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Wild Fish Populations (wild + fish_population)
Selected AbstractsFirst record of saddleback syndrome in wild parrotfish Sparisoma cretense (L., 1758) (Perciformes, Scaridae)JOURNAL OF FISH BIOLOGY, Issue 3 2008G. Koumoundouros The saddleback syndrome is recorded for the first time in a wild fish population of the Mediterranean Sea. The deformed specimen belongs to Sparisoma cretense and presents the typical saddleback phenotype of missing spines in the dorsal fin. [source] Synergistic effects of esfenvalerate and infectious hematopoietic necrosis virus on juvenile chinook salmon mortalityENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2005Mark A. Clifford Abstract Sublethal concentrations of pollutants may compromise fish, resulting in increased susceptibility to endemic pathogens. To test this hypothesis, juvenile chinook salmon (Oncorhynchus tshawytscha) were exposed to sublethal levels of esfenvalerate or chlorpyrifos either alone or concurrently with infectious hematopoietic necrosis virus (IHNV). Three trials were performed with fish exposed to concentrations of IHNV between 0.8 × 102 and 2.7 × 106 plaque-forming units/ml and to 5.0 ,g/L of chlorpyrifos or 0.1 ,g/L of esfenvalerate. The presence and concentration of IHNV in dead fish were assayed by virus isolation and plaque assay techniques, respectively. Among groups exposed to both esfenvalerate and IHNV, 83% experienced highly significant (p < 0.001) mortality, ranging from 20 to 90% at 3 d post-virus exposure, and cumulatively died from 2.4 to 7.7 d sooner than fish exposed to IHNV alone. This trend was not seen in any other treatment group. Virus assays of dead fish indicate a lethal synergism of esfenvalerate and IHNV. Chlorpyrifos had no observed effect on total mortality or IHNV susceptibility. The present results suggest that accepted levels of pollutants may be seemingly nonlethal to fish but, in fact, be acting synergistically with endemic pathogens to compromise survivorship of wild fish populations through immunologic or physiologic disruption. [source] Selenium effects: A weight-of-evidence approachINTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 1 2007Blair G McDonald Abstract Selenium is increasingly an issue for a wide range of mining, industrial, and agricultural operations. Appropriate methods for evaluating the impacts of selenium in aquatic ecosystems are vigorously debated in the literature. Two common approaches include the use of tissue residue guidelines and reproductive toxicity testing using field-collected fish; however, each approach on its own does not provide sufficient evidence that wild fish populations are in fact impaired. The limitations of each method are discussed, and recommendations to improve the relevance of each line of evidence are provided. A 3rd line of evidence, field measurement of fish population dynamics, is proposed and also discussed. A framework, consistent with an ecological risk assessment methodology, for the design, application, and interpretation of selenium weight-of-evidence investigations is proposed. [source] Disease interaction between farmed and wild fish populationsJOURNAL OF FISH BIOLOGY, Issue 2004E. J. Peeler This paper reviews the literature on disease interaction between wild and farmed fish and recommends strategies to reduce the disease risks to both populations. Most, if not all, diseases of farmed fish originate in wild populations. The close contact between farmed and wild fish readily leads to pathogens exchange. Aquaculture creates conditions (e.g. high stocking levels) conducive to pathogen transmission and disease; hence pathogens can overspill back, resulting in high levels of challenge to wild populations. This is exemplified by sea lice infections in farmed Atlantic salmon. Stocking with hatchery reared fish or aquaculture escapees can affect disease dynamics in wild populations. Whirling disease has been spread to many wild rainbow trout populations in the US with the release of hatchery reared stock. The greatest impact of aquaculture on disease in wild populations has resulted from the movement of fish for cultivation. Examples of exotic disease introduction following movement of live fish for aquaculture with serious consequences for wild populations are reviewed. The salmon parasite, Gyrodactylus salaris, has destroyed wild salmon populations in 44 Norwegian rivers. Crayfish plague has wiped out European crayfish over much of Europe. Eels numbers have declined in Europe and infection with the swimbladder nematode Anguillicola crassus has in part been blamed. The impact of disease in farmed fish on wild populations can mitigated. Risk analysis methods need to be refined and applied to live fish movement and new aquacultural developments. Appropriate biosecurity strategies, based on risk assessments, should be developed to reduce pathogen exchange and mitigate the consequences. [source] An investigation into the prevalence of Renibacterium salmoninarum in farmed rainbow trout, Oncorhynchus mykiss (Walbaum), and wild fish populations in selected river catchments in England and Wales between 1998 and 2000JOURNAL OF FISH DISEASES, Issue 2 2008E Chambers Abstract A cross-sectional survey of Renibacterium salmoninarum infection in farmed rainbow trout (RBT) and wild fish populations was carried out in 10 farms and six river catchments, respectively, in England and Wales. The majority of the wild fish were sampled in 1998 and the farmed fish in 2000. Grayling, Thymallus thymallus, and brown trout, Salmo trutta, were the main wild species sampled. Two fish, one grayling and one salmon, Salmo salar, were R. salmoninarum culture-positive, compared with 40 confirmed polymerase chain reaction-positive wild fish. The highest prevalence of R. salmoninarum infection was found in grayling in rivers with RBT farms with a history of R. salmoninarum infection. One hundred and fifty fish were sampled from each RBT farm, but none of the fish was found to be R. salmoninarum -positive. Evidence was found, for the first time, for the presence of R. salmoninarum in an eel, Anguilla anguilla. [source] Trophic state, fish community and intensive production of salmonids in Alicura Reservoir (Patagonia, Argentina)LAKES & RESERVOIRS: RESEARCH AND MANAGEMENT, Issue 4 2001P. F. Temporetti Abstract The Governments of the Provinces located in Patagonia, Argentina, promote the intensive breeding of salmonids in the Andean Patagonian region. Although annual production is low (450 ton ha,1 year,1), some effects are significant. Waste produced by salmonid breeding (feed losses, faeces and excretion) increases nutrient and organic matter concentrations, which cause modifications of water quality, sediments and biota. A consequent risk is the elevation of eutrophication levels. Possible changes in water composition, sediments, algae and wild fish populations were studied. Sites affected by fish farming showed increased nutrient concentration, and phytoplankton and periphyton biomass. Chlorophyll a was similar at both sites (affected and unaffected by fish farm sites). Sediments clearly reflect fish farm waste inputs: total phosphorus and organic matter increased 12-fold and fourfold, respectively. The species present in the gill-net catches were the autochthonous Percichthys trucha, Odontesthes hatcheri, Diplomystes viedmensis, and the introduced salmonids Oncorhynchus mykiss, Salmo trutta, Salmo salar sebago and Salvelinus fontinalis. About 50% of the total catch was salmonids. A major portion of the catch per unit weight was composed of rainbow trout, followed by perch. The catch per unit weight obtained for this reservoir agrees with the range of values previously determined (Quiros 1990) for Patagonian reservoirs. Compared with previous studies by Freyre et al. (1991), a variation in catch composition exists. This consists mainly of an increase in the numbers and condition of O. mykiss and a decrease in P. trucha. Presence of fish that escaped from hatcheries, recognizable by their eroded fins, was observed; particularly in a sampling station near the fish cage systems. Variations in catches could be caused by cyclical changes in fish populations (Wooton 1991), by direct and indirect effects of intensive fish farming, or by a combination of both events, and can only be understood through long-term studies of catch variation. [source] | ||||||||||