9710 - Laserfiche WebLink

Home Browse Search

PERFORMANCE OF PIT TAG INTERROGATION SYSTEMS 405 Rattlesnake Creek project, we used three tag models produced by Digital Angel Corporation: BE (n = 1,343) at the beginning, ST (n = 2,566) in the middle, and SGL (n = 702) at the end of the study. Each subsequent tag had better read ranges than the former. At low EMF noise levels and optimum orientation, the ST model had up to 42% better read range than the BE tag (Peterson Engineering Services 2002), and the SOL tag had up to 9.3% better read range than the ST tag (Downing et al. 2005). As stated by Zydlewskiet al. (2006), these increases in read nmge are relatively small compared with what would be expected from the use of the next larger size of PIT tag (i.e., 23 mm in size). . Tagging in Beal'er Creek.-A total of 3,913 rainbow trout, steelhead, and brook trout (FL: range = 65-760 mm, mean = 120 mm, median = 115 mm, SD = 52.9) were PIT-tagged (1,672 ST tags and 2,241 SOL tags) in the Beaver Creek watershed in 2004 and 2005. Juvenile steel head and rainbow trout (n = 3,230) made up the majority of the tagged fish (79%). We used electrofishing gear to collect fish throughout the watershed of Beaver Creek and a two-way fish trapping weir located at rkm 1. Most of the electrofishing occurred during the summer, spring, and fall. The weir was operational from 22 October through 22 December in 2004 and from 20 March through 5 December in 2005. Installation and configuration of interrogation systems.-ln both Rattlesnake and Beaver creeks, we installed a custom-made PIT tag interrogation system to monitor fish movement. We needed a system that could be deployed in a natural section of stream, could distinguish between downstream and upstream move- ments, and would not need daily attention like a weir or trap. Each interrogator had six antennas arranged in three arrays of two antennas each (i.e., a 3 X 2 design). When a tag was detected, these systems provided information on what lmtenna it was read on and the date and time that the detection occurred. The PIT tag interrogation system in Rattlesnake Creek was installed at rkm 0.2. just upstream of its confluence with the White Salmon River. Although some antennas were installed in August 2001 (Con- nolly et al. 2005), it was not until 2003 that we acquired a multiplexing transceiver, Digital Angel's Model FSlOOIM, capable of autotuning and operating up to six antennas. Subsequently, we designed and installed an interrogation system with three arrays of two antennas each. The antennas were systematically nwnbered in a successively downstream manner, river left to river right (Figure 2). The transceiver wa~ located in a weatherproof housing near the stream. The FSlOOIM transceiver operated on 24-V DC power. Flow ! I Ant. #2 II Ant. #1 I Array A Pass-bys Ant. #4 II Ant. #3 Array B Hybrids Ant. #6 II Ant. #5 Array C Pass-bys FiGURE 2.-A conceptual diagram of the three-aIT'dY, six- antenna PIT tag interrogation system used in Rattlesnake and Beaver creeks. Pa~s-by antennas were anchored to the substrate at all four comers; hybrid antennas (Ant.) were anchored on the upstream side so that the downstream side could pivot up in the water column. This power was provided by a 24-V AC-to-DC linear power supply, which was cOlmected to grid power. Antennas were constructed with polyvinyl chloride (PVC) pipe to create rectangular shapes that varied in length and width. The antennas (numbers I and 2) in the upstream-most array (array A) each measured 3.1 m X 0.6 m. The middle array (array B) had a river left antenna (number 3) that measured 3.1 m X 0.6 m and a river right antenna (number 4) that measured 2~0 m X 0.8 m. The downstream-most array (array C) had a river left antenna (number 5) that measured 3.1 m X 0.6 m and a river right antenna (number 6) that mea~ured 2.0 m X 0.8 m. By varying the lengths of the antennas, we were able to span. mosl of the low-flow wetted width, thalweg, and one stream bank with a single antenna, and by adding a second antenna, we were able to include all or some of the stream's bank-full width. We used two methods to attach the antennas to the substrate to maximize the detection of PIT -tagged fish and the probability that the antennas would function during a dynamic range of stream flows. Antennas within the upstream-most (array A) and downstream- most (array C) arrays (Figure 2) were attached at all