Abstract

To control an unwanted Procambarus clarkii population in a pond near Zurich (Switzerland), it was intensively trapped throughout 1997. Over 7,000 adult P. clarkii were captured between June and November. CPUE averaged 4.1 but decreased to 1.3 towards the end of the trapping campaign. It is unlikely that this decrease is a success of the control measures, since CPUE is strongly temperature controlled. Average weight of the captured animals was 29 g (corresponding to ca. 50 mm total body length and 38 mm carapace length, respectively). It was similar at the beginning and the end of the trapping campaign (ca. 32 g), indicating that the removed crayfish were replaced within a short time by young animals. The fisheries authority of Canton Zurich decided to use poison to eradicate the P. clarkii-population. Since ovigerous females were found throughout the entire 1997 campaign, it is unlikely that complete elimination can be achieved by a single poisoning action. A more reasonable goal would be to reduce and then stabilise the unwanted population at a low density. In the case of P. clarkii, this can be achieved most effectively by decreasing recruitment, e.g. by introducing predatory fish like eel, perch or pike.

Supplemental Documents

• There are no supplementary documents for this article

Cited By

Citations: