黄海中北部不同断面鱼卵、仔稚鱼群落结构特征

为了解黄海中北部近岸海域不同断面的鱼卵、仔稚鱼群落结构特征,基于2017年5月、6月和7月对黄海中北部近岸海域内不同断面表层水平拖网的调查数据,对该海域鱼卵和仔稚鱼的种类组成、数量分布、多样性等进行分析。结果表明:3个航次共采获鱼卵5493粒,仔稚鱼43尾,经鉴定共20种,隶属于7目16科20属,种类以鲈形目为主要类群。采获鱼卵、仔稚鱼的数量在不同月份和不同断面间有所差异,总体来看数量分布不均匀。采获鱼卵、仔稚鱼对应成鱼的适温类型主要由暖温种和暖水种组成,仅有少量冷温种,各生态类型种类数随断面不同有所变化,暖温种在调查海域内由北向南呈递减的趋势,暖水种则呈递增的趋势。鱼卵、仔稚鱼优势种和重要种组成在不同月份和不同断面间均有所差异,鳀(Engraulis japonicus)为5月航次调查海域及T1和T2断面的鱼卵优势种,仔稚鱼没有出现优势种。3个航次采集的鱼卵、仔稚鱼对应成鱼平均营养级分别为3.58、3.51和3.41,呈现逐渐降低的趋势。调查海域内鱼卵、仔稚鱼的丰富度指数(D)、多样性指数(H′)和均匀度指数(J′)均以5月航次最高, 6月航次最低。此外,两个断面各站位之间的丰富度指...     

莱州湾春、夏季鱼卵、仔稚鱼群落结构及环境因子相关性

于2014年5月、8月和2015年5月、8月,利用大型浮游生物网,对莱州湾海域20个站位进行4个航次拖网调查,分析了鱼卵、仔稚鱼的种类组成、数量分布、优势种以及群落结构特征与环境因子的相关性。结果表明:4个航次共采获鱼卵、仔稚鱼22种,其中1种仔稚鱼未鉴定出种类,1种仔稚鱼鉴定到科,其余20种隶属于8目16科20属;鱼卵、仔稚鱼优势种季节变化明显;鱼卵、仔稚鱼数量分布与环境因子数据的多元分析表明,盐度对鱼卵数量影响较为明显,温度对仔稚鱼数量影响较为明显,仔稚鱼数量还与溶解氧(DO)、亚硝酸盐、无机氮、活性磷酸盐呈显著相关(P0.05),与氨氮(NH_3~-N)、叶绿素a含量呈极显著相关(P0.01),鱼卵数量与桡足类密度呈显著正相关(r=0.479,P=0.032),而仔稚鱼数量与桡足类密度呈显著负相关(r=-0.510,P=0.022)。     

青岛崂山青山湾人工鱼礁区及附近海域鱼卵仔稚鱼种类组成与数量分布

为研究人工鱼礁对产卵鱼类的诱集效果和庇护效应,2014—2015年对青岛崂山青山湾海域人工鱼礁区及附近海域鱼卵和仔稚鱼的种类组成和数量分布进行了水平和垂直拖网调查. 2014年春、夏、秋3个季节的7个航次调查中,共采集鱼卵7306粒、仔稚鱼52尾,隶属于4目9科11属12种;2015年同期进行的13个航次调查中,共采集鱼卵10373粒、仔稚鱼159尾,隶属于6目11科14属15种.2年间鱼卵和仔稚鱼样品均以鲈形目数量最多,鲽形目次之,其中鱼卵样品中仅有少鳞鱚和短吻红舌鳎构成优势种;仔稚鱼样品以少鳞鱚优势度最高,但不存在仔稚鱼优势种.鱼卵和稚鱼的高优势度物种的季节间演替明显.春、夏、秋季鱼类浮游生物群落Margalef丰富度指数、Shannon多样性指数和Pielou均匀度指数平均值均较低,说明该海域鱼类浮游生物群落结构稳定性较低.2年间所采集物种对应的成鱼平均营养级分别为3.71和3.78,均属第三营养级中的低级肉食性鱼类,绝大多数为暖温种,无冷温性种类,表现出明显的暖温带特点.综合分析认为,人工鱼礁区鱼类浮游生物群落的多样性相对较高,这与鱼礁区流速和流场特征及复杂的空间异质性有关.     

黄河调水调沙对河口及邻近海域鱼卵、仔稚鱼群落结构的影响

为了解调水调沙(Water-Sediment Regulation Scheme, WSRS)对黄河口海域鱼卵、仔稚鱼的群落结构和时空分布格局的影响,分别于2017年(非调水调沙年)和2018年(调水调沙年)的6—7月在黄河口海域利用水平拖网开展了6个航次的鱼卵、仔稚鱼调查。运用聚类分析和冗余分析(RDA)等方法对该海域非调水调沙年和调水调沙年的鱼卵、仔稚鱼丰度和群落结构的空间分布及环境因子状况等进行了综合的分析比较,结果表明:6个航次调查共采获鱼卵6212粒,仔稚鱼431尾,隶属于8目12科14属,其中,河口定居性鱼类短吻红舌鳎(Cynoglossus joyeri)为控制黄河口及邻近海域夏季鱼类浮游生物群落演替格局的主要种类;鱼卵受环流和调水调沙的共同影响,其空间分布在各调查阶段有所不同,仔稚鱼则趋向于在河口近岸海域分布;河口东北部及东南部靠近莱州湾区域是黄河口及邻近海域鱼类浮游生物群落的主要聚集区;调水调沙年鱼卵、仔稚鱼的采获总量以及底层鱼类鱼卵的采获数量均明显高于非调水调沙年,调水调沙带来的丰富径流和泥沙有利于黄河口海域渔业资源的补充;冗余分析结果表明,海洋鱼类的群落结构与环境...     

长江口水域夏季鱼卵和仔稚鱼年间变化

基于2005年、2008年、2009年和2011年8月(夏季)在长江口水域(30°30'—31°45'N,121°15'—123°10'E)4个航次的浮游生物拖网资料,分析了长江口水域鱼卵和仔稚鱼的种类组成、数量分布特征及其年间变化。结果表明:4个航次采集的鱼卵和仔稚鱼鉴定到种的种类有17种,隶属于8目13科,以鲈形目种类最多,11种,其次是鲱形目,5种,其他各目种类均小于5种;种类数存在明显年间差异,2005年种类数最多(鱼卵3种,仔稚鱼8种),其次是2009年和2011年,2008年种类数最少(鱼卵1种,仔稚鱼5种)。优势种年间更替明显,长蛇鲻(Saurida elongata)、虾虎鱼(Gobiidae spp.)和中华小公鱼(Stolephorus chinensis)在2005年是优势种,2008年优势种为鳀鱼(Engraulis japonicus),2009年优势种为鳀鱼、寡鳞飘鱼(Pseudolaubuca engraulis)、虾虎鱼等,2011年虾虎鱼和小公鱼(包括小公鱼属未定种Stolephorus spp.和中华小公鱼Stolephorus chinensis)成为优势种。2005年鱼卵和仔稚鱼数量分布的密集区在嵊泗列岛附近水域,2008年鱼卵和仔稚鱼出现较少,未出现明显的数量密集区;2009年鱼卵数量较少,仔稚鱼数量较多,密集区主要分布在在长江口以外123°E附近水域;2011年鱼卵主要分布在在长江北支口门外附近水域,仔稚鱼在调查区内分布相对均匀。     

中街山列岛海域鱼卵、仔稚鱼群落结构特征及其与环境因子的关系

为了解中街山列岛海域鱼卵仔稚鱼空间分布、种类组成及与环境因子的关系,于2010年5月—2012年2月在中街山列岛海域利用水平和垂直拖网开展了8个航次的鱼卵、仔稚鱼调查。运用非度量多维标度排序、聚类分析和典范对应分析(CCA)等方法对该海域鱼卵、仔稚鱼的空间分布进行了综合分析。结果表明:两年水平拖网共采集到鱼卵1783粒,仔稚鱼67尾;垂直拖网共采集到鱼卵576粒,仔稚鱼59尾。2010年平拖优势种为短吻红舌鳎(Cynoglossus joyneri),垂拖重要种为鲉形目未定种(Scorpaeniformes sp.)和扁舵鰹(Auxis thazard)。2011年平拖重要种为短吻红舌鳎、鰏属未定种(Leiognathuss sp.)、龙头鱼(Harpodon nehereus)和鳀(Engraulis japonicus);垂拖重要种为短吻红舌鳎、龙头鱼和中华小公鱼(Stolephorus chinensis)。经单因子相似性分析(ANOSIM),鱼卵仔稚鱼的优势种和重要种群落物种组成存在显著差异(P0.01)。研究结果表明,温度和盐度对鱼卵仔稚鱼的影响较大,夏季是中街山列岛海域鱼类产卵的重要时期。该海域以恋礁的小型底层鱼类为主,是褐菖鲉(Sebastiscus marmoratus)、龙头鱼等小型底层经济鱼类的重要产卵场和育幼场。     

黄海中部近岸春夏季鱼卵、仔稚鱼群落结构特征

2013年4月下旬至7月上旬,采用浅水I型网垂直拖网的调查方式对黄海中部20m以浅海域(34°30'—35°30'N,119°20'—120°20'E)的鱼卵、仔稚鱼种类组成与数量分布进行了6个航次的综合调查。春夏季共采集鱼卵21种(未定种3种),共计2247粒,隶属于9科15属。仔稚鱼22种(未定种1种),共计286尾,隶属于13科17属。鱼卵优势种为日本鳀Engraulis japonicus、赤鼻棱鳀Thryssa kammalensis、江口小公鱼Stolephorus commersonnii、皮氏叫姑鱼Johnius belengerii和属Callionymus spp.。仔稚鱼优势种为大银鱼Protosalanx chinensis、白姑鱼Argyrosomus argentatus、日本鳀、赤鼻棱鳀和皮氏叫姑鱼。鱼卵丰度和分布与经度呈负相关、与SST呈正相关,但与其他环境因子如纬度、表层盐度(SSS)和水深等无显著相关性。仔稚鱼丰度和分布与上述环境因子均未表现出显著相关性。基于Bray-Curtis指数的聚类分析表明,鱼卵优势种包括集中分布于研究水域34°48'N以南海域(江口小公鱼、皮氏叫姑鱼和青鳞小沙丁Sardinella zunasi)、10m等深线以内(赤鼻棱鳀),以及北部水域(日本鳀和属)3种主要聚集类型;仔稚鱼优势种包括集中分布于34°48'N—35°12'N海域(赤鼻棱鳀和日本鳀)、连云港外海浅水区(白姑鱼、皮氏叫姑鱼和梭鱼Liza haematocheilus,以及南部水域(褐菖鲉Sebastiscus marmoratus和鲬Platycephalus indicus)3种主要聚集类型。研究结果揭示了黄海中部近岸海域鱼卵、仔稚鱼群落的时空分布格局动态,为科学认识环境变动下该海区渔业种群数量动态和资源变化提供了科学依据。     

莱州湾渔业资源群落结构和生物多样性的变化

通过1959～1999年间4次按季节进行的底拖网调查,分析了莱州湾渔业资源和优势种组成以及群落结构的变化。结果表明,1998年平均渔获量大幅度下降,分别仅为1959、1982和1992～1993年的3.3％、7.3％和11.0％;虽然季节间优势种有一定的变动,但鳀鱼、黄鲫、斑鰶和赤鼻稜鳀等小型中上层鱼类自80年代以来已替代了带鱼、小黄鱼成为优势种;渔业资源群落结构也随时间发生了较大的变化,多样性自1959～1982年增加,然后呈下降趋势。 外部的扰动特别是捕捞,在中等强度下会使鱼类多样性增加,但过高的捕捞强度又会使多样性下降。目前莱州湾渔业资源群落结构简单,处于较不平衡状态,群落演替将继续,在外部扰动大幅度降低的情况下,具有较强恢复力的小型中上层种类资源能够很快恢复和增长。     

莱州湾及黄河口水域鱼类群落结构的季节变化

根据2011年5月—2012年4月对莱州湾及黄河口水域9个航次的渔业底拖网调查数据,对该水域鱼类群落结构特征及其季节变化进行了初步研究。结果表明:莱州湾及黄河口水域共捕获鱼类62种,隶属于11目、34科、53属,主要由暖水种和暖温种组成,其中鲈形目种类最多(37种),其次是鲉形目(7种)和鲽形目(6种)。春季优势种包括矛尾鰕虎鱼(Chaeturichthys stigmatias)、鲱衔(Callionymus beniteguri)、短吻红舌鳎(Cynoglossus joyneri)、矛尾复鰕虎鱼(Synechogobius hasta)和方氏云鳚(Enedrias fangi),其渔获量占总渔获量的70.8%;夏季包括矛尾鰕虎鱼、斑鰶(Konosirus punctatus)、鲱衔和短吻红舌鳎,占总渔获量的68.1%;秋季包括矛尾鰕虎鱼、赤鼻棱鳀(Thrissa kammalensis)、鳀(Engraulis japonicus)、青鳞小沙丁鱼(Sardinella zunasi)、斑鰶、小黄鱼(Larimichthys polyactis)和矛尾复鰕虎鱼,占总渔获量的87.1%。平均单位时间渔获量存在显著季节变化,以秋季最高(22.63kg/h),其次是夏季(16.75kg/h),春季最低(1.29kg/h)。春季(5月)平均单位时间渔获量为0.69kg/h,为1959年、2003年、2006年和2008年春季(5月)的0.3%、0.3%、1.7%和541.2%,鱼类资源量虽有所回升,但总体呈大幅下降的趋势。鱼类种类数、丰富度指数和多样性指数夏季较高,秋季次之,春季最低,但是以渔获尾数计算的均匀度指数,夏季最大,春季最小,以渔获量计算的均匀度指数则相反,且丰富度指数和多样性指数与表层温度呈极显著相关(P0.01),丰富度指数和均匀度指数与表层盐度呈极显著相关(P0.01)。     

长江口水域鱼卵、仔稚鱼种类组成和数量的分布与变化

根据2005年4和11月、2006年4和9月在长江河口水域进行的鱼卵、仔稚鱼种类和数量调查,并结合1990年9月和1991年3月的历史数据,对该水域的鱼卵、仔稚鱼群落结构的种类组成和数量的季节变化作了研究,其结果共发现鱼卵、仔稚鱼36种(类),以海洋鱼类种类最多。秋季航次鱼卵、仔稚鱼的平均种类数和丰度均高于春季。河口咸淡水区鱼卵总数显著高于淡水区,而仔稚鱼总数略低于淡水区。与1990—1991年数据相比,2005—2006年春、秋季的鱼卵和仔稚鱼丰度均有所增加。1990、2006年秋季(9月)鱼卵、仔稚鱼种类组成差异较大,特别是翘嘴红鲌和太湖新银鱼丰度差异较大。这些都说明近20年来,长江河口水域鱼卵、仔稚鱼种类组成和数量均发生了明显的改变。     

Seasonal and interannual variation of the ichthyoplankton off the coast of Northern Morocco

Changes in the qualitative and quantitative composition of the ichthyoplankton off the coast of Northern Morocco (36–28° N) are analyzed in different seasons of 1994–2008. Pelagic eggs and larvae of over 80 fish species belonging to 57 families are recorded. In cold periods at the Morocco coast, there is maximum spawning of fish belonging to the subtropical (Mediterranean-Atlantic) fauna, the dominant of which are European pilchard Sardina pilchardus, common scad Trachurus trachurus, and Atlantic mackerel Scomber japonicus. In warm periods, in addition to the aforementioned species, the ichthyopankton often comprises eggs and larvae of fish form the tropical fauna. Among the latter are round sardinella Sardinella aurita and West-African mackerel T. trecae dominate. The spawning biomass of principal commercial fish is also calculated by the quantity of eggs laid by females.     

Larval fish variability in response to oceanographic features in a nearshore nursery area

The influence of oceanographic features on ichthyoplankton assemblages in the warm temperate nearshore region of Algoa Bay, South Africa, was assessed. The nearshore ichthyoplankton comprised 88 taxa from 34 families. Samples were collected at six stations between August 2010 and July 2012 using a plankton ring net of 750 mm diameter and 500 µm mesh aperture. The majority of larvae collected were in a preflexion stage, indicating the potential importance of the nearshore for newly hatched larvae. Engraulidae dominated the catch (38·4%), followed by Cynoglossidae (28·1%) and Sparidae (8·4%). Larval fish abundance was highest during austral spring and summer (September to February). Unique patterns in responses of each dominant fish species to oceanographic features in the nearshore indicate the sensitivity of the early developmental stage to environmental variables. Using generalized linear models, ichthyoplankton abundance responded positively to upwelling and when warm water plumes originating from an Agulhas Current meander entered Algoa Bay. Highest abundances of Engraulis encrasicolus and Sardinops sagax were observed during Agulhas Plume intrusions into Algoa Bay. When a mixed and stratified water column persisted in the nearshore region of Algoa Bay, larval fish abundance decreased. The nearshore region of Algoa Bay appears to serve as a favourable environment for the accumulation of ichthyoplankton.     

Species composition and distribution of summer ichthyoplankton in Chupa Estuary (Kandalaksha Bay of the White Sea)

On the basis of ichthyoplankton surveys performed in July 2002 and June 2004–2005 in Chupa Estuary and adjacent waters of Kandalaksha Bay, species composition and distribution of eggs and larvae of fish were studied. Early stages of development of seven fish species were found in the composition of ichthyoplankton. The bulk of abundance of ichthyoplankton was formed of Clupea pallasii marisalbi larvae. It was shown that the sites of aggregation of larval C. pallasii marisalbi from June to July are constant and located in the central and preestuarine areas of Chupa Estuary. Possible routes of their passive migrations within Chupa Estuary and the adjacent water area of Kandalaksha Bay are considered. It is suggested that the drift of larvae beyond the estuary proceeds slowly, and after hatching they can long stay in the estuary concentrating in its central and preestuarine areas.     

An analysis of temporal variability in abundance, diversity and growth rates within the coastal ichthyoplankton assemblage of South Georgia (sub-Antarctic)

The study of spatial and temporal distribution and diversity of ichthyoplankton (fish eggs and larvae) can provide fisheries-independent information on the population dynamics and recruitment processes of marine fish species. Ichthyoplankton studies in the Southern Ocean have to date been largely constrained to the summer months. We analysed ichthyoplankton data collected from a year round, long term (2002–2008), plankton trawl sampling programme in a large fjord system (Cumberland Bay) at South Georgia, sub-Antarctic (54.25°S, 36.5°W) to assess temporal changes in larval fish diversity and abundance. Larvae of 22 species, representing nine families, were identified although three, Krefftichthys anderssoni (Myctophidae), Lepidonotothen nudifrons/Trematomus hansoni (Nototheniidae) and Champsocephalus gunnari (Channichthyidae), dominated abundance in all years. Significant seasonal and interannual differences in the larval fish assemblage were revealed by multivariate analyses. Estimates of larval growth are provided for five abundant species. Considerable inter-specific differences in relative larval growth rate were recorded but interannual variability within species was small. However, in the commercially important C. gunnari, multiple larval cohorts, representing a protracted spawning season, were observed to grow at different rates, and this may be related to temperature and/or food availability. A comparison with historical growth data from South Georgia suggests there has been little change in growth rate for the main species over the last three decades.     

Summer Ichthyoplankon in Onega Bay of the White Sea: Species Composition and Spatial Distribution

Data on the species composition and distribution of ichthyoplankton in Onega Bay of the White Sea are presented for June–July 2007, 2010–2012, and 2015–2016. In the ichthyoplankton, the specimens of the early developmental stages of 21 fish species were registered; the larvae of the White Sea herring Clupea pallasi marisalbi, capelin Mallotus villosus, and Pacific sand lance Ammodytes hexapterus were the most abundant. It is shown that the northwestern and southeastern zones, distinguished in Onega Bay by hydrophysical parameters, also differ in species composition and in ichthyoplankton abundance.     

State of the Ichthyoplankton Community along the Crimean Peninsula in August 2011

Data on species composition, spatial distribution of ichthyoplankton, and feeding of fish larvae in August 2011 are presented for the shelf and the open waters along the Crimean Peninsula from Kerch Strait to Karkinit Bay. In the ichthyoplankton, fish eggs and larvae represented 19 species from 16 families. The average egg abundance was 111 egg/m² and larvae abundance was 22 ind./m². The elimination ratio of the European anchovy Engraulis encrasicolus, which dominates in the plankton from the final stages of development to the prelarvae in 2011, was similar to that observed in 1957. The high number of larvae of the older age group in the western halistatic zone is explained by the peculiarities of the hydrological regime. Decrease in the pressure of predatory jelly macroplankton and an fodder zooplankton (zooplankton abundance) contribute to the survival of the fish larvae.