The study also indicates that temperature affects the growth of ruffe less than yellow perch but that ruffe need more food than perch to survive. Since then they have become the most abundant fish trawled from the Duluth-Superior harbor and a competitive threat to native perch and other benthic fish. Sea Grant researchers Ray Newman, associate professor with the University of Minnesota, and graduate student Fred Henson, conducted laboratory experiments with ruffe taken from the Duluth-Superior harbor. The ruffe also attained sexual maturity sooner than perch. Even so, ruffe need more food.
More food is needed to sustain a given biomass of ruffe than the same biomass of perch.
Ruffe leave a bigger ecological footprint and are more likely to significantly alter the benthic forage base. Newman and Henson suspect that the ruffe's ability to devour benthic prey and continue growing in colder months enhances its ability to compete with native species and impacts the estuary's forage base. The University of Minnesota is an equal opportunity educator and employer.