Date of Award
Master of Science
Scaphirhynchus sturgeons are species of concern throughout their ranges. To revitalize their populations, a thorough understanding of their habitat use during all life stages is critical. However, limited information exists about fine-scale habitat use during early life. To determine the feasibility of using radio telemetry to monitor habitat use in the field, I assessed growth and survival of age-0 sturgeon tagged with 0.2 g, non-functioning telemetry tags during an eight-week period in a controlled setting and then tested field performance in the Middle Mississippi River (MMR). Three treatments were evaluated: 1) control, 2) internally implanted tags, and 3) externally attached tags. Growth and survival varied across treatment groups (all comparisons P<0.05). Sturgeon with internally implanted tags grew slowly and had low survival, while sturgeon within the control group and those with external tags grew faster and had higher survival (~100%). A trial was conducted to determine swimming performance of each of the treatment groups, which resulted in no differences in critical swimming speed among the tag types. Based on these results, a field-based telemetry evaluation was performed to determine if it is feasible to monitor fine-scale habitat use. Four wild, age-0 Scaphirhynchus sturgeon were externally tagged with functioning radio transmitters in the MMR. After less than 24-h, the tagged fish were no longer detectable, likely due to environmental conditions (e.g., extreme depths and high conductivity). Thus, efforts should be directed to creating a small telemetry transmitter that uses technology (e.g., ultrasonic) that transmits well in deep rivers while maintaining a minimum tag weight and maximizing battery life. Fine scale habitat use of age-0 sturgeon may ultimately be able to be quantified in the MMR and other deep rivers in the future, if technologies improve.
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