

Stock enhancement has been viewed as a positive fisheries management tool for over 100 years. However, decisions to undertake such activities in the past have often been technology-based, i.e., driven by the ability to produce fishes, with most stock enhancement projects having limited or no demonstrated success. The reasons for this have been due to an inability to identify and/or control the underlying reasons why a fishery is under-performing or not meeting management objectives. Further, stock enhancement has often been applied in isolation from other fisheries management tools (e.g., effort control). To address these issues and consider stock enhancement in a broader ecosystem perspective, a new approach for stock enhancement is proposed. The proposed model comprises four major steps; a review of all information about an ecosystem/fishery/stock and the setting of clear management targets; a comparison of all relevant fisheries management tools with the potential to meet the management targets; the instigation of a scientifically based, pilot-scale, stock enhancement program with clear objectives, targets, and evaluations; and a full-scale stock enhancement program if the pilot project meets the objectives. The model uses a flow-chart that highlights a broad range of scientific and other information, and the decisions that need to be made in relation to stock enhancement and fisheries management in general. In this way all steps are transparent and all stakeholders (managers, scientists, extractive and non-extractive users, and the general public) can contribute to the information collection and decision making processes. If stock enhancement is subsequently identified as the most-appropriate tool, then the stepwise progression will provide the best possible chance of a positive outcome for a stock enhancement project, while minimizing risks and costs. In this way, stock enhancement may advance as a science and develop as a useful fisheries management tool in appropriate situations.     

The use of inter-specific hybrids in aquaculture and fisheries

Inter-specific hybrid fishes have been produced for aquaculture and stocking programmes to increase growth rate, transfer desirable traits between species, combine desirable traits of two species into a single group of fishes, reduce unwanted reproduction through production of sterile fish or mono-sex offspring, take advantage of sexual dimorphism, increase harvestability, increase environmental tolerances, and to increase overall hardiness in culture conditions. Hybrids constitute a significant proportion of some countries' production for certain taxa; for example, hybrid striped bass in the USA, hybrid clarid catfish in Thailand, hybrid characids in Venezuela, and hybrid tilapia in Israel. Despite its widespread use, there is a general impression that inter-specific hybridization is not a very useful tool for aquaculture. We believe this impression stems from inaccurate reporting of some useful hybrids, limited testing of strains used for hybrids, and from early work on salmonids that did not result in hybrids of commercial advantage.Experimentation with new hybrid fishes is ongoing, especially in marine culture systems where sterile fish may be preferred because of the concern that fish may escape into the marine and coastal environment.Hybridization has been used in tandem with polyploidization to improve developmental stability in hybrid progeny. The results of inter-specific hybridization can be variable and depend on the genetic structure (including the sex) of the parent fish. Inadvertent hybridization and backcrossing can lead to unexpected and undesirable results in hybrid progeny, such as failure to produce sterile fish, loss of color pattern, and reduced viability.Hybridization is only one tool to improve aquaculture production and will require knowledge of the genetic structure of the broodstock, good broodstock management and monitoring of the viability and fertility of the progeny. Hybridization does represent a genetic modification wherein genes are moved between different species; implications for biodiversity conservation and regulation of this type of modification are discussed.     

Relationship of size at return with environmental variation,hatchery production,and productivity of wild pink salmon in Prince William Sound,Alaska: does size matter?

Pink salmon (Oncorhynchus gorbuscha) returning to Prince William Sound (PWS), Alaska, have increased to historically high levels of abundance in recent years, but average body size at return has declined. We examined how body size at return of PWS pink salmon was related to 10 biophysical factors, including the scale of hatchery production. We also examined the effect of body size at return on productivity of wild pink salmon in PWS. For the 1975–1999 brood years, we found that an index of total abundance of pink salmon in the Gulf of Alaska and sea surface temperature during the year of return best explained the variation in pink salmon body size over time. Body size at return was significantly correlated with productivity of wild pink salmon. We used stepwise-regression to fit a generalized linear version of the Ricker spawner-recruit model to determine if body size would explain significant variation in wild-stock productivity in context with other environmental variation, including hatchery production. The results indicate that variability in wild-stock productivity is primarily driven by density-independent factors in the marine environment, but that body size of wild spawners also significantly affects productivity of wild PWS pink salmon. We conclude that the success of large-scale enhancement increasing the total run in PWS may have contributed to the decline in body size because of density-dependent growth in the Gulf of Alaska. We used a simulation model to estimate the impact of hatchery-induced changes in adult body size on wild-stock production in PWS. We estimated an annual wild-stock yield loss of 1.03 million pink salmon, less than 5% of the annual hatchery return of 24.2 million adult pink salmon for brood years 1990–1999.