What do muskies eat anyway?
MN DNR Fisheries Report
Muskie were successfully established in Lake Vermilion through a stocking program
that began in 1984. The muskie population has done well and the lake is quickly
gaining a reputation as a quality muskie fishery. A number of people have expressed
concern that the muskie introduction may have a negative impact on other fish
species, particularly walleye. They are concerned that muskies will eat substantial
numbers of walleye and reduce the walleye population. It certainly is wise to be
cautious about introducing a new species into a lake, as such introductions are
sometimes detrimental to the native fish community. The introduction of muskie
into Lake Vermilion was done only after meeting stringent criteria for new muskie
introductions and a thorough review of the possible consequences. Based on all
the information available, it was decided that introducing muskies would provide
a new trophy type of fishery while having a minimal impact on other species.
Since the introduction of muskie, there has been no major change in the walleye
population or in the populations of other species. The 1997 assessment net
catch of walleye was one of the highest on record for Lake Vermilion.
The decision to introduce muskie into Lake Vermilion was based in part on the
abundance of tullibee and white sucker in the lake, species that are known to
be preferred prey items for muskie. Research has shown that muskie prefer prey
without sharp spines, such as tullibee and sucker. Perch have also been shown
to be an important prey item, probably because they are small enough that
their spines are not a factor and because they are found in stands of aquatic
vegetation that muskie also inhabit. Walleye have not been known to be a major
forage species for muskie, even in lakes with abundant walleye populations.
Although muskie will certainly eat walleye occasionally, the numbers eaten
are minor compared to other natural mortality and angler harvest.
A research project was recently conducted in Wisconsin that looked at the
feed habits of muskie. Stomach contents were examined from 1,092 muskie captured
in 34 Wisconsin lakes from July 1991 to October 1994. The muskie were captured
throughout the open water season by trapnetting, electrofishing and angling.
The muskie stomachs were flushed with water to disgorge the contents without
injuring the fish. The captured muskie ranged in size from nine inches to 46
inches. Based on the number and size of consumed food items, yellow perch and
white sucker were, by far, the most important fish species consumed by muskies.
Only five walleye were found in the 1,092 muskie stomachs examined. Sunfish,
crappie and various minnow species were eaten more frequently than walleye
in the study lakes. Tullibee were not common in many of the study lakes and
therefore were relatively unimportant as food items. However, previous research
has shown that tullibee are important food items for muskie in lakes where
they are abundant, such as Lake Vermilion. One interesting aspect of the study
was that researchers found that muskies would feed on crayfish in lakes with a
high population of rusty crayfish. Since the eastern portion of Lake Vermilion
has a high population of rusty crayfish, it is likely that muskie there will also
feed on crayfish, although probably not enough to decrease the rusty crayfish population.
It is important to understand that muskie and walleye have co-existed in many
lakes across the northern United States and southern Canada for centuries.
In fact many of the premier muskie lakes in the region are also excellent
walleye lakes. This would not be possible if muskie decimated walleye populations
as is sometimes suggested. The most important strategies for maintaining walleye
populations are to protect habitat, preserve water quality and prevent over-harvest.
If anyone has questions about muskie or other fish species in Lake Vermilion please
feel free to call me at our Ely office.
Large Lake Specialist for Lake Vermilion Minnesota Dept. of Natural Resources,
Section of Fisheries
Phone Number: 218-365-7280