Fish Species (fish + species)

Distribution by Scientific Domains

Kinds of Fish Species

  • common fish species
  • different fish species
  • freshwater fish species
  • important fish species
  • indigenous fish species
  • invasive fish species
  • many fish species
  • marine fish species
  • native fish species
  • non-native fish species
  • other fish species
  • pelagic fish species
  • several fish species
  • small fish species

  • Terms modified by Fish Species

  • fish species richness

  • Selected Abstracts


    ABSTRACT The fatty acid, lipid, cholesterol and energy contents in five commercially important fish species from South Caspian Sea (common kilka, Caspian kutum, golden gray mullet, common carp and pike perch) were evaluated. The fatty acid compositions of these five fish species ranged from 28.99 to 41.05% saturated fatty acids, 40.99,56.25% monounsaturated fatty acids and 14.22,23.03% polyunsaturated fatty acids. Among these, those occurring in the highest proportions were palmitic acid (20.42,27.9%), palmitoleic acid (11.09,26.26%), oleic acid (16.1,36.94%), eicosapentaenoic acid (3.22,7.53%) and docosahexaenoic acid (3.86,11.36%). The lipid, cholesterol and energy contents ranged from 1.97% to 10.23%, 57,302 mg/100 g and 4365.4,5544.2 cal g/dm, respectively. The obtained Statistical results showed that in these fishes, many of the above mentioned indices had significant differences (P , 0.01) and the cluster analysis results of fatty acid compositions showed that common carp and pike perch had good similarity, followed by the Caspian kutum and golden gray mullet. However, common kilka did not show any similarity to others. PRACTICAL APPLICATIONS Fish consumption has been linked to health benefits such as reduced risk of coronary heart disease. This is largely attributed to the lipid, cholesterol, energy contents, fatty acid compositions and the polyunsaturated fatty acids present in fish oils. The ,-3 : ,-6, polyunsaturated fatty acid/saturated fatty acid and eicosapentaenoic acid + docosahexaenoic acid/C16 ratios are considered to be useful criteria for comparing relative nutritional and oxidation values of fish oils. [source]


    ABSTRACT Sensory profiling and Near-Infrared (NIR) reflectance analysis were carried out on cod (Gadus morhua), saithe (Pollachius virens), rainbow trout (Salmo gardineri), herring (Clupea harengus) and flounder (Platichthys flessus). A nine-member trained panel performed the profiling on cooked fillet samples and NIR was measured on the same material as whole, raw fish and raw fillet. For each species, samples varied in storage time (1,11 days in ice at OC) and season (spring, autumn and winter). One descriptive vocabulary was developed, containing 46 descriptive words altogether: 7 for appearance, 15, odor, 16, taste and 8 texture words. Multivariate data analysis was used to reduce the 46 words to 18, covering the main systematic variations in appearance, odor, taste and texture in conformance with a previous study. The same 18 sensory attributes were modeled by NIR measurements on whole, new fish and fillet. The predictive results showed explained variances to be higher for appearance and texture rhan for odor, and lowest for taste. The results indicate that NIR spectroscopy of raw fish as a supplement to sensory analysis might be useful as a rapid tool in Quality Monitoring for measuring the sensory parameters of appearance and texture of cooked fish. [source]

    Conservation Strategies for Endemic Fish Species Threatened by the Three Gorges Dam

    diseño de reserva; especies endémicas; modelo de comunidad; peces; presa Three Gorges Abstract: The largest damming project to date, the Three Gorges Dam has been built along the Yangtze River (China), the most species-rich river in the Palearctic region. Among 162 species of fish inhabiting the main channel of the upper Yangtze, 44 are endemic and are therefore under serious threat of global extinction from the dam. Accordingly, it is urgently necessary to develop strategies to minimize the impacts of the drastic environmental changes associated with the dam. We sought to identify potential reserves for the endemic species among the 17 tributaries in the upper Yangtze, based on presence/absence data for the 44 endemic species. Potential reserves for the endemic species were identified by characterizing the distribution patterns of endemic species with an adaptive learning algorithm called a "self-organizing map" (SOM). Using this method, we also predicted occurrence probabilities of species in potential reserves based on the distribution patterns of communities. Considering both SOM model results and actual knowledge of the biology of the considered species, our results suggested that 24 species may survive in the tributaries, 14 have an uncertain future, and 6 have a high probability of becoming extinct after dam filling. Resumen: El proyecto de represa más grande a la fecha, la Presa Three Gorges fue construida en el Río Yangtze (China), el río con mayor riqueza de especies en la región Paleártica. Entre las 162 especies de peces que habitan el canal principal del alto Yangtze, 44 son endémicas y por tanto están seriamente amenazadas de extinción global por la presa. Consecuentemente, es urgente desarrollar estrategias para minimizar los impactos de los cambios ambientales drásticos asociados con la presa. Tratamos de identificar las reservas potenciales para las especies endémicas entre los 17 afluentes en el alto Yangtze, en base a datos de presencia y ausencia de las 44 especies endémicas. Se identificaron las reservas potenciales para la especies endémicas caracterizando los patrones de distribución de especies endémicas con un algoritmo de aprendizaje adaptivo denominado "mapa auto-organizante" (MAO). Con este método, también predijimos las probabilidades de ocurrencia de especies en reservas potenciales en base a los patrones de distribución de las comunidades. Tomando en cuenta tanto los resultados del modelo MAO como el conocimiento actual de la biología de especies en consideración, nuestros resultados sugieren que 24 especies pueden sobrevivir en los afluentes, 14 tienen un futuro incierto y 6 tienen una alta probabilidad de extinguirse después del llenado de la presa. [source]

    Chemical Characterization of Liver Lipid and Protein from Cold-Water Fish Species

    Peter J. Bechtel
    ABSTRACT:, The largest US harvests of marine fish for human consumption are from Alaska waters. Livers from these fish are combined with other fish offal and made into fish meal and oil or discarded. The purpose of this study was to characterize liver lipids and proteins from important commercial species including walleye pollock (WP), pink salmon (PS), Pacific halibut (PH), flat head sole (FS), and spiny head rock fish (RF), and underutilized species including arrow tooth flounder (AF) and big mouth sculpin (BS). Liver lipid content ranged from 50.3% in WP to 3.3% in PS. Protein content ranged from 7.7% in WP to 18.4% in BS. PS livers had the highest content of ,-3 fatty acids at 336 mg/g of oil and AF had the lowest content at 110 mg/g of oil. There were significant differences in the content of 9 amino acids with methionine and lysine values ranging from 2.66% to 3.43% and 7.19% to 9.45% of the total amino acids, respectively. Protein from the cold water marine fish livers was of high quality and the oils contained substantial quantities of ,-3 fatty acids. Fish livers had distinct chemical properties and can be used for the development of unique food ingredients. [source]

    Identification of Tetrodotoxin and Fish Species in an Adulterated Dried Mullet Roe Implicated in Food Poisoning

    Y.W. Hsieh
    ABSTRACT: There was 1 victim of neurotoxic food poisoning from an adulterated dried mullet roe in Kaohsiung, Taiwan, in March 2001. The victim exhibited typical neurotoxic symptoms. The residue of dried mullet roe retained by the victim was assayed for toxicity and mitochondrial DNA. Its toxicity was 3450 mouse units per gram. The toxin was partially purified and identified as tetrodotoxin and derivative. The sequence of the 376-nucleotide region in the cytochrome b gene of the mitochondrial DNA exhibited the same genotype and the same restriction site for SapI as that of the toxic puffer fish Lagocephalus lunaris. [source]

    Hypocretin/orexin in fish physiology with emphasis on zebrafish

    ACTA PHYSIOLOGICA, Issue 3 2010
    P. Panula
    Abstract One hypocretin/orexin (hcrt) gene has been identified in several fish species. The first pufferfish gene was identified in 2002 and the zebrafish gene was cloned in 2004. Its structure is very similar to that of mammals, and it encodes for two active peptides with C-termini similar to those of mammals. The gene is expressed in the brain in only one hypothalamic nucleus, which sends projections to the telencephalon, diencephalon, mesencephalon and rhombencephalon. The terminal fibres are found in close contact with many aminergic cell groups, including those of raphe serotonergic, locus coeruleus noradrenergic, several dopaminergic cell groups and the sole histaminergic hypothalamic cluster. One receptor corresponding to mammalian hcrt 2 receptor has been identified in fish. Overexpression of hcrt in zebrafish has been reported to consolidate wakefulness and inhibit rest. On the other hand, fish lacking the hcrt receptor show short and fragmented sleep instead of sleepiness and cataplexy. Food deprivation increases hcrt mRNA expression in zebrafish brain, and intracerebroventricular hcrt peptides stimulate food consumption and feeding behaviour in goldfish. Hcrt peptides thus have important roles in fish physiology. Many genetic and functional methods available render fish, especially zebrafish, a suitable organism to study new aspects of hcrt physiology in vertebrates. [source]

    Identification of novel markers expressed during fin regeneration by microarray analysis in medaka fish

    Masanobu Nishidate
    Abstract Urodeles and fish have a remarkable ability to regenerate lost body parts, whereas many higher vertebrates, including mammals, retain only a limited capacity. It is known that the formation of specialized cell populations such as the wound epidermis or blastema is crucial for regeneration; however, the molecular basis for their formation has not been elucidated. Recently, approaches using differential display and microarray have been done in zebrafish for searching molecules involved in regeneration. Here, we used the medaka fish, a distantly diverged fish species, for microarray screening of transcripts up-regulated during regeneration. By setting criteria for selecting transcripts that are reliably and reproducibly up-regulated during regeneration, we identified 140 transcripts. Of them, localized in situ expression of 12 transcripts of 22 tested was detected either in differentiating cartilage, basal wound epidermis, or blastema. Our results provide useful molecular markers for dissecting the regeneration process at a fine cellular resolution. Developmental Dynamics 236:2685,2693, 2007. © 2007 Wiley-Liss, Inc. [source]

    Evidence for a widespread involvement of NO in control of photogenesis in bioluminescent fish

    ACTA ZOOLOGICA, Issue 4 2010
    Jenny Krönström
    Abstract Krönström, J. and Mallefet, J. 2009. Evidence for a widespread involvement of NO in control of photogenesis in bioluminescent fish. ,Acta Zoologica (Stockholm) 91: 474,483. The presence of nitric oxide synthase (NOS) and nerve fibres in the photophores of seven bioluminescent fish species (Hygophum benoiti, Myctophum punctatum, Electrona risso, Cyclothone braueri, Vinciguerria attenuata, Maurolicus muelleri and Porichthys notatus) with endogenous photocytes, were investigated. Antibodies directed against neuronal and inducible NOS (n and iNOS respectively) and NADPH-diaphorase activity were used to reveal the locations of NOS, while antibodies directed against acetylated tubulin were used to visualize nerve fibres. The nNOS antibody labelled structures in all investigated photophores except in the organs from P. notatus. The photocytes of P. notatus showed NADPH-diaphorase activity. In the myctophid species, NOS-like immunoreactivity was found in small intracellular structures of the photocytes and in nerve fibres reaching the photocytes. nNOS-positive fibres were also found among lens/filter cells in V. attenuata, and in M. muelleri the cytoplasm of lens/filter cells contained NOS-like material. In C. braueri, a cell type located at a collecting chamber for luminous products in the photophore contained NOS-like material. All photophores received an innervation reaching the photocytes, as well as other components including lens/filter areas. The results of this study comply with an involvement of nitric oxide in the control of bioluminescence in several fish species. [source]

    Profiling invasive fish species: the importance of phylogeny and human use

    Carles Alcaraz
    ABSTRACT Understanding the ecological differences between native and invasive species is of considerable scientific and practical interest. We examined such differences between native and invasive inland fish species from the Iberian Peninsula in order to analyse the importance of phylogenetic correction and variability (in addition to central tendency). We collected 26 quantitative and qualitative variables on the ecology, life-history traits and human use of the 69 inland fish species of the Iberian Peninsula, including native, invasive and migratory species. The taxonomic distribution of invasive fish species deviated significantly from world freshwater richness and in contrast to native species, invasive fish belongs to only five taxonomic orders but to a wide spectrum of families not native to the Iberian Peninsula. Because the life-history traits were highly dependent on taxonomy, the results, with or without applying phylogenetic methods, differed and after accounting for phylogeny, invasive species displayed higher and wider latitude in general and a different reproductive season mainly among salmonids and cyprinids. Human use was also significantly different between native and invasive fish species and produced more variability in life-history traits of invasive species and uneven taxonomic distribution because of the high diversity of species introduced. We show that accounting for taxonomy and studying variability in addition to central tendency is important in the comparison of life-history traits between native and invasive species. [source]

    Determining prey distribution patterns from stomach-contents of satellite-tracked high-predators of the Southern Ocean

    ECOGRAPHY, Issue 2 2006
    J. C. Xavier
    The distribution of many cephalopod, crustacean and fish species in the Southern Ocean, and adjacent waters, is poorly known, particularly during times of the year when research surveys are rare. Analysing the stomach samples of satellite-tracked higher predators has been advocated as a potential method by which such gaps in knowledge can be filled. We examined the viability of this approach through monitoring wandering albatrosses Diomedea exulans at their colony on Bird Island, South Georgia (54°S, 38°W) over the winters (May,July) of 1999 and 2000. At this time, these birds foraged in up to three different water-masses, the Antarctic zone (AZ), the sub-Antarctic zone (SAZ) and the sub-Tropical zone (STZ), which we defined by contemporaneous satellite images of sea surface temperature. A probabilistic model was applied to the tracking and diet data collected from 38 birds to construct a large-scale map of where various prey were captured. Robustness/sensitivity analyses were used to test model assumptions on the time spent foraging and relative catch efficiencies and to evaluate potential biases associated with the model. We were able to predict the distributions of a wide number of cephalopod, crustacean of fish species. We also discovered some of the limitations to using this type of data and proposed ways to rectify these problems. [source]

    Insect community organisation in estuaries: the role of the physical environment

    ECOGRAPHY, Issue 3 2002
    D. Dudley Williams
    Insects are reportedly uncommon in marine habitats and, from a spatial/temporal intercomparison perspective, estuaries are among the least studied. We examined the natural variability seen among insect community organisation in estuaries on both sides of the North Atlantic, and evaluated the role of their physical environments. Community composition was found to be strongly influenced by three physical factors: estuary size, the degree of inundation by incoming tides, and substrate size/stability. Insects formed a significant proportion (17,54%, by numbers) of the benthic community of coarse-grained-substratum estuaries, and species richness increased with estuary size. Nymphs/larvae of mayflies, stoneflies, caddisflies, elmid beetles and chironomids dominated channel sites inundated by up to 25% of all incoming tides, but a gradual loss in species richness occurred downstream. However, even the most seaward sites supported high insect densities (up to 25,016 and 5433 m,2, supporting 26 and 4 species, at sites inundated by 75 and 100% of all incoming tides, respectively). Sites covered by tides for between 3 and 5 h twice daily were dominated by orthocladine chironomids, especially of the genus Orthocladius. Chironomid larvae contribute significantly to the diets of some coastal fish species, particularly juvenile flounder and sticklebacks. We present a schematic model summarising the relationships between estuary size, degree of inundation by salt water and insect community structure. [source]

    Long term effects of cormorant predation on fish communities and fishery in a freshwater lake

    ECOGRAPHY, Issue 2 2001
    Henri Engström
    Cormorant impact upon natural fish populations has long been debated but little studied because of the requirements of sound data that are often hard to fill. In this study I have monitored fish community composition/abundance before and after a cormorant colony was established in a high productive lake, Ymsen, of south-central Sweden. Data on fish abundance before cormorant establishment enabled me to control for changes in fish densities prior to cormorant colonisation. To control for possible changes in fish populations caused by factors other than cormorant predation (i.e. large-scale regional changes due to climate) data were compared with a control lake, Garnsviken, with no cormorants. Since Lake Ymsen also harbour an important commercial fishery, cormorant impact upon fishery yields was evaluated. The most important fish species in the diet of the cormorants were ruffe (75% by number), roach (11%) and perch (10%). Except for perch, commercially important fish made up a very small fraction of the cormorant diet. Eel, the most important fish for the fishery, was absent in the cormorant diet, pikeperch constituted 0.2% and pike 1.5%. Estimated fish outtake by the cormorants was 12.8 kg ha,1 yr,1 compared to 8.6 kg ha,1 yr,1 for the fishery. Despite considerable fish withdrawal by the cormorants, fish populations did not seem to change in numbers or biomass. The present study indicates that cormorant impact upon fish populations in Lake Ymsen was small and probably in no case has led to declines of neither commercial nor of non-commercial fish species. Still, the number of breeding cormorants in Lake Ymsen, in relation to foraging area, is among the highest known for Swedish lakes. [source]

    Non-native species disrupt the worldwide patterns of freshwater fish body size: implications for Bergmann's rule

    ECOLOGY LETTERS, Issue 4 2010
    Simon Blanchet
    Ecology Letters (2010) 13: 421,431 Abstract In this study, we test whether established non-native species induce functional changes in natural assemblages. We combined data on the body size of freshwater fish species and a worldwide data set of native and non-native fish species for 1058 river basins. We show that non-native fish species are significantly larger than their native counterparts and are a non-random subset of the worldwide set of fish species. We further show that the median body size of fish assemblages increases in the course of introductions. These changes are the opposite of those expected under several null models. Introductions shift body size patterns related to several abiotic factors (e.g. glacier coverage and temperature) in a way that modifies latitudinal patterns (i.e. Bergmann's rule), especially in the southern hemisphere. Together, these results show that over just the last two centuries human beings have induced changes in the global biogeography of freshwater fish body size, which could affect ecosystem properties. [source]

    Microgeographic genetic isolation in chub (Cyprinidae: Squalius cephalus) population of the Durance River: estimating fragmentation by dams

    C. Dehais
    Dehais C, Eudeline R, Berrebi P, Argillier C. Microgeographic genetic isolation in chub (Cyprinidae: Squalius cephalus) population of the Durance River: estimating fragmentation by dams. Ecology of Freshwater Fish 2010: 19: 267,278. © 2010 John Wiley & Sons A/S Abstract ,, Weirs and dams are wide spread throughout the world's river systems. The most direct effect of these barriers is the limitation of organism movements, i.e., the alteration of connectivity by fragmentation of the aquatic habitat. Whereas the impact of fragmentation on migratory fish species has been well studied, insights on nonmigratory species are still needed. In particular, knowledge on the effects of dams on cyprinid populations at the watershed scale is lacking. Therefore, we studied the genetic structure of eleven chub (Squalius cephalus) samples lined up in the highly fragmented Durance River (France). Using five microsatellite loci, we show that even if the overall genetic differentiation is low, isolation by distance does occur and that genetic diversity increases from upstream to downstream. Dams seem to participate jointly with waterway distance in the explanation of this pattern. However more precise conclusions cannot be made. Guidance for future studies are given. [source]

    Hydrological connectivity in coastal inland systems: lessons from a Neotropical fish metacommunity

    P. H. M. De Macedo-Soares
    de Macedo-Soares PHM, Petry AC, Farjalla VF, Caramaschi EP. Hydrological connectivity in coastal inland systems: lessons from a Neotropical fish metacommunity. Ecology of Freshwater Fish 2010: 19: 7,18. © 2009 John Wiley & Sons A/S Abstract,,, We assessed the influence of hydrological connectivity in structuring fish communities through seasonal samplings of environmental variables and fishes in a coastal lagoon and associated pools in the Restinga de Jurubatiba National Park, Brazil. Community structure attributes such as species richness, numerical density and biomass, Shannon,Wiener diversity index and evenness were compared between periods of the lowest and highest hydrological connectivity, while the environmental gradient and fish zonation were explored through ordination techniques. The greater hydrological connectivity established in the rainy season promoted the homogenisation of most environmental variables and fish species, which differed markedly from the arrangement observed in the dry season. Despite variation in fish species composition, community attributes showed non-significant differences between the dry and rainy seasons. The patterns of composition and numerical density in pools were strongly influenced by local factors, especially salinity, dissolved oxygen, total phosphorous concentration and water colour in the dry season, in addition to total nitrogen concentration and depth in the rainy season. Comparable to the role played by flood pulses in river-floodplain systems, the hydrological connectivity in these tropical coastal waterbodies seems to strongly influence fish community structure, and, therefore to determine regional biodiversity. [source]

    Tagging effects on three non-native fish species in England (Lepomis gibbosus, Pseudorasbora parva, Sander lucioperca) and of native Salmo trutta

    S. Stak
    Abstract,,, To address the dearth of information on tagging effects and long-term survivorship of tagged fish in native and introduced species, laboratory and field investigations were undertaken on three non-native fish species (pumpkinseed Lepomis gibbosus; topmouth gudgeon Pseudorasbora parva; pikeperch Sander lucioperca) tagged with coded-wire (CW), passive integrated transponder (PIT), radio (RT) telemetry and/or acoustic tags (AT), with survivorship of native brown trout (Salmo trutta) examined in the field. Laboratory results revealed high survivorship following tag attachment/insertion and resumption of feeding within 24,48 h of tagging (all mortalities could be attributed to an unrelated outbreak of fungal infection), with retention rates being high in both pumpkinseed and pikeperch but low in topmouth gudgeon (excluded from field studies). In the field, short-term post-operation survival was high in pikeperch, pumpkinseed and brown trout. In pumpkinseed and trout, 100% of RT fish survived a 24,30 day tracking study, with 60% and 80%, respectively, recaptured alive at least 3 months post-tagging. Of PIT tagged pumpkinseed, 44% were recaptured (after 6,18 months), with small-sized, CW-tagged fish (0.38 g weight) captured up to 1 year after tagging. In pikeperch, all AT fish except one (the smallest specimen) survived their full expected tracking period (i.e. tag life) , the single lost specimen survived at least half of its expected tracking period (i.e. 6 month battery life). Overall, the tagging methods used were highly effective in pumpkinseed and pikeperch, showing good retention and survival, but PIT tagging of topmouth gudgeon was plagued by low survivorship and tag rejection. [source]

    Fish movement and habitat use depends on water body size and shape

    D. A. Woolnough
    Abstract,,, Home ranges are central to understanding habitat diversity, effects of fragmentation and conservation. The distance that an organism moves yields information on life history, genetics and interactions with other organisms. Present theory suggests that home range is set by body size of individuals. Here, we analyse estimates of home ranges in lakes and rivers to show that body size of fish and water body size and shape influence home range size. Using 71 studies including 66 fish species on five continents, we show that home range estimates increased with increasing water body size across water body shapes. This contrasts with past studies concluding that body size sets home range. We show that water body size was a consistently significant predictor of home range. In conjunction, body size and water body size can provide improved estimates of home range than just body size alone. As habitat patches are decreasing in size worldwide, our findings have implications for ecology, conservation and genetics of populations in fragmented ecosystems. [source]

    Fish distribution and diet in relation to the invasive macrophyte Lagarosiphon major in the littoral zone of Lake Dunstan, New Zealand

    T. O. Bickel
    Abstract,,, Invasive macrophytes are usually associated with negative impacts on habitat quality and a threat to native biodiversity. However, they might provide the same beneficial functions of native macrophytes, i.e., the provision of food and shelter for fish, in the absence of native macrophytes. To assess the value of the invasive macrophyte Lagarosiphon major as a fish habitat, we investigated the spatio,temporal variation in the distribution of a small littoral fish species (common bully) in the littoral of Lake Dunstan, a New Zealand hydro lake. Large- and fine-scale common bully distribution could partly be explained by the occurrence of dense L. major stands. Additionally, variability in catch per unit effort was partly explained by season and recruitment. Diet analysis indicated that common bullies in the Lagarosiphon-dominated littoral fed on invertebrates (Mollusca, Trichoptera, Chironomidae) found on exotic L. major, therefore suggesting its role as a food provider in the system. These results indicated that invasive macrophytes can provide important ecosystem functions in disturbed habitats that are otherwise devoid of native macrophytes. Any macrophyte management strategy should therefore carefully consider the costs and benefits associated with macrophyte control. [source]

    Feeding ecology of fishes associated with Egeria spp. patches in a tropical reservoir, Brazil

    F. M. Pelicice
    Abstract ,, This research characterised feeding ecology of fishes associated with patches of Egeria najas and Egeria densa, two submerged macrophytes, in Rosana Reservoir, Upper Paraná River basin, Brazil. Fishes were sampled using a 1 m2 throw trap in patches of different macrophyte biomass and in three diel periods during a wet season. Fish diet (10 species) was primarily composed of autochthonous items (zooplankton, algae and aquatic insect larvae). Almost all intra-specific diet patterns had moderate to low levels of diet similarity, indicating a high variability in diet. Some species showed no diel patterns in feeding activity, whereas others were primarily diurnal or nocturnal. No differences in feeding activity were observed among habitats of medium and high macrophyte biomasses, and species tended to feed on the same items among these habitats. The most abundant fish species demonstrated low inter-specific diet overlap and appear not to compete for food resources. We suggest that Egeria patches are feeding grounds and shelter for small-sized fish species. Resumen 1. Esta investigación caracterizó la ecología trófica de las especies de peces asociadas a manchas de Egeria najas e E. densa, dos macrofitas sub-aquaticas, en la represa de Rosana (alto Río Paraná, Brasil). Los peces fueron colectados con un throw trap de 1 m2 en manchas con distintas biomasas de macrófitas y en tres períodos del día, durante la estación lluviosa. 2. La dieta de 10 especies estuvo compuesta principalmente de componentes autóctonos (zooplancton, algas y larva de insectos acuáticos). Casi todas las especies presentaron patrones de dieta intra-específica con similitudes moderadas o bajas (elevada variabilidad). Algunas especies no mostraron ningún patrón de actividad alimenticia durante el día mientras que otras fueron principalmente diurnas o nocturnas. No se observó ninguna diferencia de actividad alimenticia entre los habitats de media y alta biomasa de macrófitas, y las especies tendieron a alimentarse de los mismos componentes entre estos habitats. 3. Las especies de peces más abundantes mostraron un solapamiento alimenticio bajo y parecen no competir por recursos alimenticios. Sugerimos que las manchas de Egeria funcionan como lugar de alimentación y abrigo para los peces de pequeño tamaño. [source]

    Assessing the potential for fish predation to impact zebra mussels (Dreissena polymorpha): insight from bioenergetics models

    M. A. Eggleton
    Abstract,,, Rates of annual food consumption and biomass were modeled for several fish species across representative rivers and lakes in eastern North America. Results were combined to assess the relative potential of fish predation to impact zebra mussels (Dreissena polymorpha). Predicted annual food consumption by fishes in southern waters was over 100% greater than that in northern systems because of warmer annual water temperatures and presumed increases in metabolic demand. Although generally increasing with latitude, biomasses of several key zebra mussel fish predators did not change significantly across latitudes. Biomasses of some less abundant fish predators did increase significantly with latitude, but increases were not of the magnitude to offset predicted decreases in food consumption. Our results generally support the premise that fishes in rivers and lakes of the southern United States (U.S.) have inherently greater potential to impact zebra mussels by predation. Our simulations may provide a partial explanation of why zebra mussel invasions have not been as rapid and widespread in southern U.S. waters compared to the Great Lakes region. Resumen 1Modelamos la tasa de consumo anual de alimento y biomasa para varias especies de peces en una muestra representativa de ríos y lagos del este de Norte América. Combinamos los resultados para evaluar el potencial relativo que estas especies de peces pueden ejercer sobre la abundancia del mejillón asiático Dreissena polymorpha. Las predicciones sobre consumo para peces en lagos y ríos del sur fueron más del 100% comparadas con sistemas septentrionales. Esto se puede deber a las temperaturas anuales más altas y aumentos en la demanda metabólica de peces en ríos y lagos del sur de Norte América. 2La biomasa de varias especies claves de peces que consumen D. polymorpha no cambió apreciablemente con latitud. La biomasa de algunos peces que consumen D. polymorpha aumentó significativamente con latitud, pero este aumento no era de una magnitud suficiente para compensar la disminución en el consumo de alimento. 3Nuestros resultados apoyan generalmente la premisa de que los peces en ríos y lagos del sur de los Estados Unidos (EE.UU.) tienen un potencial inherente mayor para poder controlar D. polymorpha. Nuestras simulaciones proporcionan una explicación parcial de por qué las invasiones de D. polymorpha no han sido tan rápidas y ampliamente distribuidas en aguas sureñas comparado con la región de los Grandes Lagos. [source]

    Habitat use and population structure of four native minnows (family Cyprinidae) in the upper Missouri and lower Yellowstone rivers, North Dakota (USA)

    T. L. Welker
    Abstract,,, In 1997 and 1998, sampling was conducted on the Missouri and Yellowstone rivers, North Dakota, to obtain information on the distribution, abundance, and habitat use of the flathead chub (Platygobio gracilis Richardson), sicklefin chub (Macrhybopsis meeki Jordan & Evermann), sturgeon chub (Macrhybopsis gelida Girard), and western silvery minnow (Hybognathus argyritis Girard), four declining fish species (family Cyprinidae) native to the Missouri River basin, USA. The study area consisted of four distinct river segments near the confluence of the Missouri and Yellowstone rivers , three moderately altered segments that were influenced by a main-stem dam and one quasi-natural segment. One moderately altered segment was located at the confluence of the two rivers (mixing-zone segment (MZS)). The other two moderately altered segments were in the Missouri River adjacent to the MZS and extended up-river (above-confluence segment (ACS)) and down-river (below-confluence segment (BCS)) from this segment. The quasi-natural segment (Yellowstone River segment (YRS)) extended up-river from the MZS in the Yellowstone River. Catch rates with the trawl for sicklefin chub and sturgeon chub and catch rates with the bag seine for flathead chub and western silvery minnow were highest in the BCS and YRS. Most sicklefin and sturgeon chubs were captured in the deep, high-velocity main channel habitat with the trawl (sicklefin chub, 97%; sturgeon chub, 85%), whereas most flathead chub and western silvery minnow were captured in the shallow, low-velocity channel border habitat with the bag seine (flathead chub, 99%; western silvery minnow, 98%). Best-fit regression models correctly predicted the presence or absence of sicklefin chub, flathead chub, and western silvery minnow more than 80% of the time. Sturgeon chub presence and absence were predicted correctly 55% of the time. Best-fit regression models fit to fish number data for flathead chub, sicklefin chub, and sturgeon chub and fish catch-per-unit-effort (CPUE) data for flathead chub also provided good fits, with R2 values ranging from 0.32 to 0.55 (P < 0.0001). The higher density and catch of the four native minnows in the YRS and BCS suggest that these two segments are better habitat than the ACS and MZS. [source]

    Recruitment patterns of six species of cyprinid fishes in the lower River Trent, England

    A. D. Nunn
    Abstract,,,Fisheries data were collected for six species of 0-group cyprinid fishes from eight sites in the lower reaches of the River Trent, England, between May and October 1999 inclusive, using a micromesh seine net. Recruitment and growth patterns were observed via monthly length,frequency histograms and estimations of mean length. In the cases of roach and dace, growth was approximately linear through the summer, before declining in September and October. In the cases of chub and gudgeon, and to a lesser extent bream and bleak, however, there were suggestions of multiple recruitment events. It is argued that some of the fish species examined in the present study adopt fractional or protracted spawning strategies in the lower River Trent. [source]

    Diet dynamics of the juvenile piscivorous fish community in Spirit Lake, Iowa, USA, 1997,1998

    M. E. Pelham
    Abstract , We assessed temporal dynamics and variation among species and age-classes in the diets of age 0 and age 1 piscivorous fish species in Spirit Lake, Iowa, USA during 1997 and 1998. Species included walleye Stizostedion vitreum, yellow perch Perca flavescens, smallmouth bass Micropterus dolomieui, largemouth bass Micropterus salmoides, black crappie Pomoxis nigromaculatus and white bass Morone chrysops. Thirty taxa were identified in diets, including 12 species of fish. We found dramatic differences in diets among species, among age-classes within species and over time. Walleye, largemouth bass, smallmouth bass and white bass were piscivorous at age 0. Black crappie began piscivory at age 1. Yellow perch also began piscivory at age 1, but fish were a very small fraction of age-1 diets. The primary temporal pattern, seen in several species and age-classes, was an increase in piscivory from spring to fall. This pattern was due to the lack of small, age-0 prey fish in spring. Although some patterns were evident, the taxonomic composition of the diets of all species was highly variable over time, making generalizations difficult. A surprising result was the absence of yellow perch in the diet of age-0 walleye, despite their abundance in Spirit Lake and prominence in diets of age-1 walleye and other age 1-piscivores. Age-0 yellow perch were consistently too large to be eaten by age-0 piscivores, which preyed primarily on invertebrates and smaller fish such as johnny darters Etheostoma nigrum and age 0 bluegill Lepomis macrochirus. This finding suggests that predator-prey interactions and resulting population dynamics may be quite different in Spirit Lake than in other systems dominated by walleye and yellow perch., [source]

    Threatened obligatory riverine fishes in human-modified Polish rivers

    T. Penczak
    Abstract , The fate of obligatory riverine fish species (rheophils), which are the objects of anglers' exploitation (chub ,Leuciscus cephalus, nase ,Chondrostoma nasus, barbel ,Barbus barbus, gudgeon ,Gobio gobio), and brown trout (Salmo trutta m. fario) and grayling (Thymallus thymallus) (in the Gwda River basin only), were investigated in large alluvial rivers (Pilica and Warta) and in the medium-sized Gwda River basin. The Pilica (1973) and the Warta (1986,1987) were divided by large dams without fish ladders in their middle courses. The Gwda River was divided by only a few dams along its course, but its tributaries carrying pure water had numerous small dams that supplied water for fish farms. Other stresses influencing fish populations in these rivers were: pollution, overfishing, hydroelectric plants and bank revetments. Because the listed stresses occurred alternately and at various periods of time in these rivers, this enabled attributing the cause for extinction and reduction of the abundance and distribution. In the salmon Gwda River basin, a drastic decrease in spatial distribution and reduction of occurrence ranges of brown trout, grayling and barbel was evident in respect to the first study period (1980s) in the 1990s. In the large, alluvial Pilica River, nase, barbel and dace are on the edge of extinction and chub and gudgeon are vulnerable. In the Warta's tailwater, barbel is an extinct species, and chub, dace and gudgeon are vulnerable ones. In a site in the backwater, none of the above mentioned species became extinct, but their abundance and occurrence frequency decreased a bit in respect to the pre-impoundment period. Roach-generalist, which was used in this research as a "control" species, increased in abundance in all 3 rivers. These investigations univocally proved that the dams cause catastrophic stress for obligatory riverine species., [source]

    Determination of the bacterial pathogen Edwardsiella tarda in fish species by capillary electrophoresis with blue light-emitting diode-induced fluorescence

    ELECTROPHORESIS, Issue 18-19 2004
    Lijun Yu
    Abstract High-performance capillary electrophoresis (HPCE) has been applied to the identification, separation, and quantitation of intact bacteria. We demonstrate that a pathogen (Edwardsiella tarda) which causes systemic infection in commercially important fish species can be rapidly identified and determined (<10 min) after direct injection into fish fluid by CE blue light-emitting diode (LED)-induced fluorescence. SYTO 13 (488 nm/509 nm), a cell-permeable green nucleic acid stain, was used to stain the cells. Remarkably high efficiency (>1 200,000 theoretical plates/m) was achieved with this rapid and efficient CE method. It was found that proper sample vortexing (90 s) would be beneficial to disperse aggregated cells and facilitate the focusing of intact cells during electrophoresis. Ionization of the surface constituents of Edwardsiella tarda cells provided efficient surface charges for the intact cells to be separated from the EOF and damaged or lysed cells when the separation was performed in running buffer (3.94 mM Tris, 0.56 mM borate, 0.013 mM EDTA) at pH 10.5. The limit of detection (LOD) and recovery were found to be 4.2×104 cells/mL and 70.0%, respectively. This proposed CE method could become an effective tool for diagnosis and tracking of certain diseases caused by bacteria in fish species as well as in human beings. [source]

    Genotoxicity testing of the herbicide trifluralin and its commercial formulation Treflan using the piscine micronucleus test

    Serpil Könen
    Abstract In this study, the genotoxic effects of a widely used herbicide, trifluralin, and its commercial formulation, Treflan, were evaluated using the micronucleus test in a commercially important fish species, Oreochromis niloticus (Nile Tilapia). Fish were exposed to 1, 5, and 10 ,g/L doses of trifluralin and Treflan for 3, 6, and 9 days under laboratory conditions. Ethylmethanesulfonate, at a single dose of 10 mg/L, was used as positive control. Micronuclei were evaluated on the peripheral erythrocytes. Both Treflan and trifluralin treatments significantly increased the micronucleus frequencies in peripheral erythrocytes of O. niloticus. Furthermore, the genotoxicity of the active ingredient, trifluralin, was observed to be higher than that of the commercial formulation Treflan. Our results indicate that herbicide trifluralin has genotoxic potential in fish. Environ. Mol. Mutagen., 2008. © 2008 Wiley-Liss, Inc. [source]

    Comparative study of microcystin-LR-induced behavioral changes of two fish species, Danio rerio and Leucaspius delineatus

    Daniela Baganz
    Abstract The spontaneous locomotor behavior separated into day/night activity phases of two fish species Danio rerio and Leucaspius delineatus was recorded and quantified continuously under sublethal long-term exposure to microcystin-LR in tanks. Microcystin-LR was applied in concentrations of 0.5, 5, 15, and 50 ,g L,1. By using an automated video-monitoring and object-tracing system, the average motility (swimming velocity) and the average number of turns were assessed. Clear dose-dependent effects of microcystin-LR on the behavior of both test fish were measured. During the daytime, the motility of Danio rerio as well as Leucaspius delineatus increased significantly by exposure to the lowest concentrations, whereas higher concentrations led to significantly decreased motility. Influenced by microcystin-LR, the swimming time of Leucaspius delineatus reversed, going from a prominently diurnal activity to a nocturnal one; Danio rerio remained active during the daytime. Most of the relative changes in the behavioral patterns of Danio rerio and Leucaspius delineatus suggest these fish have comparable susceptibility to microcystin-LR and may indicate some adverse consequences for fish populations, for example, in connection with reproduction and predator,prey interactions. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 564,570, 2004. [source]

    Mercury-induced reproductive impairment in fish,,

    Kate L. Crump
    Abstract Mercury is a potent neurotoxin, and increasing levels have led to concern for human and wildlife health in many regions of the world. During the past three decades, studies in fish have examined the effects of sublethal mercury exposure on a range of endpoints within the reproductive axis. Mercury studies have varied from highly concentrated aqueous exposures to ecologically relevant dietary exposures using levels comparable to those currently found in the environment. This review summarizes data from both laboratory and field studies supporting the hypothesis that mercury in the aquatic environment impacts the reproductive health of fish. The evidence presented suggests that the inhibitory effects of mercury on reproduction occur at multiple sites within the reproductive axis, including the hypothalamus, pituitary, and gonads. Accumulation of mercury in the fish brain has resulted in reduced neurosecretory material, hypothalamic neuron degeneration, and alterations in parameters of monoaminergic neurotransmission. At the level of the pituitary, mercury exposure has reduced and/or inactivated gonadotropin-secreting cells. Finally, studies have examined the effects of mercury on the reproductive organs and demonstrated a range of effects, including reductions in gonad size, circulating reproductive steroids, gamete production, and spawning success. Despite some variation between studies, there appears to be sufficient evidence from laboratory studies to link exposure to mercury with reproductive impairment in many fish species. Currently, the mechanisms underlying these effects are unknown; however, several physiological and cellular mechanisms are proposed within this review. [source]

    Reproductive health of bass in the Potomac, USA, drainage: Part 1.

    Exploring the effects of proximity to wastewater treatment plant discharge
    Abstract Intersex (specifically, testicular oocytes) has been observed in male smallmouth bass (SMB; Micropterus dolomieu) and other centrarchids in the South Branch of the Potomac River, USA, and forks of the Shenandoah River, USA, during the past five years. This condition often is associated with exposure to estrogenic endocrine-disrupting chemicals in some fish species, but such chemicals and their sources have yet to be identified in the Potomac. In an attempt to better understand the plausible causes of this condition, we investigated the reproductive health of bass sampled up- and downstream of wastewater treatment plant (WWTP) effluent point sources on the Potomac River in Maryland, USA. Smallmouth bass were sampled from the Conococheague Creek and the Monocacy River, and largemouth bass (LMB; Micropterus salmoides) were collected near the Blue Plains WWTP on the mainstem of the Potomac River. Chemical analyses of compounds captured in passive samplers at these locations also were conducted. A high prevalence of intersex (82,100%) was identified in male SMB at all sites regardless of collection area. A lower prevalence of intersex (23%) was identified in male LMB collected at the Blue Plains site. When up- and downstream fish were compared, significant differences were noted only in fish from the Conococheague. Differences included condition factor, gonadosomatic index, plasma vitellogenin concentration, and estrogen to testosterone ratio. In general, chemicals associated with waste-water effluent, storm-water runoff, and agriculture were more prevalent at the downstream sampling sites. An exception was atrazine and its associated metabolites, which were present in greater concentrations at the upstream sites. It appears that proximity to effluent from WWTPs may influence the reproductive health of bass in the Potomac watershed, but inputs from other sources likely contribute to the widespread, high incidence of testicular oocytes. [source]

    Altered reproduction in fish exposed to pulp and paper mill effluents: Roles of individual compounds and mill operating conditions

    L. Mark Hewitt
    Abstract For the last 20 years, studies conducted in North America, Scandinavia, and New Zealand have shown that pulp and paper mill effluents affect fish reproduction. Despite the level of effort applied, few leads are available regarding the factors responsible. Effluents affect reproduction in multiple fish species, as evidenced by decreased gonad size, decreased circulating and gonadal production of reproductive steroids, altered expression of secondary sex characteristics, and decreased egg production. Several studies also have shown that effluent constituents are capable of accumulating in fish and binding to sex steroid receptors/binding proteins. Studies aimed at isolating biologically active substances within the pulping and papermaking process have provided clues about their source, and work has progressed in identifying opportunities for in-mill treatment technologies. Following comparisons of manufacturing processes and fish responses before and after process changes, it can be concluded that effluent from all types of mill processes are capable of affecting fish reproduction and that any improvements could not be attributed to a specific process modification (because mills normally performed multiple modifications simultaneously). Improved reproductive performance in fish generally was associated with reduced use of molecular chlorine, improved condensate handling, and liquor spill control. Effluent biotreatment has been effective in reducing some effects, but biotreated effluents also have shown no difference or an exacerbation of effects. The role of biotreatment in relation to effects on fish reproduction remains unclear and needs to be resolved. [source]