IC




L  BR A    R y
INSTITUTE FOR FISHERIES RESEARCH
University Museums Annex
Ann Arbor, Michigan 48104
MICHIGAN DEPARTMENT OF NATURAL RESOURCES
FISHERIES DIVISION
Technical Report: No. 1980-1
February 1980
HATCHERY-REARED FINGERLING TIGER MUSKIES
UNHARMED BY DIET CHANGE FROM PELLETS
TO SPINY-RAYED PREY FISH
George B. Beyerle, Fisheries Research Biologist
SUMMARY
Pellet-reared tiger musky fingerlings ate an average of 2.0 young
bluegills per day for 14 days. No mortality of tiger muskies
occurred. It is concluded that pellet-reared tiger musky fingerlings
will suffer no unusual detrimental effects when they consume spinyrayed prey fishes.




HATCHERY-REARED FINGERLING TIGER MUSKIES
UNHARMED BY DIET CHANGE FROM PELLETS
TO SPINY-RAYED PREY FISH
George B. Beyerle, Fisheries Research Biologist
INTRODUCTION
Some biologists have expressed concern about the ability of pellet-reared
predator fish to successfully consume spiny-rayed prey fish. Calbert et al.
(1974) found that the stomach wall of pellet-reared percids was not as thick
as in wild fish. Thus, when a pellet-reared predator fish consumed a
spiny-rayed prey fish, the spines might easily penetrate the stomach wall,
killing the predator fish. However, Beyerle (1978) found that no mortality
of walleyes occurred when 20 pellet-reared walleye fingerlings consumed
518 young bluegills. The ability of pellet-reared tiger musky fingerlings
to consume bluegills was tested at the Wolf Lake State Fish Hatchery in 19178.
PROCEDURE
Two standard hatchery troughs (274 X 50 X 50 cm) were set up with water
at 19 C flowing through each at a rate of 10 liters per minute. On July 28,
each trough was stocked with 20 tiger muskellunge fingerlings (mean length,
8.9 cm; range, 8.4-9. 7cm) which had been raised intensively on W-7 dry
diet. Each trough was then stocked with food fish. To one trough was
added 200 fathead minnows (mean length, 2. 5 cm; range, 2. 3-3. 0 cm),
and to the other 200 bluegills (mean length, 3. 0 cm; range, 2.8-3. 8 cm).
The troughs were checked daily and the supply of food fish in each was
replenished so that about 200 fish were present in each trough at all times.
At the completion of the 14-day test, the total number of food fish eaten by
the tiger muskies was determined for each trough.
RESULTS
No mortality of tiger muskies occurred in either trough. During the test
the tiger muskies in one trough consumed 1, 743 minnows (395 g), an
average of 6. 2 minnows (1.4 g) per musky per day. The tiger muskies
in the second trough consumed 567 bluegills (181 g), an average of 2.0
bluegills (0.6 g) per musky per day. It appears that pellet-reared tiger
muskellunge can successfully consume spiny-rayed food fishes without
physical damage to themselves.




LITERATURE CITED
Beyerle, G. B. 1978. Hatchery-reared fingerling walleyes unharmed
by diet change from pellets to spiny-rayed prey fish.
Prog. Fish-Cult. 40(3): 93.
Calbert, H. E., D. A. Stuiber, and H. T. Huh. 1974. Raising yellow
perch (Perca flavescens) and walleye pike (Stizostedion vitreum
vitreum) for human food use. Presented at Sixth Interstate
Muskellunge Workshop, Morehead, Kentucky, 25-26 September
1974.