Southeastern Naturalist L.H. Warren and P.W. Bettoli 2014 Vol. 13, No. 3 506 2014 SOUTHEASTERN NATURALIST 13(3):506–514 Evidence of Natural Reproduction by Muskellunge in Middle Tennessee Rivers Lila H. Warren1,2,* and Phillip W. Bettoli3 Abstract - Native Esox masquinongy (Muskellunge) in the Cumberland River drainage, TN, were nearly extirpated in the 1970s due to decades of over-fishing and habitat degradation from coal mining, logging, and other land-use practices. In an effort to preserve the species in that drainage, a stocking program began in 1976 in the upper Caney Fork River system in middle Tennessee where Muskellunge were not native. A trophy Muskellunge fishery eventually developed, but it was unknown whether Muskellunge were reproducing in the upper Caney Fork River system or whether the fishery was wholly dependent on the stocking program. To establish evidence of natural reproduction, we used seines, backpack electrofishing, and boat electrofishing gear in 2012 to find age-0 Muskellunge in the upper Caney Fork River system. Natural reproduction of Muskellunge was documented in the mainstem Caney Fork River above Great Falls Dam and in 3 of its 4 major tributaries. Seventeen age-0 Muskellunge were collected and one other was observed, but not handled. Age-0 Muskellunge grew rapidly (1.80–2.34 mm/day), and the largest fish collected during the study reached a total length of 399 mm by 9 October 2012. A cessation of stocking for several years coupled with routine monitoring could reveal whether natural recruitment is sufficient to sustain the fishery. Introduction Esox masquinongy Mitchill (Muskellunge) is the largest member of the Family Esocidae and is a popular and economically valuable sportfish endemic to North America. At one time there were thought to be two or three Muskellunge subspecies or “races” based on regional differences in coloration and squamation (e.g., Crossman et al. 1986, Trautman 1981). Presently, the taxonomic classification is without a division into subspecies (Nelson et al. 2004). In the southern US, the native range of Muskellunge extends to tributaries in the upper reaches of the Tennessee River and Cumberland River in middle and eastern Tennessee, southeastern Kentucky, and western North Carolina (Etnier and Starnes 1993, Parsons 1959). Muskellunge populations have not been well studied in the southern US (Brenden et al. 2006), and the most recent published study on riverine Muskellunge in Tennessee is more than 50 years old (Parsons 1959). In the early 20th century, Muskellunge were so prevalent in their native streams on the Cumberland Plateau of Tennessee that anglers used nets, traps, gigs, trot 1Tennessee Cooperative Fishery Research Unit, Tennessee Technological University, Cookeville, TN 38505. 2Current address - West Virginia Division of Natural Resources, Beckley, WV 25801. 3US Geological Survey, Tennessee Cooperative Fishery Research Unit, Tennessee Technological University, Cookeville, TN 38505. *Corresponding author - lilawarren@gmail.com. Manuscript Editor: Nathan Dorn Southeastern Naturalist 507 L.H. Warren and P.W. Bettoli 2014 Vol. 13, No. 3 lines, and even shotguns to harvest fish (Parsons 1958). Angling effort and Muskellunge fishing success declined during the early 1950s, and illegal harvesting was identified as one of several problems the species faced (Parsons 1958). Muskellunge populations were described as “rapidly dwindling” in the 1950s, and habitat in more than 168 km of native Muskellunge streams in Tennessee had been destroyed by acid mine drainage (Parsons 1959). The decline of native Muskellunge in Tennessee waters mirrored declines in many jurisdictions of Canada and the northern United States (Kerr 2011). Great Falls, a large waterfall on the Caney Fork River near Rock Island, TN, had historically prevented Muskellunge and other large native piscivores such as Sander vitreus Mitchill (Walleye) and Sander canadensis Griffith and Smith (Sauger) from colonizing the upper Caney Fork River and its tributaries (Little et al. 1983). In 1955, 20 native Muskellunge fingerlings were transplanted from Rock Creek, TN, a Cumberland Plateau stream, to the upper Caney Fork River in a pilot study to test stocking efficacy, and five of the fish were re-sighted in 1957 (Parsons 1958). Muskellunge populations were severely depleted throughout their native range in Cumberland Plateau streams by the early 1970s (Riddle 1975) and were declared endangered in the state of Tennessee in 1975 by the Tennessee Wildlife Resources Commission. To prevent the disappearance of Muskellunge from the Cumberland Plateau, the Tennessee Wildlife Resources Agency (TWRA) began stocking Muskellunge into the upper Caney Fork River system above Great Falls Dam in 1976. Although the upper Caney Fork River system was not part of the native range of Muskellunge in Tennessee, TWRA chose it as a focal area for establishing a Muskellunge population because it is in the Cumberland River drainage, it is similar in habitat to the species’ native streams in Tennessee, and there was no threat of future habitat degradation by coal mining (Little et al. 1983). Additionally, the earlier pilot study confirmed that Muskellunge stocked into the upper Caney Fork River could survive (Parsons 1958). The efforts by TWRA to expand the distribution of Muskellunge into non-native waters are similar to past and present efforts elsewhere in North America; nearly half of all the current Muskellunge populations in North America are the result of introductions (i.e., range expansions into non-native waters; Kerr 2011). From 1976 through 2011, the TWRA has stocked a total of 9943 Muskellunge fingerlings into the upper Caney Fork River and its tributaries above Great Falls Dam. Sixty-six percent of those stocked Muskellunge originated from hatcheries in Kentucky; 18% were from Tennessee’s Eagle Bend State Fish Hatchery, and 16% originated from hatcheries in Missouri. The genetic relationships among Muskellunge stocks in the southern US have not been described as they have been for northern populations (e.g., Great Lakes Basin; Kapuscinski et al. 2013), and Tennessee’s stocking program was not executed within any genetic conservation framework such as that seen in other State stocking programs (e.g., Wisconsin; Jennings et al. 2010). Tennessee Muskellunge populations recovered sufficiently from their endangered status, and the fishery in the upper Caney Fork River system was reopened in 1988 with a 915-mm minimum total length (TL) limit and a creel limit Southeastern Naturalist L.H. Warren and P.W. Bettoli 2014 Vol. 13, No. 3 508 of one fish per day (TWRA 2011). The Muskellunge fishery in the upper Caney Fork River system is considered a trophy fishery, and anglers there have reported catching fish longer than 1.3 m TL in recent years. During annual spring electrofishing surveys, adult Muskellunge that display signs of spawning activity (i.e., flowing eggs or milt, lesions, torn fins) are routinely captured. Some natural reproduction was thought to occur in the upper Caney Fork watershed above Great Falls Dam (J. Swearingen, TWRA, Crossville, TN, pers. comm.); however, it was not known with certainty whether natural reproduction was occurring or whether recruitment was sufficient to maintain the fishery. Soon after the Muskellunge stocking program began in 1976, Little et al. (1983) recognized the need to determine whether natural reproduction was occurring. Despite this recommendation, there has been no formal investigation of natural reproduction in the system. Therefore, the primary objective of this study was to determine if natural reproduction of Muskellunge occurs in the upper Caney Fork River system. Secondly, when naturally reproduced age-0 fish were found, we sought to describe age-0 Muskellunge distribution and growth. Study Area This study was conducted on the upper Caney Fork River and its four major tributaries (Calfkiller River, Collins River, Rocky River, and Cane Creek) above Great Falls Dam (Fig. 1). The Caney Fork River is a tributary to the Cumberland River. The Tennessee Electric Power Company constructed Great Falls Dam (35°48'06"N, 85°37'20"W) upstream of Great Falls in 1916 for the purpose of power generation; it was sold to the Tennessee Valley Authority (TVA) in 1939. Great Falls Lake is 35.4 km long and has a surface area of approximately 740 ha at full pool. Seventy-six km of the Collins River, 20 km of the Calfkiller River, 16 km of the Rocky River, and 11 km of Cane Creek were sampled in this study. An additional 7-km reach of the mainstem Caney Fork River near its confluence with Cane Creek was sampled. Methods The last stocking of fingerling (age-0) Muskellunge in the upper Caney Fork River system occurred in October 2011 before we initiated our survey of natural reproduction. We batch microtagged (Northwest Marine Technology, Shaw Island, WA) 600 fish (range: 262–375 mm TL, mean: 323 mm TL) in the dorsal musculature before they were stocked into the Collins River. All fingerlings stocked in 2012 were introduced after our survey work; therefore, any age-0 fish we collected were the result of natural spawning in 2012. We used seining, backpack electrofishing, and boat electrofishing in 2012 to capture age-0 Muskellunge in the main stem of the upper Caney Fork River and its four major tributaries above Great Falls Dam (Fig. 1). All Muskellunge collected in 2012 were checked for a microtag to ensure that they were naturally reproduced fish and not part of the cohort stocked in 2011. We targeted likely age-0 Muskellunge habitat, which according to the literature is shallow water with aquatic vegetation Southeastern Naturalist 509 L.H. Warren and P.W. Bettoli 2014 Vol. 13, No. 3 and low flow or backwater (Farrell and Werner 1999, Parsons 1959). We used a bag seine (6 m x 1.8 m with a 1.8 m x 1.8 m bag; 6.7-mm mesh in the wings and 4.7-mm mesh in the bag) to sample wild age-0 Muskellunge between 23 June and 22 August 2012 following the general methods of Farrell and Werner (1999), Murry Figure 1. Map showing locations where age-0 Muskellunge were sampled in the upper Caney Fork River system, TN, and numbers collected at each. Backpack electrofishing and seining sites are indicated with triangles and circles indicate sites where boat electrofishing gear was used. Arrows point to locations where 18 age-0 Muskellunge were collected; reaches where multiple fish were collected are indicated with tw o arrows. Southeastern Naturalist L.H. Warren and P.W. Bettoli 2014 Vol. 13, No. 3 510 and Farrell (2007), and Kapuscinski et al. (2012) (i.e., the seine was pulled parallel to shore for 20 m and then swung into shore). Sampling sites ranged from about 20 to 100 m of shoreline, and no more than three seine hauls were made at each site. Each site seined was sampled within 24–48 hours using backpack DC-electrofishing gear (Smith-Root model LR-24). A single zigzag pass was made through each site by a two-person crew. By sampling the same sites with two gears, we hoped to gain some insight into how efficient each gear was in terms of capturing age-0 Muskellunge. We suspected age-0 fish were too big to be caught with seines by August, and thus, between 23 August and 26 October 2012 we used a Smith-Root 2.5 GPP electrofishing unit mounted in a 4.3-m jet-drive powered johnboat to sample additional likely Muskellunge nursery habitats in reaches of all four tributaries accessible by motorboat, as well as reaches of the upper Caney Fork River mainstem that were too deep to be seined or electrofished using backpack electrofishing gear. Boat electrofishing transects were not of a predetermined length of shoreline or time, but total effort (i.e., seconds that an electric field was produced) at each site was recorded. Each age-0 Muskellunge captured was weighed (g) and measured (TL; mm). Before they were released, all fish captured in the present study were tagged with a passive integrated transponder (PIT) tag (Biomark, Inc., Boise, ID) to identify possible recaptures. Waypoints identifying fish-capture locations were mapped using ArcGIS 10.0 (ESRI, Redlands, CA). Results Wild age-0 Muskellunge were observed in the Calfkiller River (n = 1), Cane Creek (n = 5), the Collins River (n = 11), and the upper Caney Fork River (n = 1) (Fig. 1); one of those 18 fish was not netted but its location was recorded. No age-0 Muskellunge were collected in the Rocky River. The first fish (150 mm TL, 13 g) was collected in a seine haul on 25 June 2012; the last fish captured (281 mm TL, 92 g) was in a boat electrofishing sample on 26 October 2012. The shortest fish (148 mm TL, 15 g) was caught 2 July 2012; the longest fish (399 mm TL, 320 g) was caught 9 October 2012. No wild fish had a PIT-tag (i.e., none were recaptures from earlier in the season) or a microtag (i.e., none were hatchery fish stocked the previous fall). Eleven fish were collected (a twelfth was observed) using boat electrofishing gear (6.2 hours of actual electrofishing time) in 9 field days. Six fish were collected in 80 seine hauls in 11 field days (mean catch per seine haul = 0.075 ± 0.030 SE). No wild Muskellunge were collected by backpack electrofishing (5.9 hours of electrofishing time) over 9 field days. Age-0 Muskellunge length increased dramatically over the 123 days between the first and last capture (25 June–26 October 2012). The only two fish collected from the upper Collins River, collected late in the season, were much smaller than their counterparts and they were excluded from the regression model to estimate growth. For the remaining fish, the size-at-date relationship appeared linear over the sampling interval (F = 216.11; df = 1, 13; P < 0.0001; R2 = 0.94; Fig. 2) and produced an estimated growth rate of 2.34 mm/day. No strong pattern of differential Southeastern Naturalist 511 L.H. Warren and P.W. Bettoli 2014 Vol. 13, No. 3 growth among the different streams was evident. When the two fish from the upper Collins River were included in the model, the daily growth rate declined to 1.80 mm/day (F = 38.12; df = 1, 15; P < 0.0001; R2 = 0.7176). Discussion We documented natural reproduction in four of the five rivers sampled in the upper Caney Fork River system. Whether 2012 was a good (or poor) year for natural reproduction and recruitment in the upper Caney Fork River system is unknown, but the data presented herein can serve as a baseline for future studies of Muskellunge recruitment in the Caney Fork River system. The sporadic nature of stocking efforts, the documentation of natural reproduction in the current study, and the trophy fishery presently supported in the upper Caney Fork River system indicate that natural reproduction could be sustaining this fishery. Age-0 Muskellunge grow quickly throughout their range. Scott and Crossman (1973) generalized that Muskellunge in Canadian waters grow at about 2.2 mm/ day over their first 70 days and typically reach 254 to 305 mm TL at the end of their first growing season. Average lengths for age-1 Muskellunge ranged from 216 mm to 330 mm TL in prior studies in Tennessee and five other states (Axon 1978, Belusz 1978, Brewer 1980, Parsons 1959, Larscheid et al. 1999, Miles 1978). The Figure 2. Growth of age-0 Muskellunge collected in the lower reaches of the Collins River (open circles) and Cane Creek, Calfkiller River, and the upper Caney Fork River (filled circles) above Great Falls Dam, TN, 2012. Two fish collected in the upper reaches of the Collins River (stars) were excluded from the regression model. Day 1 = 25 June 2012, the date the first Muskellunge was captured. Day 123 = 26 October 2012, the date the last two fish were captured. Southeastern Naturalist L.H. Warren and P.W. Bettoli 2014 Vol. 13, No. 3 512 first Muskellunge captured in the present study in late June and early July 2012 were clearly age-0 fish based on their small size (148–150 mm TL), as were the other Muskellunge we captured during the 2012 growing season, and were not wild or stocked age-1 fish hatched in 2011. Although lengths of ~150 mm TL were not achieved as early in the growing season by age-0 Muskellunge in stream populations studied by Parsons (1959) in Tennessee or Brewer (1980) in Kentucky, spawning activity in 2012 was observed in mid-March 2012 (J. Swearingen, TWRA, pers. comm.) due to a mild winter, or about 4–6 weeks earlier than is typical for Muskellunge in Tennessee and Kentucky streams. Assuming early or mid-April hatch dates and growth rates of ~2 mm/day, age-0 Muskellunge would be expected to achieve lengths of 150 mm TL or more by late June and early July. Rapid growth over a long growing season allowed age-0 Muskellunge in our study to average 340 mm (SE = 22.5; n = 7) by October 2012, which is entirely consistent with the literature for an average length towards the end of a first growing season. Our estimates of daily growth (1.80–2.34 mm/day) are crude estimates due to small sample size and the possibility of reach-specific effects (e.g., differential spawning or hatch dates; forage availability) that we could not account for. Nevertheless, the growth rate estimates were also consistent with prior studies of Muskellunge. No age-0 Muskellunge were collected early in the season from the upper Collins River to compare to the only two relatively small age-0 fish that we collected from that reach late in October 2012 (which were excluded from the first growth model). Additional work will be required to compare growth of age-0 Muskellunge in the upper Collins River to other reaches of the upper Caney Fork River system to establish a general understanding of reach-specific spawning dates or growth-rate differences. Documentation of Muskellunge natural reproduction in the upper Caney Fork River system where a trophy fishery exists indicates that the TWRA has been successful in restoring this native piscivore to the upper Cumberland River drainage, albeit in waters where they were not native. Restoration efforts in Green Bay, WI, initiated in 1989 after native Muskellunge were extirpated, were successful in reestablishing a trophy fishery, and although spawning activity has been observed there, natural reproduction has not been documented, and the fishery has been sustained by stocking (Kapuscinski et al. 2007). In the St. Lawrence River, where Muskellunge are native, the goals of re-establishing a self-sustaining population and providing a trophy fishery have both been successful (Farrel l et al. 2007). The identification of naturally produced age-0 Muskellunge is just the first step in documenting a self-sustaining fishery. Because stocking has been irregular since 1976 and annual boat electrofishing surveys by the TWRA did not begin until 2007, it is difficult at the present time to determine whether the Muskellunge populations in the upper Caney Fork River system are self-sustaining. If stocking is discontinued, managers should be able to discern within a few years through annual boat-electrofishing surveys of age-0 and adult Muskellunge whether those populations are, in fact, self-sustaining or whether supplemental stockings are needed to maintain the fishery. Southeastern Naturalist 513 L.H. Warren and P.W. Bettoli 2014 Vol. 13, No. 3 Acknowledgments Funding for this research was provided by the Tennessee Wildlife Resources Agency; the Center for the Management, Utilization, and Protection of Water Resources at Tennessee Technological University; and the USGS Tennessee Cooperative Fishery Research Unit. We extend our thanks to Jack Swearingen, Tennessee Wildlife Resources Agency, for his assistance during all phases of this work, as well as to all of the anglers who volunteered their opinions on the location of potential spawning and nursery habitats. This manuscript benefitted from constructive comments on earlier drafts by J.M. Redding, S.B. Cook, D. Isermann, and two anonymous reviewers. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the US Government. Literature Cited Axon, J.R. 1978. An evaluation of the Muskellunge fishery in Cave Run Lake, Kentucky. Pp. 328–333, In R.L. Kendall (Ed.). Selected Coolwater Fishes of North America. American Fisheries Society Special Publication 11, Washington, DC. 437 pp. Belusz, L.C. 1978. An evaluation of the Muskellunge fishery of Lake Pomme de Terre and efforts to improve stocking success. Pp. 292–297, In R.L. Kendall (Ed.). Selected Coolwater Fishes of North America. American Fisheries Society Special Publication 11, Washington, DC. 437 pp. Brenden, T.O., B.R. Murphy, and E.M. Hallerman. 2006. Effect of discharge on daytime habitat use and selection by Muskellunge in the New River, Virginia. Transactions of the American Fisheries Society 135:1546–1558. Brewer, D.L. 1980. A study of native Muskellunge populations in eastern Kentucky streams. Bulletin Number 64. Kentucky Department of Fish and Wildlife Resources, Frankfort, KY. 107 pp. Crossman, E.J., S. Campbell, and L.E.M. Munro. 1986. The Muskellunge—What’s in a name? P. 345, In G.E. Hall (Ed.). Managing Muskies. American Fisheries Society Special Publication 15, Bethesda, MD. 372 pp. Etnier, D.A., and W.C. Starnes. 1993. The Fishes of Tennessee. University of Tennessee Press, Knoxville, TN. 681 pp. Farrell, J.M., and R.G. Werner. 1999. Distribution, abundance, and survival of age-0 Muskellunge in upper St. Lawrence River nursery bays. North American Journal of Fisheries Management 19:309–320. Farrell, J.M., R.M. Klindt, J.M. Casselman, S.R. LaPan, R.G. Werner, and A. Schiavone. 2007. Development, implementation, and evaluation of an international Muskellunge management strategy for the upper St. Lawrence River. Environmental Biology of Fishes 79:111–123. Jennings, M.J., B.L. Sloss, G.R., Hatzenbeler, J.M. Kampa, T.D. Simonson, S.P. Avelallemant, G.A. Lindenberger, and B.D. Underwood. 2010. Implementation of genetic conservation practices in a Muskellunge stocking program. Fisheries 35:388–395. Kapuscinski, K.L., B.J. Belonger, S. Fajfer, and T.J. Lychwick. 2007. Population dynamics of Muskellunge in Wisconsin waters of Green Bay, Lake Michigan, 1989–2005. Environmental Biology of Fishes 79:27–36. Kapuscinski, K.L., J.M. Farrell, and B.A. Murry. 2012. Feeding strategies and diets of young-of-the-year Muskellunge from two large river ecosystems. North American Journal of Fisheries Management 32:635–647. Southeastern Naturalist L.H. Warren and P.W. Bettoli 2014 Vol. 13, No. 3 514 Kapuscinski, K.L., B.L. Sloss, and J.M. Farrell. 2013. Genetic population structure of Muskellunge in the Great Lakes. Transactions of the American Fisheries Society 142:1075–1089. Kerr, S.J. 2011. Distribution and management of Muskellunge in North America: An overview. Fisheries Policy Section, Biodiversity Branch. Ontario Ministry of Natural Resources. Peterborough, ON, Canada. Larscheid, J., J. Christianson, T. Gengerke, and W. Jorgensen. 1999. Survival, growth, and abundance of pellet-reared and minnow-reared Muskellunge stocked in northwestern Iowa. North American Journal of Fisheries Management 19:230–237. Little, J., J.M. Smith, and R.M. Hatcher. 1983. Restoration of the Ohio River Muskellunge in Tennessee. Unpublished Agency Report 64. Tennessee Wildlife Resources Agency, Nashville, TN. 18 pp. Miles, R.L. 1978. A life-history study of the Muskellunge in West Virginia. Pp. 140–145, In R.L. Kendall (Ed.). Selected Coolwater Fishes of North America. American Fisheries Society Special Publication 11, Washington, DC. 437 pp. Murry, B.A., and J.M. Farrell. 2007. Quantification of native Muskellunge nursery habitat: Influence of body size, fish community composition, and vegetation structure. Environmental Biology of Fishes 79:37–47. Nelson, J.S., E.J. Crossman, H. Espinosa-Perez, L.T. Findley, C.R. Gilbert, R.N. Lea, and J.D. Williams. 2004. Common and scientific names of fishes from the United States, Canada, and Mexico. American Fisheries Society Special Publication 29, Bethesda, MD. 386 pp. Parsons, J.W. 1958. The study and management of the Muskellunge in Tennessee. Unpublished agency report. Tennessee Game and Fish Commission, Nashville, TN. 23 pp. Parsons, J.W. 1959. Muskellunge in Tennessee streams. Transactions of the American Fisheries Society 88:136–140. Riddle, J.W. 1975. Status of the native Muskellunge, Esox masquinongy ohioensis, of the Cumberland Plateau, Tennessee. M.Sc. Thesis. Tennessee Technological University, Cookeville, TN. 70 pp. Scott, W.B., and E.J. Crossman. 1973. Freshwater fishes of Canada. Fisheries Research Board of Canada Bulletin 184. Ottawa, ON, Canada. 966 pp. Trautman, M.B. 1981. The Fishes of Ohio. Ohio State University Press, Columbus, OH. 782 pp. Tennessee Wildlife Resources Agency (TWRA). 2011. TWRA Region 3 Muskellunge management plan. Unpublished Agency Report. Nashville, TN. 19 pp.