Muskellunge Management: Fifty Years of Cooperation Among Anglers, Scientists, and Fisheries Biologists
Seasonal Movements of Muskellunge in North Bend Lake, West Virginia [Extended Abstract]
Scott F. Morrison and Lila H. Warren
The Muskellunge Esox masquinongy is native to North Fork Hughes River, West Virginia, which contains North Bend Lake, a 12.4-km-long, 123-ha impoundment. The lake serves as an important brood source for the West Virginia Division of Natural Resources Muskellunge propagation program. Muskellunge movement was monitored using acoustic telemetry from March 26, 2010 through January 2, 2014 to document seasonal movements and to verify any Muskellunge migration through the outlet structure of the dam. Twenty-four fish (mean total length = 91 cm; range = 68–109 cm) were collected using pulsed DC boat-mounted electrofishing equipment and surgically implanted with Sonotronics model CT-05-48-I acoustic transmitters. Twelve fish were males and 12 were females, and all tagged fish were sexually mature. Twelve fish were tagged in March 2010, six in March 2011, four in March 2012, and two in May 2012. Six submersible data loggers (Sonotronics model SUR-2) were stationed throughout the lake. Our data loggers did not provide full areal coverage of the lake, but because they provided full lateral coverage (shoreline to shoreline shoreline) at their deployment locations, movement by tagged Muskellunge into specific areas of North Bend Lake could be evaluated. Data were downloaded monthly throughout the study. Fish were actively tracked by boat in April, June, and July 2013 in North Bend Lake and in October and November 2013 in the tailwaters of North Bend Dam using a portable digital receiver (Sonotronics USR- 08), an omnidirectional hydrophone (Sonotronics TH-2), and a directional hydrophone (Sonotronics DH-4). Individual fish logged 5,345–134,826 detections (mean, 52,335 detections per fish). Fish were located by data loggers for 3–45 months (mean, 19 months): 7 fish were tracked for less than a 1 year, 11 for 1–2 years, 4 for 2–3 years, and 2 for 3–4 years. Data loggers recorded 1,256,046 detections from tagged fish with a range of 37,542–387,347 detections per data logger (mean, 209,341 detections per data logger). Two data loggers located in the downstream part of the lake recorded the greatest number of detections of tagged fish. Each of these data loggers stored 31% of all detection, for a total of 62% of all detections. The other four data loggers stored the remaining 38% of all detections. However, most fish moved throughout the lake, with 20 of the 24 implanted fish recorded at all six data loggers. Seasonal movement (spring = March–May, summer = June–August, fall = September–November, and winter = December–February) of marked fish was consistent during the 4 years of the study. Fish occupied the upstream half of North Bend Lake in spring and spent the summer and winter in the downstream half of the lake (Figure 1). Based on their upstream movements in early spring, Muskellunge appeared to use the upper areas of the lake for spawning purposes. In West Virginia, Muskellunge generally spawn in April when water temperatures reach 10°C (Miles 1978). Throughout the study, 77–96% of all locations recorded during April were from the two data loggers located in the uppermost portion of North Bend Lake. There was no difference between males and females in the timing of movement past the uppermost receivers in spring. Fish occupied the lower lake in early and late fall, but during mid-fall, 80% of all detections were recorded by data loggers located in the upper part of the lake. Determining reasons for collective upstream movement in October was beyond the scope of this study, but the movement may have been related to higher oxygen levels or greater availability of prey in the upper lake at that time of year. Seven implanted fish, or 29%, left the lake through the outlet structure of the dam. Four were actively tracked in the tailwaters in fall 2013, and one fish was harvested by an angler 56 km downstream of the lake in November 2011. Another fish was caught by an angler in the North Bend tailwaters in 2015. One additional fish that apparently escaped through the outlet structure of the dam was last detected by the data logger that was closest to the dam, a pattern followed by the other six fish found in the tailwaters. The lake elevation at the time each escaped fish was last detected was at least 0.31 m above normal pool (Figure 2), but fish did not escape during the highest lake level events or at a particular lake level. The lake level was falling at the time of escapement for five fish and rising for the other two fish. Six of the seven emigrant fish were males. The fact that more males left the study area than females may have important implications for establishing Muskellunge fisheries in impoundments. Examining the reasons for this disparity in behavior between males and females was beyond the scope of this study, and drawing any conclusions related to behavioral differences would require a larger sample size of tagged fish. Four Muskellunge emigrated during winter, two in summer, and one during fall. No fish migrated through the outlet structure of the dam in spring, which was consistent with our observation that all fish used the upper portions of the lake during this season. Fish left the lake at all times of day and night. Knowledge of seasonal movements of Muskellunge in North Bend Lake, particularly in spring, will enhance future broodstock collection efforts. Dam escapement by Muskellunge has the potential to substantially reduce Muskellunge densities in small impoundments, particularly those sustained by stocking, or to generate new populations in tailwaters. These are important considerations in developing Muskellunge management plans for similar systems. A detailed manuscript of this study can be found in the Journal of the Southeastern Association of Fish and Wildlife Agencies 2:42–49.