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Fish Movements (fish + movement)
Selected AbstractsFish movement and habitat use depends on water body size and shapeECOLOGY OF FRESHWATER FISH, Issue 1 2009D. 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 movements: the introduction pathway for topmouth gudgeon Pseudorasbora parva and other non-native fishes in the UKAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 3 2010G. H. Copp Abstract 1.The contamination of fish consignments (for stocking or aquaculture) is a major pathway by which non-native organisms, including fish, are introduced to new areas. One of the best examples of this is the topmouth gudgeon Pseudorasbora parva, which was accidentally imported into Romania and then throughout Europe in consignments of Asian carp species. 2.The introduction and spread of topmouth gudgeon in the UK has been linked to imports and movements of the ornamental variety (golden orfe) of ide Leuciscus idus. To examine this hypothesis, relationships between authorized movements of both native and non-native fish species (in particular ide) and the occurrence in England of topmouth gudgeon were tested at the 10×10,km scale. 3.Topmouth gudgeon occurrence in the wild was significantly correlated with the trajectories of movements of ornamental fish species (ide/orfe, sunbleak Leucaspius delineatus) as well as a few non-ornamental fish species (European catfish Silurus glanis, Atlantic salmon Salmo salar and grass carp Ctenopharyngodon idella). 4.These results highlight the mechanism by which non-native fish species disperse from the point of first introduction, and especially that movements of fish within the country represent an important mechanism for accidental introductions of non-native species. © Crown copyright 2010. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd. [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] Past and present patterns of connectivity among populations of four cryptic species of freshwater mussels Velesunio spp. (Hyriidae) in central AustraliaMOLECULAR ECOLOGY, Issue 10 2004JANE HUGHES Abstract We examined genetic structure and levels of connectivity among subpopulations within each of four cryptic species belonging to the freshwater mussel genus Velesunio. We used allozymes and a fragment of the mitochondrial cytochrome c oxidase I gene to examine genetic variation in populations from isolated waterholes, belonging to four major inland drainages in eastern Australia. Based on evidence from other invertebrates in the region we predicted that, in each species, we would find evidence of historical connectivity among populations from different drainages. This was clearly not the case, as for the two species that occurred in more than one drainage there was evidence of both current and past restriction to gene flow. Moreover, given the potential for extensive dispersal of these mussels through the river systems during flood times via their fish hosts, we predicted low levels of genetic variation among populations from waterholes in the same drainage. Contrary to our expectations, all four species showed some evidence of restricted gene flow among waterholes within drainages. This suggests that either (a) mussel larvae are not produced during flood times, when their fish hosts would be free to move between waterholes, or (b) mussel larvae are attached to their hosts at these times, but the fish movement is limited between waterholes. [source] Springs in time: fish fauna and habitat changes in springs over a 20-year intervalAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2008Elizabeth A. Bergey Abstract 1.Despite the range of threats to springs and the number of spring-endemic species, studies of temporal changes in the fauna of springs have rarely been reported. Changes in the fish of 22 Oklahoma (USA) springs were compared among surveys in 1981, 1982, and 2001. 2.Twenty-year assemblage differences were correlated with physical alteration of specific springs and stocking of native fish, which was made possible by past habitat changes that produced pools. Physical alteration of springs is a major ongoing threat to Oklahoma springs. 3.Variation in spring fish assemblages among the three surveys was apparently affected by fish movement in and out of springs, and the greater rain-induced connectivity between springs and streams during one year. 4.Although flow reduction is a commonly cited threat to springs, there was little evidence of flow reduction impacts in this study because Oklahoma springs may have been affected prior to 1981 and high-flow springs, which most often contain fish, were in areas with low groundwater water use. Copyright © 2008 John Wiley & Sons, Ltd. [source] Effect of habitat fragmentation on spawning migration of brown trout (Salmo trutta L.)ECOLOGY OF FRESHWATER FISH, Issue 3 2006C. Gosset Abstract , Human-induced habitat alteration is one of the main causes of the decline of freshwater fish populations. The watershed of the River Bidasoa (Spain) is an example of heavily fragmented habitat. The local brown trout (Salmo trutta L.) population is disturbed, with evidence of poor recruitment as well as low adult densities in the main stem. Forty male and female adult migratory trout were tagged with external or internal radio transmitters and released. Fixed stations with data loggers and mobile antennae were used with daily surveys to track fish movements during the migration and spawning period (3 months). Migration distances did not exceed 10 km, and half of the fish never entered a tributary in the study area. Fragmentation because of weirs on the main stem apparently prevented fish from reaching their spawning destination. Fish that entered the tributaries were first confronted with an accessibility problem because of low discharge. However, each fish chose one tributary, without making attempts to run up in other tributaries. Once in the tributary, fish were restrained in their upstream movements by dams. The study area appeared to be isolated from the vast upper part of the watershed. Within the study area, upper parts of tributaries also seemed strongly disconnected from the main stem. This study illustrates the negative impact of river fragmentation on S. trutta migration pattern. Population sustainability can be directly affected through the low availability of spawning grounds for migratory fish. Long-term effects of fragmentation may cause reproductive isolation within watersheds, which in the case of trout also means isolated phenotypic population units. [source] Influence of lateral gradients of hydrologic connectivity on trophic positions of fishes in the Upper Mississippi RiverFRESHWATER BIOLOGY, Issue 3 2009KATHERINE A. ROACH Summary 1. Riverscapes consist of the main channel and lateral slackwater habitats along a gradient of hydrological connectivity from maximum connection in main channel habitats to minimum connection in backwaters. Spatiotemporal differences in water currents along this gradient produce dynamic habitat conditions that influence species diversity, population densities and trophic interactions of fishes. 2. We examined the importance of lateral connectivity gradients for food web dynamics in the Upper Mississippi River during spring (high flow, moderately low temperatures) and summer (low flow, higher temperatures). We used literature information and gut contents analyses to determine feeding guilds and stable isotope analysis to estimate mean trophic position of local fish assemblages. During June and August 2006, we collected over 1000 tissue samples from four habitats (main channel, secondary channels, tertiary channels and backwaters) distributed within four hydrologic connectivity gradients. 3. Mean trophic position differed among feeding guilds and seasons, with highest values in spring. Mean trophic position of fish assemblages, variability in trophic position and food chain length (maximum trophic position) of the two dominant piscivore species (Micropterus salmoides and M. dolomieu) in both seasons were significantly associated with habitat along the lateral connectivity gradient. Food chain length peaked in tertiary channels in both seasons, probably due to higher species diversity of prey at these habitats. We infer that food chain length and trophic position of fish assemblages were lower in backwater habitats in the summer mainly because of the use of alternative food sources in these habitats. 4. A greater number of conspecifics exhibited significant among-habitat variation in trophic position during the summer, indicating that low river stages can constrain fish movements in the Upper Mississippi River. 5. Results of this study should provide a better understanding of the fundamental structure of large river ecosystems and an improved basis for river rehabilitation and management through knowledge of the importance of lateral complexity in rivers. [source] Predicting and managing the effects of hypersalinity on the fish community in solar salt fields in north-western AustraliaJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2 2006B. W. Molony Summary Five concentrator ponds (CPs) of a solar salt field in Port Hedland, Western Australia were sampled by seine and gill nets over a 12-month period in order to describe the fish community and examine relationships between diversity, abundance and catch per unit effort (CPUE) with salinity. Salinity varied between 40.2 and 113.7, during the sampling period. Forty-one species of fishes were recorded from the CPs, with fewer species recorded from CPs of higher salinity. A significant inverse relationship was identified between salinity and the number of species (diversity) captured in gill nets, indicating that one species is lost with every 16, increase in salinity. A significant relationship between salinity and CPUE was also identified with gill-net samples, indicating a reduction of 1 kg h,1 with every increase in salinity of 5.5,. As CPs are connected by one-way flaps, fish movements are only possible into CPs of higher salinity. Thus, reductions in diversity, abundance and CPUE suggested fish mortalities, likely as a result of maximum or rapidly changing salinities exceeding the tolerance ability of individual species. As fish kills are not infrequent events in solar salt fields and result in economic losses due to loss of production and clean-up costs, the results may allow managers to identify high risk species and times of year of fish kills by using salinity measurements. Commercial, indigenous and/or recreational fishing opportunities are viable options for reducing fish biomasses within the CPs and are discussed. Although absolute salinity values were higher than those recorded from tropical Australian estuaries, salinity deviations within each CP are similar to other estuaries and the effect on the ichthyo-community is likely to be similar. [source] Individual-based models of cod movement and population dynamicsJOURNAL OF FISH BIOLOGY, Issue 2003H. J. Edwards Many fish species undergo seasonal changes in distribution, as a result of horizontal migrations between feeding, nursery and spawning grounds. Exploring the processes involved in these movements may be the key to understanding interactions with other species, man and the environment, and is therefore crucial to effective fisheries management. Recent tagging experiments providing information on the distribution of migratory fish stocks have indicated pronounced regional and temporal differences in the migratory behaviour of cod, suggesting complex interactions between this commercially important fish species and the environment. This paper presents a model of the horizontal movements of demersal fish, principally cod, using an individual-based modelling approach to explore and predict the relationship between demersal fish movements and key environmental and ecological factors. The model simulates the basic biological processes of growth, movement and mortality, and is driven by the analysis of physical tagging data recorded by electronic data storage tags (DSTs). Results show that the incorporation of behavioural data from DSTs into spatially explicit individual-based models can provide realistic simulations of large-scale fish stocks, thus giving a better understanding of their basic ecology and allowing more effective management of commercially important fish species. Possibilities of future improvements and extensions to the model are discussed. [source] The demography of introduction pathways, propagule pressure and occurrences of non-native freshwater fish in EnglandAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 5 2010G. H. Copp Abstract 1.Biological invasion theory predicts that the introduction and establishment of non-native species is positively correlated with propagule pressure. Releases of pet and aquarium fishes to inland waters has a long history; however, few studies have examined the demographic basis of their importation and incidence in the wild. 2.For the 1500 grid squares (10×10,km) that make up England, data on human demographics (population density, numbers of pet shops, garden centres and fish farms), the numbers of non-native freshwater fishes (from consented licences) imported in those grid squares (i.e. propagule pressure), and the reported incidences (in a national database) of non-native fishes in the wild were used to examine spatial relationships between the occurrence of non-native fishes and the demographic factors associated with propagule pressure, as well as to test whether the demographic factors are statistically reliable predictors of the incidence of non-native fishes, and as such surrogate estimators of propagule pressure. 3.Principal coordinates of neighbour matrices analyses, used to generate spatially explicit models, and confirmatory factor analysis revealed that spatial distributions of non-native species in England were significantly related to human population density, garden centre density and fish farm density. Human population density and the number of fish imports were identified as the best predictors of propagule pressure. 4.Human population density is an effective surrogate estimator of non-native fish propagule pressure and can be used to predict likely areas of non-native fish introductions. In conjunction with fish movements, where available, human population densities can be used to support biological invasion monitoring programmes across Europe (and perhaps globally) and to inform management decisions as regards the prioritization of areas for the control of non-native fish introductions. © Crown copyright 2010. Reproduced with the permission of her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd. [source] | |||||||||||||