浅水湖泊人工繁育鳜放养规格对其成活、生长和产量的影响

文章采用标志放流回捕方法评估了人工繁育鳜放流规格对其成活、生长和产量的影响。2012年5—6月选取3种不同大小规格的人工繁育鳜鱼苗各800尾, 中等规格鳜苗种和大规格鳜苗种分别采用剪尾鳍和编码金属标标记后放入试验湖泊小赛湖, 2012年12月试验湖泊逐渐降低水位, 回捕收集放流鳜并鉴定身份。结果显示3种规格放流鳜的总成活率为40.5%, 其中大规格放流鳜的成活率为63%, 明显高于中规格放流鳜(39.1%)和小规格放流鳜(19.5%)。放流鳜的终末体长和体重均随放流规格的增加而增加, 且3种规格放流鳜的终末体长和体重均呈现显著差异。放流鳜的产量和净收益在大规格处理组最大, 在小规格处理组最小。结果表明鳜放流规格对鳜放流成功与否有重要影响, 建议长江中游湖泊鳜的最佳放流规格应不小于50 mm。     

浅水湖泊人工繁育鳜放养规格对其成活、生长和产量的影响（英文）

文章采用标志放流回捕方法评估了人工繁育鳜放流规格对其成活、生长和产量的影响。2012年5—6月选取3种不同大小规格的人工繁育鳜鱼苗各800尾,中等规格鳜苗种和大规格鳜苗种分别采用剪尾鳍和编码金属标标记后放入试验湖泊小赛湖, 2012年12月试验湖泊逐渐降低水位,回捕收集放流鳜并鉴定身份。结果显示3种规格放流鳜的总成活率为40.5%,其中大规格放流鳜的成活率为63%,明显高于中规格放流鳜(39.1%)和小规格放流鳜(19.5%)。放流鳜的终末体长和体重均随放流规格的增加而增加,且3种规格放流鳜的终末体长和体重均呈现显著差异。放流鳜的产量和净收益在大规格处理组最大,在小规格处理组最小。结果表明鳜放流规格对鳜放流成功与否有重要影响,建议长江中游湖泊鳜的最佳放流规格应不小于50 mm。     

绥芬河大麻哈鱼增殖放流效果评估

为评估绥芬河大麻哈鱼增殖放流效果,本研究于2012—2017年在绥芬河东宁段对大麻哈鱼溯河洄游群体进行跟踪监测.共采集样本462尾,其中,标记个体(剪脂鳍)41尾.根据调查数据,计算了大麻哈鱼增殖放流回捕率,评估了增殖放流效果.结果表明: 2010—2012年的大麻哈鱼增殖放流回捕率为0.295%,大麻哈鱼增殖放流数量效益为1∶2.87.标记组和非标记组群体年龄组均为1⁺～5⁺龄,平均年龄分别为3.93和3.63龄.采用Logistic 曲线方程计算标记组和非标记组大麻哈鱼的50%初次性成熟叉长(L₅₀)分别为53.13和49.89 cm.ARSS分析结果显示,大麻哈鱼两组群体的叉长生长差异不显著,但两组间的性成熟比例差异显著.本研究表明大麻哈鱼增殖放流对其资源增殖保护具有重要作用,为今后增殖放流工作提出了建议.     

东江草鱼标志放流技术研究

东江放流草鱼的全长为(18.2±2.0)cm,体长为(14.8±1.6)cm。在标记前进行草鱼食性转化驯养。试验采用两种标志方法对草鱼进行标记,第一种方法用直径为0.14 mm的铜丝把椭圆形塑料标志牌(8mm×5mm×1mm)挂在草鱼背鳍第一和第二支鳍骨间缝隙处,第二种方法剪除左侧腹鳍。标记后需进行为期10 d的暂养,使其穿刺部位愈合。总共放流草鱼10万尾,其中标志草鱼4万尾(挂牌标记1万尾,切腹鳍标记3万尾),标志草鱼占放流草鱼总数的40%,放流后1个多月时间内,总共回捕放流草鱼881尾,其中标志草鱼278尾,标志草鱼占回捕放流草鱼总数的百分率(标志率)为31.6%,总回捕率为0.695%。同时,食性分析发现放流草鱼已摄食江中水草和水葫芦的根,并带进一些藻类,饱食度高(4～5级),表明其在1个多月时间内完全适应了江中环境,放流效果好,标志放流技术可行。该技术要点:(1)放流草鱼的体长在11～17 cm范围内,既适于作切腹鳍标志,又适合作挂牌标记,其挂牌位置为背鳍肌肉内第一与第二支鳍骨间缝隙:(2)标记后需要经过约10 d的暂养治疗使伤口愈合;(3)放流前应作2周的食性转化训练,从吃饲料转变为吃草;(4)在水草茂盛的江段放流有利于放流草鱼尽快找到食物,较快适应环境,提高成活率。     

基于稳定同位素技术的增殖放流牙鲆群体鉴别

牙鲆是我国黄渤海重要的增殖放流鱼类,野生群体和放流群体的鉴别是评估牙鲆增殖效果的前提。为了研究稳定同位素技术在增殖放流牙鲆群体鉴别中的应用,本研究以秦皇岛近海增殖放流区捕捞牙鲆幼鱼为对象,先使用项目组前期开发的形态学和分子标记相结合的方法区分野生群体和放流群体,再分别测定肌肉碳、氮稳定同位素值和耳石(全耳石和耳石核心区域)碳、氧稳定同位素值,并以养殖群体为对照。结果表明: 利用肌肉δ¹³C值(野生群体:-17.19‰±0.73‰;放流群体:-17.10‰±0.61‰;养殖群体:-20.75‰±0.07‰)和δ¹⁵N值(野生群体:11.81‰±0.38‰;放流群体:11.62‰±0.48‰;养殖群体:8.64‰±0.60‰)及全耳石中δ¹³C值(野生群体:-4.47‰±0.35‰;放流群体:-4.63‰±0.29‰;养殖群体:-6.59‰±0.58‰)可鉴别出养殖群体,但是无法区分野生群体和放流群体;利用耳石核心区δ¹³C值(野生群体:-4.66‰±0.30‰;放流群体:-5.41‰±0.21‰;养殖群体:-5.37‰±0.19‰)可鉴别出野生群体。3个群体全耳石和耳石核心区δ¹⁸O值均有重叠,无法对群体进行鉴别。表明利用耳石核心区δ¹³C值可鉴别重建牙鲆幼鱼群体中的野生群体和放流群体,并在生殖洄游亲鱼群体的鉴别方面有一定的应用前景,这为后续估计增殖放流对牙鲆早期资源量的补充及深入开展增殖放流效果评估工作提供了基础数据和技术手段。     

长江口中华绒螯蟹放流亲蟹的繁殖力评估

在长江口中华绒螯蟹亲蟹生殖洄游期间, 通过研究中华绒螯蟹放流群体和自然群体繁殖力随壳宽的变化规律, 比较放流群体和自然群体繁殖力的差异, 从而评估人工增殖放流亲蟹的繁殖力。结果显示, 随着壳宽的增大, 中华绒螯蟹放流群体和自然群体的繁殖力都显著增加(P<0.05)。在相同壳宽范围内, 放流群体和自然群体的繁殖力之间没有显著差异(P>0.05)。回归分析显示, 放流群体繁殖力(F)与壳宽(CW)呈幂函数关系: F=3.979CW6.208(R2=0.822);自然群体F与CW呈幂函数关系: F=1.696CW6.636(R2=0.673)。协方差分析显示, 放流群体与自然群体F与CW的两条曲线在显著性为0.05时拟合较好。研究结果表明, 放流群体与自然群体的繁殖力与壳宽之间无显著性差异, 推断放流亲蟹能够适应长江口天然水域环境, 并与自然群体的繁殖力水平相当。     

长江口中华绒螯蟹放流亲蟹的繁殖力评估（英文）

在长江口中华绒螯蟹亲蟹生殖洄游期间,通过研究中华绒螯蟹放流群体和自然群体繁殖力随壳宽的变化规律,比较放流群体和自然群体繁殖力的差异,从而评估人工增殖放流亲蟹的繁殖力。结果显示,随着壳宽的增大,中华绒螯蟹放流群体和自然群体的繁殖力都显著增加(P0.05)。在相同壳宽范围内,放流群体和自然群体的繁殖力之间没有显著差异(P0.05)。回归分析显示,放流群体繁殖力(F)与壳宽(CW)呈幂函数关系:F=3.979CW6.208(R2=0.822);自然群体F与CW呈幂函数关系:F=1.696CW6.636(R2=0.673)。协方差分析显示,放流群体与自然群体F与CW的两条曲线在显著性为0.05时拟合较好。研究结果表明,放流群体与自然群体的繁殖力与壳宽之间无显著性差异,推断放流亲蟹能够适应长江口天然水域环境,并与自然群体的繁殖力水平相当。     

水温对大鲵野外放流的影响初探

大鲵是我国特有的两栖纲有尾目隐鳃鲵科动物。然而由于生境破坏、环境污染和人为捕杀等原因,该物种数量锐减,被列为国家Ⅱ类重点保护野生动物。为恢复大鲵野生资源数量,进一步评估水温、水质、饵料生物和两岸植被类型等生境因子对大鲵人工放流结果的影响,作者于2013年4月在秦岭山脉南麓(宁陕东河)、北麓(周至黑河)选择放流点分别人工放流16尾和15尾健康大鲵个体。利用PIT芯片进行标记追踪,实时监测水温变化,定期采集周边生境因子数据,一年后南、北麓回捕标记个体8尾和0尾,回捕率分别为50%和0。结果显示,南麓放流点日平均水温显著高于北麓放流点(p0.01),最高温度较北麓放流点高3.85℃,最低温度较北麓放流点高4.26℃,且南麓放流点水温日均温差变化较小。我们认为水温是影响放流成功与否的重要因子,因此,依据野生大鲵的生境特征标准,选择水温更加适宜的放流点,可能是大鲵人工放流成功和实现野生资源增殖的有效途径。     

长江珍稀鱼类中华鲟物种特性及资源保护

中华鲟(Acipenser sinensis)是中国特有鲟类,由于人为因素影响处于濒临灭绝状态。国际自然保护联盟红色名录(IUCN Red List)在2010年收录其为极危物种。本文介绍了中华鲟的资源现状、物种特性以及游泳能力的研究进展。该物种保护措施主要包括人工繁殖、增殖放流和保护区建设。回顾了中华鲟的人工繁殖在近30年取得的成果以及全人工繁殖过程的困难;概述了中国在中华鲟增殖放流中所做的工作,中华鲟的标记回捕的困难使增殖放流效果短期难以评价;探讨了保护区建设对于保护中华鲟的重大意义。通过对中华鲟现阶段研究的综述,以期为后续中华鲟的研究提供参考。     

基于微流控芯片的鲑科鱼类单核苷酸多态性分型系统构建

为开发针对大规模样本、低通量位点的单核苷酸多态性(Single nucleotide polymorphism, SNP)分型技术, 研究依据虹鳟高通量SNP芯片检测鲑科4个属不同物种群体样本的结果, 筛选获得了96个高质量共享多态性位点, 应用Fluidigm 96.96微流控动态芯片平台, 构建了用于鲑科物种增殖放流个体识别的SNP分型系统。以细鳞鲑为例评估芯片分型结果可靠性, 分型成功率为98.63%, 与Affymetrix高通量芯片分型一致性达到97.92%。基于该芯片分型结果, 使用CERVUS 3.0.7软件对96尾细鳞鲑子代样本及其候选亲本和干扰亲本进行亲权鉴定, 结果能够准确重现复杂家系的真实系谱, 在用于单亲本亲权鉴定时, 第一亲本非排除率(Non-exclusion probability for first parent, NE-1P)为4.362×10–4, 用于双亲本亲权鉴定时, 双亲非排除率(Non-exclusion probability for parent pair, NE-PP)为6.538×10–12, 完全满足增殖放流回捕个体分子鉴定的需求。基于该芯片分型数据进行STRUCTURE遗传结构分析, 可以明确区分不同来源野生群体的遗传组分, 并对待测个体的遗传组分进行初步判别, 能够满足种群遗传结构初步评估的需求。研究构建的包含96个位点的SNP分型系统, 适合应用于鲑科鱼类增殖放流个体识别、种群遗传结构动态评估, 以及在此基础上开展的增殖放流效果评估。     

Genetic risk of domestication in artificial fish stocking and its possible reduction

Genetic hazards associated with the stocking of fish juveniles produced in hatcheries were studied with simple mathematical models. Domestication is the process of acquiring a genetic characteristics that are advantageous in a hatchery environment but that are disadvantageous in a natural environment due to the selection pressure in the hatchery differing from that in the natural environment. Conditions for the propagation of mutants enhancing domestication were obtained for a variety of stocking strategies specified by parameters related to hatchery productivity and kind of brood stock used. By using this, the possibility of reducing the risk of domestication was studied. As a means of reducing the risk, selective use of wild-born individuals for brood stock was considered. The effectiveness of this was analyzed for both the cases where all brood stock is collected from the wild, and the male brood stock is collected from the wild and the female brood stock is born and reared in a hatchery. We also estimate how much hatchery release can be increased without increasing the risk by employing these means. It is concluded that the use of only male brood stock from the wild is not very effective in reducing the risk of domestication. Further, it is concluded that selective use of the wild-born individuals of both sexes for brood stock is highly desirable if the contribution of released individuals to the natural reproduction is high. In other words, substantial increase of hatchery release may be possible while keeping risk at a level comparable to that under moderate hatchery release, if it is accompanied by the selective use of wild-born individuals for brood stock.     

Population dynamics and potential of fisheries stock enhancement: practical theory for assessment and policy analysis

The population dynamics of fisheries stock enhancement, and its potential for generating benefits over and above those obtainable from optimal exploitation of wild stocks alone are poorly understood and highly controversial. I review pertinent knowledge of fish population biology, and extend the dynamic pool theory of fishing to stock enhancement by unpacking recruitment, incorporating regulation in the recruited stock, and accounting for biological differences between wild and hatchery fish. I then analyse the dynamics of stock enhancement and its potential role in fisheries management, using the candidate stock of North Sea sole as an example and considering economic as well as biological criteria. Enhancement through release of recruits or advanced juveniles is predicted to increase total yield and stock abundance, but reduce abundance of the naturally recruited stock component through compensatory responses or overfishing. Economic feasibility of enhancement is subject to strong constraints, including trade-offs between the costs of fishing and hatchery releases. Costs of hatchery fish strongly influence optimal policy, which may range from no enhancement at high cost to high levels of stocking and fishing effort at low cost. Release of genetically maladapted fish reduces the effectiveness of enhancement, and is most detrimental overall if fitness of hatchery fish is only moderately compromised. As a temporary measure for the rebuilding of depleted stocks, enhancement cannot substitute for effort limitation, and is advantageous as an auxiliary measure only if the population has been reduced to a very low proportion of its unexploited biomass. Quantitative analysis of population dynamics is central to the responsible use of stock enhancement in fisheries management, and the necessary tools are available.     

Stocking efficiency and the effects of diet preconditioning on the post-release adaptation of hatchery-reared juveniles of Atlantic salmon (Salmo salar L.) in an Atlantic temperate stream

This study explores the stocking efficiency of Atlantic salmon juveniles in a 4th order stream located at the southern limit of its Eastern Atlantic distribution. Moreover, with the idea of implementing new protocols and methods to improve ??traditional?? hatchery practices and rear a more ??wild?? like fish, the study examines the response of this species to natural diet preconditioning prior to release. The field study indicated that most juveniles disappeared from the stocked reaches within two months of their release, resulting in a recapture rate after a year of 0.0?C1.1?%. There were no differences in stocked juvenile??s density along the stream during the first months following stocking. The preconditioning experiments showed that juveniles of Atlantic salmon suffered a significant decrease in their condition factor when diet was changed from artificial pellets to live preys, either if the change occurred before (i.e., in a manipulative experiment) or after their release in the stream. Although weight, length, condition factor and specific growth rates reached by juveniles at the end of the rearing period were higher in individuals fed on pellets than in those fed on macroinvertebrates, differences disappeared only a week after their release in the stream. These results may have implications regarding the stocking success when releasing hatchery-reared Atlantic salmons in suboptimal environments. In particular, the study indicates that stocked salmon adaptation in the selected stream may not be improved by short conditioning periods to natural diet prior to their release, while we discuss potential explanations for the observed results.     

Intra- and Interspecific Competition in Hatchery Landlocked Salmon and Brown Trout in Semi-Natural Streams

I studied inter- and intraspecific competition in two hatchery stocks: landlocked salmon with long-hatchery background and a heterogenic brown trout stock. These species are potential competitors in the natural environment when landlocked salmon is being restored to wild by stocking hatchery juveniles. Behavioural responses were studied in four indoor laboratory flumes (400 cm long and 37 cm wide) and habitat use in six semi-natural outdoor streams (26 m long and 1.5 m long). Video recordings were used to monitor fish behaviour and electrofishing for fish positioning in the outdoor channels. The study design included five treatments: two densities of brown trout and salmon in solitary and both species together. The results of the study demonstrated that juvenile brown trout changed their behaviour in laboratory streams in response to presence of the landlocked salmon and the density of the conspecifics also tended to alter the habitat use by brown trout in semi-natural streams. Landlocked salmon juveniles showed no response to treatments. I conclude that possible poor adaptive ability to conditions outside hatchery by the hatchery salmon together and more competitive brown trout stocks may limit the success of management action in restoring landlocked salmon back to their natural streams of stocking.     

Rapid expansion of an enhanced stock of chum salmon and its impacts on wild population components

A harvested stock of chum salmon homing to Kurilskiy Bay, Iturup Island, consists of two genetically distinct river populations that reproduce in two rivers that drain into the bay and are characterized by limited gene flow. One of these is small and can be regarded as wild, whereas the other is much larger and, until recently, was composed of naturally reproducing components spawning in the river??s mainstem and tributaries, with almost no hatchery reproduction during the past two decades. The only human impact on reproduction of the chum salmon stock was regulation of the escapement, with officially accepted limits to avoid ??over-escapement??. Recently the hatchery began to release a large amount of chum salmon juveniles. As confirmed by data on variation in both age composition and microsatellite DNA, first-generation hatchery-origin fish that returned from the first large releases occupied spawning grounds and presumably competed directly with, and potentially displaced wild fish. The most dramatic example is a genetically distinct beach-spawning form of chum salmon that was swamped by much more numerous hatchery-origin fish of the river-spawning form. In order to restore and support naturally reproduced population components, careful estimation of the carrying capacity of natural spawning grounds is necessary with efforts to increase escapement to these habitats. We also recommend concerted efforts to restore and conserve a unique beach-spawning population of chum salmon. We further recommend development of a marking program for direct estimation of straying and evaluation of ecological and genetic impacts of hatchery fish on neighboring wild and natural populations.     

Stock enhancement to address multiple recreational fisheries objectives: an integrated model applied to red drum Sciaenops ocellatus in Florida

An integrated socioecological model was developed to evaluate the potential for stock enhancement with hatchery fishes to achieve socioeconomic and conservation objectives in recreational fisheries. As a case study, this model was applied to the red drum Sciaenops ocellatus recreational fishery in the Tampa Bay estuary, Florida, U.S.A. The results suggest that stocking of juvenile fish larger than the size at which the strongest density dependence in mortality occurs can help increase angler satisfaction and total fishing effort (socioeconomic objectives) but are likely to result in decreases to the abundance of wild fishes (a conservation objective). Stocking of small juveniles that are susceptible to density‐dependent mortality after release does not achieve socioeconomic objectives (or only at excessive cost) but still leads to a reduction of wild fish abundance. The intensity and type of socioeconomic gains depended on assumptions of dynamic angler‐effort responses and importance of catch‐related satisfaction, with greatest gains possible if aggregate effort is responsive to increases in abundance and satisfaction that are greatly related to catch rates. These results emphasize the view of stock enhancement, not as a panacea but rather as a management tool with inherent costs that is best applied to recreational fisheries under certain conditions.     

Microsatellite DNA markers: evaluating their potential for estimating the proportion of hatchery-reared offspring in a stock enhancement programme

We describe a statistical method for estimating the effectiveness of a stock enhancement programme using nuclear DNA loci. It is based on knowing the population allele frequencies and the genotypes of the hatchery parents (mother only, or mother and father), and on determining the probability that a wild-born animal will by chance have a genotype consistent with hatchery origin. We show how to estimate the proportion of released animals in the wild population, and its standard error. The method is applied to a data set of eight microsatellite loci in brown tiger prawns (Penaeus esculentus), prior to the start of a possible enhancement programme. We conclude that, for this particular data set, the effectiveness of such an enhancement programme could be quantified accurately if both maternal and paternal genotypes are known, but not if maternal genotypes only are known. Full paternal genotyping would require offspring genotyping and thus would be expensive, but a partly typed paternal genotype from a mass homogenate of offspring would be almost as effective and much cheaper. The experiment would become feasible based on maternal genotypes alone, if a further three typical microsatellite loci could be found to add to the existing panel of eight. The methods detailed should be of interest to any enhancement project that relies on nuclear DNA markers to provide tags.     

Genetic implications of hatchery rearing in Atlantic salmon: effects of rearing environment on genetic composition

In an experiment to investigate genetic consequences of hatchery rearing in salmon, allozyme variation at five polymorphic loci was examined in Atlantic salmon of known initial genetic composition, which were reared throughout freshwater life in the hatchery or stocked into the wild as swim-up fry. The genetic composition of the juveniles in the hatchery remained homogeneous from fertilization up to stocking, and from stocking to 2+ in the wild, however, those remaining at the hatchery developed genetic differences among smolting and nonsmolting 1+ parr. These differences were attributed to conditions leading to early smolting at 1+ among the hatchery fish, with 1+ smolts diverging from the gene pool from which they were derived, whereas those stocked into the wild did not smolt until a year later and retained the original genetic composition. The results are discussed in relation to hatchery rearing of salmon and implications for the use of reared fish in stocking and enhancement programmes.     

Brown trout Salmo trutta released to support recreational fishing in a Norwegian fjord

One- and two-year-old hatchery reared juveniles of seven freshwater resident and anadromous populations of Scandinavian brown trout were released in the outer and inner part of the Oslofjord and in the River Akerselva, flowing through the city of Oslo. Recapture rates were highest (mean 20.3%) for river released fish and lowest for those released in the outer (16.8%) and inner (12.1%) fjord. In general, recapture rate increased with fish size at release (r=0.76). When released in fresh water, most of the recaptures were from fresh water and when released in the fjord, most recaptures were from the fjord. In general, freshwater resident stocks showed a higher degree of freshwater residency than anadromous stocks. However, mean migratory distance was longer for freshwater resident than anadromous fish. Trout moved longer distances at sea when released in the outer than in the inner fjord. Specific growth rate and size at recapture varied among release sites and stocks; they were highest for fish released in the outer fjord and lowest for river-released trout. There was no consistent difference in sea growth between freshwater resident and anadromous stocks. Estimated total yield was highest for fish released in the outer fjord, whereas there was no significant difference in yields between trout released in the river and the inner Oslofjord.