Detection range of two acoustic transmitters in four reservoir habitat types using passive receivers

Abstract

Abstract Background Recently, South Dakota Department of Game, Fish, and Parks (SDGFP), has undertaken a suite of rigorous acoustic telemetry studies. The goals and scope of the individual research projects vary but all use the same receiver array throughout Lake Sharpe in central South Dakota. Prior to initiating the telemetry studies, we sought to describe the detection probability of receivers from a representation of habitats within Lake Sharpe, South Dakota. We used both a V9-2H transmitter and a V13-1L transmitter in combination with VR2W 69 kHz passive receivers [all from Innovasea (Vemco)] to determine detection probability in four novel habitats of Lake Sharpe. Both transmitter and receiver were moored at fixed distances (200 m 400, and 600 m) for multiple consecutive days and detection probability compared between transmitter type, distance, site, and diel period using ANOVA following arcsine square-root transformation. Results We found significant differences in detection probability between the four habitat types for both the V9 and V13 transmitters. Sites protected from wind and wave action, and with little boat traffic, had larger detection ranges compared to areas that were wind exposed and host more boat traffic. The site immediately downstream from a hydroelectric dam that is exposed to both high wind fetch and is popular for boating, exhibited the poorest detection probability at all distances for both transmitter types. V13 transmitters consistently exhibited greater detection probability relative to V9 transmitters and this difference was greater at further distances. In general, detection probability was higher at nighttime compared to daytime and these differences were significant dependent on transmitter, site, and distance. Conclusions Using the information presented, SDGFP has modified their receiver array to maximize the ability to detect acoustic transmitters in the novel habitats of Lake Sharpe. Specifically, receiver spacing was reduced and/or expanded dependent on the distance, where 50% detection probability was attained. More work is needed to identify those factors that influence detection probability of acoustic telemetry systems.