Seasonal water level manipulation for flood risk management influences home-range size of common bream Abramis Brama L. in a lowland river

The increased threat of flooding from climate change requires ever greater management of rivers to alleviate flood risk. Although the impacts of river modification on fish communities are well documented, the effects of river management practices on fish behaviour have received relatively little attention. Here, a long-term (4 years) acoustic telemetry study was used to analyse the spatial–temporal behaviour of common bream in a lowland river system (River Witham, Lincolnshire, UK) in which water levels are artificially manipulated biannually as part of a flood storage strategy. Levels are lowered in the autumn and increased again in the spring, to increase in-river winter flood storage capacity. Home-range size varied according to season, with home ranges being larger in the spring and summer months in comparison with those recorded during the autumn and winter months. When water levels within the river system were artificially manipulated, the bream responded by altering their home-range size, increasing it after the levels had been raised and reducing it following the lowering of the river levels. This is in contrast to the cumulative overall distances bream were recorded to travel, which were unaffected by water level manipulation, suggesting water level manipulation did not affect activity levels. Although such changes in behaviour do not necessarily equate to a negative impact on fitness, reduced home-range size brought about by water level manipulation does have implications for habitat availability and the number of competitive, predatory and parasitic interactions encountered. Copyright © 2013 John Wiley & Sons, Ltd

Effects of surgically implanted tags and translocation on the movements of common bream Abramis brama (L.)

Data collected from wildlife telemetry studies relies on tagging and attachment having minimal impactson behaviour. Though a widespread technique, relatively few studies evaluate the impacts of differingtagging methods on both welfare and behaviour. Here we use tracking data, collected for other aims, toinvestigate the impact of inter-peritoneal surgical implantation of acoustic transmitters on the healthand behaviour of common bream, Abramis brama (L.). In five separate capture events, the behaviour interms of distances moved and linear range of newly tagged fish (n = 61) were compared to previouslytagged fish (n = 55) present in the same river at the same time. In the first 5 days post-tagging, newlytagged fish moved significantly further than previously tagged fish. Despite this difference, the linearranges moved by the two groups of fish were equivalent. During 6–10 days post tagging there was nosignificant differences between the two groups. Thus, the tagging procedure had short term, but not longterm behavioural impacts. In addition, a number of tagged fish were recaptured between 51 and 461days post-surgery. Recaptured fish appeared to have clean, well-healed incisions and exhibited ‘normal’behaviour in that they were caught alongside a large number of conspecifics. Three recaptured taggedfish were translocated ∼35 km downstream, to ascertain how translocation would affect their behaviour.The translocated fish had a greater linear range than control fish, with all three fish returning to the siteof capture within 6 to 24 days, suggesting that common bream can exhibit site fidelity

Effects of flow regulation on the movement patterns and habitat use of a potamodromous cyprinid species

River regulation for hydroelectricity production results in rapid changes of flow and habitat features, but its effects in the movement patterns of freshwater fish are not well understood. Radiotelemetry was used to track Iberian barbel during a year cycle in non-regulated and regulated rivers. We applied a kernel density method to estimate and compare home range sizes of the two populations. Seasonal patterns of movement and the intra-annual variation in habitat preferences were also compared. Barbel inhabiting regulated river exhibit larger and more continuous home and core ranges, in opposition to the smaller and patchy areas used by fish inhabiting the non-regulated river. Seasonal movements of both populations were differentiated by the drought period. Barbel from the non-regulated river had to search for suitable refuges, with specific habitat characteristics, in which they remained aggregated during harsh summer conditions. Conversely, barbel from regulated river kept a continuous distribution along the river. This study contributes to the management of regulated rivers by providing insights about which flow components are more altered by hydropeaking operations and which are the most critical annual periods for fish movements. It also suggests several restoration actions, such as the protection of fish summer refuges, the restoration of large-scale temporal streamflow variability and the reduction of daily rates of discharge rise and fall, which should be continuously monitored in order to increase their efficiency and provide new knowledge.info:eu-repo/semantics/publishedVersio