Conservation of barbel (Barbus barbus) in the River Great Ouse

• Main Author: Twine, Karen Gemma
• Other Authors: Cowx, Ian G.; Hirst, Ian
• Published: University of Hull 2013
• Subjects: 570; Biological sciences
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612643

There have been growing fears relating to the distribution and a perceived lack in natural recruitment of barbel in European rivers. This project reviewed existing literature, examined the suitability of Environment Agency data to assess barbel populations and designed investigations to identify possible bottlenecks in recruitment focusing on all life history stages and environmental influences, with the intention of developing a practical management plan for the River Great Ouse fishery that can be applied to other rivers. This study examined seasonal movements of 20 wild barbel via radio telemetry in a nine kilometre river stretch on the upper Great Ouse, recording weekly movements over an 18 month period. The project aimed to ascertain the effects of environmental influences on movement and habitat use. Radio tracking over 100 consecutive days throughout the spring periods in 2010 and 2011 gave an understanding of their daily movements, identified barriers limiting longitudinal movements and located active spawning gravels. Health of spawning gravels was assessed by monitoring changes in diatom growth and hyporheic water quality during the embryonic development stage. Representative freeze core samples from spawning gravels were used to assess fine sediment infiltration. Larval drift measured the number of larvae leaving the spawning grounds, a range of methodologies were used to capture 0+ to 3+ barbel. Habitat and feeding preferences were then evaluated. It was found that temperature and flow impacted movement, individuals moved through the entire river stretch, despite the presence of a weir that was previously thought of as impassable. Variations in sediment loading were found between spawning habitats, but fine sediment and organic matter were improved with gravel jetting. Larval drift and electric fishing were found to be the most effective methods for catching young barbel, but the necessary habitats to support these young fish were not readily available within the study stretch.