September 11, 1997
TO: Lake Michigan Fisheries Community
FROM: Bill Horns, Great Lakes Specialist
SUBJECT: Lake Michigan Fisheries Issues
It has been a good summer for salmon and trout fishing on Lake Michigan and the commercial fishery still benefits from abundant populations of whitefish and chubs. But this is a dynamic and continually changing lake, so we have no shortage of challenges and uncertainties, including the health of yellow perch and alewife populations. In this memo I have tried to highlight a few key issues. If you have questions or comments about the topics discussed here or any other issues related to Lake Michigan fisheries, contact me by phone (608.266.8782), FAX (608.267.7857), or e-mail (william.horns@wisconsin.gov). Thank you for your interest in the Department's program on Lake Michigan.
No good news yet regarding yellow perch in Lake Michigan and Green Bay. The Department is working with scientists and biologists from around Lake Michigan to monitor yellow perch reproduction in Lake Michigan and Green Bay and to support continuing research. Assessments for 1997 are incomplete, but results so far indicate that 1997 was another poor year for yellow perch reproduction in Lake Michigan. In Green Bay, early collections gave some hope for a good year class, but subsequent collections have not been so encouraging. Space does not allow a full discussion of all the research and monitoring activities, but for more information about perch in Green Bay you can call Brian Belonger, our biologist in Peshtigo (715.582.5006), and for more information about activities in Lake Michigan you can call our office in Milwaukee (920.382.7929). One of the primary research questions is whether yellow perch eggs from Lake Michigan are fully viable. To address this question, University of Wisconsin scientists at the Center for Great Lakes Studies in Milwaukee are comparing eggs and fry produced by yellow perch in Lake Michigan with eggs and fry produced by fish from Lake Ontario, Green Bay, and Lake Mendota. If the eggs from Lake Michigan fish are fully viable and produce healthy fry, we may be able to reject Early Mortality Syndrome and exposure of the parent fish to pollutants as causes for the problem; this would allow scientists to focus on other factors such as the diet of young perch and predation by alewives. This study is supported by the University, the DNR, and Sea Grant, but would not have been possible without assistance from interested commercial and sport fishers.
Last winter the Department worked with commercial fishers to study incidental catch rates of lake trout in gill nets set for chubs during winter. Data were collected by Department employees riding commercial boats, with the fishers reimbursing the Department for the time and expenses of those biologists. The purpose of the study was to assess the likely impacts of rule changes requested by commercial fishers. Under current regulations, chub nets may not be set in water shallower than 360 feet (60 fathoms) from January 16 through the end of February (during the remainder of the year chub nets may be set as shallow as 25 fathoms) and cannot be set outside of the Northern and Southern Chub Fishing Zones. Commercial fishers have asked to fish 1) closer to shore during winter and 2) north of the current northern boundary of the Southern Chub Fishing Zone. The study showed clearly that the number of lake trout killed in commercial nets increases if fishing is moved closer to shore during the winter period. Department biologists have recently met with interested sport and commercial fishers to discuss the implications of the study and a possible second year of research. We are hoping to find common ground with sport and commercial fishing interests before advancing any rule changes. If you would like a copy of the report on the chub study, let me know.
Each year, every commercial fishing license holder must meet a minimum catch requirement in order to be licensed for the new year. That is, his or her harvest for the past fishing year must exceed a specified minimum for one of the three commercial fishing zones. This requirement assures that only active fishers are able to retain licenses. When the commercial yellow perch fishery was closed in Lake Michigan, commercial fishers asked the Department to review the minimum catch requirement, arguing that, although all fishers had the opportunity to harvest chubs, it would be harder to meet the minimum harvest without the ability to harvest yellow perch. In response to this concern, the Department has proposed to allow the minimum catch requirement to be recomputed each year, so that it will reflect changes in the fishery, and to relax the requirement further during any year when quotas are cut by the Department. Public hearings on this proposal have been scheduled for 5 p.m. on October 20, 1997 (Room 604, City Hall, 100 N. Jefferson, Green Bay) and October 23, 1997 (Room 141, Southeast Region DNR Headquarters, 2300 N. Dr. Martin Luther King Jr. Dr., Milwaukee).
Catches of chinook salmon, coho salmon, and steelhead have been good this year, and another state record steelhead was caught (27.11 pounds, off Algoma). But there may be a cloud on the horizon; we have heard consistent reports of reduced alewife abundance. A decline should not be surprising; there are probably more predators in the lake than ever before. Even though Wisconsin, Illinois, and Indiana cut chinook stocking in the 1980's, Michigan did not follow suit, and, with increasing natural reproduction by chinook salmon in Michigan's streams and declining prevalence of BKD throughout the lake, the number of salmon at large in the lake may be higher than ever. Later this fall, the Great Lakes Science Center in Ann Arbor will conduct its annual trawl survey of forage species, including alewives, and we will watch that with great interest. This annual survey provides our best lakewide information about trends in forage fish abundance, but I would also be interested in hearing your thoughts. Based on your own observations on the lake, do you think alewives were more abundant, less abundant, or about the same in 1997, compared with 1996? Our biologists are working with counterparts in Michigan, Indiana, and Illinois to review lakewide salmon and trout stocking policies, but, if alewives are on the way down again, the decline cannot be stopped; even if stocking were drastically cut in 1998, predation by salmon and trout already in the lake would almost certainly continue to deplete the alewife population.
The ruffe is a Eurasian fish species that was transported in a ship's ballast from Europe or Asia to Lake Superior in the early 1980's. Since then it has proliferated in the St. Louis River and generated a great deal of concern about how it might affect native fish populations in North America. The International Ruffe Symposium, held in Detroit in March, brought together 100 managers, administrators, and scientists from around the world to present and discuss the results of ruffe research. According to Minnesota Sea Grant, the results reported at the Symposium offer hope that the ruffe may not be as destructive as feared. In particular, the research showed little, if any, negative impact of ruffe on yellow perch populations. For more information, contact Minnesota Sea Grant (218.726.7677) and ask for a copy of the May issue of their newsletter, the Seiche.
Midwest Fish and Wildlife Conference will feature sessions on yellow perch, anadromous salmonids, and cormorants. The Midwest Fish and Wildlife Conference, to be held in Milwaukee in December, will include special sessions on: