Fish Abundances and Behaviors Near a Large Electric Fish Barrier on the Chicago Sanitary and Ship Canal

Several electrical barriers are operating in the Chicago Sanitary and Shipping Canal to block the movement of Aquatic Nuisance Species between the Great Lakes and Mississippi River Basins. Fish behavior and the spatial and temporal patterns of fish abundances at the barrier were studied to better inform barrier operations.  Two separate studies are presented. In one, we placed caged Gizzard shad (Dorosoma cepedianum) in cages alongside conductive and non-conductive boat hulls and recorded their behavior as the boats traversed the barrier system. In the second we used boat mounted DIDSONs to record the seasonal abundances and behaviors of fishes observed near the barrier and in the electrical field. The caged fish study revealed that the current operating parameters incapacitated 100% of fish tested, and incapacitated fishes sooner as they entered the barrier system compared to the prior operating parameters. The DIDSON studies identified patterns in behavior and distribution of fishes at the barrier, and effects of fish length and schooling on distribution patterns. The results of these studies have identified better ways to manage risk of fish passage the barrier system and can be utilized in other areas where barrier systems are in place or are being considered.