Last year, NACA entered a partnership with the Environment Agency and contracted the British Trust for Ornithology to look into the predation by cormorants in the Wensum valley with particular reference to identifying if there were certain environments which favoured predation and, at the same time to discover whether there were circumstances which reduced predation.
The problem of cormorant predation has been around for several years and has been particularly severe in south Essex
Early discussions with RSPB indicated that they were reluctant to have any part in research
Whilst many of the conclusions might be considered to be obvious to many anglers; it is useful nonetheless to have a formal report from such a body as the BTO. The report extends to some 39 pages and among the various conclusions are the following:
* Heavy weed growth discourages cormorant numbers.
* Lakes are more susceptible than flowing waters.
* Removal of roosting trees should be considered
* Intensively stocked waters are most vulnerable.
* Stocking with larger fish reduces predation.
* Trials with 'fake'/artificial vegetation should be considered.
* More research should be conducted into the provision of 'birdproof' fish refuges.
* While shooting has some short term benefit; new birds quickly migrate to fill the vacancies.
* Scaring systems merely move the problem to some other, less protected, water.
* The physical presence of anglers appears to be among the most effective method of predation prevention.
A copy of the report may be obtained from the BTO. It is Research Report No. 262, obtainable from the National Centre for Ornithology, The Nunnery, Thetford, Norfolk 1P24 2PU. Telephone 01842 750050 fax 01842 750030 cost £5.00 inc p.&p..
R. C. July 2001.