We evaluated the effect of adding artificial vegetation to the rearing environment on behavior, habitat selection, and growth of hatchery esocids in laboratory experiments. First, Muskellunge (Esox masquinongy) and the hybrid Tiger Muskellunge (Muskellunge × Northern Pike E. lucius ) resided separately in pools either with or without artificial vegetation (250 stems/m2) for 2 weeks. Both taxa raised in vegetated pools dispersed and spent more time away from the sides of the pools than did individuals residing in open pools. Tiger Muskellunge in vegetated pools also startled less often than fish in open pools, whereas vegetation did not decrease Muskellunge startle behavior. We next examined habitat selection between esocids raised in tanks with and without vegetation. Fish were tested in semivegetated pools, and for Tiger Muskellunge acclimated in vegetation, more fish (80%) used the vegetated half of the pool compared with fish raised in open tanks (61%). Muskellunge, regardless of treatment, spent a high proportion (>90%) of time in vegetation. Finally, growth of both taxa was similar between esocids reared in vegetated tanks compared with esocids reared in open tanks. The presence of artificial vegetation in tanks caused changes in behavior for both esocid taxa, but Tiger Muskellunge were more flexible in modifying their behavior. Behavioral responses resulting from exposure to vegetation could increase survival after stocking in lakes.
Cause and control of muskellunge fry mortality at Chautauqua hatchery, New York
In 1966‐67, 1970, and 1973‐76, New York State’s muskellunge (Esox masquinongy) hatchery, located on Chautauqua Lake, sustained total or near total losses of muskellunge fry at or near the swim‐up stage of development. Eggs incubated at the Chautauqua Hatchery and transferred to other stations resulted in swimming fish, but those held at Chautauqua did not. The chemistry of lake and well water at the muskellunge hatchery showed no departures from normal. During the production seasons of 1974 through 1976 the hatchery was operated on a controlled, experimental basis in an attempt to determine the cause of the fry losses. Fry die‐offs could be correlated with neither the physical or chemical properties of the water nor with the presence of a fish pathogenic virus or pathological tissue changes. Controlled laboratory experiments strongly implicated bacteria as the agents responsible for the muskellunge fry losses. Organisms recovered included predominately Pseudomonas sp., although Aeromonas hydrophila was also isolated; both are well‐known fish pathogens. Ultraviolet treatment of lake and well water supplies during incubation and yolk absorption resulted in effective control of fry losses.
Comparison of growth, survival and body composition of muskellunge and tiger muskellunge fed four commercial diets
Feed is one of the largest annual costs in fish production. Various commercial feeds are used for muskellunge (Esox masquinongy ) and tiger muskellunge (E. masquinongy × E. lucius ), but no data are available that compare growth and survival of these two fishes on these diets. Growth and survival were evaluated over 8 weeks for both muskellunge (initial mean total length, 172 mm) and tiger muskellunge (187 mm) fed four commercially available feeds: Biodiet Grower, Biodry 1000, Abernathy S8‐2 (84), and W‐16. Across all diets, tiger muskellunge grew more than 1.5 times as fast as muskellunge. Both muskellunge and tiger muskellunge grew faster on three diets developed for coldwater species (Biodiet, Biodry, and Abernathy), than on the one developed for coolwater species (W‐16). Muskellunge also grew faster when fed Biodiet or Biodry than when fed Abernathy. Differences in growth may be related to dietary protein levels. Body composition was affected by diet; percent fat was highest for both species fed Biodry, and protein levels were higher for tiger muskellunge fed Biodiet or Abernathy. Survival was high and was not affected by diet type for either species. Based on growth rates, body composition, and feed cost, we recommend Biodiet or Biodry as a diet for muskellunge and Biodry or Abernathy for tiger muskellunge.
Effects of dietary protein concentration on growth, survival and body composition of muskellunge (Esox masquinongy) and tiger muskellunge (Esox masquinongy x E. lucius) fingerlings
Growth rate, survival and body composition of muskellunge Esox musquinongy (initial mean total length = 125 mm) and tiger muskellunge E. masquinongy × E. lucius (initial mean total length = 115 mm) fed semi‐purified diets differing in protein level from 31 to 40% and 34 to 45%, respectively, were evaluated in 8‐wk trials. The minimum protein level that yielded satisfactory growth rates for muskellunge was 37%, whereas tiger muskellunge growth rates were highest for fish fed a 45% protein diet. Growth differences were caused by changes in protein quantity, not quality, as amino acid ratios were similar for test diets and showed no imbalances among diets. Condition factors for both fishes increased with dietary protein. Survival of muskellunge (73%) and tiger muskellunge (97%) was not pffected by diet type. Body protein increased and fat content decreased in both fishes when fed higher dietary protein. Results suggest that both fishes respond similarly to dietary changes, but that substantial differences exist in protein requirements.
Pennsylvania’s practices for intensive culture of hybrid muskellunge
Artificial propagation of esocids has been practices since the late1800s and hybrid muskellunge were first cultured in the 1930s. Intensive culture of hybrid muskellunge developed when it was discovered that they could be maintained on artificial diets. Present spawning, incubation and hatching techniques are essentially refinements of those developed for muskellunge. Development of new feeds and feeding techniques was a major factor in achieving the current state of the art for culture of this fish. Cooperative efforts and interstate workshops have been instrumental in achieving widespread success with hybrid culture. Current research is directed at refinements to culture techniques and improvements to facility design, equipment and feeds.
Survival, growth and prey of Esocidae in experimental systems
Survival (July to November) of young‐of‐the‐year esocids stocked in 0.2‐hectare experimental ponds in Missouri was: muskellunge (Esox masquinongy), 24%; northern pike (Esox lucius), 58%; and the F1 hybrid of these two species (commonly called the “tiger muskie”), 74%. Survival of yearlings from April to September was: muskellunge, 80%; northern pike, 90%; and hybrids, 85%. Growth rate of yearlings of all three forms was rapid in late spring, declined to a seasonal low in July, and then increased until the ponds were drained in September. Average weight gain of the hybrids (719 g) during their second year of life in ponds was significantly greater than that of northern pike (617 g) or muskellunge (615 g). Maintenance diets (grams of food per gram of fish) calculated for fish in tanks (1.2 × 4.8 × 1.1 m) for 28‐day periods were as follows: northern pike, 0.23; muskellunge, 0.51; and hybrids, 0.62. Food conversion efficiencies in tanks were: northern pike, 29.0%; muskellunge, 25.0%; and hybrids, 22.0%. Non‐game species were more vulnerable than game fishes to esocid predation in tanks. An esocid can be stocked in addition to or as an alternative to largemouth bass (Micropterus salmoides), walleye (Stizostedion v. vitreum), or striped bass (Morone saxatilis) because of a faster rate of growth. The hybrids may be the most desirable form of the three esocids because of rapid growth rate, intermediate angling vulnerability, and ease of rearing in a hatchery compared to either parent species.
Growth and food consumption by tiger muskellunge: Effects of temperature and ration level on bioenergetic model predictions
We measured growth of age‐0 tiger muskellunge as a function of ration size (25, 50, 75, and 100% Cmax) and water temperature (7.5–25°C) and compared experimental results with those predicted from a bioenergetic model. Discrepancies between actual and predicted values varied appreciably with water temperature and growth rate. On average, model output overestimated winter consumption rates at 10 and 7.5°C by 113 to 328%, respectively, whereas model predictions in summer and autumn (20–25°C) were in better agreement with actual values (4 to 58%). We postulate that variation in model performance was related to seasonal changes in esocid metabolic rate, which were not accounted for in the bioenergetic model. Moreover, accuracy of model output varied with feeding and growth rate of tiger muskellunge. The model performed poorly for fish fed low rations compared with estimates based on fish fed ad libitum rations and was attributed, in part, to the influence of growth rate on the accuracy of bioenergetic predictions. Based on modeling simulations, we found that errors associated with bioenergetic parameters had more influence on model output when growth rate was low, which is consistent with our observations. In addition, reduced conversion efficiency at high ration levels may contribute to variable model performance, thereby implying that waste losses should be modeled as a function of ration size for esocids. Our findings support earlier field tests of the esocid bioenergetic model and indicate that food consumption is generally overestimated by the model, particularly in winter months and for fish exhibiting low feeding and growth rates.
Iodophore disinfections of muskellunge eggs under intensive culture in hatcheries
The iodophor Povidone-Iodine (1% active I2) was used at three concentrations, 100, 28, and 13 mg/L (1:100,1:350, and 1:750) for 10 min, in an attempt to disinfect fertilized eggs of muskellunge (Esox masquinongy) and to test the efficacy and toxicity of the compound on the eggs of cool-water species. No treatment effect was observed between treatments and controls or among treatments. However, no toxic effects of the iodophor were found at the concentrations of active I2 considered efficacious for salmonids.
Effects if hatchery broodstock collection on adult muskellunge populations. North American Journal of Fisheries Management
Stocking programs for Muskellunge Esox masquinongy throughout North America rely on the collection of wild adult Muskellunge to acquire gametes for hatchery propagation. The process of collecting, transporting, confining, handling, and spawning broodstock Muskellunge may cause mortality that could alter Muskellunge density, size structure, and population survival rates. We used long‐term Muskellunge capture–recapture data collected from the Iowa Great Lakes and Clear Lake in northern Iowa to estimate the number and proportion of Muskellunge captured annually and the initial mortality rates resulting from broodstock collection. We also evaluated whether Muskellunge apparent survival rates differed between individuals used as broodstock and those that were not captured annually. Finally, we evaluated whether the number of initial mortalities or the number of individuals captured were related to annual population survival estimates. Collectively, 7,010 adult Muskellunge (3,896 males and 3,114 females) captures occurred between 2001 and 2017, and population densities within a system ranged from 0.11 to 0.39 fish/ha. An average of 33% (range = 13–76%) of the population was captured during broodstock operations annually. Between 0 and 28 (0.0000 to 0.0191 fish/ha) Muskellunge died at each hatchery annually, and more males died than females (total of 150 males and 68 females; 3.9% and 2.2% of captured fish, respectively). However, annual mortalities were generally a low proportion of Muskellunge in the lake (<2%; <0.001 fish/ha). There was some evidence of size‐selective mortality, particularly for males, where larger individuals (875–975 mm) were more likely to die, but we found no evidence to suggest that broodstock collection affected annual population survival estimates. Muskellunge broodstock mortality appears to act in a compensatory manner with natural mortality, and other sources of population mortality are more likely to have a greater effect on the population.
Effects of Stocking Size and Rearing Method on Muskellunge Survival in Chautauqua Lake, New York
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 since the 1960s may have increased predatory pressure on fingerlings and increased the importance of greater length at stocking.