Leino, R.L., and H. McCormick, 1997.  Reproductive Characteristics of the Ruffe, Gymnocephalus cernuus, in the St. Louis River Estuary on Western Lake Superior: a Histological Examination of the Ovaries Over One Annual Cycle, University of Minnesota, U.S. Environmental Protection Agency

Reprinted form Canadian Journal of Fisheries and Aquatic Sciences 54:256-263, 1997

Reproductive Characteristics of the Ruffe, Gymnocephalus cernuus, in the St. Louis River Estuary on Western Lake Superior: a Histological Examination of the Ovaries Over One Annual Cycle

Abstract
The Eurasian ruffe, Gymnocephalus cernuus, is a small percid that has recently been introduced into the Duluth Superior Harbor at the western end of Lake Superior. Because of its adverse impact on native species, its presence has caused considerable concern in the North American fisheries community. Ruffe have experienced phenomenal reproductive success in their new home and are rapidly extending their range. The reproductive success of this species seems to be partly related to the manner of spawning. We describe the dynamics of oogenesis of different age groups during the 1994 reproductive cycle. Spawning commenced within a week or two of ice-out and extended for approximately 8 weeks. Histological observations revealed that different age groups of ruffe spawned somewhat in succession, with older fish spawning first. As the season progressed, earlier spawners engaged in repeat spawning, probably two or three times before the end of the spawning period. These observations suggest that the unstable spring weather characteristic of this region has a minimal effect on the success of ruffe age groups, in contrast with several native species that spawn only once in the spring and that could suffer losses of age groups during a postspawning cold spell.

Entire Paper
Contact: Richard L. Leino, Department of Anatomy and Cell Biology, School of Medicine, University of Minnesota, Duluth, MN 55812
Keywords: Ruffe, Basic_biology, Environmental_impacts
Product Type: Research, Basic_biology, Impact
User Type: General