In acoustic telemetry studies done on fish, there is a common rule where the implanted acoustic tag cannot weigh more than 2% of the study species body weight, or else it could lead to premature death or a change in behavior (Jepsen et al. 2005). We tested this rule for walleye in Mille Lacs Lake in central eastern Minnesota, in order to determine if this rule stands for lake fish. We collected juvenile walleye where half of them were over 100g, and the acoustic tag was under 2% of their body weight, as well as walleye under 100g, where the tag weight is over 2% of their body weight, and their respective control counterparts. After collection, surgery, and acclimation, we performed behavioral observations, observed growth indices, wound healing, and performed a swim stress test to emulate what the fish with implanted tags would undergo in the lake. When comparing the growth indices, behavioral observations, and the stress endurance swim test, there was no significant statistical difference between the control and surgery treatment groups of the juvenile walleye. Additionally, when comparing the two groups of walleye that underwent surgery, those under 100g, and over 100g, there was no significant difference between predetermined wound healing ratings. Overall, the 2% rule is a conservative guideline to follow when performing acoustic telemetry projects, but we found that there was no difference in walleye where the tag weighed up to 4.8% of the fish’s total body weight. Since there is a smaller size restriction on walleye and similar lake fish, there is opportunity for more smaller juvenile fish being able to be monitored and available for study.
Claussen, Rachel, "Validation of acoustic transmitters in juvenile walleye in Mille Lacs Lake, Minnesota" (2018). Internship Reports (Restricted). 318.
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