Sunday, 21 November 2010

Cormorants on the increase despite cull

A survey of the numbers of cormorants being shot by fishery owners reveals they're still on the increase.

More than 2,000 were culled last year, according to Swansea University. But overall numbers have increased from 18,000 in the mid-1990s, to a current estimate of 21,000.

Dr. Dan Forman, the academic who led the study, said cormorants can destroy a fishery. He said eight birds can kill 100 fish in one session, while the birds will return three or four times a day to a water and gorge themselves until stocks are exhausted.

Bird groups are calling for alternatives to lethal methods of control. They claim fish refuges can help protect stocks.

This is all very well on small, commercial pools. But next to impossible on navigable rivers or the large, clear gravel pits which seem to the suffer the most from the birds' attentions.

Pike anglers know only too well how fisheries suffer. Long, lean pike point to a lack of prey and a water where the natural balance has been upset.

So far, studies have failed to get to grips with the cormorant's impact on other fish-eating birds, ranging from kingfishers and grey herons, to divers like the grebe and merganser.

Reasons for the bird's rapid increase - or rather the migration inland of what was a coastal or esturial species - have also received scant attention from scientists, although the collapse of stocks of sea fish seems the most likely.

Will the latest survey make any difference..? Watch this space.

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