Benthic Macroinvertebrate and Chemical Assessment of Water Quality in Relation to the Shope Creek Trout Farm

Abstract

Abstract North Carolina is the second largest commercial producer of rainbow trout, Oncorhynchus mykiss, in the United States, yet few studies have measured the effects of trout farm effluent on regional water bodies. Our objective was to assess water quality directly upstream and downstream of a low-production rainbow trout farm located on Shope Creek, a second-order stream in western North Carolina, using both biological and chemical assessment methods. Benthic macroinvertebrates were collected upstream and downstream of the trout farm annually from 2009 to 2011 using Hester-Dendy samplers. Organisms were identified to family and compared using the Family Level Biotic Index. We found no significant difference between mean upstream and downstream index values, suggesting no negative impacts of trout farm effluent on the macroinvertebrate community. Water samples were collected from each site on four days over a two month period, with three subsamples taken per site, per day. There were no significant differences between mean ammonia or phosphate levels upstream or downstream of the trout farm. While biochemical oxygen demand levels were significantly higher at the downstream site, this increase did not appear to affect the macroinvertebrate community. Between 2009 and 2011 the Shope Creek trout farm produced approximately 500 kg of fish annually. This is much lower than average annual regional trout farm production rates of 34,000 kg of fish, which likely accounts for the minimal impacts observed in this study.