Document Category: Culture

Tiger muskellunge (female muskellunge, Esox masquinongy, x male northern pike, E. lucius) 14.5 cm long were reared for 45 days in a three‐pass (pass I, II, and III) water reuse system. Cumulative growth rates for the fish were 0.143 cm/day in the first use of the water (pass I), 0.125 in the second use (pass II), and 0.108 in the third use (pass III). Food conversions were poorer in passes II and III. Survival offish in each pass was good and no abnormal mortalities or disease problems were encountered. Dissolved oxygen, ammonia, and pH data indicated that oxygen consumption and ammonia production had daily minimum values between 0200 and 0600 h and maximum values between 1600 and 2000 h. Maximum un‐ionized ammonia levels of 0.0172 mg/L were recorded in pass III. Average daily oxygen consumption and ammonia production rates were 97 g oxygen per kilogram of food fed (97 g oxygen/per 3400 kcal) and 6 g ammonia per kilogram of food fed and were substantially lower than corresponding rates reported for salmonids.

The hybrid tiger muskellunge (male northern pike x female muskellunge) was reared intensively on artificial diets during 1976 and 1977. The total number of 15-23 cm fingerlings produced during 1976 and 1977 were 88,000 and 109,00 hybrids respectively. Survival from eggs ranged from 11-15% for 1976 and 22% for 1977. The improved survival during 1977 was attributed to better egg quality and modifications of feeding techniques which resulted in a lower incidence of cannibalism. Growth rates averaged between 0.140 and 0.175 cm/day during 1976 and 0.180 cm/day during 1977. Improved feeding techniques again were responsible for the better growth rates. Columnaris and bacterial gill disease caused mortalities but these mortalities were low in comparison to the total loss due to cannibalism.

We investigated the effects of carp pituitary extract (CPE) and human chorionic gonadotropin (hCG) on the sperm production in muskellunge Esox masquinongy . Total volumes of milt collected from fish (mean weight, 4.8 ± 1.5 kg) injected with CPE, hCG, or the saline control were 5.36 ± 3.75 mL, 3.1 ± 1.52 mL, and 3.89 ± 2.16 mL, respectively. Sperm concentration, protein and mineral concentrations of semen, and osmolality of seminal plasma were similar in control and hormonally treated fish. Hormonal injections did not affect the initial percentage of motile sperm compared to untreated fish. However, motility of sperm from the CPE group was lower than for the saline group at 75 s after activation (statistical significance was P = 0.06). The fertilizing capacities of spermatozoa after cryopreservation from CPEinjected fish were similar to, if not better than, control fish. We report here, for the first time, the successful cryopreservation of muskellunge semen, which produced 30.1 ± 3.8% survival to the eyed‐embryo stage versus 72.9 ± 8.7% survival obtained with fresh semen.

Energy costs for rearing tiger muskellunge were compared using water heated with oil, gas or electric heat pump. An oil-fired boiler proved to be the most expensive, costing approximately 50% more than natural gas. A water-to-water heat pump was most efficient costing 40% less than gas. Electric rates, however, are most susceptible to local fluctuations particularly “electric demand” charges. In the worst case, operation of a heat pump would equal gas heating costs.

The cost of culturing tiger muskellunge was compared at temperatures of 15.6°C, 20°C and 22°C. Heating ambient water (7.8°C to 20°C and 22°C cost 57% and 85% more, respectively, than heating water to 15.6°C. By establishing culture water temperature regimes, hatchery managers should be able to exercise better control over biological factors such as fish growh, feed conversion, incidence of disease and cannibalism that may interfere with optimum production.

The use of conventional pond-rearing techniques for culture of purebred muskellunge has provided erratic and unpredictable results but the fingerlings produced are large enough to provide maximum survival after stocking. The most dependable phases of muskellunge culture are spawning, incubation and pond rearing of fingerlings from 3 to 8 inches or larger. The phase of culture that needs the most improvement is from swimming fry to fingerlings of about 3 inches. The ability to control environmental conditions and provide adequate forage is essential to stabilized production.

Intensive culture techniques using pelleted feed have revolutionized the rearing of hybrid muskellunge and northern pike; it has not been nearly as successful with purebred muskellunge. Rearing in tanks using live food has been successful but growth is somewhat slow. For some production programs it appears feasible to rear fingerlings to 3 inches in tanks using live forage and then transfer them to ponds to grow to stocking size. Solutions to production problems vary and are dependent upon local conditions and facilities as well as the size of fingerling need for cost-effective stocking.

Natural food diets (zooplankton and minnows) and artificial dry diets were compared as a means of increasing fry survival during the intensive culture of muskellunge at the Iowa Spirit Lake Hatchery. Muskellunge fry fed the natural diets had a constant supply of zooplankton available; at about 1.5 inches fathead minnows were added to their daily diet until stocking occurred. Survival to stocking size (5.3 inches) was 18.0%. Artificial feeding of muskellunge was initiated on an experimental basis in 1982 and tested on a production scale in 1983. Brine shrimp and Abernathy feed were used for the initial training process with brine shrimp withdrawn when the fry converted to dry feed. In 1982, only 8.0% of the initial total were reared to stocking size because a malfunction in the water supply caused the death of 910 fish. In 1983, 53% of the artificall7y fed musky survived to a mean stocking size of 5.4 inches, compared with 18.0% for those on a minnow diet. Cost comparisons for the two rearing methods in 1983 were $1.76/fish for the live food diet and $0.29/fish for the artificial diet.

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.

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A method of rearing maskinonge to an advanced fingerling stage was investigated. One hundred thousand fry were planted in a natural habitat; a marshy bay normally used by maskinonge as a spawning ground. An attempt was made throughout the summer to remove all possible fish and turtle predators. Altogether 17,334 coarse fish, exclusive of fry of the year, and 563 turtles were removed from the area. Less than one‐third of the fish and somewhat more than one‐half of the turtles were removed previous to planting the maskinonge fry.

Maskinonge spawn in the spring and the fry remain in the spawning marshes at least until the first of November. The fry show little tendency to range about during the period.

When first commencing to feed maskinonge fry took plankton crustacea and the cladoceran, Polyphemus pcdiculus, was utilized to a large extent. About 1 week later they commenced to take very small minnow fry as well as plankton. After they were about 5 weeks old the diet was composed entirely of fish. Cannibalism did not occur when there was an abundant supply of other food.

Maskinonge grew very rapidly under the conditions provided, reaching an average length of nearly 10 inches by the first of November.

A yield of 0.8 advanced fingerlings for each 1,000 fry planted was obtained. However, since the removal of fingerlings was not completed the yield was probably greater. Many predatory fish, notably yellow perch and rock bass, remained in the area throughout a greater portion of the experimental period. There can be little doubt that their predatory activities reduced the yield.

Advantages of raising maskinonge fingerlings under the conditions described are the abundant natural food supply, making possible excellent growth, and the possibility of eliminating predators to a large extent.