Preliminary Examination of Cultured Fish Consumption by the Diamondback Water Snake Nerodia rhombifera

Abstract

The black hole so called for the lack of accounting, in aquaculture may account for unexplained losses of 20% or more per year in cultured organisms. Among potential causes are poor water quality and disease episodes, predation by birds, mammals, and reptiles/amphibians, and theft. At the Aquaculture Research Station of the University of Arkansas at Pine Bluff the diamondback water snake was commonly encountered. These live-bearing snakes of up to 2 m in length were observed consuming cultured channel catfish and baitfish, including goldfish. To begin to assess their capacity for damage, we held 3, 0.6-0.9 m adult snakes in large tanks. Each tank was supplied with a small water source for the goldfish, golden shiners and catfish fingerlings added, ad libitum. The consumption was monitored for three weeks. Consumption was no fish, 5 fish, and 1 fish; for an average of 0.7 fish/individual/week. Based on daytime observations of 5-10 snakes per 0.1 ha pond (likely an underestimate due to nocturnal activity in warm weather and under harassment) at the station and these results, an estimated loss of 5-10% per year may be expected.