Esox Masquinongy Mitchill Research Articles

Using stable isotope data to quantify niche overlap and diets of muskellunge, northern pike and walleye in a deep Minnesota lake

AbstractMuskellunge (Esox masquinongy Mitchill), northern pike (Esox lucius L.) and walleye (Sander vitreus Mitchill) often coexist in lake communities, yet uncertainty exists about the potential for interspecific competition among these top predators. Stable isotope data were used to assess niche overlap and diets of these predators in Elk Lake (Minnesota, U.S.A). δ13C indicated primary production sources (e.g. pelagic v. littoral) and δ15N indicated trophic position; the bivariate distribution of these isotopes defined the species’ isotopic niche. Niche overlap probabilities were calculated and stable isotope mixing models were used to quantify diet proportions. Muskellunge and northern pike niches overlapped little (<10%), while walleye overlapped muskellunge (15%–60%) and northern pike (33%–53%) more extensively. Muskellunge diets focused (50%) on cisco (Coregonus artedi Lesueur), walleye primarily assimilated non‐cisco prey fish (80%), and northern pike diets were dominated by non‐cisco prey fish (45%) and invertebrates (40%). The presence of a cisco population and the flexibility of northern pike to use invertebrate resources may decrease potential competition among these predators. However, cisco are threatened by climate change and eutrophication, and our results suggest that extirpation of cisco may cause major changes in potential competitive interactions among these top predators. Moreover, cisco were unique among prey species in their ability to exploit pelagic energy, such that loss of cisco will likely alter energy flow in lake food webs where they currently exist.

Thermal ecology of subadult and adult muskellunge in a thermally enriched reservoir

The movement of adult muskellunge, Esox masquinongy Mitchill, has been investigated in a variety of systems, but temperature selection by muskellunge has not been examined where well-oxygenated waters were available over a range of temperatures for much of the year. Thirty subadult and adult muskellunge tagged internally with temperature-sensing radio tags were tracked from March 2010 to March 2011 in a Tennessee reservoir. Mean tag temperatures were 18.9 °C in spring (March to May), 22.1 °C in summer (June to August), 16.5 °C in autumn and 9.8 °C in winter (December to February). When the greatest range in water temperatures was available (7.1–33.3 °C; May to early August 2010), their realised thermal niche (mean ± 1 SD) was 22.3 °C ± 1.8; the realised thermal niche was affected by fish size (smaller fish selected slightly warmer temperatures) but not sex. An electric generating steam plant discharging warm water resumed operation in January 2011, and most (86%) tagged fish occupied the plume where temperatures were ≈10 °C warmer than ambient water temperatures. No mortalities were observed 15 days later when plant operations ceased. Their affinity for the heated plume prompted concerns that muskellunge will be too easily exploited when the plant operates during winter.

Identification of stocked muskellunge and potential for distinguishing hatchery‐origin and wild fish using pelvic fin ray microchemistry

AbstractThe effectiveness of pelvic fin ray microchemistry of muskellunge, Esox masquinongy Mitchill, to identify stocked individuals along with the potential to identify naturally reproduced fish were evaluated. Fish and water samples were obtained from one hatchery and seven lakes with natural differences in water Sr:Ca to determine whether location‐specific environmental signatures were recorded in sectioned muskellunge pelvic fin rays, including fish of known environmental history. Water and fin ray Sr:Ca were strongly correlated. Six lakes in Illinois possessed Sr:Ca signatures that were distinct from the hatchery where muskellunge were raised, resulting in pronounced shifts in Sr:Ca across sectioned fin rays of stocked fish. Hatchery and lake‐specific Sr:Ca signatures were stable across years. Sixteen of 19 individual fish known to have been stocked based on PIT tags implanted at stocking were correctly identified as hatchery‐origin fish using fin ray core Sr:Ca. Results also indicated that the hatchery Sr:Ca signal can be retained for at least 7 years in fin rays of stocked fish. Fin ray microchemistry is a non‐lethal approach for determining environmental history of muskellunge that could be used to assess movement patterns in lake and river systems and the degree to which muskellunge populations are supported by natural reproduction and stocking.

Status of aboriginal, commercial and recreational inland fisheries in North America: past, present and future

AbstractThe inland fisheries of North America (i.e. Canada and the United States of America) are diverse in terms of the sectors that harvest fish, the waters fished and the species targeted. Aboriginal fisheries have a long tradition of harvesting fish for food and ceremonial purposes using gears such as dip nets and spears, and targeting species such as suckers (Catostomidae) and upriver migrating salmon (Salmonidae). The commercial sector includes large‐scale industrial operations on the Great Lakes and Mississippi River as well as smaller‐scale fisheries throughout North America that harvest fish for food or the bait industry. The recreational fishery is the largest sector (millions of participants) and includes everything from specialised catch‐and‐release fisheries for muskellunge, Esox masquinongy Mitchill and black bass (Micropterus spp.) to put‐and‐take fisheries for rainbow trout, Oncorhynchus mykiss (Walbaum). All sectors provide substantial socio‐economic benefit and regionally can have significant cultural value and yield an important amount of food protein. Using the best available information and a number of assumptions, total harvest for all three sectors in the inland waters of North America was estimated to be >480 000 t yr−1. Nonetheless, there are a number of internal threats that face these fisheries including over‐exploitation, bycatch/release mortality as well as external threats such as inter‐sectoral conflict, environmental change, water availability, invasive species and habitat alteration. Given that most inland fisheries are managed at the state/provincial level, there is a need to adopt management strategies that are holistic, coordinated and trans‐jurisdictional if inland fisheries in North America are to be sustainable in the future. There is also a critical need for information management systems that enable regional data to be scaled up to the national or continental level, which would facilitate the generation of inland fisheries status reports and the monitoring of trends through time. All stakeholders must recognise that while inland fisheries tend to not receive the same attention from the media, public or politicians as marine fisheries, the potential for local and broad‐scale irreversible changes exist and need to be identified and addressed if the many ecosystem services that inland fisheries provide are to be maintained.

Movement, home range and habitat selection of stocked juvenile muskellunge, Esox masquinongy, in Forbes Lake, Illinois: exploring the effects of latitudinal origin

Abstract Intraspecific, seasonal and diel variation in movement behaviours of three stocks of juvenile (age‐2; 399–610 mm total length) muskellunge, Esox masquinongy Mitchill, were assessed using radio telemetry in Forbes Lake (225 ha), IL, USA. Experimental populations included muskellunge from the Upper Mississippi (Leech Lake, MN, USA) and Ohio (Cave Run Lake, KY, USA) river drainages, as well as progeny from North Spring Lake, IL, a mixed‐origin stock. No differences in hourly movement rates or home ranges were detected among stocks. Movement rates were greatest during spring (mean ± SE = 42 ± 4 m h−1), lowest during summer (16 ± 3 m h−1) and intermediate in autumn (28 ± 5 m h−1). Additionally, movement rates during the summer were greater at night than crepuscular periods. Home range sizes were similar during spring and autumn (mean ± SE = 17–18 ± 3–4 ha) and decreased during summer (5 ± 3 ha). Although habitat selection characteristics were generally similar among stocks, fish from the Upper Mississippi River drainage occupied deeper water more frequently and selected the pelagic zone more strongly during the spring than those from the Ohio River and mixed‐origin stocks. Within the littoral zone, muskellunge selected coarse woody habitat and aquatic macrophytes. Collectively, these findings suggest little behavioural differentiation among genetically divergent stocks when evaluated in a common reservoir environment.

Sectioned pelvic fin ray ageing of muskellungeEsox masquinongyfrom a Virginia river: comparisons among readers, with cleithrum estimates, and with tag–recapture growth data

Abstract The potential utility of pelvic fin rays as ageing structures was evaluated for southern US muskellungeEsox masquinongyMitchill populations by comparing age estimates among three readers and against cleithrum estimates, and by comparing observed length changes of tagged fish with changes predicted from growth equations based on pelvic fin ray age estimates. Mean coefficient of variation in age estimates among all readers and between the two readers with prior ageing experience was 17.8% and 5.6%, respectively. Exact and within 1‐year agreement rates between pelvic fin rays and cleithra were 76% and 100%, respectively. Mean (± 2 SE) estimated absolute error between observed and predicted length changes for 13 tagged muskellunge was 30 ± 14 mm. This evaluation indicated that pelvic fin rays may prove to be a useful, non‐lethal method for ageing muskellunge in southern US waters. Validation studies are still needed to ensure that growth rings form consistently throughout fish's life span.

Oocyte recruitment and spawning chronology in pike, Esox lucius, and muskellunge, Esox masquinongy

During the reproductive cycle, the progression of oogenesis differs markedly between northern pike, Esox lucius Linnaeus, and muskellunge, Esox masquinongy Mitchill. Both species have group-synchronous ovaries but have different oocyte recruitment strategies. Pike is a single spawner, developing eggs in a single clutch annually, whereas muskellunge is a fractional spawner, producing two clutches of eggs per year. During the spawning period in large female muskellunge, oocyte counts indicate that the second clutch of eggs is equally important to the first. An event portrait of the spawning period for muskellunge is provided, whereby arrival of adults to a spawning site, egg yield, and hatching success agree with the fractional spawner concept. A hypothesis of the temporal sequence of evolutionary relationships in recruitment of oocytes for esocoid fishes is presented. The reproductive strategy of muskellunge belongs to a common esocoid ancestor, whereas that in pike is derived and unique. The significance of this divergence in closely related species remains consistent with the ecological theory that evolution of reproductive strategies is adaptive to diverse environmental conditions.

Comparative urogenital morphology and external sex determination in muskellunge, Esox masquinongy Mitchill

Primary and secondary sexual characteristics in northern pike, Esox lucius Linneaus, and muskellunge, Esox masquinongy Mitchill, differ markedly. Differences in the internal urogenital anatomy include the structure of the genital ducts and the angle they form with the ventral surface. Externally, the genital and urinary ducts open directly to the environment in northern pike, whereas in muskellunge they open into a muscular papilla and then through a urogenital pore. Differences in sexual dimorphism between the two closely related esocids constitute a structural basis to explain the known differences in spawning behaviour and reproductive success. Differences in secondary sexual characteristics explain why the methods developed by Demchenko or Casselman to externally sex pike are inapplicable to muskellunge. To develop and test two external sexing techniques for muskellunge, specimens were collected from two regions in Canada from 1980 to 1987. Examination of reproductive products obtained from stripping provided an accurate indicator of sex and sexual maturity, but demonstrated serious limitations. A simple method to sex muskellunge by examination of the external urogenital morphology is described for juveniles and adults. Dissection of fish revealed that with the urogenital examination technique we sexed juveniles with a success rate of 92–98%, and adults with 100% accuracy.

Gyrodactylus fryi n. sp. (Monogenea) from Esox masquinongy Mitchill in Ontario

Gyrodactylus fryi n. sp. (Monogenea) is described from the body surface of Esox masquinongy Mitchill in Ontario. Gyrodactxlus fryi resembles most closely G. lingulatus Rogers, 1968 from the cyprinid Hypentelium etowanum (Jordan) in Alabama in having well-developed hamuli, a compact ventral bar with no anterolateral processes, a tongue-shaped ventral bar membrane, and a penis with small spines in two arched rows. Gyrodactylus fryi is easily distinguished from G. lingulatus by marginal hook size (11 to 14 μm long. 7 to 8 μm wide proximally, 14 to 16 μm wide distally) and shape (relatively small base with a long thin blade). Gyrodactylus fryi resembles at least nine other Gyrodactylus species known from cyprinid and catostomid fishes. The study concludes that a close ecological association between a piscivorous ancestral E. masquinongy and cyprinid and (or) catostomid fishes led eventually to evolutionary radiation of a gyrodactylid lineage from prey to predator.

Fluctuations in the muskellunge (Esox masquinongy Mitchill) population of Chautauqua Lake, New York

Population and exploitation estimates were made from angler recaptures of Chautauqua Lake muskellunge,Esox masquinongy Mitchill. Fish were tagged during Conservation Department studies in 1941–1946, 1961–1965 and 1976–1978. Population estimates of adult fish ranged from one to seven fish per hectare and angler exploitation rates of tagged fish fluctuated from 3.8% to 14.1%. Relative catch indicators suggest a major decline in the lake's muskellunge population during the last decade. Overexploitation, habitat alteration and interspecific competition with recently introduced fish species were cited as probable causes of the decline.

Hybridization in the Family Esocidae

Of 11 possible hybrids of species in the family Esocidae, six were known from nature and they are reviewed. The occurrence of a seventh, Esox lucius × Esox americanus americanus, is recorded. Of 22 possible reciprocal combinations of these species, five were previously known, five are still unknown, and 12 are newly described here. These 12 are based on artificial hybrids of known gametic constitution. Data are given on: description (young and oldest material available); growth; fertility; vitality and meristics are compared with parent populations. The low level of interspecific sterility was surprising. Some interspecific sterility exists between the two largest (Esox masquinongy Mitchill, Esox lucius Linnaeus) and the two smallest (Esox americanus Gmelin) forms. Total sterility does not exist as artificially one or other of the reciprocals was successful in each cross, including Esox masquinongy × Esox americanus. The hybrids exhibited the blending and intermediate nature usual in fish hybrids but colour pattern seemed tied to a particular parent. In nature only certain species hybridize, but it would appear that incompatibility of gametes has proceeded only to a limited extent. Other factors such as distribution, habitat, size, and behavior may be preventing hybridization.

The Food and Growth of the Maskinonge (Esox masquinongy Mitchill) in Canadian Waters

Maskinonge from three regions were studied: the Lake of the Woods district in Ontario (called Western); the Kawartha Lakes and Georgian Bay district in Ontario (Central) and the St. Lawrence River district in Quebec (Eastern). Examination of 202 stomachs, 81 containing food, showed the maskinonge to be a general carnivore, preying mainly on fish over 150 mm. in length. The families Percidae, Catostomidae, Ameiuridae, Centrarchidae, Hiodontidae, Esocidae and Cyprinidae were represented, along with at least one Cambarus. The yellow perch, Perca flavescens, was the species eaten most frequently in all three regions. A common white sucker (Catostomus commersonnii) was found in a stomach of the hybrid E. masquinongy × E. lucius. Examination of the teeth of each specimen showed that they were being continuously replaced throughout the summer season.Rate of growth varied with sex and locality. Females had a significantly faster rate of growth, both in length and in weight, than did males. Maskinonge from the Western Region were shorter and weighed less than fish of the same age from the other two regions. Maskinonge of the Eastern and Central Regions reached the legal size of 30 inches fork length during their fifth summer, but in the Western Region they did not attain this size until their seventh summer. The length-weight relationship appears to be the same in the Eastern and Central Regions, whereas maskinonge from the Western Region tended to be heavier than those of comparable lengths from the other two regions. In all regions the length-weight relationship was a straight line when plotted logarithmically, its slope being estimated as 3.26 in the Eastern Region. Sexual maturity occurs first between the ages of three and six years, or about 575 to 800 mm. fork length. Specimens of a E. masquinongy × E. lucius hybrid appeared to be infertile. They did not differ from the maskinonge specimens in their length-weight relationships but made faster growth than did the maskinonge from the same region.