Muskellunge Research Articles

Variation in routine metabolism of juvenile muskellunge: evidence for seasonal metabolic compensation in fishes

Metabolic rate of age 0 muskellunge Esox masquinongy ranged from 0·10 at 5° C to 0·24 mg O2 g‐1 h‐1 at 25° C and was significantly higher in spring and autumn than during winter months at comparable water temperatures. Reduced metabolic rate in winter was consistent with the metabolic compensation hypothesis, implying that metabolism of muskellunge varies independently of acclimation temperature and gonadogenesis. Moreover, seasonal variation in metabolic rate has important implications for energy budget studies. Single‐season estimates of esocid metabolism may be inadequate to describe annual energy requirements; the magnitude of errors will depend on the time of year metabolic rate was measured. As a result, it is suggested that seasonal variation in metabolic rate be incorporated into energy budget determinations for fishes.

Variation in routine metabolism of juvenile muskellunge: evidence for seasonal metabolic compensation in fishes

Metabolic rate of age 0 muskellunge Esox masquinongy ranged from 0·10 at 5° C to 0·24 mg O2 g-1 h-1 at 25° C and was significantly higher in spring and autumn than during winter months at comparable water temperatures. Reduced metabolic rate in winter was consistent with the metabolic compensation hypothesis, implying that metabolism of muskellunge varies independently of acclimation temperature and gonadogenesis. Moreover, seasonal variation in metabolic rate has important implications for energy budget studies. Single-season estimates of esocid metabolism may be inadequate to describe annual energy requirements; the magnitude of errors will depend on the time of year metabolic rate was measured. As a result, it is suggested that seasonal variation in metabolic rate be incorporated into energy budget determinations for fishes.

Uptake and depletion of plasma 17α-methyltestosterone during induction of masculinization in muskellunge, Esox masquinongy:: Effect on plasma steroids and sex reversal

Oral administration of 17α-methyltestosterone (MT) was used to induce masculinization of sexually undifferentiated muskellunge, Esox masquinongy. Three groups of muskellunge (mean weight, 2.5 ± 0.6 g) were submitted to MT treatment (15 mg of MT/kg) for 60 days. An additional one group was used as a control (hormone-free diet). Food was distributed over a 10-h period by using automatic belt feeders. Blood was sampled in both control and treated fish at different intervals during and after feeding: before (0 h), at 3 h, 6 h, and cessation of feeding (10 h), and after a fast of 22 h (32 h). MT had no significant effect on growth and survival in muskellunge 6 months after the treatment. Concentrations of plasma MT increased during the feeding period and reached their maximum levels 6 or 10 h after starting feeding. This rapid increase of MT indicated a rapid absorption of this steroid. Plasma MT levels then declined and reached a radir by 22 h after cessation of feeding, suggesting that MT is rapidly metabolized and excreted. The profiles of plasma testosterone during the MT treatment did not differ significantly between control and MT-treated groups. During and after the MT treatment, the concentration of plasma testosterone did not differ significantly between control and MT-treated groups. Moreover, no sexual dimorphism of testosterone levels was observed. Six months after treatment, the sex ratio in MT-treated groups (33% males, 62% females, and 5% intersex) was opposite to control (70% and 30%, respectively) and differed significantly. This suggests that at 15 mg of MT/kg over 60 days, a paradoxical feminization took place.

Cryopreservation of Muskellunge and Yellow Perch Semen

Effect of four extenders on the success of cryopreservation of the semen of muskellunge Esox masquinongy and yellow perch Perca flavescens was tested. These extenders consisted of 0.45 M sucrose and were supplemented with either (1) 15% dimethyl sulfoxide (DMSO), (2) 15% DMSO and 10% hen's egg yolk, (3) 15% dimethylacetamide (DMA), or (4) 15% DMA and 10% egg yolk. The use of extender with DMA alone yielded only about 7% muskellunge sperm fertilizing ability after cryopreservation. Supplementation of this extender with egg yolk produced a fertilization rate (36.6% of the control where fresh sperm was used) not significantly different from rates obtained with extenders containing DMSO. No significant differences were found among particular pools (consisting of semen from three different males per pool) of muskellunge semen used in this experiment. Fertilization rates of cryopreserved yellow perch semen (range, 69.6% to 77.3%) were not significantly different among all extenders tested. Cryopreservation success differed significantly between milt samples from individual yellow perch males. Yellow perch eggs could be stored up to 77 min at 10°C (fertilization success ranged from 57.2% to 64.8%). Our results provided 25–35% improvement of cryopreservation technology for yellow perch semen (measured as fertilization rate) and new data for cryoprotectant use in muskellunge. We were also able to prolong in vitro viability of yellow perch eggs during storage compared with earlier attempts.

Distribution, Abundance, and Survival of Age-0 Muskellunge in Upper St. Lawrence River Nursery Bays

Abstract Distribution, abundance, and survival of age-0 muskellunge Esox masquinongy were evaluated at 10 bays in the Thousand Islands section of the St. Lawrence River over a 7-year period, 1990–1996. Muskellunge fry (24 mm) identified with thermal or oxytetracycline otolith markers were stocked in 1990–1992, 1994, and 1996, and fin-clipped fingerlings (76 mm) were stocked in the bays in 1994 and 1996. Success of the stockings was evaluated to examine the feasibility of enhancing bays that have natural reproduction (natural) and establishing populations in unused bays (restoration). Most age-0 muskellunge were found in shallow habitats (<1.5 m), and success of capture by seining decreased with increasing water depth. Estimates of age-0 abundance by mark–recapture and catch–area were not significantly different. Population density ranged from 0 to 42 muskellunge/ha of nursery habitat, and no significant differences were observed between natural (18.8 fish/ha) and restoration bays (20.5 fish/ha). For all y...

Trends in Wisconsin's Muskellunge Fishery

Abstract Wisconsin's populations of muskellunge Esox masquinongy provide an important recreational fishery. Our objectives were to (1) evaluate progress of the Wisconsin Department of Natural Resources muskellunge management plan, (2) examine subsequent changes in the fishery, and (3) evaluate Wisconsin's muskellunge waters classification system. With the goal of maintaining viable populations and a trophy fishery, the 1979 plan endorsed more restrictive harvest regulations, an increased supply of muskellunge fishing opportunities, and increased data collection. Since the 1980s, muskellunge fishing opportunities have increased 75% in terms of lake acres and 51% in terms of stream miles. Hatchery production and stocking efficacy have improved to the point where the department needs to reevaluate current stocking practices. With the establishment of a shorter season, a higher statewide minimum length limit, and an increased use of special regulations, harvest regulations have become progressively more restr...

Effects of Length Limits on Muskellunge in Bone Lake, Wisconsin

Minimum length limits are a commonly used management tool for protecting fisheries from exploitation and for improving population size structure. However, little is known about the effects of minimum length limits on populations of muskellunge Esox masquinongy. We monitored changes in the muskellunge population in Bone Lake, a 1,781-acre lake in northwest Wisconsin over a 31-year period (1964–1995) during which time length limits were changed from 30 in to 34 in and from 34 in to 40 in. These changes were compared with population changes in nearby Deer Lake (807 acres), where the length limit remained at the statewide minimum of 32 in. Mean length of adult muskellunge in Bone Lake increased from 31.3 in in 1964 to 36.0 in in 1995. Adult (≥30-in) muskellunge abundance in Bone Lake increased more than five-fold during the study and reached a density of 0.99 fish/acre. Abundance of larger (≥38-in) muskellunge increased 269% following minimum length limit increases between 1982 and 1995. Relative weight (Wr) of Bone Lake muskellunge decreased during the study, suggesting intraspecific competition for food resources. The muskellunge population in Deer Lake also had positive increases in size structure, but the increases were not as great as those in Bone Lake, and population abundance did not change. Results from this study suggest that high minimum length limits can increase abundance and mean length of a muskellunge population, but biologists need to consider long-term effects on the fish community if high densities are achieved.

An Ecological Context for Evaluating the Factors Influencing Muskellunge Stocking Success

From an ecological perspective, predation, competition or resource partitioning, and abiotic factors interact to affect species distribution and abundance. To make management recommendations, I review research dealing with the relative influence of these factors in determining stocking success of muskellunge Esox masquinongy. Survival of stocked muskellunge is affected by losses to resident predators. Prey preference and composition are also important, and better muskellunge survival and growth occurs in systems with soft-rayed or fusiform prey rather than in centrarchid-dominated systems. However, potential for competition with resident fishes has not been carefully considered. Abiotic factors, particularly temperature, can influence stocking mortality and subsequent growth. Survival increases with size and is maximized with large muskellunge fingerlings (>240 mm), but cost-effectiveness can vary substantially with predator and prey populations. Hatchery rearing techniques can also affect muskellunge stocking success. Pellet-reared fish have lower survival than minnow-reared fish because predation mortality is higher, but both groups exhibit similar food consumption and growth. The parental population can affect survival and growth because temperature-related differences in bioenergetic variables occur among muskellunge populations. In addition to compromising genetic integrity, the mixing of populations with different physiological characteristics may have negative consequences for native populations. Thermal regimes of recipient waters should be considered in choosing the most appropriate population for stocking outside the native range. Muskellunge stocking should be pursued within an ecological context that integrates the relative importance of predation, competition, and abiotic factors. This framework provides a guide for making management decisions concerning populations, hatchery rearing techniques, sizes, and timing of muskellunge introductions into systems with specific characteristics.

Growth and Ultimate Length of Muskellunge from Ontario Water Bodies

Abstract Growth of muskellunge Esox masquinongy from 12 Ontario sources was investigated by examining 582 samples from the Cleithrum Project archive and other specific studies; 88% of the samples were from angler-caught “trophy” fish. We detail sampling problems and develop methods for resolving them. Muskellunge from some sources were unsexed; sex was discriminated (probability of correct classification, 98.3%) from the von Bertalanffy growth parameters ultimate length (L∞) and growth coefficient, K. When one sex was inadequately sampled, the von Bertalanffy growth parameters of one sex were used to estimate those of the other. When samples were small and inadequate (<11), we used concordance sum of squares to match growth and give an interim estimate from the adequately sampled source with the best growth match. In Ontario populations, mean ultimate total lengths range widely: from 81.4 to 140.0 cm for females and from 70.7 to 115.9 cm for males. Females can be grouped into three types of growth, produc...

Survival, Growth, and Abundance of Pellet-Reared and Minnow-Reared Muskellunge Stocked in Northwestern Iowa

Abstract Recent advances in artificial feeding techniques have increased the numbers and reliability of fingerling production of muskellunge Esox masquinongy in Iowa. Most of the muskellunge fingerlings produced in Iowa since 1984 were raised on dry pelleted feed. We compared the survival of pellet-reared fingerlings with traditional minnow-reared fingerlings stocked into Spirit and West Okoboji lakes in northwest Iowa. Beginning in 1991, all muskellunge fingerlings were marked with freeze brands to differentiate the type and year that fingerlings were stocked. Adult muskellunge were caught each spring with 360-ft, 2.5-in-bar-mesh gill nets. All muskellunge caught were examined for brands, individually marked with visual implant tags, and released into the same lake as captured. Abundance and survival of stocked fingerlings to year-classes were estimated from recaptures of branded and individually marked muskellunge. In most years none of the pellet-reared fingerlings survived. The poor survival of these ...

Effects of Stocking Size and Rearing Method on Muskellunge Survival in Chautauqua Lake, New York

Abstract We examined the effects of rearing method and size at stocking on the survival of muskellunge Esox masquinongy in Chautauqua Lake, New York. Since 1961, changes in rearing methods have coincided with declining abundance of adult muskellunge. In particular, a change from pond rearing to trough rearing coincided with declining catches of adult muskellunge in pound nets. The decline was only partly reversed by changes from trough rearing to pond finishing of fingerlings. Changes in survival to age 5 from 1961 to 1996 indicated that both rearing method and stocking length significantly affected survival. Greater length at stocking resulted in higher survival rates. After accounting for length at stocking, survival was highest for pond-reared fingerlings, intermediate for pond-finished fingerlings, and lowest for trough-reared fingerlings. A modified Ricker stock–recruitment model indicated that survival of fingerlings declined over time. Increases in the adult stock of walleye Stizostedion vitrium si...

Diets of Muskellunge in Northern Wisconsin Lakes

Abstract The muskellunge Esox masquinongy is an important sport fish in Wisconsin and elsewhere, but more information about its diet is needed to better understand its role in aquatic systems and its effects on other fish. Stomach contents were examined for 1,092 muskellunge (226–1,180 mm total length, TL) captured in the littoral zone from 34 Wisconsin water bodies from Jul 1991 to Oct 1994. Food occurred in 34.3% (N = 375) of the stomachs, with most (74%) containing a single item. Overall, the proportion of muskellunge with food differed significantly among seasons, with the greatest proportion occurring in fall (69.0%), followed by summer (53.5%) and then spring (25.4%). Prey items consisted of 547 fish, representing 12 families and 31 species, along with 35 nonfish items; fish composed 98% of the diet. Relative importance values of diet items varied by taxa, season, and water body, but the main food items eaten by muskellunge in each season were yellow perch Perca flavescens and white sucker Catostomo...

Muskellunge Stocking Strategies in Wisconsin: The First Century and Beyond

Abstract After nearly a century of the propagation of muskellunge Esox masquinongy in Wisconsin, hatchery production is capable of meeting the stocking needs of management. Stocking of fertilized eggs, fry, fingerlings, or yearling muskellunge can each be used to develop a cost-effective stocking strategy if environmental conditions of a specific water body are known. Although low poststocking survival has been a problem for management, stocking still contributes to the sport fishery, however, future stocking strategies need to consider the effects of stocked muskellunge on natural stocks of muskellunge and other fishes.

The Muskellunge, Esox masquinongy - distribution and biology of a recent addition to the ichthyofauna of New Brunswick

The Muskellunge, Esox masquinongy - distribution and biology of a recent addition to the ichthyofauna of New Brunswick

マスキー法をクリアするために-5(&lt;特集&gt;実用化のキーテクノロジー)

マスキー法をクリアするために-5(&lt;特集&gt;実用化のキーテクノロジー)

The presence of uric acid, an antioxidantive substance, in fish seminal plasma

High concentrations of uric acid in seminal plasma of a range of teleost fish species are reported for the first time. Concentrations of urate amounted to 223.4; 121.9–130.0, 355.9, 735.6, 124.0, 192.7 and 148.0 μM for rainbow trout (Oncorhynchus mykiss), yellow perch (Perca flavescens), muskellunge (Esox masquinongy), Northern pike (Esox lucius), carp koi (Cyprinus carpio), bream (Abramis brama), and tench (Tinca Tinca), respectively. Uric acid is an important anti-oxidant, therefore, it has a potential role in protection of fish spermatozoa against oxidative damage.

The Influence of Spawning Habitat on Natural Reproduction of Muskellunge in Wisconsin

Abstract Many of Wisconsin's native populations of muskellunge Esox masquinongy exhibit declining reproductive success and failing natural recruitment. As a result, self-sustaining populations of muskellunge are diminishing. This study focused on spawning habitat factors that influence egg development and survival and, consequently, the reproductive success of muskellunge. Muskellunge spawning habitat characteristics in lakes with self-sustaining populations were compared with spawning habitat characteristics in lakes that were once self-sustaining but are now maintained by stocking. The hatching success of artificially fertilized eggs was assessed under natural lake conditions. Spawning sites were typically marshy areas in water less than 1 m deep. Characteristics of the spawning habitat influenced successful reproduction. Spawning areas in stocked lakes had low dissolved oxygen (DO; 1.2–5.4 mg/L) at the substrate–water interface, whereas self-sustaining lakes had more variable DO (0.5–9.6 mg/L) with som...

Androgenesis and homozygous gynogenesis in muskellunge (Esox masquinongy): evaluation using flow cytometry.

The purpose of this work was to study the effects of ultraviolet (UV) irradiation on denucleation of eggs and investigate the heat-shock conditions for diploidization for induction of androgenesis in muskellunge, Esox masquinongy. Several egg incubation media, including saline, Ringer's solution, and Ringer's solution supplemented with bovine serum albumin (BSA), were found suitable to maintain the egg fertility as high as in muskellunge ovarian fluid. The optimal doses of UV radiation were 660-1320 J/m2, at which 100% haploid larvae were produced at a hatching rate of 22.5 +/- 2.8%. UV irradiation at low doses (165-330 J/m2) generated abnormal larvae, which were morphologically identical to haploids. Using a flow cytometry method, it was found that cellular DNA content of these larvae was close to that of diploids but significantly lower in value and had a wider distribution (expressed as coefficient of variation) than that of control fish. This suggested that a low dose of UV irradiation might cause gene mutations, alteration of chromosomal conformation and fragmentation, but did not prevent maternal DNA from participating in mitotic division. Interference of maternal DNA residues could be another reason for the poor viability of androgenetic fish. A high dose of UV radiation (1980 J/m2) caused development of severely deformed embryos, indicating that UV radiation also damaged molecules in the eggs other than the denucleation. Our results suggest that classic color and allozyme markers might not be sufficient to prove a complete androgenesis. In order to optimize time and duration of shock for induced diploidization, we investigated the heat-shock conditions for inhibiting the first mitotic cleavage through induction of homozygous gynogenesis. We found that heat-shock treatment at 31 degrees C for 9 min starting at 1.4 tau 0 (a dimensionless factor describing progress in embryo development) after fertilization produced the highest percentage of diploids at hatching.

An Overview of Fisheries Management for Lake Simcoe

ABSTRACT Eutrophication, increased fishing pressure, habitat destruction and invasion of non-native plants and animals have transformed Lake Simcoe and its assemblage of fishes over the past 150 years. Notable changes include die extirpation of lake sturgeon (Acipenser fulvescens), decline of muskellunge (Esox masquinongy), and failure of recruitment of lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis). Many species, including lake trout, lake whitefish, lake herring (Coregonus artedi), and yellow perch (Perca flacescens), have undergone major fluctuations in abundance. Fisheries management actions have evolved with changes in the lake ecosystem and changes in scientific knowledge. Early regulations substantially restricted the commercial fishery and imposed many of the existing controls on the sport fishery. Along period of adjustment and addition to these regulations along with reliance on supplemental stocking (i.e., stocking of a species where a self-reproducing population of that species exists) of native fish as well as introduction of non-native fish followed. In the last 3 decades, a scientific approach and ample monitoring have been established as basic requirements for making sound management decisions. Supplemental stocking of native species and stocking of non-native species have been largely replaced by stocking of native species for rehabilitation. Successful fisheries management in the future will need to address the uncertainty about the state of complex aquatic ecosystems, and identify the possible states of the system and the probable consequences of specific management actions.

Early gonadal development and sexual differentiation in muskellunge (Esox masquinongy)

Primordial germ cells (PGCs) were first identified in muskellunge (Esox masquinongy) of 14 mm total length (TL) 3 weeks post fertilization. At 32 mm TL, gonad strings were complete and formed a typical gonad shape in cross section. Blood vessels were first found in the gonads with Crossmon staining at 46 mm TL. Some of the PGCs underwent mitotic division at this stage. The ovarian sac started to develop in a fish of 82 mm TL, while the germ cells were still considered to be undifferentiated. In a fish of 138 mm TL, female gonads could be clearly identified from the ovarian sac and groups of oogonia, whereas in another type of gonad, the morphology of undifferentiated gonads was maintained. Germ cells became numerous in both sexes at 211 mm TL. Female gonads contained lobes with germ cells, including oogonia, early-prophase oocytes, and large oocytes. Spermatogonia and cells undergoing mitosis were observed in the testis. Ovaries in a fish of 250 mm TL were at the early stage of perinucleolus (early diplotene). Our observations indicate that in muskellunge (i) the PGCs remained in a resting state for up to 8 weeks post fertilization, (ii) gametogenesis occurred earlier in females than in males, (iii) the gonads developed from an undifferentiated stage directly into an ovary or testis, and (iv) the somatic elements in the gonads differentiated prior to the germ cells.