AUTHORS: Shasta Kamara, Program of Ecology, Evolution, and Conservation Biology, University of Illinois Urbana-Champaign; Jackson Glomb, Department of Natural Resources and Environmental Sciences, University of Illinois Urbana-Champaign; Cory Suski, Department of Natural Resources and Environmental Sciences, University of Illinois Urbana-Champaign
ABSTRACT: American Paddlefish (Polyodon spathula) have important commercial and recreational fisheries throughout their range, which covers a wide latitudinal gradient. Seasons for Paddlefish angling and harvest are broad and often set by dates, and, as a result Paddlefish can experience capture and release across a range of temperatures. Currently, the impact of thermal variation on Paddlefish response to capture stressors has not been defined, precluding us from making informed management decisions regarding the timing and duration of angling and harvest seasons. Therefore, the objective of this study was to quantify the response of Paddlefish to simulated capture and release across a range of temperatures using two experimental approaches. In the first study, juvenile Paddlefish were acclimated to 13, 17.5, and 22° C. Fish from each of these temperatures were subjected to a simulated angling experience and recovered for 30 minutes, 4 hours, or 8 hours; a second group of fish were given a critical thermal maximum test (CTmax) to quantify heat tolerance. The second study sought to quantify post-release behavior of adult Paddlefish after simulated commercial capture at different temperatures using tri-axial accelerometers. Results from the first study showed that Paddlefish acclimated to 13°C recovered from exercise within 4 hours, while fish acclimated to 22°C did not recover, even after 8 hours. The 17.5°C and 22.0°C treatments had higher CTmax than the 13.0°C treatment suggesting an upper limit to thermal tolerance. Results thus far indicate that Paddlefish experiencing warmer temperatures have reduced performance relative to cooler fish, suggesting that temperatures over 20 degrees may be stressful for released Paddlefish after exercise. Together, these projects can help inform how Paddlefish respond to capture stressors across a range of temperatures and inform future management options to minimize impacts on individuals.
