江西云居山自然保护区鱼类调查初报

江西云居山自然保护区处于九岭幕阜山脉东段余脉,是鄱阳湖周边生物多样性较高区域之一。2012年10月,对该保护区鱼类资源进行了实地调查。调查发现区内野生淡水鱼类共计17种,隶属于4目5科,以鲤形目鲤科鱼类为主,多为山区溪流小型鱼类。同时分析了该保护区鱼类资源的现状及存在的问题,并给出了相应的保护对策。     

南澳白沙湾海藻养殖区内外渔业资源声学评估

为初步了解南澳岛白沙湾海藻养殖区鱼类资源状况,利用便捷式分裂波束式Simrad EY60科学探鱼仪,于2015年4月28日、12月2日与2016年4月19日对该海域进行3次声学调查,结果显示,3次调查中藻区内、外鱼类资源丰度密度分别为3.45/1.38×105、0.63/1.45×105、3.67/2.98×105尾/n mile2。藻区内春季鱼类资源量显著高于冬季,资源丰度密度随季节变化显著;藻区外资源丰度密度变化较小且均匀;藻区内、外鱼类资源丰度密度最高值出现于2~6 m水层,6~8 m次之,表、底层最小,资源丰度密度受深度影响显著。在海藻养殖期间,藻区内鱼类资源丰度密度较藻区外大且年变化明显,表明海藻生物量对鱼类资源量及其分布变化具有一定影响。本次调查通过声学评估技术对海藻养殖区鱼类资源进行初步评价,为其具有改善水质环境、恢复渔业资源的作用提供理论依据。     

唇鲮人工繁殖鱼苗生长试验

唇鲮作为北盘江九盘段特有鱼类国家级水产种质资源保护区特有保护鱼类品种之一,为进一步探索了解唇鲮生长繁殖习性,鱼苗生长过程,从保护区内采集唇鲮亲本进行人工繁殖鱼苗生长试验探索.试验结果:成功进行人工催产受精,孵化鱼苗至鱼苗生长出唇鲮特有嘴型.     

我国鱼类生物多样性保护策略

我国水生生态系统、鱼类物种多样性水平高,目前对重要养殖鱼类的种质资源进行了系统的调查研究发现,尚有大量野生种质资源未开展保护。水环境变化、外来物种入侵、过度捕捞等对鱼类资源造成严重威胁。针对我国鱼类生物多样性保护和管理存在的主要问题,提出了我国鱼类生物多样性保护工作的对策与措施。     

福建建溪细鳞鲴国家级水产种质资源保护区的鱼类多样性

2011—2013年对福建省建溪细鳞鲴国家级种质资源保护区的4个江段进行了鱼类资源现状调查。共采集到鱼类77种,隶属于4目18科57属。渔获物分析表明,该保护区鱼类以鲤形目鱼类为主,占鱼类总种类比的64.9%;常见种有黄颡鱼(Pseudobagrus fulvidraco)、细鳞鲴(Xenocypris microlepis)、翘嘴鲌(Culter alburnus)、光泽黄颡鱼(Pseudobagrus nitidus)、子陵吻虎鱼(Ctenogobius giurinus)、银(Gnathopogon argentatus)等15种,以杂食性、底层、适应缓流生活的鱼类为主。保护区内的鱼类多样性指数、单船捕捞努力量较低,主要经济鱼类个体出现小型化现象。     

黄河鱼类资源保护目标的研究

黄河是我国的第二大河,近些年来黄河的生态系统健康受到了威胁,鱼类资源遭到了严重破坏。作者于2002—2007年对黄河的水生生物及鱼类进行了调查研究。调查共采集到鱼类标本41种,其中珍稀濒危保护鱼类4种,地方性保护鱼类11种,结合调查的实际情况,根据黄河流域现存鱼类资源的稀有性和其在水域中的作用地位,提出关键性保护鱼类的代表性鱼类,提出生态流量、水质和水环境3个关键性保护指标。     

湖南鱼类资源变动趋势与增殖保护途径探讨

湖南鱼类资源变动趋势与增殖保护途径探讨林益平（湖南省水产局４１０００６）湖南素称“鱼米之乡”，鱼类资源是湖南一大自然资源优势。本文试从描述鱼类资源基础与自然条件入手，通过对目前鱼类资源变动情况的分析，探讨增殖保护鱼类资源的途径，以利鱼类资源长盛不衰和...     

我国鱼类资源的危机和保护

对我国海洋和淡水鱼类资源危机的现状、导致鱼类资源危机的各种因素进行了分析,指出我国鱼类资源危机的严重性。提出污水处理、生态修复、伏季休渔、依法治渔、保护鱼类生物多样性等保护措施。     

廉江龙头沙人工鱼礁区初显集鱼效果

根据2002年11月和2006年11月对廉江龙头沙人工鱼礁区进行渔业资源底拖网调查的结果,初步评估人工鱼礁建设对礁区及邻近海域渔业资源的养护效果.结果显示:投礁后,礁区内资源种类(特别是鱼类)增加明显,由投礁前的9种增加到23种,增加了1.56倍,而对照海区资源种类(特别是鱼类)明显减少,由投礁前的26种减少至15种,减少了42.31%;投礁后各类资源的资源密度明显比投礁前高,礁区内和对照海区总资源密度分别比投礁前增加了9.25倍和1.06倍;投礁一年多来,礁区内已初步形成新型的人工生境,头足类成为礁区内的新增优势类群,杜氏枪乌贼成为对照海区的第一优势种,初步显示出人工鱼礁对游泳生物(特别是鱼类和头足类)的诱集效果,并且这种效果已波及到礁区邻近海域.     

秦岭甘峪河鱼类资源现状及保护评析

为了解甘峪河秦岭细鳞鲑国家级水产种质资源保护区(下称"保护区")鱼类资源现状,评析保护区成立5年来的保护效果;在保护区内海拔每升高100m设定1个样点,共计10个样点,采取电捕法分别于2011年5月和2016年8月在各样点进行采样调查。采用Shannon-Wiener指数(H′)、Pielou均匀度指数(J′)、Simpson指数(D′)分析鱼类多样性,采用Pinkas相对重要性指数(IRI)研究鱼类物种优势度。结果表明,保护区鱼类组成单一,仅2目3科3种鱼类。鲤科、鲑科和鳅科鱼类各1种,拉氏鱥(Phoxinus lagowskii)为主要种,秦岭细鳞鲑(Brachymystax lenok tsinlingensis)为一般种,岷县高原鳅(Triplophysa minxianensis)为少见种。两次调查中,拉氏鱥分别占73.76%和71.73%,秦岭细鳞鲑分别占21.63%和26.18%,岷县高原鳅仅占4.61%和2.09%。较低的鱼类物种多样性指数反映出保护区鱼类群落结构简单、脆弱,极易受外界干扰。两次调查共捕获161尾秦岭细鳞鲑,均重(16.6±17.1)g,最大个体重仅81.5g。2016年采集标本的最大个体重和均重均小于2011年。保护区成立5年后,重点保护鱼类秦岭细鳞鲑占比增加,鱼类多样性指数有所升高,反映出保护区对该鱼种的保护效果显著。保护区内秦岭细鳞鲑个体呈明显小型化,岷县高原鳅的资源量有下降趋势。     

Potential movement of fish and shellfish stocks from the sub‐Arctic to the Arctic Ocean

An assessment of the potential for 17 fish or shellfish stocks or stock groups to move from the sub‐Arctic areas into the Arctic Ocean was conducted. A panel of 34 experts was convened to assess the impact of climate change on the potential movement of the 17 stocks or stock groups. The panel considered the exposure of species to climate change, the sensitivity of species to these changes and the adaptive capacity of each stock or stock group. Based on expert opinions, the potential for expansion or movement into the Arctic was qualitatively ranked (low potential, potential, high potential). It is projected that the Arctic Ocean will become ice‐free during the summer season, and when this happens new areas will open up for plankton production, which may lead to new feeding areas for fish stocks. Five stocks had a low potential to move to, or expand in, the high Arctic. Six species are considered as potential candidate species to move to, or expand in, the high Arctic. Six stocks had a high potential of establishing viable resident populations in the region. These six stocks exhibit life history characteristics that allow them to survive challenging environmental conditions that will continue to prevail in the north. This study suggests that several life history factors should be considered when assessing the potentiality of a species moving in response to changing climate conditions.     

A survey of the Fish Fauna of Sudanese Irrigation Systems with Reference to the Use of Fishes in the Management of Ecological Problems (the Control of Aquatic Weeds, Malaria and Infective Schistosomiasis)

This paper reports on a fundamental study of the fish fauna already present within the irrigation canals. The fauna was investigated with a view to determining its use in the control of nuisance biota. Twenty-seven species of fish were collected, comprising 22 genera and 12 families. This fauna is closely allied to the fauna of the source water, the Blue Nile. Several Blue Nile species are absent and some of those collected are new recordings for the area. Each species of fish collected had neither a suitable feeding habit nor a wide enough distribution to have any significant effect on the levels of nuisance biota. This includes the mosquito fish. Gambusia affinis, which was specifically introduced for mosquito control. Improvement in the ecological conditions within the canals involves both the management of the already-existing fish stocks and the introduction and management of additional species. A reduction in the levels of aquatic weeds using phytophagous fishes should be a high priority with malacopliagous and larvivorous species also being introduced and their stocks managed. Species suitable for introduction, which are generally endemic to the Nile system, are suggested. The fish species diversity falls as the canals become smaller and the water within them subject to much greater variations in flow and quality. The lowest order canals (field canals) are probably unsuitable for permanent fish stocks. The nuisance biota within field canals can be controlled by simple improvements in crop-watering procedures. The widely distributed and diverse fauna found within minor canals suggests that problems due to fish-kills brought about by heavy pesticide and herbicide usage are not so severe as previously thought. The management of the ecological problems is a complex task due to the interrelationships of many factors.     

Aquaculture's potential impacts on conservation of wild stocks and biodiversity

Abstract

Anderson theorizes that development of the aquaculture of a fish species (also captured in an open‐access fishery) favours the conservation of its wild stocks, if competitive market conditions prevail. However, his theory is subject to significant limitations. While this is less so within his model, it is particularly so in an extended one outlined here. These other models allow for the possibility that aquaculture development can impact negatively on wild stocks thereby shifting the supply curve of the capture fishery, or raise the demand for the fish species subject both to aquaculture and capture. Such development can threaten wild fish stocks and their biodiversity. While aquaculture development could in principle have no impact on the biodiversity of wild stocks or even raise aquatic biodiversity overall, its impact in the long‐term probably will be one of reducing aquatic diversity both in the wild and overall. The development of aquaculture does not automatically ensure long‐term sustainability of fish and other aquatic supplies.     

Conservation of freshwater fish in the British Isles: Proposals for management

1. Recent checklists of the freshwater fish of the British Isles have included 42 native and 13 introduced species. Of the former, however, two are extinct now and eight are threatened in various ways. In addition there are several important stocks of common native species under threat. 2. Protection for British fish exists mainly through legislation and protected sites of various designations. The legislation is inadequate in some respects and very few of the protected sites were actually established for their fish interest. Nevertheless, in Great Britain, 37 species of fish occur in National Nature Reserves. The overall status of fish in Sites of Special Scientific Interest is unknown. 3. The main conservation options for managing freshwater fish resources are habitat restoration, stock transfer to new sites, captive breeding and cryopreservation. The first two of these are regarded as the most useful for the long-term conservation of threatened species. Improved legislation would also help, especially in relation to preventing the import and transfer of potentially harmful species. 4. As well as the implementation of conservation management programmes for rare fish, research and monitoring studies are also needed in order to aid management and maintain a watch on populations of important species. In addition, national fish databases and registers of important stocks are an important background for overall fish conservation and management.     

Application of sex reversal technology in ornamental fish culture

Many species of ornamental fish, includingboth egg-layers and livebearers, exhibit a marked sexualdimorphism due to the more pigmented bodies and larger finsusually observed in males. This results in male fish commandingup to four times the price of females. Because of this pricediscrepancy, the culture of monosex (all-male) stocks ofornamental fish could be of a significant economic advantage.This paper outlines the current sex reversal technology alreadydeveloped for several fish species important for aquaculture andexamines its potential applicability to ornamental fish culture.The methods to obtain all-male stocks include direct androgentreatment and the production of YY males. The direct approach iseasy to implement and straightforward. However, in somelivebearers such as the guppy, treatment of newly born fry iscomplicated because they already have sexually differentiatinggonads and the masculinization may be temporary. In this regard,the paper stresses the importance of correctly timing treatmentin relation to gonadal development to achieve permanentmasculinization     

Comparative susceptibility among three stocks of yellow perch,Perca flavescens (Mitchill), to viral haemorrhagic septicaemia virus strain IVb from the Great Lakes

The Great Lakes strain of viral haemorrhagic septicaemia virus IVb (VHSV‐IVb) is capable of infecting a wide number of naive species and has been associated with large fish kills in the Midwestern United States since its discovery in 2005. The yellow perch, Perca flavescens (Mitchill), a freshwater species commonly found throughout inland waters of the United States and prized for its high value in sport and commercial fisheries, is a species documented in several fish kills affiliated with VHS. In the present study, differences in survival after infection with VHSV IVb were observed among juvenile fish from three yellow perch broodstocks that were originally derived from distinct wild populations, suggesting innate differences in susceptibility due to genetic variance. While all three stocks were susceptible upon waterborne exposure to VHS virus infection, fish derived from the Midwest (Lake Winnebago, WI) showed significantly lower cumulative % survival compared with two perch stocks derived from the East Coast (Perquimans River, NC and Choptank River, MD) of the United States. However, despite differences in apparent susceptibility, clinical signs did not vary between stocks and included moderate‐to‐severe haemorrhages at the pelvic and pectoral fin bases and exophthalmia. After the 28‐day challenge was complete, VHS virus was analysed in subsets of whole fish that had either survived or succumbed to the infection using both plaque assay and quantitative PCR methodologies. A direct correlation was identified between the two methods, suggesting the potential for both methods to be used to detect virus in a research setting.     

Population genetic structure of lumpfish along the Norwegian coast: aquaculture implications

The potential for genetic contamination of stocks arising from translocation and subsequent release or escape of translocated and/or genetically mixed stocks may be a significant risk to wild populations. In this context, we undertook a population genetic survey of stocks of lumpfish (Cyclopterus lumpus) along the Norwegian coast to establish the existing genetic population structure, which will aid the development of policy of the species’ use as cleaner fish in salmonid aquaculture. This was done by using 14 microsatellite loci and 287 specimens collected at five fishing grounds, covering most of the Norwegian coastline from south to north, with additional 18 samples of first-generation reared fish from a fish farm outside Tromsø (North Norway). Overall, there was no indication of significant spatial genetic structuring or of positive correlation between geographic and genetic distance among the wild lumpfish samples. These results suggest that, should translocated individuals escape from aquaculture in Norway, this will probably have little to no impact on the genetic composition of the local fish population.     

Recruitment sources for fish stocks inside a floodplain river impoundment in Bangladesh

Abstract The sources of fish recruitment in the hydrologically modified, impounded Pabna Irrigation and Rural Development Project (PIRDP) flood control and irrigation scheme in NW Bangladesh were investigated. Catches at sluice gates were analysed to determine the migratory behaviour of fish. Fish attempted to migrate through the undershot sluice gates when they were opened, both with and against the currents, and both in and out of the PIRDP. Many fish were caught by the fishermen at such locations, but it is argued that some fish were probably able to enter the PIRDP from outside. One to two percentage of fish survived the dry season at the PIRDP, mostly in the deeper, perennial water bodies, both in rivers and lakes, and both inside and outside the flood control scheme. Fewer species survived inside the scheme, and the numbers of species remaining declined as the dry season progressed. It was shown in companion papers that fish production inside the PIRDP was lower than outside in both 1995 and 1996 even though the growth and reproductive potential of individual fish were at least as good inside as outside. The apparently negative impact of the PIRDP was explained by the reduced accessibility of the scheme to some migrant fish, as reflected by the inside/outside species compositions. It was concluded that fish catches within the PIRDP are sustained mainly from recruits produced by residing annual populations, while the biodiversity of the stocks was augmented by limited recruitment of fish migrating through the sluice gates from external sources. Two management approaches were proposed for increasing recruitment to the impounded PIRDP fishery as cheap alternatives to fish stocking: the use of dry season reserves to protect the residing spawning stocks; and the management of flood control sluice gates to maximise recruitment from external sources.     

A simple method for estimating MSY from catch and resilience

The Law of the Sea requires that fish stocks are maintained at levels that can produce the maximum sustainable yield (MSY). However, for most fish stocks, no estimates of MSY are currently available. Here, we present a new method for estimating MSY from catch data, resilience of the respective species, and simple assumptions about relative stock sizes at the first and final year of the catch data time series. We compare our results with 146 MSY estimates derived from full stock assessments and find excellent agreement. We present principles for fisheries management of data‐poor stocks, based only on information about catches and MSY.     

Consideration of fish introductions into the Sepik River, Papua New Guinea

Abstract. The fish fauna of the Sepik River system, Papua New Guinea is described. The fish species diversity in this large river is low, even by comparison to other overs in the south of the island. There are particular biological constraints to increasing the yield of the fishery based on native fish stocks. The yield of the Sepik River fishery is low by comparison to rivers in other zoogeographie regions. People in the Sepik also suffer from protein malnourishment. The introduction of appropriate fish species would significantly improve the stocks upon which the fishery is based. The economic cost of stocking is not an issue. Yield estimates suggest that the long-term benefits of improved stocks could be considerable. The indigenous freshwater fish fauna is unique and arguments against stocking relate to the conservation of that fauna and the existing fisheries. Alternatives to stocking are discussed. If stocking does not occur then a permanently disadvantaged fishery must be accepted. Decisions rest with the government and will be based on further research and consideration. Considerations must relate to the particular inland fisheries development problems in the country. The approach being taken is to appraise fish introductions properly before they occur. A cautious approach is recommended and suggestions about particular species that might be suitable for introduction are premature at present.