TrackingWe were able to locate 85 of the 95 tagged fish from both years combined. Missing individuals were assumed to have 1) moved into areas where we could not access, 2) been harvested and not reported, 3) been taken beyond our detection distance by a predator, or 4) had tags fail. We were also able to visually verify the survival of 21 of the 85 individuals.
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AnglingIn total, we had 34 reported angling events for our tagged Muskellunge in both years combined. Of those 34 reports, only 12 came from the warm-water period (July-August), even with lots of directed fishing effort from our team. We noticed that, with increasing temperature, Muskellunge were less likely to strike or follow baits.
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Mortality
In total, we had 10 apparent mortalities prior to the tracking season (before July) in both years combined, and one individual was harvested, bringing the total warm-water sample size to 74 individuals. These mortalities were assumed because none of these tags moved throughout the sampling period. Additionally, we attempted to visually verify the survival or mortality of these individuals with cameras and by snorkeling with no success (and the tags still never moved). During the warm-water period in both years combined, we observed a total of 8 mortalities, 4 post-angling and 4 natural. We were able to locate and retrieve the bodies of 7 of the 8 individuals to fully confirm mortality. The one individuals we could not retrieve had been swept over a dam during a high flow event.
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Table 1. Tabulated values for the fates of angled and non-angled tagged Muskellunge on the James River, Virginia during the warm-water period (July-August) with both years and all sites combined. The proportions of individuals that died post-angling were greater than the proportion that died naturally during the warm-water period (statistical difference based on Fisher's Exact Test).
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Temperature
Figure 1. Temperature plots for the James River, Virginia for 2020 in Big Island (A) and 2021 in the upriver (B) and Lynchburg (C). Plotted over the temperature data are points denoting when tagged fish were caught: blue circles indicate that the fish was later found alive and red triangles indicate that the fish died after the angling event. Overlaid on the plots are red rectangles to show the warm-water periods (July-August).
Current Conclusions
Muskellunge caught and released in the warm-water period (July-August) on the James River, Virginia do appear to have a higher probability of mortality than individuals that are not caught and released. However, catch rates for Muskellunge during the warm-water period are extremely low, particularly in the upriver reaches of the James River. It appears that Muskellunge experience extreme stress during the warm-water period and tend to cease moving and/or feeding activity unless absolutely necessary. Often, Muskellunge were observed congregating in cool-water refugia and exhibiting little to no movement or interest in any baits. Additionally, during the summer, water levels are extremely low, limiting boating access to many areas on the James River where Muskellunge can be caught, leading to a decreased probability of Muskellunge being caught in the warm-water period. Therefore, the data suggests that additional mortality from warm-water catch-and-release of Muskellunge in the James River does not pose a significant threat to the James River Muskellunge fishery.
Future Work
We will be combining these data with data from the SJL telemetry study, as well as the multi-state pond study, to get a more broad understanding of the potential effects of warm-water catch-and-release mortality in southern Muskellunge fisheries. Additionally, we will be looking at the James River data more in-depth to evaluate the potential effects of warm-water catch-and-release mortality on the trophy potential for the fishery (NOTE: these analyses are currently underway and will hopefully be finalized soon). Finally, after the conclusion of the catch-and-release mortality study, we will begin evaluating summer habitat use and movement for Muskellunge in the James River.