**The title, authors, and abstract for this completion report are provided below.  For a copy of the completion report, please contact the GLFC via e-mail or via telephone at 734-662-3209**




Sara Adlerstein1, Edward Rutherford2, Stephen C. Riley3, Robert Haas4, Michael Thomas4, David Fielder5, James Johnson5, Ji He5, and Lloyd Mohr6



1 University of Michigan, SNRE, 3010 Dana, University of Michigan, Ann Arbor, MI 48109

2 University of Michigan, SNRE, University of Michigan, Museum Annex, Ann Arbor, MI 48109

3 US Geological Survey, Great Lakes Science Center, 1451 Green Rd, Ann Arbor, MI 48105

4 Michigan Department of Natural Resources, 33135 S. River Rd, Mt. Clemens, MI 48045

5 Michigan Department of Natural Resources, 160 E. Fletcher, Alpena, MI 49707

6 Ontario Ministry of Natural Resources, 1450 7th Ave. E., Owen Sound, ON N4K 2Z1, Canada



September 2007




We compiled and evaluated data from five gillnet and trawl surveys conducted in Saginaw Bay and Lake Huron in US and Canadian waters and developed model-based indices of abundance for selected species. Annual indices were estimated based on catch rates and using generalized linear and additive models. Models incorporated year and other factors that affected catch rates such as sampling location and different gears used within surveys. Annual indices from Saginaw Bay fall gillnet surveys from 1989 to 2001 fluctuated with no patterns for yellow perch ages 1 and 2 and decreased for ages 3 to 6 and also for walleye ages 1 to 6. Indices from 1993 to 2002 for freshwater drum and channel catfish increased after 1995, for lake whitefish decreased after 1996 and fluctuated with no pattern for gizzard shad and white perch. Annual indices from Saginaw Bay fall trawl surveys from 1986 and 2002 for yellow perch (mostly ages 1 and 2) decreased after 1989 but recovered to intermediate levels in 1995, and for walleye (mostly ages 0 to 2) fluctuated with no trends. Indices increased for alewife and trout perch after 1990 and for spottail shiner after 1994, and fluctuated with no pattern for rainbow smelt and white perch. Annual indices from Lake Huron lake trout spring gillnet surveys from 1975 to 2002 for lake trout ages 3 to 6 tended to decrease but showed recoveries in later years mostly in northern Lake Huron. Indices for alewife fluctuated with no patterns before 1995 and decreased in later years. For all other species indices decreased after 1985: rainbow smelt, round whitefish and yellow perch levels decreased steadily during the whole period and burbot, longnose sucker and lake whitefish levels increased until 1985 and decreased thereafter. Annual indices from the Lake Huron fall forage fish trawl survey from 1973 to 2005 decreased for lake trout except at Detour, the northernmost port, and initially tended to increase but decreased after about 1985 for rainbow smelt and bloater; decreases occurred after 1995 for trout perch and lake whitefish, and 2000 for spottail shiner. Indices for slimy sculpin, deepwater sculpin and ninespine stickleback initially tended to decrease, recovered, and decreased again after 1990. For alewife, levels initially fluctuated with no pattern then decreased after 1995. Johnny darter was the only species for which indices did not decline in later years. Annual indices from the Lake Huron Canadian gillnet survey decreased for rainbow smelt and longnose sucker from 1981 to 2005, after 1990 for lake whitefish, yellow perch, deepwater chubs, and burbot, and after 2000 for alewife. Indices for white sucker were stable. For lake trout, Chinook salmon, and round whitefish indices tended to increase steadily. Our results showed that despite challenges posed by survey characteristics conducted in Saginaw Bay and in the Lake Huron main basin, data available from the full period of these monitoring efforts are adequate to estimate model-based indices of abundance for main species represented in the surveys. Estimating these indices requires incorporating model predictors to account for spatial and temporal variation in effort within surveys that can affect catch rates and other factors affecting those rates such as changes in gear. This study is a first step in taking an integrative view of surveys in Lake Huron and may lead to improvements in data collection and data management and promote further research in understanding ecosystem dynamics.