放流胭脂鱼鱼种增殖长江珍稀鱼类资源

胭脂鱼栖息于长江水域中的国家二级保护的珍稀鱼类,最大体重可达到30kg,它的幼鱼具有较好的观赏经济价值。近年来,由于栖息环境条件恶化,导致资源量呈下降趋势。为了补充和增殖长江水域胭脂鱼资源,确保胭脂鱼资源生存延续和资源量     

海南陵水湾口海域不同季节鱼类资源声学探查

在2014年11月至2016年1月间的不同季节,利用便携式分裂波束科学探鱼仪对海南陵水湾口海域的鱼类资源进行了4次声学调查。通过回波积分方法并结合拖网采样对调查海域内渔业资源结构组成、数量密度、资源量密度及其空间分布进行了探查与评估。结果发现,2014年11月共捕获游泳生物和底栖无脊椎动物86种,其中55种声学评估种类平均资源数量密度和平均资源量密度分别为9.34×105尾/km2和5.08 t/km2。2015年8月共捕获游泳生物和底栖无脊椎动物114种,其中63种声学评估种类平均资源数量密度和平均资源量密度分别为1.12×105尾/km2和0.93 t/km2。2016年1月共捕获游泳生物和底栖无脊椎动物105种,55种声学评估种类平均资源数量密度和平均资源量密度分别为0.16×105尾/km2和0.32 t/km2。2015年5月共捕获游泳生物和底栖无脊椎动物56种,其中声学评估种类34种。2014年11月和2015年8月鱼类回波均匀分布于30 m以浅水层,2015年5月主要集中于10~20 m水层,2016年1月则主要分布于20 m以浅水层,20~30 m水层次之且略大于0~10、10~20 m水层的一半。调查海域内单体目标强度以小于–58 d B的小规格鱼类目标为主,目标强度有随水深增加而增大的趋势,且大于–50 d B的单体目标均分布于10 m以深水层。     

2010年春季长江口鱼类群落空间分布特征

为探索长江河口生境条件改变对重要生物的影响状况,揭示生境条件对生物资源影响的机理,根据2010年5–6月在长江口进行的渔业资源与生态环境调查数据与历史资料,用根据扫海面积计算的栖息密度研究了鱼类群落结构的变动状况,以及5–6月鱼类群落结构及其与环境因子的关系。结果显示,2010年5–6月共记录鱼类40种。种类数目较多的科分别是鳀科和虾虎鱼科(均为5种),其次为石首鱼科(4种)及舌鳎科(3种);鱼类栖息密度以当年卵化幼鱼为主,矛尾虾虎鱼、棘头梅童鱼、凤鲚和刀鲚为栖息密度最大的4种鱼类,占调查区域鱼类栖息密度的94.11%。聚类分析和非度量多维测度分析发现,春季鱼类有明显的空间分布差异,除趋势典范对应分析的9个环境因子中,水深、表层盐度和底层盐度对河口内部鱼类丰度和栖息密度影响最大,而底层pH值、表层盐度和底层温度则对河口外部鱼类群落影响最大。与历史资料相比,目前记录的鱼类物种数目(40种)少于1985年5月或6月(69种,62种),而栖息密度(5.20×104ind/km2)高于1985年5月或6月(1.72×104 ind/km2,2.29×104 ind/km2)。本研究表明虽然长江口仍为棘头梅童鱼、刀鲚、...     

长江口渔场渔业生物资源动态分析

本文用 2 0 0 3年在长江口渔场 3个航次的调查数据 ,对该水域的渔业资源状况进行了分析。结果表明 :三个调查航次共捕获渔业生物 79种 ,其中鱼类 4 9种 ,隶属于 11目 ,30科 ,4 5属 ;虾蟹类共有 2 0种 ;头足类共有 10种 ,隶属于 3目 ,6科 ,6属。三个调查航次都是以鱼类的资源量指数最高 ,资源尾数密度表现为虾蟹类高于头足类 ,资源重量密度除 6月份虾蟹类低于头足类外 ,4月和 9月 2个航次都高于头足类。鱼类和虾蟹类的资源量指数值在 9月份达到最大 ,而 6月份为最低 ;头足类的资源量指数以 4月份最高 ,9月份最低。优势种组成的变化表现为 :4月份为黄鲫和小黄鱼 ,6月份为、黄和太平洋褶柔鱼 ,9月份为带鱼和小黄鱼。     

舟山渔场衢山岛海域春夏季鱼类数量变化

利用2008年3月和6月衢山岛海域渔业资源调查资料,研究衢山岛海域鱼类种类组成和多样性的变化,分析主要优势种密度对鱼类总密度的贡献率。结果表明,两个航次拖网调查,共鉴定鱼类30种,其中暖温种15种,暖水种13种。3月的鮸和刀鲚,6月的六丝矛尾虾虎鱼分别是本海域较重要的优势种。3月和6月鱼类重量密度分别为125.05 kg/km2和95.01 kg/km2,尾数密度为8.41×103ind/km2和37.74×103ind/km2。鱼类重量密度与尾数密度分布趋势一致,呈现调查水域南部高于北部的分布趋势。依据贡献β值,衢山岛海域鱼类数量的变化与主要优势种数量变化有关。鱼类的种类组成与水团有着密切关系。     

珠海桂山风电场水域渔业资源声学评估与空间分布

2019年10月24日至26日,使用便携式Simrad EY60科学探鱼仪对珠海桂山岛海上风电场水域的渔业资源进行了声学调查,研究了该水域的渔业资源组成、数量密度、资源量密度及其空间分布。本次调查共捕获游泳生物和底栖无脊椎动物72种,其中34种参与声学评估。扫海面积法估算的鱼类平均数量密度与资源量密度分别为1.09×10⁴尾/km²,227.48 kg/km²;声学方法估算的鱼类数量密度与资源量密度分别为5.97×10⁵尾/km²,15.13 t/km²。风电场水域鱼类聚集性分布明显,在风电场西北与东南外围水域密度较高,中间水域的密度较低。鱼类单体目标强度（TS）分布范围为-68~-41dB,其中-68~-58 dB的单体TS占主要部分（79.12%）,对应鱼类的体长范围为3~8 cm;随着水深的增加,单体平均TS先减小后增大。本研究是桂山风电场水域渔业资源的首次声学调查,结果较准确地反映了风电场水域多种鱼类的资源量及其分布信息,可为科学评价海上风电场建成运营后对渔业资源的长期影响提供基础数据。     

南海主要珊瑚礁(鱼旨)科鱼类的组成与分布

1998年3~5月和1999年5~6月,采用手钓、延绳钓和刺网3种作业方式在西沙的浪花礁、华光礁、琛航岛、永兴岛、北礁和南沙的渚碧礁、南薰礁、东门礁、美济礁、赤瓜礁、永署礁、华阳礁等12座珊瑚礁水域进行了2个航次的鱼类资源调查,捕获科鱼类6属25种,渔获量计942尾256.4kg;其中在南沙调查区捕获6属22种,共641尾205.5kg,优势种依次为尾纹九棘鲈、蜂巢石斑鱼、六角石斑鱼、黑边石斑鱼;在西沙调查区捕获6属14种,共301尾50.9kg,优势种依次为尾纹九棘鲈、六角石斑鱼、黑边石斑鱼、蜂巢石斑鱼,同时分析了主要种类尾纹九棘鲈、六角石斑鱼和蜂巢石斑鱼的生物学特征。     

厦门西部海域春季游泳动物资源的调查研究

根据2015年3月厦门西部海域游泳动物资源调查资料,对该海域的游泳动物组成特征进行了初步探讨。结果显示,共捕获游泳动物98种,其中鱼类51种、虾类16种、蟹类23种、口足类5种、头足类3种。优势种类有日本蟳(Charybdis japonica)、脊尾白虾(Exopalaemon carinicauda)、凤鲚(Coilia mystus)、叫姑鱼(Johnius belengerii)和哈氏仿对虾(Parapenaeopsis hardwickii)等5种。各站位游泳动物Margalef丰富度指数(D)平均值为5.358,Shannon-Wiener多样性指数(H')平均值为2.365,Pielou均匀度指数(J')平均值为0.732,平均资源量为307.068 kgkm2。鱼类、虾类、蟹类、口足类、头足类的资源量分别为192.7、28.8、72.7、7.9、5.0 kg/km2。与历史资料比较,游泳动物的种类和资源量均明显下降,亟需加强渔业资源的管理与保护。     

珠江水域(广西段)三年禁渔期效果评估

珠江水域自2011年起开始实行禁渔期制度,每年4月1日至6月1日禁渔。为了解禁渔期对鱼类资源的修复效果,自2011年禁渔期开始起,在广西重要禁渔江河设置调查采样断面,收集渔民每年3月份和6月份每天的渔获物数据,对渔获物的结构、捕获量及多样性等数据变化进行分析评估。渔民的捕捞方式以网捕为主,辅以钓捕和笼捕。3年共调查14个断面,59户渔民,总计110个月 2 798 d,捕获的鱼类4目10科29属34种,共18 867.85 kg,其中鲤形目鱼类占总种数的55.88 %。实行禁渔期后,江河渔业资源呈现增加趋势,66.67 %的断面后一年度的日均鱼类捕获数量比前一年度高,53.85 %的断面后一年度的日均鱼类捕获质量比前一年度高。但3个调查年度捕获的鱼类种类数变化不大,不到广西鱼类种类数量的1/10,Shannon-Weiner多样性指数低至1.560。调查结果表明,禁渔期制度已初见成效,但效果有限,每年2个月的禁渔期无法改变江河鱼类资源枯竭问题,应通过延长禁渔时间、限制捕捞、人工增殖等手段多层面开展水域生态环境修复工作,才能达到有效修复渔业资源及渔业生态环境的目的。     

渤海鱼类群落结构的年际变化

基于2010年和2012–2014年每年8月渤海渔业资源底拖网调查数据,根据优势种、单位个体重、相对资源量、Jaccard种类组成相似性系数和群落结构数量生物量曲线等指标,研究渤海鱼类群落结构的年际变化,结果显示:(1)2010年和2012–2013年,总鱼类和底层鱼类种类数一直呈下降趋势,2014年有所恢复;2010年和2012–2014年暖温种种类数基本上呈下降趋势;(2)底层鱼类优势种由小个体的虾虎鱼(Gobiini sp.)代替大个体的小黄鱼(Pseudosciaena polyactis),中上层鱼类优势种则由植食性为主的黄鲫(Setipinna taty)和斑(Konosirus punctatus)转向浮游动物食性的鳀(Engraulis japonicus);(3)2010年和2012–2014年渤海底层鱼类和总鱼类年间站位相对资源量两两间都不存在显著性差异(P0.05),2013年与2014年间总鱼类及2014年与2010年底层鱼类年间站位相对资源量方差无显著性差异(P0.05),其他年份两两间都为方差不齐(P0.05),底层鱼类和总鱼类站位相对资源量年际存在极端异常值;(4)2010年和2012–2014年单位数量鱼体的个体重逐年下降,渤海鱼类这几年严重趋向小型化;(5)5种组内相似、组间相异贡献率高的鱼类种类,其年度相对资源量和分布变化较大;根据生物量与数量优势度曲线及W统计值判断,2010年渤海鱼类群落结构比较稳定,2012年相对稳定,2013年和2014年处于干扰状态,特别是2013年的鱼类群落结构处于比较严重的干扰状态。综上所述,渤海鱼类群落结构在2010年和2012–2014年发生了较大改变,处于受干扰不稳定状态。     

东海刺鲳资源状况及数量分布

本文利用2001~2005年东海区底层拖网调查资料,分析了东海刺鲳的资源状况和数量分布。结果表明,东海刺鲳近年来资源数量稳定而且缓慢增长,2001~2005年平均资源密度为1.49kg/h,从数量分布来看,8、9月是刺鲳分布范围最广、资源密度最高的月份,主要分布海域为鱼山、江外和长江口渔场。分析4个季节刺鲳的分布水深变化情况表明,主要分布水深为50~90m,刺鲳分布具有季节移动现象,夏季最靠近近海。刺鲳的群体结构不稳定,以幼鱼和1龄鱼为主。     

Evaluating potential competitive bottlenecks between invasive common carp and native bluegill and yellow perch

Processes influencing fish recruitment are often highly complex and inherently difficult to understand. Invasive species may complicate recruitment through habitat and food web modifications resulting in competitive bottlenecks. Common carp Cyprinus carpio have been distributed worldwide, and their introductions have resulted in destructive effects on aquatic ecosystems and food web dynamics. Common carp are highly fecund, and high densities of age‐0 carp may occur in some years that may reduce invertebrate prey resources and adversely affect native age‐0 fishes. We used enclosures and field observations to examine potential effects of age‐0 common carp on growth and survival of age‐0 yellow perch Perca flavescens and bluegill Lepomis macrochirus. Yellow perch and bluegill were stocked into enclosures with and without common carp (31 fish/m³) using a substitution experimental design, and fish growth and survival and invertebrate prey resources were assessed. Common carp reduced growth of yellow perch but not bluegill and did not affect survival of either species in mesocosms. Next, we used patterns of common carp, bluegill, and yellow perch abundance and total length across 38 lake‐years to evaluate potential interspecific interactions in natural systems. Age‐0 common carp abundance was not negatively related to size or abundance of bluegill or yellow perch. However, adult common carp and age‐0 yellow perch abundance were inversely related, suggesting a potential competitive bottleneck. Thus, age‐0 common carp may suppress growth of yellow perch when prey is limited, but adult common carp may have larger effects than early life stages on native juvenile fishes.     

Competition for food between Eurasian perch (Perca fluviatilis L.) and ruffe (Gymnocephalus cernuus [L.]) over different substrate types

Abstract –  Food consumption by Eurasian perch ( Perca fluviatilis L.) and ruffe ( Gymnocephalus cernuus [L.]) was studied in single and mixed-species treatments in the laboratory, where alternative food resources, chironomids and zooplankton, were offered simultaneously. The effects of structural complexity, which was represented by substrate grain size, and of feeding level on food consumption were analysed. Across all experiments, the outcome of competition between perch and ruffe depended on food abundance and on the structural complexity of the environment. Perch and ruffe both changed their food consumption in the presence of a heterospecific competitor. With high food supply, perch consumed more benthic food than ruffe. With low food supply, the consumption of perch decreased strongly, while that of ruffe remained high on fine sediment. Under all conditions tested, the mechanism of competition appeared to be of interference rather than of exploitative nature. It is suggested that with decreasing lake productivity caused by re-oligotrophication, habitat shifts of both species will occur, which will alleviate interspecific competition. Ruffe will forage over fine sediment and perch over coarse sediment, whereby both species will achieve the highest foraging efficiency under conditions of low food supply.     

Abiotic and biotic correlates of yellow perch recruitment to age‐2 in southern Lake Michigan, 1984–2007

Abstract Seven abiotic and biotic variables were tested to determine whether they influence the recruitment to age two of yellow perch, Perca flavescens (Mitchill), in waters of southern Lake Michigan, USA. Recruitment was analysed using a Ricker stock‐recruitment relationship that accounts for density dependency. Significant model variables tested individually and ranked by total variance explained included the abundance of sexually mature yellow perch, alewife, Alosa pseudoharengus (Wilson) and spottail shiner, Notropis hudsonius (Clinton). Variables found unrelated to recruitment or generally less explanatory included the abundance of round goby, Neogobius melanostomus (Pallus), mean water temperature, variation in water temperature and water clarity. The best‐fitting multivariable model explained 69% of the recruitment variability and included abundances of sexually mature yellow perch, alewife and spottail shiner. These results suggest that yellow perch recruitment in southern Lake Michigan is regulated in part by biotic interactions with other species of the near‐shore community, including alewife and spottail shiners, in addition to the abundance of reproductively mature yellow perch.     

Habitat use by age-0 yellow perch in two South Dakota glacial lakes

Abstract– We determined the habitat use of age-0 yellow perch ( Perca flavescens ) in two South Dakota (USA) lakes. Larval perch abundance was based on trawl catches and related to environmental variables on two late spring dates. Juvenile perch abundance was based on late July shoreline seine and bottom trawl catches. Day and night juvenile abundance relations to environmental variables were examined. Larval abundance appeared to be related to biological environmental variables, and no significant (P≥0.05) correlations with physical habitat variables were found. Juvenile yellow perch abundance was related to physical variables, particularly substrate, water temperature and water depth. The only biological variable that could be related to juvenile abundance was chironomid abundance. Finally, juvenile perch abundance was positively associated with abundance of other juvenile fishes and minnows, but these associations varied by lake, time of day and habitat type. Understanding age 0 perch habitat use will allow fishery biologists to better assess sampling designs and recruitment processes.     

The population biology of perch, Perca fluviatilis L., in simple fish communities with no top piscivore

Abstract– The population dynamics of perch, Perca fluviatilis L., in the absence of a top piscivore, pike Esox lucius L., were examined in simple fish communities in shallow lakes (mean depth < 1.5 m) in northeast Scotland. Perch in Sand and Lower Lochs were unexploited, whereas perch in Loirston were exploited. Population characteristics were fast growth rates, short life span (< 6 years) and no dominant year classes in Sand and Lower Lochs. The strong 1974 year class in Loirston may have been due to intensive exploitation of older age groups. Abundance of perch, expressed as biomass, was low for European waters, namely 30 kg. ha⁻¹ in Loirston (comprising mainly 1 - to 2-year-old-fish), and biomass of adults (≥ 2 years) was 8.9 kg and 4.7 kg. ha⁻¹ in Sand and Lower Lochs respectively. Recruitment in Sand and Lower Lochs appeared to be governed by water temperature, but the overall low abundance and population stability of perch in the 3 lochs was attributed to cannibalism.     

Night sampling improves indices used for management of yellow perch in Lake Erie

Abstract  Catch rate (catch per hour) was examined for age-0 and age-1 yellow perch, Perca flavescens (Mitchill), captured in bottom trawls from 1991 to 2005 in western Lake Erie: (1) to examine variation of catch rate among years, seasons, diel periods and their interactions; and (2) to determine whether sampling during particular diel periods improved the management value of CPH data used in models to project abundance of age-2 yellow perch. Catch rate varied with year, season and the diel period during which sampling was conducted as well as by the interaction between year and season. Indices of abundance of age-0 and age-1 yellow perch estimated from night samples typically produced better fitting models and lower estimates of age-2 abundance than those using morning or afternoon samples, whereas indices using afternoon samples typically produced less precise and higher estimates of abundance. The diel period during which sampling is conducted will not affect observed population trends but may affect estimates of abundance of age-0 and age-1 yellow perch, which in turn affect recommended allowable harvest. A field experiment throughout western Lake Erie is recommended to examine potential benefits of night sampling to management of yellow perch.     

The shift to smaller zooplankton in Lake Victoria cannot be attributed to the ‘sardine’ Rastrineobola argentea (Cyprinidae)

After the population increase of introduced Nile perch (Lates niloticus) in Lake Victoria, a decrease in the relative abundance of herbivorous cladocerans and calanoids was reported for the pelagic zone. The shift from large herbivores to small-bodied predatory cyclopoids has been attributed to the increase of the zooplanktivorous cyprinid dagaa (Rastrineobola argentea), which rose concomitantly with the Nile perch. However, we observed that in the Mwanza Gulf of the lake cyclopoids dominated the zooplankton community already before the rise of dagaa. Furthermore, there are indications that dagaa takes fewer calanoids than expected from their representation in the environment, although a slight preference for cladocerans may exist. Calanoids dominated the diet of small Nile perch of about 4 cm length, but juvenile Nile perch did not occur in the study area until after the size shift in zooplankton. The lumped biomass of dagaa and small Nile perch is lower than the biomass of the original haplochromine-dominated community of zooplanktivorous fish. Thus, the decline of large zooplankters in the lake cannot be explained by intensified predation after the replacement of zooplanktivorous haplochromines by dagaa and Nile perch. Increased eutrophication, resulting in a shift in predominance from diatoms to cyanophytes, is suggested as an alternative explanation for the shift in zooplankton composition.     

The movement pattern and density distribution of perch, Perca fluviatilis L., in a channelized lowland river

Abstract. The movement pattern and the abundance of perch, Perca fluviatilis L., were studied in the Kleine Nete, a eutrophic, canalized lowland river in north Belgium. Since the behaviour of perch is strongly affected by habitat type, two kinds of river section were chosen, based on physical characteristics: homogeneous sections with regard to depth, bottom type and current speed; and heterogeneous sections with a riffle and pool pattern. The fish were caught by electrofishing and all perch larger than 10 cm were marked individually. The population densities were much higher in the heterogeneous parts. In these sections about 30% of marked perch stayed within a home range, while in the homogeneous sections all were mobile. The older individuals showed a stronger tendency to accept a home range than the 1- or 2-year-old perch. This difference may be explained by different behaviour: young perch live in small schools, while older perch are often solitary. The low densities and the high mobility of perch in the homogeneous river sections indicate that these parts of the river are not a suitable habitat for perch. Habitat improvement of the homogeneous sections wilt probably result in higher overall population densities.     

Domestication of Silver Perch,Bidyanus bidyanus,Broodfish

Abstract

Most breeding programs for the Australian native freshwater silver perch, Bidyanus bidyanus, are based on fish originally captured from natural populations. However, over the last 20 years, there has been a dramatic decline in the distribution and abundance of silver perch in the wild and the species now has the conservation status of “vulnerable.” Unless broodfish can be domesticated a serious shortage is imminent. The aims of this study were to determine the age and size at sexual maturity and the reproductive performance of silver perch reared in captivity. Fingerlings (mean weight, 4.0 g) from a hatchery were stocked into an aerated 0.32-ha earthen pond at a density of 22,000 fish/ ha for 12 months, harvested, and restocked at 10,000 fish/ha for a further 2 years. The fish were fed a formulated diet containing 35% crude protein. No fish were mature at 1 year of age; at 2 years, most males (93%; total length, 304.0 mm, weight 412.7 g), but no females were mature; and at 3 years, most females (97%; 316.4 mm, 549.6 g) were mature. Three-year-old fish injected with 200 IU/kg human chorionic gonado-trophin spawned viable gametes. High fecundity (mean 139,286 eggs/ kg), fertilization rates (84.5%) and hatch rates (76.8%) demonstrate that broodfish can be domesticated and the life cycle of silver perch can be closed. The use of domesticated broodfish will eliminate reliance on wild populations and provide a basis for future hatchery production and selective breeding programs.