Microhabitat use by Iberian nase Chondrostoma polylepis and Iberian chub Squalius carolitertii in three small streams, north-west Portugal

Abstract –  Microhabitat use of Iberian nase Chondrostoma polylepis (Steindachner 1865) and Iberian chub Squalius carolitertii (Doadrio 1988) was studied in three small streams of the Lima basin, north-west Portugal. Measurements were made for 210 and 248 individuals, respectively, distributed in two size classes, based on fish ages, during winter, spring, summer and autumn 1998. Both species moved to shallow and slow-flowing microhabitats in summer and autumn, but this mainly reflected seasonal variation in microhabitat availability. Larger individuals of both species used deeper and lower percentage cover areas than smaller conspecifics, however significant ontogenetic differences were only found for water velocity. Different patterns of nonrandom microhabitat use were displayed by both cyprinids. Larger I. nase were in deeper and more discovered waters than those available in the habitat, whereas I. chub was over-represented in slow-flowing areas. There was no evidence of interspecific competition for microhabitat, therefore it is unlikely that spatial resource was limited during the present study.     

Seasonal variation in marine growth of sea trout, Salmo trutta, in coastal Skagerrak

Abstract –  Sea trout ( Salmo trutta ) originating from small coastal streams can be found at sea throughout the year, in contrast to conspecifics from larger rivers, which typically spend the autumn and winter in fresh water. Such an extended marine stay has been observed in coastal Skagerrak. We studied the seasonal variation in marine growth of Skagerrak sea trout based on scale increment patterns and body lengths of 563 individuals captured at sea. Growth, measured as increased body length, was rapid during summer while there was no evidence for continued growth during autumn and winter. Growth decreased with increasing age of the fish. Our results suggest that coastal Skagerrak is an important feeding area for sea trout during summer, and that an extended marine stay during autumn and winter may have trade-off benefits other than somatic growth. Alternative benefits might be increased winter survival and decreased migratory costs of juvenile fish.     

Diel and seasonal abundance of fishes in the Platte River, Nebraska, USA

ABSTRACT:   The objective of the present study was to determine diel and seasonal patterns of fluvial fish composition and abundance. Electrofishing grids were used to collect fish in the Platte River at North Bend, Nebraska, USA. Sampling was started at 12.00 h and continued every 3 h for a 24-h period. More species were taken during the day than at night in the spring. In contrast, more species were taken at night than during the day in summer. In the fall, equal numbers of species were caught during the day and night. Comparisons of fish densities showed significant differences among the three seasons. Major taxa were significantly more abundant in spring, but river shiner Notropis blennius and western silvery minnow Hybognathus argyritis were more abundant in the fall. The greater nocturnal abundance of fish in summer and fall than in the spring may be due to changes in the physical and chemical characteristics during the study periods. The significance of seasonal difference in abundance of fish assemblages may indicate a response to changes in available habitats.     

Diel vertical migration of myctophid fishes (Family Myctophidae) in the transitional waters of the western North Pacific

The diel vertical migration patterns of adult myctophid fishes were determined in the transitional waters of the western North Pacific off Japan, using day–night sampling from 20 to 700 m depths with a commercial otter trawl in the summer of 1995. A total of 12 species belonging to 9 genera were collected. Four patterns were recognized in the diel vertical migration of 11 of the 12 species. (1) Migrants showing clear day–night habitat separation with peak abundance above 200 m at night: Symbolophorus californiensis, Tarletonbeania taylori, Notoscopelus japonicus, Diaphus theta, Ceratoscopelus warmingi, and Diaphus gigas. (2) Semi-migrants, in which part of the population often remains in the daytime habitat at night. The distribution depths of migratory and nonmigratory individuals do not overlap: Stenobrachius leucopsarus . (3) Passive-migrants, in which there is no separation of day–night habitats, but the upper limit of daytime distribution depth shifts to a shallower layer at night, probably as the fish follow migratory prey: Lampanyctus jordani . (4) Nonmigrants: Stenobrachius nannochir, Lampanyctus regalis (> 140 mm SL), and Protomyctophum thompsoni . The day–night habitat temperature ranges are also given for the 11 species. No remarkable east–west differences were seen in the vertical migration patterns compared with previous knowledge of eight of these species in the eastern Pacific. The diel migration patterns are newly described for three other species endemic to the western Pacific. The standing stock of myctophids in the study area was conservatively estimated at 18.5 ± 4.7 g m⁻² (avg. ± SD).     

东海生态系统中鱼卵、仔稚鱼种类组成、数量分布及其与环境因素的关系

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。     

岱衢洋鱼类资源及其群落多样性的季节变化

根据2010年春季(5月)、夏季(8月)、秋季(11月)与2011年冬季(2月)对岱衢洋进行的共4个航次的底拖网渔业资源调查资料, 对该海域的鱼类资源状况及其多样性进行了分析, 结果表明: 所捕获的38种鱼分别隶属于1门2纲8目21科31属; 暖温性鱼类无论在种类数量还是生物量与尾数密度方面均居主导地位; 凤鲚四季均为该海域的优势种; 在时间分布上, 生物量与资源尾数密度均以夏季为最高, 而冬季则恰好相反, 且该两季的生物量与资源尾数密度间均存在显著差异(P<0.05), 另外, 在空间分布上, 生物量与尾数密度四季总体上均呈北高南低、东高西低的趋势; 生物量与平均底层温度呈二次曲线相关(P<0.01); 春、秋两季的Margalef丰富度指数( D )、Shannon-Wiener多样性指数( H' )和Pielou均匀度指数( J' )均存在显著差异(P<0.05); 与东海近、外海海域鱼类群落的多样性比较, 岱衢洋的Shannon- Wiener多样性指数( H' )较低。     

Patterns of drift and power station entrainment of 0+ fish in the River Trent, England

Entrainment of 0+ riverine fish (mostly pelagic cyprinids) by a power station intake, and down-river drift over a nearby weir, followed the same pattern, occurring throughout the year and being greatest during the night in the first weeks of life (i.e. in summer), reaching a peak shortly after dusk. Entrainment and drift of benthic species, and of fish older than 0+, were negligible. Mortality following entrainment was 100%. Impingement of fish on the intake screens was negligible, probably because individuals larger than the screen mesh were able to escape the intake current. The species composition and length-frequencies of the drifting fish, but not their overall abundance, showed some variation with distance from the river margin. It is argued that the fish vulnerable to entrainment are those 0+ individuals which are dispersing in the river by drifting.     

Site fidelity and movement patterns of wild subadult red drum, Sciaenops ocellatus (Linnaeus), within a salt marsh-dominated estuarine landscape

Abstract  During summer and autumn 2002, 12 subadult red drum, Sciaenops ocellatus (Linnaeus) (261–385 mm total length) were surgically implanted with ultrasonic transmitters and released within the upper reach of the Duplin River Estuary, Sapelo Island, GA, USA. A fixed array of submerged receivers automatically recorded the time that individual tagged fish were detected at 10 sites within the study area. Ten red drum implanted with transmitters were located within the receiver array for 6–96 days post-release. All fish exhibited a high degree of site fidelity at low tide, and movements appeared to be influenced by both tidal and diel cycles. Dispersal on flood tides was observed, but destinations (upriver or downriver) and paths taken (main channel, intertidal channels or flooded marsh surface) varied among individuals. Flood-tide movements were generally restricted to daylight hours. If the start of flood tide occurred after sunset, fish remained stationary. Variation in details of movement patterns among individuals notwithstanding, predictable behaviour and strong site fidelity make subadult red drum vulnerable to recreational fishing in the restricted tidal channels of the tidal marsh–estuary complex. However, the same predictability provides fisheries managers a means of targeting specific areas for protection of over-fished populations of this species.     

Biology and habitat use of three-spined stickleback (Gasterosteus aculeatus) in intermittent Mediterranean streams

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.     

漳河山西段鱼类和大型底栖动物群落结构特征

2017年对漳河山西段鱼类、大型底栖动物进行调查,分析物种组成、多样性及空间差异特征。结果显示：(1)共采集到鱼类24种,优势种为棒花鱼Abbottina rivularis (Basilewsky, 1855)、麦穗鱼Pseudorasbora parva (Temminck et Schlegel, 1846)、拉氏大吻鱥Rhynchocypris lagowskii (Dybowski, 1869)、高体鳑鲏Rhodeus ocellatus (Kner, 1867)、中华鳑鲏Rhodeus sinensis Günther, 1868、子陵吻鰕虎鱼Rhinogobius giurinus Rutter, 1879;大型底栖动物44种,年平均密度为256个/m_²,优势种为中华锯齿米虾Neocaridina denticulate sinensis Kemp、蜉蝣科稚虫Ephemeridae、扁蜉科稚虫Heptageniidae、椭圆萝卜螺Radix swinhoei H.Adams。(2)各采样河段鱼类Shannon-Wiener指数、Margalef指数平均值分别为1.53、1.68,夏季多样性好于春、秋季;大型底栖动物两个多样性指数平均值分别为1.14、1.47,春季多样性好于夏、秋季。(3)聚类分析结果显示,鱼类组成分为清漳河、浊漳河两组,清漳河鱼类指示物种包括短须颌须鮈Gnathopogon imberbis (Sauvage et Dabry, 1874)、拉氏大吻鱥Rhynchocypris lagowskii (Dybowski, 1869),浊漳河指示物种为鳑鲏属Rhodeus的鱼类;大型底栖动物组成同样分为清漳河、浊漳河两组,清漳河平均密度及物种数低于浊漳河,其昆虫纲蜻蜓目物种数多于浊漳河,而昆虫纲龙虱科、蝎蝽科、黾蝽科、鱼蛉科以及甲壳纲、腹足纲、双壳纲、寡毛纲、蛭纲的物种数少于浊漳河。底栖动物物种结构的差异受流域内营养物质输入以及水环境质量的影响较大。     

Migration pattern of shirauo Salangichthys microdon Bleeker, in the Ishikari River system and adjacent nearshore sea area, Japan, as estimated by otolith microchemistry analysis

ABSTRACT:   The purpose of the present paper was to reveal the migration pattern of shirauo Salangichthys microdon Bleeker, in the Ishikari River system and its adjacent coastal sea areas. To this end, the strontium–calcium (Sr:Ca) ratios of the otoliths of 98 individuals were examined. Profiles of the Sr:Ca ratios during the life history after hatching in the estuary of the Ishikari River fell into two different patterns. One was characterized by a high (slightly fluctuating) Sr:Ca ratio throughout the life history; the other was characterized by an initial high Sr:Ca ratio followed by a lower value later in life. The former pattern was considered to be that of estuary–sea residents and the latter that of upstream migrants. Most upstream migrants migrated upstream once, although several did it twice. Back-calculated body lengths during the upstream and seaward migrations of the upstream migrants varied widely from 6.4 mm to 39.8 mm and from 13.5 mm to 79.4 mm, respectively. These findings suggest that estuary–sea residents and upstream migrants co-occurred spatiotemporally, and suggest a wide variation in migration patterns in the shirauo's life history.     

东海区夏、秋季大型水母分布区渔业资源特征分析

本文根据1999～2004年的夏季和秋季东海区大型水母和渔业资源的状况,分析了大型水母分布区内的渔业资源特征。结果表明大型水母夏季主要分布于30°30′～33°00′N间,秋季主要分布于32°00′N以北海域,并呈现由夏季到秋季逐渐往北转移的趋势;2003年是大型水母数量最高的年份,该年水母主要分布区内的渔业资源种类数最少,CPUE最低,Margalef种类丰富度指数也最低;2003年夏季水母高发区内渔获种类的优势度也较其它年份发生了显著变化,优势种变为黄;2003年水母高发区内带鱼、小黄鱼和银鲳的当龄鱼较少,银鲳的肥满度增加,小黄鱼的肥满度降低,而带鱼的肥满度未发生显著变化。本文对水母高发区内渔业资源变化的原因进行了初步解释,并对水母的防治措施提出了初步的建议。     

Movement,depth distribution and survival of spinetail devilrays (Mobula japanica) tagged and released from purse‐seine catches in New Zealand

相似文献   

Seasonal fluctuations in the flux of particulate organic matter discharged from net pens for fish farming

ABSTRACT:   Fish farming using net pens consumes large amounts of food for the reared fish, resulting in organic enrichment of the sediment below the fish farm from organic discharge in the forms of fish feces and food residues. Sediment traps were set at a net pen within and outside a fish farm, and organic flux on the sea floor was compared. The year-mean organic flux to the sea floor caused by fish farming from September 2003 to September 2004 was estimated at 2.11 gC/m²/day in total organic carbon (TOC) and 0.26 gN/m²/day in total nitrogen (TN), which were 2.5 times (TOC flux) and 2.2 times (TN flux) larger than that for natural organic flux outside the fish farm. The seasonal fluctuation patterns of organic flux to the sea floor below the fish farm did not necessarily coincide with those for the amount of food spent for the fish farming. The largest organic flux to the sea floor occurred in the autumn, when the vertical mixing of the water had just started. Therefore, organic enrichment of the sediment on the sea floor of a fish farm proceeded during this season.     

Demersal fish fauna in the Doto nearshore waters, northern Japan: Species composition and seasonal variation

ABSTRACT:   The species composition of demersal fish was studied in nearshore waters (33–116 m depth) of south-eastern Hokkaido, the coldest area around the Japan Archipelago due to the influence of the cold Oyashio Current, using bottom gillnet samples collected during October 1996, August 1997, May 1998 and September 1999. The water temperature just above the sea bottom in the study area was lowest (< 2°C) during May and then rose through autumn (> 14°C). Cottids were the most abundant family in terms of both overall biomass and number, but their gravimetric dominance decreased from May (84%) through October (14%), whereas pleuronectids and stichaeids increased. Of the 57 fish species sampled, plain sculpin Myoxocephalus jaok was the dominant species in terms of overall biomass, accounting for 29.0% of the total biomass, followed by horned sculpin Enophrys diceraus (19.5%), Kamchatka flounder Atheresthes evermanni (6.5%) and blackline prickleback Acantholumpenus mackayi (4.9%). Plain sculpin dominated during May and September, but its predominance was low during October (9.6%), when witch flounder Glyptocephalus stelleri (22.7%) and blackline prickleback (10.8%) became important. This seasonal change appears to reflect the annual life cycle events of the fish, such as spawning.     

Modelling the life-history variation of Arctic charr

Abstract –  A model based on proximate considerations of life histories of Atlantic salmon, Salmo salar , was examined for its applicability to fit the variation in life-history of wild Arctic charr, Salvelinus alpinus , based on a qualitative assessment of information related to growth and lipid dynamics of Arctic charr. The original salmon model is discussed in context of modifications required to account for added complexities in the life history of Arctic charr in relation to anadromy versus residency. A study from North Norway shows that individual charr that emigrate from the lakes to the sea, maintain a high growth rate in the lake in late summer and early autumn compared with resident fish. Their relatively low lipid level in autumn combined with a high rate of change of lipid during winter was associated with postponement of maturation in the anadromous individuals. Individuals that remain resident in the lake arrested growth in autumn. Their high lipid level in autumn combined with a low rate of change of lipid during winter was associated with maturation the following summer, without emigration from freshwater. Results from this and other related studies show similarities with the model derived from lipid and growth dynamics of Atlantic salmon. The adjusted charr model illustrates possible proximate explanations for the high variation in life-history strategies of Arctic charr. However, the model does not account for the characteristic return migration of immature charr into freshwater several weeks after their entry to the sea. The proximate physiological stimulus for this movement of immature fish is not entirely clear.     

枸杞岛贻贝养殖筏架附着海藻的群落结构

为了解贝类筏式养殖区的大型海藻种类组成和分布格局及季节变动等群落水平的特征,实验于2018年春季(5月)、夏季(8月)、秋季(11月)和2019年冬季(2月)对枸杞岛贻贝养殖筏架上的附着海藻进行采样和分析.结果 显示,全年共采集到49种附着海藻,隶属11目20科33属.在物种数季节变化上,秋季最高(29种),春季最低(...     

通江湖泊石臼湖鱼类群落结构现状及其季节变化

石臼湖是长江下游唯一的自然通江湖泊,为掌握其鱼类资源状况,本研究于2017年1月至2018年3月采用多目刺网和定制串联笼壶采集石臼湖渔获物,分析了石臼湖鱼类群落结构及其季节变化.结果显示,共采集到鱼类36种,隶属于6目7科28属,其中鲤科鱼类最多,占总物种数的69.44％;鱼类物种组成以定居性、杂食性、中上层鱼类为主,...     

黄海南部、东海北部夏秋季小黄鱼数量分布及与浮游动物的关系

对夏秋季黄海南部、东海北部海域的小黄鱼和浮游动物的数量分布及其它们之间的关系进行了研究,结果表明:夏秋季节,黄海南部、东海北部小黄鱼主要出现在大沙、江外、吕四和沙外渔场,夏季最高生物量分布区出现在长江口和江外渔场交界处的31°30′N、125°00′E海域,秋季最高生物量分布区出现在大沙和沙外渔场交界处的32°30′N、125°00′E海域。2个季节浮游动物优势种的组成主要以浮游甲壳动物、浮游幼体以及毛颚类动物为主。浮游动物有2个密集分布区:一个在近岸一侧123°00′E经度线附近,夏季呈南北方向分布,秋季呈西北-东南走向;另一个在32°00′N、125°00′E附近海域。从夏季到秋季,浮游动物优势种的组成有了较大的更替,优势种的范围更加扩大;夏季占绝对优势的中华哲水蚤到秋季已经不在优势种之列。夏秋季小黄鱼主要分布区与浮游动物的高密度分布区存在着良好的对应关系。夏季小黄鱼和其他浮游食性鱼类的强烈的摄食影响可能造成了秋季浮游动物丰度的急剧下降。小黄鱼主要分布区内饵料浮游动物优势种的季节变化可能对其食物选择的变化有重要的影响。     

流溪河保护区鱼类群落结构及其时空变动

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。