The Osprey Observer

What fish and why?

Each year the team of volunteers monitoring the Site B nest are asked to record the fish caught by 03(97). Inevitably it is not always possible to identify every fish, but nevertheless, we are starting to build up a very detailed picture of the favoured prey species. Volunteer David Perril has been comparing fish caught this year with those brought to the nest by 03 in previous summers...

Based on observations gathered in 2004 we posed the question What Fish and When?. Now, four years later, we are changing the question to what fish and why?

In 2004 the monitoring team had noted a total of 90 fish being brought to the nest site by 03(97) during the incubation period, and despite the fact that Rutland Water is very well stocked with trout, analysis of the data suggested that the total catch contained a very high proportion of roach compared with trout - see chart on right.

Roach continued to top the 'fish list' for the next three summers, but then things started to change. In 2007 we noted that of the fish brought to the nest site whilst observers were present, 85 were trout and just 46 roach - a significant shift compared to previous years when 03(97) had always caught more roach than trout.  The trend continued during 2008 and analysis of the data collected for the years 2004 to 2008 indicates a steady decline in the number of roach caught whilst the number of trout caught has increased.

No records are kept for the numbers of coarse fish being caught at Rutland Water but we are not aware of any evidence to suggest a decline in the numbers of roach and other coarse fish present here. 

So what is it that has prompted this significant, but as yet unexplained change? If you have any thought, please send us an email - we'd be delighted to hear from you!

Previous stories from the Osprey Observer

Stories that have appeared on this page earlier this year have been moved to archive pages: March/April, May/June and July-October.

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