PARENT SESSION
Oral Session # 44: Resource Management I: Theory; Aquatic Systems.
Presiding: C Swan
Wednesday, August 6. 8:00 AM to 11:30 AM, SITCC Meeting Room 106.
The removal of rusty crayfish from Sparkling Lake, WI.
Hein, Catherine1, Vander Zanden, M1, Magnuson, John1, Roth, Brian1, 1 Center for Limnology, Madison, WI, USA
ABSTRACT- The rusty crayfish (Orconectes rusticus), native to the Ohio River Valley, has become a problematic invader throughout many areas of the U.S. and Canada, including northern Wisconsin. It replaces congeners, reduces the abundance of macroinvertebrates and macrophytes, and has negative effects on the recruitment of sport fishes. While prevention of further dispersal is most effective, rusty crayfish have already become established in many lakes. We are attempting to eradicate rusty crayfish from Sparkling Lake, Vilas County, Wisconsin through intensive removal with traps and the implementation of trophy fishing regulations on important crayfish predators. This talk will focus on the trapping aspect of the removal effort. In August of 2001, we removed approximately 11,000 crayfish over two weeks. We further reduced the population by removing 38,500 crayfish over 40 days in the summer of 2002. Catch rates declined with removal, but also changed due to temporal differences in behavior during the summer. The ratio of females to males in traps increased from 2001 to 2002, perhaps due to competitive interactions occurring outside traps. We found no change in the average carapace length of crayfish caught during the removal. Few attempts at removing crayfish from natural systems without using biocides have been made, and prior attempts have failed. By combining an increase in predation with intensive removal, we may be able to push the population to collapse through depensatory dynamics.
Key words: invader, eradication, Orconectes rusticus, aquatic