海州湾及邻近海域春夏季典型断面鱼类浮游生物群落的结构特征

根据2015年5―7月在海州湾及邻近海域存在空间异质性的南北两个典型断面进行的鱼卵、仔稚鱼水平拖网调查数据,采用多元统计分析等方法研究了该海域春、夏季鱼类浮游生物群落的空间变化。结果表明,本次调查共获得鱼卵33587粒,仔稚鱼713尾。出现鱼卵25种(未定种1种),隶属于14科25属,仔稚鱼13种(未定种1种),隶属于13科13属。鱼卵优势种主要是鳀(Engraulis japonicus)、多鳞鱚(Sillago sihama)、(魚銜)属(Callionymus spp.)、皮氏叫姑鱼(Johnius belengerii)、江口小公鱼(Stolephorus commersonni)和短吻红舌鳎(Cynoglossus joyneri);仔稚鱼优势种主要是(魚銜)属和斑鰶(Konosirus punctatus)。鱼类浮游生物种类组成年代际变化明显,目前以生命周期短、个体小、资源更新节律快的小型鱼种为主;研究表明,鱼类浮游生物的优势种在不同月份和断面之间存在一定变化,5、6月南北两断面优势种组成不同,7月开始出现共同优势种。从鱼类浮游生物的空间分布来看,近岸海域的丰度较高,5、6月鱼类浮游生物的平均丰度均为北面断面1高于南面断面2,7月反之。鱼类浮游生物群落在两个典型断面随月份呈现出不同特征,水深、温度和盐等海洋环境因子综合影响着春、夏季海州湾及邻近海域鱼类浮游生物群落结构。     

A general model of temporary aquatic habitat use: Water phenology as a life history filter

Temporary aquatic habitats are not widely appreciated fish habitat. However, fish navigate the transient waters of intertidal zones, floodplains, intermittent and ephemeral streams, lake margins, seasonally frozen lakes and streams, and anthropogenic aquatic habitats across the globe to access important resources. The selective pressures imposed by water impermanence (i.e., freezing, drying, tidal fluctuations), however, operate similarly across taxa and ecosystems. These similarities are formalized into a conceptual model relating habitat use to surface water phenology. Whereas all necessary life history functions (spawning, foraging, refuge, and dispersal) can be accomplished in temporary habitats, the timing, duration, and predictability of water act as a “life history filter” to which habitats can be used and for what purpose. Habitats wet from minutes to months may all be important—albeit in different ways, for different species. If life history needs co‐occur with accessibility, temporary habitats can contribute substantially to individual fitness, overall production and important metapopulation processes. This heuristic is intended to promote research, recognition and conservation of these frequently overlooked habitats that can be disproportionately important relative to their size or brevity of existence. There is a pressing need to quantify how use of temporary aquatic habitats translates to individual fitness benefits, population size and temporal stability, and ecosystem‐level consequences. Temporary aquatic habitats are being impacted at an alarming rate by anthropogenic activities altering their existence, phenology, and connectivity. It is timely that scientists, managers and policymakers consider the role these habitats play in global fish production.     

Unveiling the influence of the environment on the migration pattern of the Atlantic pomfret (Brama brama) in North‐eastern Atlantic waters

Hydroclimatic variability is one of the main factors that drives inter‐annual changes in fish migration patterns. This study analyses the relationship between climate‐oceanographic factors and migration of the Atlantic pomfret (Brama brama) in NE Atlantic waters. Geo‐referenced catch data from logbooks of longliners operating in European Atlantic waters from 2002 to 2013 were linked to environmental indices at different temporal and spatial scales. Our results point to a strong influence of temperature at 200 m depth as the key factor along with the upwelling in the Galician (NW Iberian) waters. However, sea surface temperature (SST) indirectly affects the geographical display of Atlantic pomfret migration, and large migrations are observed in scenarios of high SSTs in the migratory area (c. above 14.7°C). Migrations are constrained during years when temperatures are below this threshold. A longer time‐series of annual landings (1950–2013) supports this evidence and highlights the significant influence of temperature at 200‐m depth along with the landings of the previous year. Length frequency distributions suggest an increase in size between consecutive seasons supporting the hypothesis that migration is a feeding strategy and a return to tropical waters of origin for spawning. Our study shows that the temperature of intermediate waters is a key variable in determining the northward migration of the Atlantic pomfret whereas density‐dependence and surface climatic conditions trigger secondary effects on the migration pattern of this species.     

The daily egg production method: recent advances, current applications and future challenges

More than 120 surveys over 25 years suggest that appropriate use of the daily egg production method (DEPM) provides unbiased but rather imprecise estimates of spawning biomass (coefficient of variation generally above 30%). Knowledge of species reproductive biology and early life history and a survey design adapted to local population dynamics are required to optimize DEPM performance in terms of bias, precision and cost. Clupeoid applications dominate worldwide (mainly for anchovies and sardines) and estimates are often used to tune indirect assessment models or to calibrate other fisheries‐independent methods. The method seems better adapted to the life history of anchovies than of sardines, leading to more precise estimates of anchovy spawning biomass and facilitating extensions of the method to estimate total biomass and numbers at age. The continuous underway fish egg sampler is often used as a secondary sampler in the ichthyoplankton survey of the DEPM to reduce the cost and improve the precision of egg production. Multinomial models were recently developed to analyse egg incubation data and used in a Bayesian procedure for egg ageing and delimitation of daily cohorts. These were incorporated in model‐based estimators to get spatially explicit estimates of egg production, daily fecundity parameters and spawning biomass that can improve the precision of DEPM. Uncertainty in daily fecundity estimation of clupeoids is mainly because of spawning fraction estimation by the post‐ovulatory follicle (POF) method. Exploration of recent histological and molecular techniques for POF characterization and laboratory experiments to test the effect of temperature on POF degradation can help to improve spawning fraction estimation. Available estimates of egg production and mortality, daily fecundity, spawning area and biomass from different populations, species and ecosystems are being used to improve the understanding of clupeoid spawning dynamics, their relation with ecosystem productivity and to build comprehensive population models. Finally, a counter‐intuitive finding of this review is that, although the DEPM is almost exclusively applied to clupeoids, recent evidence indicates that it may be easier and cheaper to use in other teleost families, including demersal species.     

DNA barcoding of fish eggs collected off northwestern Cuba and across the Florida Straits demonstrates egg transport by mesoscale eddies

Identifying spawning sites for broadcast spawning fish species is a key element of delineating critical habitat for managing and regulating marine fisheries. Genetic barcoding has enabled accurate taxonomic identification of individual fish eggs, overcoming limitations of morphological classification techniques. In this study, planktonic fish eggs were collected at 23 stations along the northwestern coast of Cuba and across the Florida Straits to United States waters. A total of 564 fish eggs were successfully identified to 89 taxa within 30 families, with the majority of taxa resolved to species. We provide new spawning information for Luvarus imperialis (Louvar), Bothus lunatus (Plate Fish), Eumegistus illustris (Brilliant Pomfret), and many economically important species. Data from most sites supported previously established patterns of eggs from neritic fish species being found on continental shelves and oceanic species spawning over deeper waters. However, some sites deviated from this pattern, with eggs from reef‐associated fish species detected in the deep waters of the Florida Straits and pelagic species detected in the shallow, continental shelf waters off the coast of northwestern Cuba. Further investigation using satellite imagery revealed the presence of a mesoscale cyclonic eddy that likely entrained neritic fish eggs and transported them into the Florida Straits. The technique of combining DNA‐based fish egg identification with remotely‐sensed hydrodynamics provides an important new tool for assessing the interplay of regional oceanography with fish spawning strategies.     

Space use and inferred spawning activity of three exploited gamefish species on a large artificial reef

Intense fishing pressure has led to changes in species composition, demography and the over‐exploitation of many coastal fishes. To restore populations, artificial reefs (ARs) are used with the assumption that new habitat will increase fish productivity. Kelp bass (Paralabrax clathratus), barred sand bass (P. nebulifer) and California sheephead (Semicossyphus pulcher) are three important recreational gamefish species in southern California. Home ranging behaviour, space use and spawning‐related activity of these three species were quantified on a large AR. Kelp bass used the largest amount of area, but space use was similar among species. While no spawning behaviour could be determined for sheephead, kelp bass exhibited two different activity patterns during spawning months and barred sand bass migrated (indicative of spawning). Results of this study indicate that this large AR is providing suitable habitat for these species, and spawning‐related activity could be a sign that this AR is meeting essential life history demands.     

Biological and ecological aspects of the deep‐water red crab populations inhabiting isolated seamounts to the west of the Azores (Mid‐Atlantic Ridge)

Seamounts are common topographic features in the Mid‐Atlantic Ridge (MAR) including the Azores. However, the knowledge on the ecology of seamounts in this region remains scarce despite needs for assessment and management of seamount resources such as the developing fisheries for deep‐water crabs. We described here for the first time the biological characteristics of an unexploited virgin deep‐water red crab Chaceon affinis population on seamount areas of the MAR to test the hypothesis that its general life history characteristics are similar in different ecosystem types (coastal areas and seamounts) across Macaronesia. We used a randomly stratified design to prospect a layer between 600 and 900 m depth around the summit of two isolated seamounts off the Azores. Results were consistent with the literature information in relation to the patterns of depth distribution, size and sex structure, and reproductive aspects. On the other hand, seamounts showed higher abundances when compared to previously studied coastal areas. Abundance may be also different between seamount areas as a function of the suitable bottom type available and presence of hydrothermal vents. We recommend that the essential habitat of the species should be better mapped identifying vulnerable areas before the development of any fishery.     

Population viability and perturbation analyses to support recovery of imperilled Eastern Sand Darter (Ammocrypta pellucida)

Small‐bodied freshwater fishes are often understudied, with the result that data gaps create uncertainties that can complicate and constrain conservation strategies aimed at species recovery. Use of matrix models and perturbation population viability analyses (PVA) are ideally suited for use in studying the consequences of life‐history parameter variation and environmental stochasticity to better understand the fate of threatened small‐bodied fishes. We use data for Eastern Sand Darter (Ammocrypta pellucida) populations from the Thames River, Canada, to explore the consequences of life‐history uncertainties such as age at maturation, multiple clutch sizes and age‐specific fertility for population recovery in this species. Environmental stochasticity acting on all life‐history parameters was found to pose significant risks for the continued viability of lower Thames River populations, with significant chances of local extinction predicted under current conditions. The intrinsic rate of population increase was most sensitive to 0+ survival rates, clutch size and clutch number. As demonstrated here, population models can successfully provide a means of exploring the population dynamics of small‐bodied fishes and can inform managers of risks posed by factors acting on life‐history parameters to affect continued population viability. Management actions for Eastern Sand Darter should focus on strategies designed to ensure successful spawning and improvement of 0+ survival rates, through programmes aimed at the protection, enhancement or recovery of additional spawning and juvenile rearing habitats.     

A numerical classification of reproductive guilds of the freshwater fishes of south-eastern Australia and their application to river management

A comprehensive list of freshwater fishes from south‐eastern Australia is classified into five major reproductive guilds, based on numerical analysis of 13 life history or reproductive characteristics. The guilds defined generally support previously proposed, subjective life history‐based classifications of freshwater fish species in this region. The majority of species fell into two groups, with 18 and 19 species, and the remaining guilds each contained from 1 to 12 species. The most important biological characteristics that separated the major groups of species included: care of the eggs or young, the presence of adhesive or non‐adhesive eggs, serial or single spawning, and viviparity. Two of the main guilds could each be divided into two sub‐guilds mainly based upon the requirement for a spawning migration. The objective definition of reproductive guilds allows river and natural resource managers to consider the effects of changes in environmental management on groups of species that are likely to respond in similar ways.     

Ontogeny matters: Climate variability and effects on fish distribution in the eastern Bering Sea

Analyses of climate effects often ignore differences in life history for individual species. We analyzed a 34‐year time series of eastern Bering Sea fish surveys to evaluate changes in distribution by length and between cold and warm shelf‐wide average water temperatures for 20 species over inhabited depth, temperature, and location. All species showed evidence of ontogenetic migration. Differences in distribution between years with warm and years with cold shelf‐wide water temperatures varied among species and within species at different lengths. For species where shelf‐wide temperature effects were detected, the mid‐sized fish were most active in changing spatial distribution. For aquatic organisms ontogenetic migration occurs because life history stages have different environmental requirements. This study illustrates the need to consider species responses to climate change over different life history stages, and that studies on ecosystem responses should take ontogenetic differences into consideration when assessing impacts.     

Understanding the life histories of amphidromous fish by integrating otolith‐derived growth reconstructions,post‐larval migrations and reproductive traits

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Reliance on lakes by salmon,trout and charr (Oncorhynchus,Salmo and Salvelinus): An evaluation of spawning habitats,rearing strategies and trophic polymorphisms

Salmonid fishes may reside within or migrate between stream and lake habitats, or undergo anadromous migrations between freshwater and the ocean. While the degree of anadromy of salmonids has been thoroughly compared, no analogous review has examined the degree of lake use. To assess the extent of reliance on lake habitat in this family, we considered 16 species of salmon, trout and charr from the genera Oncorhynchus, Salmo and Salvelinus, comparing their (a) use of lakes as spawning habitat, (b) rearing strategies in lakes, and (c) occurrence and diversity of lacustrine trophic polymorphism. In identifying the primary life‐history patterns of each species and exploring the lesser‐known lacustrine behaviours, we found that the extent of reliance on lakes exhibits a negative association with the degree of anadromy. Oncorhynchus rely least on lakes, Salmo to an intermediate level and Salvelinus the most, opposite of the general prevalence of anadromy among these genera. Lakes are critical to adfluvial and lake‐resident salmonids, but they also support anadromous and fluvial life histories by providing spawning, rearing, overwintering and/or summer refuge habitat. Adfluviality, although a non‐anadromous life history, consists of similar migration‐related traits and behaviours as anadromy, including the parr–smolt transformation, sex‐biased patterns of migration and residency, and the presence of precocious males. Lakes support life‐history variants, reproductive ecotypes and trophic morphs unique to lacustrine habitat. Therefore, conservation of salmonids is dependent on maintaining the diversity and quality of their habitats, including lakes.     

Atlantic salmon Salmo salar L., brown trout Salmo trutta L. and Arctic charr Salvelinus alpinus (L.): a review of aspects of their life histories

Abstract – Among the species in the family Salmonidae, those represented by the genera Salmo, Salvelinus, and Oncorhynchus (subfamily Salmoninae) are the most studied. Here, various aspects of phenotypic and life‐history variation of Atlantic salmon Salmo salar L., brown trout Salmo trutta L., and Arctic charr Salvelinus alpinus (L.) are reviewed. While many strategies and tactics are commonly used by these species, there are also differences in their ecology and population dynamics that result in a variety of interesting and diverse topics that are challenging for future research. Atlantic salmon display considerable phenotypic plasticity and variability in life‐history characters ranging from fully freshwater resident forms, where females can mature at approximately 10 cm in length, to anadromous populations characterised by 3–5 sea‐winter (5SW) salmon. Even within simple 1SW populations, 20 or more spawning life‐history types can be identified. Juveniles in freshwater can use both fluvial and lacustrine habitats for rearing, and while most smolts migrate to sea during the spring, fall migrations occur in some populations. At sea, some salmon undertake extensive oceanic migrations while other populations stay within the geographical confines of areas such as the Baltic Sea. At the other extreme are those that reside in estuaries and return to freshwater to spawn after spending only a few months at sea. The review of information on the diversity of life‐history forms is related to conservation aspects associated with Atlantic salmon populations and current trends in abundance and survival. Brown trout is indigenous to Europe, North Africa and western Asia, but was introduced into at least 24 countries outside Europe and now has a world‐wide distribution. It exploits both fresh and salt waters for feeding and spawning (brackish), and populations are often partially migratory. One part of the population leaves and feeds elsewhere, while another part stays as residents. In large, complex systems, the species is polymorphic with different size morphs in the various parts of the habitat. Brown trout feed close to the surface and near shore, but large individuals may move far offshore. The species exhibits ontogenetic niche shifts partly related to size and partly to developmental rate. They switch when the amount of surplus energy available for growth becomes small with fast growers being younger and smaller fish than slow growers. Brown trout is an opportunistic carnivore, but individuals specialise at least temporarily on particular food items; insect larvae are important for the young in streams, while littoral epibenthos in lakes and fish are most important for large trout. The sexes differ in resource use and size. Females are more inclined than males to become migratory and feed in pelagic waters. Males exploit running water, near‐shore and surface waters more than females. Therefore, females feed more on zooplankton and exhibit a more uniform phenotype than males. The Arctic charr is the northernmost freshwater fish on earth, with a circumpolar distribution in the Holarctic that matches the last glaciation. Recent mtDNA studies indicate that there are five phylogeographic lineages (Atlantic, Arctic, Bering, Siberian and Acadian) that may be of Pleistocene origin. Phenotypic expression and ecology are more variable in charr than in most fish. Weights at maturation range from 3 g to 12 kg. Population differences in morphology and coloration are large and can have some genetic basis. Charr live in streams, at sea and in all habitats of oligotrophic lakes, including very deep areas. Ontogenetic habitat shifts between lacustrine habitats are common. The charr feed on all major prey types of streams, lakes and near‐shore marine habitats, but has high niche flexibility in competition. Cannibalism is expressed in several cases, and can be important for developing and maintaining bimodal size distributions. Anadromy is found in the northern part of its range and involves about 40, but sometimes more days in the sea. All charr overwinter in freshwater. Partial migration is common, but the degree of anadromy varies greatly among populations. The food at sea includes zooplankton and pelagic fish, but also epibenthos. Polymorphism and sympatric morphs are much studied. As a prominent fish of glaciated lakes, charr is an important species for studying ecological speciation by the combination of field studies and experiments, particularly in the fields of morphometric heterochrony and comparative behaviour.     

Energy allocation patterns in a multiple spawning sunfish: evidence for an income‐based reproductive strategy

Timing of reproduction is an important life‐history trait that varies among species as a function of energy allocation strategy, particularly as individuals are influenced by seasonal variations prior to and during the reproductive season. This study investigated size‐ and sex‐based seasonal patterns of energy allocation in bluegill, Lepomis macrochirus (Rafinesque), a species that spawns repeatedly throughout the summer, by quantifying gonad, liver and mesenteric fat masses. Results indicate that bluegill delay production of gonad tissue until the onset of the spawning season and use an ‘income spawning’ approach. Comparisons of energetic trends with crappies, Pomoxis annularis (Rafinesque) and P. nigromaculatus (Lesueur), a confamilial species of relatively similar size and morphology that spawns in the spring, highlight the flexibility of energy allocation patterns even among relatively similar fishes and shed light on bluegill life‐history strategies.     

Fishing groupers towards extinction: a global assessment of threats and extinction risks in a billion dollar fishery

Groupers are a valuable fishery resource of reef ecosystems and are among those species most vulnerable to fishing pressure because of life history characteristics including longevity, late sexual maturation and aggregation spawning. Despite their economic importance, few grouper fisheries are regularly monitored or managed at the species level, and many are reported to be undergoing declines. To identify major threats to groupers, the International Union for Conservation of Nature (IUCN) Red List criteria were applied to all 163 species. Red List assessments show that 20 species (12%) risk extinction if current trends continue, and an additional 22 species (13%) are considered to be Near Threatened. The Caribbean Sea, coastal Brazil and Southeast Asia contain a disproportionate number of Threatened species, while numerous poorly documented and Near Threatened species occur in many regions. In all, 30% of all species are considered to be Data Deficient. Given that the major threat is overfishing, accompanied by a general absence and/or poor application of fishery management, the prognosis for restoration and successful conservation of Threatened species is poor. We believe that few refuges remain for recovery and that key biological processes (e.g. spawning aggregations) continue to be compromised by uncontrolled fishing. Mariculture, through hatchery‐rearing, increases production of a few species and contributes to satisfying high market demand, but many such operations depend heavily on wild‐caught juveniles with resultant growth and recruitment overfishing. Better management of fishing and other conservation efforts are urgently needed, and we provide examples of possible actions and constraints.     

Life‐history characteristics of ide Leuciscus idus in the Eastern Baltic Sea

Otolith Sr:Ca and Ba:Ca profiles were used in parallel with age data to investigate the life‐history characteristics of ide, Leuciscus idus (L.) (n = 111), in the Väinameri Sea, West Estonia. Sr:Ca profiles were more variable and useful than Ba:Ca profiles. Flexible life‐history patterns were observed within and among the three study sites. Most of the individuals (72%) hatched in semi‐enclosed bays that are fresh water during spring spawning but are often flooded with brackish water during other seasons. The importance of lotic spawning varied among sites and was the highest (88%) in Matsalu Bay, moderate in Saunja Bay (33%) and lowest (0%) in Käina Bay. Young of the year emigrated from natal sites and entered the sea within the first summer; 95% did so during the first month post‐hatch. Juvenile ide undertook non‐spawning, freshwater migrations in the following spring; however, the reasons behind this phenomenon remain unknown. As the importance of lotic spawning has significantly decreased and multiple historically important ide spawning rivers lack anadromous runs altogether, it is suggested that actions should be taken to aid the recovery of those imperilled spawning stocks.     

A caution for conservation stocking as an approach for recovering Atlantic eels

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Consequences of connectivity alteration on riverine fish assemblages: potential opportunities to overcome constraints in applying conventional monitoring designs

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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。