Acoustic Tracking of Redband Rainbow Trout (Oncorhynchus myskiss gairdneri) in Lake Roosevelt (2015-2016), Evaluation of an Acoustic Receiver Array, and Low-Voltage Electroanesthesia for Tag Implantation.
Date of Award
Master of Science (MS) in Biology
Chapter 1. Telemetry methods are able to acquire knowledge of fish movements which are used for a variety of management decisions. Implanting tags for telemetry requires minor surgery and anesthesia. Anesthesia for tag implantation is typically achieved with chemicals. However, chemicals are inherently variable and have restrictions on their use. This has led to the use of alternative methods for achieving anesthesia such as low voltage electroanesthesia (LVEA). LVEA subjects fish to a continuous non-pulsed direct current to achieve anesthesia appropriate for tag implantation. Unlike chemicals fish are quickly anesthetized and recover from anesthesia instantaneously. My objectives were to subject several species of fish to LVEA and determine if it can bring these species to anesthesia appropriate for tag implantation and if the voltage gradient (volts applied/ distance between electrodes) varies by fish based on size, scale type, species and conductivity of the water. LVEA successfully anesthetized 280 individuals which comprised of 11 species. Ctenoid scaled fish required a significantly higher voltage gradient than cycloid scale fish (Kruskal Wallis chi square = 118, p<0.001). Water conductivity was greater where ctenoid scaled fish where collected than cycloid scaled fish (p<0.0001). Multiple regression indicated that an interaction of fish length, scale type, water conductivity, and species explained 62% of variation in voltage gradient to anesthetize fish. I suggest agencies that use LVEA record information while using this method and make the information freely available to help form a standard procedure
Chapter 2. An array of acoustic receivers is in place on Lake Roosevelt and Rufus Woods Reservoirs to study the movements of important fish species. The receivers in this array cannot determine how far away an acoustically tagged fish is from the receiver when an acoustic signal is detected on a receiver. Therefore, it is important to test the range at which these receivers can detect tags to understand where detections are likely coming from and to potentially improve the array by suggesting where to put additional receivers. I evaluated the receiver array with three methods: 1) stationary range testing which was done with a known delay tag at known distances from the receiver in 4 cardinal directions and at three depths at each location, 2) with telemetry data from tagged Redband Trout, and 3) float range testing conducted in the swift water downstream of Grand Coulee Dam. In total 43 receivers were stationary range tested. Generalized linear model indicated that detection frequency declined to 75% 100 m from receivers, 50% 300 m from receive and 25% 500 m from receiver. Tracks of tagged fish indicated 26 of 44 receivers detected greater than 70% of the fish that pass by them Float Range testing indicated the receivers below Grand Coulee
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Witte, Bryan T., "Acoustic Tracking of Redband Rainbow Trout (Oncorhynchus myskiss gairdneri) in Lake Roosevelt (2015-2016), Evaluation of an Acoustic Receiver Array, and Low-Voltage Electroanesthesia for Tag Implantation." (2017). EWU Masters Thesis Collection. 433.