Strong hatches of Saginaw Bay walleye occur when adult alewives are scarce!
Ann Arbor, MI — Recent strong hatches of walleye in Saginaw Bay were most likely a result of low alewife abundance, and not other environmental factors.
Walleye has been stocked almost annually in Saginaw Bay since the 1978, and their population has little natural reproduction despite abundant adults. This changed suddenly in 2003-2005, when record high levels of natural recruitment were observed.
Researchers from the U.S. Geological Survey and Michigan Department of Natural Resources (MDNR) teamed up to try and learn the reason for this change. Saginaw Bay is well-studied, so they compiled a broad array of environmental data from the bay to see which environmental patterns best explained the recent record hatches. It turned out that the most likely explanation was recent low alewife abundance, and not weather patterns as has been thought previously. David Fielder, an MDNR research biologist says "we believe that poor walleye reproduction prior to 2003 was due to adult alewive preying on or competing with walleye fry just after they hatch. As soon as the alewive declined in Lake Huron, walleye reproductive success greatly increased for three years in a row despite very different spring conditions." Findings from this study may allow MDNR to adjust stocking rates by predicting years when natural walleye reproduction will occur. This study also indicates that the decline in Lake Huron alewife, while bad for Chinook salmon, had positive effects in Saginaw Bay.
Original Publication Information
Results of this study "Environmental and Ecological Conditions Surrounding the Production of Large Year Classes of Walleye (Sander vitreus) in Saginaw Bay, Lake Huron," are reported by David G. Fielder, Jeffery S. Schaeffer and Michael V. Thomas in the latest issue (Volume 33, No. sup1, pp. 118-132) of the Journal of Great Lakes Research, published by the International Association for Great Lakes Research, 2007.
Contacts
For more information about the study, David Fielder, Michigan Department of Natural Resources, Alpena Fisheries Research Station, 160 E. Fletcher Street, Alpena, MI 49707 USA; fielderd@michigan.gov; (989) 356-3232.
For information about the Journal of Great Lakes Research, contact Marlene Evans, Editor, National Water Research Institute, 11 Innovation Boulevard, Saskatoon, SK, S7N 3H5, Canada; editor@iaglr.org; (608) 692-1076.
Links
Since 1967, IAGLR has served as the focal point for compiling and disseminating multidisciplinary knowledge on North America's Laurentian Great Lakes and other large lakes of the world and their watersheds. In part, IAGLR communicates this knowledge through publication of the Journal of Great Lakes Research, available to members in print and electronic form. A searchable archive of the journal is available online and includes the abstracts of articles from the journal's inception in 1975 through the most recent issue. In addition, complete articles are available to members who have signed up for an electronic subscription.
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