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Post by jollyrodger on Feb 22, 2007 22:39:27 GMT
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elwyman
Member
A nice autumn day on the Conwy
Posts: 1,035
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Post by elwyman on Feb 22, 2007 23:13:41 GMT
They were discovered in the Welsh Dee recently, all rather worrying.  |
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Post by potbelly on Feb 23, 2007 13:06:21 GMT
They were discovered in the Welsh Dee recently, all rather worrying. I thought that it was the Chinese Mitten Crab that was found in the system? I've not heard anything about the signals being in there. |
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Post by wilbert on Feb 23, 2007 16:22:49 GMT
There was a small report on Country File about 4 or 5 months ago about American Signal Crayfish being in the upper reaches of the Tweed. I think the river board employs someone to set traps and catch as many as they can but this is a pretty infective method as it only gets the larger ones plus they reproduce at quite a rate so eradicating them is very hard.
Nasty little critters and another example of the destruction a non native species can cause.
See my report in the Ribble thread about what the EA is going to do this summer on a small tributary of one of the main spawning becks.
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Post by stoater on Feb 23, 2007 18:43:34 GMT
???I knew they were in the Ettrick, but if ,as the report states, these ugly aliens are in the Till it does sound bad as the Till has miles and miles of high soft sandy banks. Poisoning wouldn't work due to this topography, even if the Tweed Foundation were prepared to sacrifice the Tills' genetic integrity, and a whole year of returning migratory fish. Trapping would only work on a huge synchronised scale, but even then it would need regular repetition.
Would these aliens reach a "natural" population level? Would "natural" predation by other fish (chub ? ) keep them down? Is there evidence of these things really ruining salmon spawning areas, and if so, under what conditions?
Worrying, for sure.
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