946 resultados para migratory fishes


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Thesis (Master's)--University of Washington, 2016-08

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Thesis (Ph.D.)--University of Washington, 2016-08

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In this research, 9 species of local and introduced fishes of the Zayandehroud River in Esfahan province (in the Sarmatian region belonging to the large paleoarctic fauna) in 6 seasons (winter 2003, spring, summer, autumn and winter 2004 and summer 2005) were parasitologically studied. The local fishes included alburnoides bipunctatus, Alburnus maculatus, Aphanius vladykovi, Capoeta aculeata & Capoeta damascina & the introduced fishes included Aristichthys nobilis, Carassius auratus, Ctenopharyngodon idella and Cyprinus carpio. Upon being hunted, the fishes were transferred alive to Esfahan Aquatics Breeding Center and physiologically studied after the determination of their species and genus by identification keys Berg (30), Coad (31), Saadati (51), Abdoli (20) and Holchic (38). 32 species of parasites were totally identified as follows: 6 Protozoan species including Ichthyophthirius multifiliis, 5 Trichodina species, 2 Myxobolus species including Myxobolus cristatus & Myxobolus saidovi, 16 monogenea species including Dactylogyrus alatus. D. anchorutus, D. baueri, D. chalcalburni, D. chramuli, D. extensus, D. gracilis, D. lamellatus, D. lenkorani and D. pukher, 4 Dactylogyrus spp. 2 Gyrodactylus species, 1 species of Digenea, Diplostomum spthaceum, 4 species of Cestoda including Bothriocephallus gowkongensis, khawia armeniaca, Ligulaintestinalis. Caryophyllaeus sp. 1 Acanthocephala: Acanthocephalo rhynchoides cholodkowsky, 2 species of the crustaceans including the mature & copepodian stages of Lernaea cyprinacea & 1 sp of the genus Lamproglena. Out of all the 166 pcs of the fishes hunted in this research, 127 fishes (76.5%) were infected, and 39 fishes (23.50%) were not infected. In the fishes studied, having 14 of 32 species of the parasites identified, Capoeta aculeata displayed the most variety of infection, and having only 1 sp of the parasites. Aristichthys nobilis displayed the least variety of infection. The new findings of the research will follow: Myxobolus saidovi sp is reported for the 1st time from Iran's fresh water fishes, Alburnus maculatus and Capoeta aculeata are new hosts for M. saidovi and M. cristatus, respectively. Regarding monogenea Capoeta damascina & C. aculeata were reported as the new hosts for parasite D. pukher. The presence of D. pukher the infection of Capoeta aculeata with D. chramuli, D. lenkorani and D. gracilis in the Zayandehroud river were the 1st report. Regarding the Cestodea, Bothriocephalus gowkongensis was reported to be hosted by Aphanius Vladykovi for the 1St time in Iran.

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Small pelagic fish species have ultimately become important on most of the Great Lakes of Africa, especially after the depletion of the larger, initially preferred fish species. In Lake Victoria, the small pelagic cyprinid Rastrineobola argentea is now the only abundant native species supporting a fast growing light fishery. In Pilkington Bay, off Lingira Island the artisanal light fishery is well established and in the last two years this bay has witnessed a sharp increase in the fishing effort. This has been followed by a modification of fishing method and a reduction in the mesh size of nets used. R. argentea now caught from this bay consist of mainly juveniles and this could result into localized recruitment overfishing. Drawing examples from what is happening to the fishery in Pilkington Bay, it is necessary to carry out research on the stocks, gear and suitable fishing crafts before light fishing spreads to most parts of the lake.

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A better understanding of the key ecological processes of marine organisms is fundamental to improving design and effective implementation of marine protected areas (MPAs) and marine biodiversity. The movement behavior of coral reef fish is a complex mechanism that is highly linked to species life-history traits, predation risk and food resources. We used passive acoustic telemetry to study monthly, daily and hourly movement patterns and space use in two species, Schoolmaster snapper (Lutjanus apodus) and Stoplight parrotfish (Sparisoma viride). We investigated the spatial overlap between the two species and compared intra-specific spatial overlap between day and night. Presence-absence models showed different diel presence and habitat use patterns between the two species. We constructed a spatial network of the movement patterns, which showed that for both species when fish were detected by the array of receivers most movements were made around the coral reef habitat while occasionally moving to silt habitats. Our results show that most individuals made predictable daily crepuscular migrations between different locations and habitat types, although individual behavioral changes were observed for some individuals across time. Our study also highlights the necessity to consider multiple species during MPA implementation and to take into account the specific biological and ecological traits of each species. The low number of fish detected within the receiver array, as well as the intraspecific variability observed in this study, highlight the need to compare results across species and individuals to be used for MPA management.

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Lake Kyoga at the time of Worthington Survey (Worthington, 1929) was fished by only natives around it. The fishing gears consisted of locally made basket traps, hooks and seine nets made out of papyrus. Fishing was mainly during the dry season as in wet season, the fishers would revert to crop growing. During 1937 to 1950s Oreochromis variabilis, oreochromis esculentus (Ngege) and Protopterus aethiopicus (Mamba) were the most important commercial fish species and contributed over 95% to the total landings until early 1950s when their proportions started to change as a result of changes in fishing techniques. The tilapiines' were then being caught using mainly basket traps and P.aethiopicus was caught in hooks prior to the mid 1950s.

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Animal-associated microbiotas form complex communities, which are suspected to play crucial functions for their host fitness. However, the biodiversity of these communities, including their differences between host species and individuals, has been scarcely studied, especially in case of skin-associated communities. In addition, the intraindividual variability (i.e. between body parts) has never been assessed to date. The objective of this study was to characterize skin bacterial communities of two teleostean fish species, namely the European seabass (Dicentrarchus labrax) and gilthead seabream (Sparus aurata), using a high-throughput DNA sequencing method. In order to focus on intrinsic factors of host-associated bacterial community variability, individuals of the two species were raised in controlled conditions. Bacterial diversity was assessed using a set of four complementary indices, describing the taxonomic and phylogenetic facets of biodiversity and their respective composition (based on presence/absence data) and structure (based on species relative abundances) components. Variability of bacterial diversity was quantified at the interspecific, interindividual and intraindividual scales. We demonstrated that fish surfaces host highly diverse bacterial communities, whose composition was very different from that of surrounding bacterioplankton. This high total biodiversity of skin-associated communities was supported by the important variability, between host species, individuals and the different body parts (dorsal, anal, pectoral and caudal fins).

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Sturgeons are important because of producing the expensive caviar. With regard to decreasing of natural stocks of these fishes, cultured sturgeons farms are expanding, so infectious or non-infectious agents can cause problems in this industry. One of the most important infectious diseases, are parasitic diseases, like gill parasites. In this study from March 2007 to June 2008, gills of 122 sturgeons of south west of Caspian Sea, 44 samples of juveniles from freshwater farms and 25 samples of cultured fishes in freshwater were collected and examined. Parasites were separated and determination of species and prevalence of them were done. Nitzschia sturionis and Diclybothrium armatum (monogenea) with general prevalence 8.7% in Acipenser persicus and 25.6% in Acipenser stellatus from sea sturgeons and Trichodina (sp.1, sp.2) and Ichthyophthirius multifiliis from freshwater sturgeons, were separated. Statistical analysis was done according to species, sex, length and weight of fishes. Pathology, morphometric and morphological characters of Nitzschia sturionis were also studied. At the end, we have suggested ways for health management of farms for prevention of parasites entry.

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Ornamental fish are more expensive in comparison with the other fish. It especially highlights in non-breeding fish (in imported one for importation costs). But of course, with entering the new and unhealthy fishes to aquarium or ponds, they may transmit a pathogen to others (interfere with Iran ornamental fish parasitic fauna). In this study (Dec. 2008- Sep. 2009), 400 fish gill arch from 4 species of ornamental fish (within focus on imported fish); namely, i.e. Goldfish (Carassius auratus), platyfish (Xiphophorus maculatus), Dwarf gourami (Colisa lalia) and Catfish (Hypostomus plecostomus) were inspected for gill ectoparasites and then pathologic effects (but in high- affected gill). In this study, seven protozoan and ten metazoan species, indeed seventeen parasite species were identified. Protozan parasites consist of: Trichodina spp. and Ichthyophthirius multifiliis were found in four fish species; Ichthyobodo necatrix (Costia necator/C. necatrix) and Cryptobia branchialis, were respectively found in Dwarf gourami and goldfish. The highest prevalence belongs to Ichthyophthirius (47%) in platyfish. Metazoan parasites consist of: Ancyrocephalus sp. (Dwarf gourami), Ancylodiscoides spp. (catfish and platyfish), Dactylogyrus vastator, D. baueri, D. formosus (only in goldfish) and Gyrodactylus spp. (in four fish species). The highest prevalence was related to Dactylogyrus vastator(82%) in goldfish. Histological effects in case with high prevalence of parasite were also observed, e.g., hypertrophy, Lamellar hyperplasia and fusion. In high-parasitized gill, there is dysfunction of gill.

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In this project, have been studied to determine the appropriate model to spatial, temporal and diversity of demersal fishes in the Sea of Oman, including Trichiuridae, Nemipteridae, Haemulidae, Arridae, Synodontidae, Batoidfishes, Carangidae, Scianidae, Carchariniformes and Serranidae. This research became operational from catch data during 2003 to 2013 (in 2007, due to the lack of ship failed). Processing and calculations was evaluated by using the software Excel, SPSS, Arc GIS and table curve 3D highest biomass and abundance was showed in strata A and C and 10-30 m depth layers was showed the best condition biomass. In other words, highest biomass was showed in the eastern region in the Oman Sea than the central and western regions. Batoidfishes and Trichiuridae had the highest biomass .Depth factors was showed a significant correlation with the biomass. Scianidae, Serranidae and Haemulidae were showed a large decline. Synodontidae was showed a very large increase. The largest of Shannon index belong to central and western region of the Oman Sea. The highest Shannon index was showed 10-20 and 50-100 m, respectively. The Distribution maps based on the biomass was analyzed by using Arc GIS software. So that were identified in the first time in a ten-year period and carefully catch stations any economic of aquatic group. In conclusion, the depth can be found in the pattern of distribution, abundance and diversity of fish from away the beach so that follow specific pattern.

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Cold smoking method is one of the commonest ways for fish smoking. It is done by the smoke that is the result of burning hard and soft woods is smoking rooms. Smoke includes a number of chemical constructs and its main part is poly aromatic hydrocarbons. More than one hundred kinds of these constructs are recognized in smoke that is produced from saturated hydrocarbons resulted from the solution of the woods Ligno cellulose in high temperature and lack of oxygen conditions. The high poisoning potentials and carcinogenic features sixteen constructs among them are proved and observed on humans. In this research, the PAH compounds were identified and observed in a three month period after smoking and during storing among three types of smoked fishes Silver carp and Caspian sea Sefid and herring. They are the most produced and consumed smoked fish in Iran. To find the relationship between the concentrations of PAH constructs and the amount of lipid in fish, first, the amount of lipid were determined separately in the skin and flesh of 30 samples of each type. The method used was Bligh and Dyer (1959). PAH compounds derivation were made for all skin and flesh samples smoked fish using organic solvents with Soxeleh and the derived samples were injected to gas chromatography (GC) by Hamilton injectors for determining their components quality and their quantity. The height of the used column was 25 meters and its diameter was 0.32 mm with the silica filler, nitrogen gas as carrier and flame ionization detector (FID) that are special for these constructs. For data analysis, Statistical tests were used by computer soft ware identified that the difference in the amount of lipid within the flesh and skin of each species and also among each other is significant. The largest amount was in Herrings flesh and skin, 18.74% in skin and 14.47% in flesh. The least amount in the skin 4.19% and the flesh 3.10% of Sefid. The amount in Silver carp was 13.28%in skin and 8.16% in flesh. The examination of the PAH compounds in smoked fish showed that is carcinogenic compounds; exist in these in these fish with different quantities in each. It seems that its amount is directly related to the amount of their lipid. The amount is different in flesh and skin. One of the most important reasons is the direct content of smoke and the concentration of lipid in tissues of all three types. The maintenance of the smoked fish for three months showed that most of PAH compounds were solved and their density decreased. The changes in density within time in different in each type and in flesh and skin. The amount of their receiving in human through the consumption of the smoked fish depends on the resulted density, the way and the amount of consumption and now we can determine and execute standards for the maximum dosage per day and per month regarding effective factors.

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Small-scale spatial and temporal variability in animal abundance is an intrinsic characteristic of marine ecosystems but remains largely unknown for most animals, including coral reef fishes. In this study, we used a remote autonomous unbaited video system and recorded reef fish assemblages during daylight hours, 10 times a day for 34 consecutive days in a branching coral patch of the lagoon of New Caledonia. In total, 50 031 fish observations belonging to 114 taxa, 66 genera and 31 families were recorded in 256 recorded videos. Carnivores and herbivore-detritus feeders dominated the trophic structure. We found significant variations in the composition of fish assemblages between times of day. Taxa richness and fish abundance were greater in the early morning and in the late afternoon than during the day. Fourteen taxa displayed well-defined temporal patterns in abundance with one taxon influenced by time of day, six influenced by tidal state and seven influenced by both time of day and tidal state. None of these 14 taxa were piscivores, 10 were herbivore-detritus feeders, three were carnivores and one was plankton feeder. Our results suggest a diel migration from feeding grounds to shelter areas and highlight the importance of taking into account small-scale temporal variability in animal diversity and abundance when studying connectivity between habitats and monitoring communities.

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Early life stages of many marine organisms are being challenged by climate change, but little is known about their capacity to tolerate future ocean conditions. Here we investigated a comprehensive set of biological responses of larvae of two commercially important teleost fishes, Sparus aurata (gilthead seabream) and Argyrosomus regius (meagre), after exposure to future predictions of ocean warming (+4 °C) and acidification (ΔpH= 0.5). The combined effect of warming and hypercapnia elicited a decrease in the hatching success (by 26.4 and 14.3 % for S. aurata and A. regius, respectively) and larval survival (by half) in both species. The length for newly-hatched larvae was not significantly affected, but a significant effect of hypercapnia was found on larval growth. However, while S. aurata growth was reduced (24.8–36.4 % lower), A. regius growth slightly increased (3.2–12.9 % higher) under such condition. Under acidification, larvae of both species spent less time swimming, and displayed reduced attack and capture rates of prey. The impact of warming on these behavioural traits was opposite but less evident. While not studied in A. regius, the incidence of body malformations in S. aurata larvae increased significantly (more than tripled) under warmer and hypercapnic conditions. These morphological impairments and behavioural changes are expected to affect larval performance and recruitment success, and further influence the abundance of fish stocks and the population structure of these commercially important fish species. However, given the pace of ocean climate change, it is important not to forget that species may have the opportunity to acclimate and adapt.

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Amongst migratory species, it is common to find individuals from different populations or geographical origins sharing staging or wintering areas. Given their differing life histories, ecological theory would predict that the different groups of individuals should exhibit some level of niche segregation. This has rarely been investigated because of the difficulty in assigning migrating individuals to breeding areas. Here, we start by documenting a broad geographical gradient of hydrogen isotopes (δ (2)H) in robin Erithacus rubecula feathers across Europe. We then use δ (2)H, as well as wing-tip shape, as surrogates for broad migratory origin of birds wintering in Iberia, to investigate the ecological segregation of populations. Wintering robins of different sexes, ages and body sizes are known to segregate between habitats in Iberia. This has been attributed to the despotic exclusion of inferior competitors from the best patches by dominant individuals. We find no segregation between habitats in relation to δ (2)H in feathers, or to wing-tip shape, which suggests that no major asymmetries in competitive ability exist between migrant robins of different origins. Trophic level (inferred from nitrogen isotopes in blood) correlated both with δ (2)H in feathers and with wing-tip shape, showing that individuals from different geographic origins display a degree of ecological segregation in shared winter quarters. Isotopic mixing models indicate that wintering birds originating from more northerly populations consume more invertebrates. Our multi-scale study suggests that trophic-niche segregation may result from specializations (arising in the population-specific breeding areas) that are transported by the migrants into the shared wintering grounds.

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Por meio de observações sub e supra-aquáticas foram registradas associações alimentares do tipo nuclear-seguidor entre três espécies de peixes characiformes - Chalceus epakros, Hemiodus semitaeniatus e Hemiodus unimaculatus - e uma espécie de raia de água doce - Potamotrygon orbignyi - nas bacias dos rios Teles Pires e Xingu, no Centro-Oeste do Brasil. Os peixes teleósteos foram observados seguindo as raias quando estas revolviam o substrato à procura de invertebrados, formando discretas nuvens de sedimento. Essas situações atraíram os peixes que se aproximaram das raias para se alimentar de pequenas presas e outros tipos de alimentos expostos desta forma. Esse é um típico exemplo de relação comensal onde um participante é beneficiado enquanto o outro não é prejudicado e representa o segundo registro na literatura de associação alimentar do tipo nuclear-seguidor entre raias potamotrigonídeas e peixes teleósteos, demonstrando o potencial de estudos naturalísticos para a descoberta de novas interações envolvendo espécies de peixes de água doce.