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RUSTY CRAYFISH (ORCONECTES RUSTICUS) DENSITY IN FOUR TRIBUTARIES OF THE ST. CROIX RIVER RELATED TO HUMAN ACTIVITY (FISHING)
Charlotte T. Martin, Student, Edgewood High School (Madison, WI)
Rusty Crayfish (Orconectes rusticus) have been found in the waterways of Wisconsin and Minnesota since the late 1960's. One of the ways that rusty crayfish are likely to have been spread is by fishermen releasing live bait. Several sites on the St. Croix and its tributaries in St. Croix State Park (MN) were classified as "fishing" (physical evidence of fishing activity) or "non-fishing" (little to no physical evidence of activity). The Kettle River, Kennedy Brook, Bear Creek, Sand Creek, and several boat launches and the backwaters of the St. Croix were sampled for the presence of rusty crayfish from June 2-11, 2008. Timed kick net surveys were supplemented with baited minnow traps, with 3 traps set out at each site and checked every 48 hours. This survey found marked difference in crayfish densities between the two fishing classifications, indicating that areas with high frequencies of fishing use have higher densities of rusty crayfish than areas not associated with fishing or other human activities.