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SteveA · 07-26-2009, 07:23 AM

I did find this:

"Pathways of introduction
The most common pathway of introduction into natural waters is stocking by humans. In the 1970-80s the stocking policy in the region was liberal, and the signal crayfish was introduced legally into a large number of natural waters. From the late 1980s onwards, the introduction of the signal crayfish into new areas was restricted by the environmental authorities due to the threat it posed to the indigenous, red-listed noble crayfish (Troschel and Dehus 1993, Skurdal et al. 1999, Edsman 2004). However, the distribution of the signal crayfish still rapidly increases, including more and more watercourses. The crayfish can spread by natural migration only within a watercourse, between migration barriers. Most of the current spread is therefore due to illegal introductions by humans."

Quoted from this article: Page 3

http://www.nobanis.org/files/factshe...eniusculus.pdf

This article, (page 3) also discribed when and why crayfish "migrate"

http://hyg.ipm.illinois.edu/pdf/hygpest200908.pdf

It's seems it is caused by extensive rainy periods.

We haven't had that lately...

07-26-2009, 07:23 AM	#3
SteveA Deceased Member Join Date: Jul 2006 Location: Gilford, NH Posts: 2,311 Thanks: 1,070 Thanked 2,054 Times in 497 Posts	Very Strange I did find this: "Pathways of introduction The most common pathway of introduction into natural waters is stocking by humans. In the 1970-80s the stocking policy in the region was liberal, and the signal crayfish was introduced legally into a large number of natural waters. From the late 1980s onwards, the introduction of the signal crayfish into new areas was restricted by the environmental authorities due to the threat it posed to the indigenous, red-listed noble crayfish (Troschel and Dehus 1993, Skurdal et al. 1999, Edsman 2004). However, the distribution of the signal crayfish still rapidly increases, including more and more watercourses. The crayfish can spread by natural migration only within a watercourse, between migration barriers. Most of the current spread is therefore due to illegal introductions by humans." Quoted from this article: Page 3 http://www.nobanis.org/files/factshe...eniusculus.pdf This article, (page 3) also discribed when and why crayfish "migrate" http://hyg.ipm.illinois.edu/pdf/hygpest200908.pdf It's seems it is caused by extensive rainy periods. We haven't had that lately... __________________ "Before you criticize someone, walk a mile in his shoes. That way, if he gets angry he'll be a mile away and barefoot!" unknown