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1.
南海中南部中层鱼资源声学积分值及时空分布初探   总被引:6,自引:4,他引:2       下载免费PDF全文
本研究利用Simrad EK60科学探鱼仪(38 k Hz)于2013年春季和2014年春季采集的南沙和中沙、西沙海域渔业声学数据,结合中层拖网取样,采用回声积分法研究了南海中南部中层鱼的资源量及其时空分布特征。结果显示,2014年春季中、西沙海域9次中层拖网作业共捕获和鉴定鱼类和头足类79种,隶属于3纲16目37科60属,其中硬骨鱼纲的种类最多(65种),鞘亚纲次之(13种),软骨鱼纲1种,硬骨鱼纲中巨口鱼科、灯笼鱼科和钻光鱼科的种类最多,分别有20种、13种和6种;南沙海域中层鱼声学积分值(nautical area scattering coefficient,m~2/nmi~2)显著低于中沙、西沙及邻近海域,前者夜间向上迁移的强度高于后者;2013年春季南沙海域夜间10~200 m和白天200~1000 m声学积分值构成没有显著差异(P0.05),而2014年春季中沙、西沙海域夜间10~200 m和白天200~1000 m声学积分值构成有极显著差异(P0.01);南沙海域白天200~1000 m不同纬度组间中层鱼声学积分值构成有极显著差异(P0.01),中沙、西沙海域声学积分值构成亦有极显著差异(P0.01);南海中南部中层鱼声学积分值是(2387±601)m~2/nmi~2,基于现存公开发表的中层鱼的声学目标强度数据并取其均值,推算南海中南部中层鱼资源量是(8200±2100)万t。研究表明,南海中南部中层鱼声学积分值比全球平均值高约29.2%,可能是我国未来具有开发价值的大宗生物资源。  相似文献   

2.
Abstract –  We present the first data on three-spined stickleback ( Gasterosteus aculeatus ) life history and habitat use in seasonal Mediterranean streams, analysing populations from NE Iberian Peninsula. Stickleback populations were strictly annual, with reproduction events involving exclusively 1+ fish. Somatic growth was concentrated in two periods, one in spring and early summer, and another in autumn and winter. During summer there was a clear stop in the somatic growth, coupled with low values of somatic condition. This growth pattern contrasts both with that of other Mediterranean stream fish species and that of stickleback in other European locations. Stickleback populations occupied mainly intermediate locations along fluvial gradients. The presence of abundant aquatic vegetation was identified as one of the main factors related with both stickleback presence and the abundance of its populations, while the latter was also negatively related with that of invasive fish and crayfish species. Stickleback tended to occur in native-dominated fish communities, being almost absent from lower stream reaches, which bear high abundances of invasive fish species.  相似文献   

3.
Hydropower structures hinder the movement and migration of fishes, impairing their life cycles. Additionally, downstream moving fish are often at risk of being injured during turbine passage. To improve hydropower production towards more fish-friendly techniques and management, knowledge on timing and extent of natural patterns of fish downstream movement is necessary. So far, migration behaviour of long-distance migrators such as eel or salmon has been well studied, but little is known about seasonal and diurnal movement patterns of nonmigratory species or medium-distance migrators. In this study, movement patterns of 39 fish species captured by stownets while transiting hydropower facilities in four impounded rivers were assessed and compared with the fish community composition directly upstream of the hydropower plants assessed by electrofishing. Strong differences between the fish community composition inhabiting the upstream sides of the dams and the fish detected in downstream passage were evident. In each study river, the downstream moving fish community composition differed significantly between spring and autumn. On average, significantly more fish were caught during the night (2.9 fish/hr) than during the day (1.3 fish/hr). Topmouth gudgeon, European grayling and pike-perch mostly moved downstream during the night, whereas roach, spirlin and bleak were the most frequent downstream moving fish during daytime. Downstream fish movement was positively related with turbidity, water temperature and discharge. The strong differences in seasonal and diurnal fish movement patterns suggest that fish damage can be strongly reduced by adaptive turbine and corridor management, for example by shutting down turbines at peak movements.  相似文献   

4.
Abstract– In late summer and fall, radio-tagged adult Sacramento pikeminnow ( Ptychocheilus grandis ) at three sites in the Eel River of northwestern California moved more at night than during the day. Fish moved up to 535 m at night and returned to their original positions the following morning. Adult Sacramento pikeminnow at all sites occupied only pools during the day, but at one site moved through high gradient riffles and occupied fast water habitats at night. Adult Sacramento pikeminnow at the upstream limit of their range in one Eel River tributary moved downstream up to 23 km during the winter and tended to return to their original position the following spring, where they remained through the summer. Fish radio tagged at downstream sites exhibited more variable behavior, moving 2-92 km over >393 days. Our observations suggest that the most appropriate scale of consideration for attempts to manage this species or estimate population size includes entire river drainages.  相似文献   

5.
Abstract –  Matsalu Bay in the Väinameri (West-Estonian Archipelago Sea) is a relatively shallow but large bay. It is the only real delta estuary in the northern Baltic Sea. The fish fauna is strongly dominated by freshwater species such as perch Perca fluviatilis , roach Rutilus rutilus , white bream Blicca bjoerkna and rudd Scardinius erythrophthalmus . The study presents CPUE data describing annual and seasonal variations in the species composition, abundance and spatial distribution, based on 1 year of monthly samplings from August 2001 to August 2002 and routine coastal monitoring (in late July–early August) between 1994 and 2003. The bay can be divided into three rather distinct parts. The fish fauna of the inner part (salinity 0–2 p.p.t.) is different from two open parts and resembles that of freshwater lakes. In the openmost part (salinity usually 4–6 p.p.t.) some marine species, such as herring Clupea harengus membras , flounder Platichthys flesus and eelpout Zoarces viviparus may seasonally be abundant. Species composition and abundance of most species varies seasonally and interannually. Only the abundance of few species such as pike Esox lucius and pikeperch Stizostedion lucioperca was not impacted by seasonality. The most dynamic period in the bay is spring, when several species (some of them very rare in summer, such as herring and smelt Osmerus eperlanus ) enter the bay for spawning.  相似文献   

6.
Abstract –  Upstream fish passage was evaluated during 12 months in the vertical-slot Igarapava Fish Ladder constructed around Igarapava Dam, in the heavily dammed Grande River, Southeast Brazil. A video monitoring system was used to observe 61,621 fish that passed the ladder, of which 93.5% were identified to 15 taxa. Among the migratory species, the most abundant were Pimelodus maculatus (33.6% of all fish), Leporinus octofasciatus (31.4%), Leporinus friderici (4.5%), and Prochilodus lineatus (3.1%). Seven taxa were classified as nonmigratory, and of these taxa, the small Bryconamericus stramineus was the most abundant (12.7%) of all fishes. Passage of the 'nonmigratory' taxa upstream in the ladder shows they are migratory in this system and have a strong behavioural drive to move to upstream habitat. Passage of most taxa had a strong seasonal pattern. While some species passed primarily during the day, others showed a distinct nocturnal pattern. Lunar phase and water temperature also strongly affected passage of some taxa. Rainfall and dam discharge had a small or null influence on most taxa; perhaps due to the fairly small catchment area of the reservoir and the highly regulated discharge at Igarapava Dam.  相似文献   

7.
南海柘林湾鱼类群落结构季节变动的研究   总被引:3,自引:0,他引:3  
为阐明南海柘林湾鱼类群落结构的动态变化,基于2011年4月(春季)、8月(夏季)、11月(秋季)和2012年2月(冬季)对南海柘林湾拖网调查的数据,对柘林湾鱼类群落结构季节动态、鱼类营养级指数季节变化进行了初步分析。结果显示,各季节调查共捕获鱼类99种,底层鱼类占49.49%,暖水性鱼类占78.78%,肉食性鱼类占79.79%。各季节质量百分比和数量百分比优势种以拟矛尾■虎鱼(Parachaeturichthys polynema)、龙头鱼(Harpodon nehereus)、皮氏叫姑鱼(Johnius belengeri)等为主。柘林湾鱼类资源密度和资源尾数密度最高季节为夏季,各季节鱼类个体体质量大多小于15 g。春、秋季鱼类组成相对丰富,冬季生物量优势度最高。柘林湾鱼类以中级肉食性和高级肉食性为主,年度平均营养级指数为3.478,属于中级水平,夏季高营养级鱼类平均体质量最高。  相似文献   

8.
Abstract –  Blue suckers, Cycleptus elongatus , are a highly mobile species speculated to have spring spawning migrations. However, previous studies have not quantified seasonal migrations of blue suckers. Use distributions were calculated at 90% and 50% for three seasons to identify geographic space-use requirements of blue suckers. Mean 90% use distributions (±SE) varied from 8.1 km (±5.3 km) in summer to 78.6 km (±9.9 km) in fall to 174.9 km (±13.1 km) in spring. The great space-use requirements of blue suckers in fall and spring indicate that the species makes substantial upstream migrations in fall and also preceding spawning in spring, then return to a core area postspawning. The broad geographical range occupied by blue suckers throughout their life-history cycle emphasises the need for interjurisdictional management of the species and highlights potential detrimental effects of blocking fish passage.  相似文献   

9.
为了解当前东海生态系统中鱼卵、仔稚鱼种类组成和数量分布的现状及其变化与物理环境因素的关系,根据2006年11月—2008年6月5个航次的鱼卵、仔稚鱼和物理环境调查资料,对鱼卵、仔稚鱼种类组成、数量分布与产卵场物理环境进行分析,探讨不同季节、不同年份鱼卵、仔稚鱼种类组成和数量分布的变化及其与物理环境的关系。结果显示,5个航次采集到74 813粒鱼卵、16 826尾仔稚鱼,共有135个种类。其中,鉴定到种的有109种,隶属于15目67科99属,还有17个种类仅能鉴定到属、6个种类仅能鉴定到科和3个种类仅能鉴定到目。2006年—2007年秋季、冬季和春季鱼卵、仔稚鱼的种类和数量随着季节变化逐渐增多;2008年春季的种类和数量较2007年春季明显偏少;2008年初夏种类的数量与2008年春季基本相近,但鱼卵的数量明显增多,仔稚鱼的数量基本相近。42种优势种类、重要种类和主要种类构成当前东海生态系统中鱼卵、仔稚鱼种类组成的主要成分。东海表层水温和盐度分布有显著的季节变化。秋、冬季表层水温锋面强度最强,春季次之,初夏最弱;锋面的位置秋季离岸最近,冬季次之,春季和初夏离岸最远,冬季偏南,初夏季节北移。表层盐度锋面主要分布在近岸区域,与岸线大致平行,其强度冬季最强,春、秋季次之,初夏季节最弱。秋、冬季节陆架深水海域的水温较沿岸海域高,鱼类生殖群体在陆架深水高温区产卵;春季和初夏季节沿岸海域明显升温,鱼类生殖群体由深水区向近岸海域进行生殖洄游,产卵场分布由陆架中部向近岸海域扩展,并在近岸海域形成了中心产卵场。鱼卵和仔稚鱼的分布与温、盐锋面和种类的温、盐属性的关系密切,主要分布在温度锋面暖水一侧,并有各自最适宜的温度和盐度范围。水温、盐度与种类的繁殖生物学特性是导致鱼卵和仔稚鱼种类组成与数量发生变化的主要因素;适宜的温度和盐度范围、锋区的辐聚和卷夹作用以及种类的生物学属性是影响鱼卵和仔稚鱼数量分布以及密集分布区形成的主要因素。  相似文献   

10.
Seasonal and spatial variation in a prairie stream-fish assemblage   总被引:5,自引:1,他引:5  
Abstract – Stream-fish assemblage and environmental data for 13 sites in the upper Brazos River, Texas, USA during 1997 and 1998 were used to assess the relationship between environmental conditions, and seasonal and spatial variation in fish species abundance and distribution patterns. There was considerable spatial variation in environmental conditions among sites. Spatial variation in species diversity and species composition was related to variation in conductance (salinity), depth and current velocity among sites and streams. Species diversity increased downstream and species composition shifted from primarily cyprinodontids upstream to cyprinids downstream. Among all dominant species, spatial components of variation in fish abundance were greater than seasonal components, suggesting that assemblage structure is determined more by average or persistent differences in environmental conditions among sites than by seasonal variation in environmental conditions.  相似文献   

11.
ABSTRACT:   From 2002 to 2006, the fish fauna associated with sea weeds drifting in the Chikuzen Sea, northern Kyushu, Japan, was examined. The total numbers of species and individuals collected were 51 and 5475, respectively. The five dominant species, accounting for approximately 80% of the total individuals, were Rudarius ercodes , Stephanolepis cirrhifer , Petroscirtes breviceps , Sebastes thompsoni and Paramonacanthus japonicus . The number of species and individuals increased significantly with the increase in water temperature, reaching maxima during early summer and autumn, respectively. Combining the present and previous data (∼50 years ago), the appearance patterns of the fishes associated with drifting sea weed were classified into the following four types: (i) long periods (continuously for 3 months or more) and autumn (LA); (ii) spring (SP); (iii) summer (SU); and (iv) rare (R). In more than half of the species, there were no changes in the appearance patterns between the present and previous studies. However, in the present study, the appearance patterns of several species changed from LA to R ( Oplegnathus punctatus and Kyphosus cinerascens ) and from R to LA and SU ( Abudefduf vaigiensis and Hyperoglyphe japonica , respectively).  相似文献   

12.
采用大连湾海域四季底拖网调查数据(2006年夏、冬季和2007年春、秋季),对其鱼类群落结构进行研究,并利用多样性指数法和丰度/生物量比较法(ABC曲线)评价鱼类群落受外界扰动的程度。研究结果表明,该海域四季共采集鱼类31种,隶属于10目24科31属,鱼类区系组成在适温性上以暖温性鱼类为主,在栖息水层上以底层鱼类为主。夏季鱼类生物量(43.16kg/h)和生物数量(950个/h)均明显高于其他3个季节。四季共有优势种为大泷六线鱼和许氏平鲉。鱼类群落多样性指数季节变化范围分别为物种丰富度指数0.76~2.16、多样性指数0.63~1.96、物种均匀度指数0.36~0.91。各季节间生物量和丰度组成的Bray-Curtis相似性均较高。多样性指数法和丰度/生物量曲线法对鱼类群落受外界扰动评价结果一致,均表明鱼类群落受到中度扰动,且秋冬季高于春夏季。本研究可为大连湾海湾生态系统健康评价和生态修复提供科学依据。  相似文献   

13.
为进一步探明长江口沿岸碎波带仔稚鱼种类组成和数量分布的季节性变化特征,2006年11月至2007年10月,在长江口沿岸碎波带的13个站位用小型拖网(1 m×4 m,网目1 mm)共采集到仔稚鱼77种,隶属于13目27科63属。各季节出现仔稚鱼种数分别为37、20、13和7种。仔稚鱼是以暖温性种类占绝对优势,按生态类型划分,河口性和淡水性种类为主,其次为海洋性种类,洄游性种类最少。根据优势度曲线可看出,夏季优势种最突出,秋季优势种最不明显。夏季与秋季的共有种最多,均为27种;冬季与春季,冬季与秋季间的共有种最少,均为11种。从数量分布来看,冬季仔稚鱼数量最少,且分布较分散,春季数量有明显增加,夏季数量达最大值,且分布趋于集中。在低盐和淡水的站位St.4、St.5、St.7和St.10,形成了以刀鲚为主要种类的仔稚鱼密集区,平均密度高达2 729尾/站。  相似文献   

14.
We examined seasonal, annual variation and horizontal distribution of zooplankton in the Sea of Japan from 1966 to 1990. Zooplankton was most abundant in the spring. The spring maximum appeared in February–March and in April–May in the southern and eastern parts of the study areas, respectively. In the summer and autumn, a secondary peak was most conspicuous in the eastern part. The difference between the estimated biomass at night and day was large in the spring and small in summer and autumn. The biomass in the offshore southern area peaked about every 3 years between 1966 and 1983, and increased abruptly in 1990. The density in the area north of 39°N or 40°N was high. Total biomass estimated in the upper 150 m layer in the Sea of Japan (106 km2) was 9.5 × 106 t in the daytime and 16.6 × 106 t at night.  相似文献   

15.
Diel variation in the ichthyofaunas associated with Zostera capricorni Ascherson was investigated in three intermittently open estuaries in the Illawarra region, New South Wales. Each estuary showed differing diel shifts in fish assemblages, which appeared to be related to estuary size. In the largest estuary (Lake Illawarra) significantly more species were caught during the night than the day for all months. In contrast, there was little diel variation in the fish assemblages at Werri Lagoon and Shellharbour Lagoon, although many species were only caught during the night at both estuaries. The distinct diel changes at Lake Illawarra was thought to be attributable to the relatively deep channels adjacent to the seagrass beds which are better habitats for larger fishes compared with the shallow sand bars without deep channels throughout the two smaller estuaries. The composition of fish species within the three estuaries were significantly different, although each assemblage was characterised by large numbers of small-sized fish (<100 mm FL) indicating the importance of intermittently open estuaries as fish habitats. It was concluded that night sampling provided a more complete picture of the ichthyofaunas associated with Z. capricorni . As a result, inclusion of night sampling in fish diversity assessments would increase the chance of catching diurnally rare species and therefore attain a better representation of the true community structure.  相似文献   

16.
A multigear sampling method to quantify fish richness and abundance in Amazonian Terra firme streams was assessed. This method is based on the four‐pass removal method using the combined application of different nets. The efficiency of the method was explored over 10 replicated sites along three streams over day, night and seasons. Use of four successive passes allowed both abundant and rare species to be collected and the abundance of common species to be estimated. On average, a high proportion (41%) of rare species was collected per sample (only one or two individuals) after four fishing passes. The efficiency of the sampling method to detect species richness per sample between successive passes was estimated using an autosimilarity approach. Although species richness and abundance increased with successive passes, no major differences were obtained between the third and fourth pass. A single pass considerably underestimated the richness and abundance of species in these type of streams, and night sampling also increased beta‐diversity by at least 20%. Abundance estimates demonstrated high efficiency with an overall sampling error of only 8 and 11% for samples and single species, respectively. Capture efficiency differed among fish species exhibiting different ecological traits and showed significant differences among seasons for total samples. Results supported the robustness of the method and its suitability to quantify fish richness and abundance in small, wadeable Amazonian Terra firme streams inhabited by highly diverse fish assemblages.  相似文献   

17.
根据2012年1月(冬季)、4月(春季)、8月(夏季)、11月(秋季)在北部湾西北部广西近海4个航次的渔业资源调查资料,进一步结合同步测定的水文情况,探讨北部湾西北部广西近海的鱼类资源分布特征和季节变化及其影响因素。调查结果表明,该调查海域共鉴定鱼类125种,鱼类资源质量密度夏季(402.46kg/km^2)>春季(343.22kg/km^2)>秋季(145.13kg/km^2)>冬季(53.99kg/km^2);尾数密度春季(84.34×10~3尾/km^2)>夏季(51.54×10~3尾/km^2)>秋季(26.53×10~3尾/km^2)>冬季(16.81×10~3尾/km^2);平均体长、体质量分别在春季和夏季最大,分别为7.15cm和7.65g;幼体比在夏季最高,为85.86%。从时间上看,春、夏季的鱼类资源密度大于秋、冬季,从空间上看,沿岸水域的资源密度大于近海水域,这与该水域各水团随季节变化的消长密切相关。依据相对重要性指数确定各季节的优势种,二长棘鲷是夏季最重要的优势种,同时也是春、夏、秋3季的共有优势种。通过贡献率β值可知,该区域鱼类总密度变化与主要优势种变化关系密切,且调查海域多为规格较小的幼鱼,其为北部湾渔场重要的产卵场、育幼场和索饵场,对整个北部湾鱼类资源的补充具有重要的作用。  相似文献   

18.
为了解流溪河光倒刺鲃国家级水产种质资源保护区鱼类群落结构,分析不同河段、不同季节鱼类群落多样性的变化,于2017年12月-2018年10月对保护区上、中、下游的鱼类开展了每个季度一次的调查。调查结果显示,共采集鱼类57种,隶属于5目14科50属,其中鲤形目43种、鲈形目6种、鲇形目5种,合鳃鱼目2种,鳉形目1种;计算57种鱼类的相对重要性指数,结果显示,尼罗罗非鱼、越南■及鲤鱼为2017-2018年度优势种;Shannon-Wiener多样性指数、Margalef丰富度指数和Pielou均匀度指数计算结果显示,下游鱼类群落的多样性及均匀度最高,夏季鱼类群落的多样性、丰富度及均匀度最高;各监测点之间的种类相似性系数显示,保护区上中游、上下游之间鱼类种类组成为中等不相似,中下游种类组成为中等相似,春夏、春冬、夏冬及夏秋季节鱼类种类组成为中等不相似,春秋、秋冬季节为中等相似;ABC分析结果显示,春、夏及冬季鱼类群落处于稳定状态,秋季处于中度干扰状态。  相似文献   

19.
秦山核电温排水对鱼类分布的影响   总被引:1,自引:0,他引:1       下载免费PDF全文
根据2010年5月(春季)、2010年9月(夏季)和2009年12月(冬季)秦山核电海域渔业资源调查资料以及秦山核电站温排水扩散数学模拟结果,通过秦山核电温排水海域鱼类季节密度的时空分布、优势种、优势种对鱼类总数量的贡献,探讨并分析了秦山核电海域温排水对鱼类分布的影响。结果显示,春季、夏季和冬季的尾数密度分别为5.55×10~3 ind/km~2、22.10×10~3 ind/km~2和10.52×10~3 ind/km~2,重量密度分别为33.80 kg/km~2、59.06 kg/km~2和66.46 kg/km~2。秦山核电海域渔业资源数量季节变化的规律与其他海域相反,冬季最高,春夏季较低,主要与冬季温排水海域具有暖池效应,形成部分鱼类滞留在此越冬有关。温排水平面分布对鱼类分布有重要的影响。主要表现在夏季温排水区域鱼类密度低于其他水域,冬季相反,鱼群滞留在温排水热羽区域,因而显示出温排水海域有较高的鱼群密度。温排水对不同适温习性鱼类影响不同,暖温种能够适应一定的低温,例如,刀鲚(Coilia ectenes)可以在温排水水域越冬,而对高温有耐受性的棘头梅童鱼(Collichthys lucidus)夏季在温排水水域成为优势种。鱼类优势种的适温性决定着鱼群的分布特征,冬季最重要的优势种为刀鲚,在尾数上的贡献率高达45.02,由于该种在温排水的热羽区域分布密集,形成温排水水域鱼群密度大于周边水域的现象。由于温排水改变了渔场环境,导致新的越冬场的形成,有可能形成新的渔汛,引起当地渔场属性的改变。  相似文献   

20.
为了解西藏哲古措土著鱼类消化道寄生蠕虫的群落结构及季节动态,于2018年9月(秋季)和12月(冬季)、2019年3月(春季)和6月(夏季)对哲古措进行了4个季节的采样调查。共采集到2种土著鱼类,分别为高原裸鲤(Gymnocypris waddellii)和异尾高原鳅(Triplophysa stewartii),与原来的记录不同。在高原裸鲤的消化道中采集到了5种寄生蠕虫,分别为聂氏拟短结绦虫(Parabreviscolex niepini)、新棘吻虫未定种(Neoechinorhynchus sp.)、异肉吸虫未定种(Allocreadium sp.)、对盲囊线虫未定种线虫(Contracaecum sp.)和束首线虫未定种(Streptocara sp.),并对形态特征进行了描述。本研究发现,哲古措土著鱼类消化道寄生蠕虫的物种组成具有一定地域性,大部分为广布性寄生虫,鸟类在其传播过程中起到了重要作用。经过分析,高原裸鲤消化道寄生蠕虫群落的Shannon-Wiener多样性指数为0.70~1.27,显示了较高的群落多样性,Berger-Parker优势度指数为0.38~0.76,优势群为线虫。线虫表现出一定的季节消长规律:秋季为周年最高,冬季下降,春季上升,夏季降至最低,推测与水温、中间宿主的种群数量、线虫的生命周期和鱼类宿主繁殖期的行为等有关。复殖吸虫、绦虫和棘头虫四季的感染率均在10%以内浮动,平均丰度也较低。异尾高原鳅的消化道中未发现任何寄生蠕虫,推测与宿主肠道空间大小、摄食量和分布空间的差异有关。本研究通过对西藏湖泊土著鱼类寄生蠕虫的调查与分析,旨在为深入了解西藏寄生虫的组成特点、研究青藏高原隆升对寄生虫与鱼类宿主协同进化提供基础理论依据。  相似文献   

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