Study Performance Report

F-53-R-15, Study 486

STUDY PERFORMANCE REPORT

F-53-R-15, Study 486

State:Michigan

Study No.:230486

Project No.:F-81-R-11

Title:Assessment of lake trout populations in Michigan’s waters of Lake Michigan.

F-81-R-11, Study 230486

Period Covered: October 1, 2009 to September 30, 2010

Study Objectives:To determine the relative abundance, length and age composition, and sea lamprey wounding and mortality rates for lake trout in Michigan’s waters of eastern Lake Michigan.Determine the total allowable catch (TAC) of lake trout from management units within 1836 treaty waters.

Summary:During the 2010 field season, lake trout sampling efforts focused on assessments of populations in eastern Lake Michigan from April to May.A total of 514 lake trout were captured during the 2010 field season.Aging and bio-data entry remain to be completed.Relative abundance estimates are highest in the southern and central regions, and lowest in the north.Mortality rates and other biological data through 2009are summarized in reports provided as part of the 2000 Consent Decree process.

Findings:Jobs 1 through 6 were scheduled for 2009-10, and progress is reported below.

Job 1.Title:Survey design and coordination.–Lake trout population assessments in 2010were conducted as per established multi-agency lake-wide assessment protocols (Schneeberger et al. 1998).

Job 2.Title:Conduct surveys and process samples.–Bottom gill-net surveys were conducted during April through May of 2010.Nets were set at four depth strata near each of four ports; a total of 514lake trout were captured (Table 1).

Job 3.Title:Manage data and maintain database.–A relational database was developed and refined for storing and managingvessel survey data.Catch data from the 2010 surveys have been entered into the standard database.Aging and diet samples remain to be processed;when available, this information will be entered into the database.

Job 4.Title:Analyze data, modeling.–From 2002 trough 2009, lake trout relative abundance estimates were lower from the northern regions of Lake Michigan compared to more southern regions and bay areas (Table 2). We provide a more thorough discussion of mortality rates and other aspects of lake trout populations in modeled regions (MM-1/2/3, MM-4, MM-5, and MM-6/7; Figure 1) in summary reports submitted as part of the 2000 Consent Decree process (see Job 6).

Statistical catch-at-age models were developed for lake trout populations in 1836 treaty-ceded waters (MM-1/2/3, MM-4, MM-5 and MM-6/7) and were used to estimate 2010TAC’s using data collected through 2009.The 2010 TACreport sections were completed and submitted to the Modeling Subcommittee (MSC) chairs for inclusion in the final report.

Job 5.Title:Write annual performance report.–This annual progress report was produced as scheduled.

Job 6. Title: Write other reports.–Sections were provided for tworeportsthat cover court-mandated settlement (2000 Consent Decree) responsibilities. The report for 2009, cited below, is provided; the report for 2010 is in progress and will be reported with the annual performance report for 2010-11.

Modeling Subcommittee, Technical Fisheries Committee.2009.Technical Fisheries Committee Administrative Report 2009: Status of Lake Trout and Lake Whitefish Populations in the 1836 Treaty-Ceded Waters of Lakes Superior, Huron and Michigan, with recommended yield and effort levels for 2009.

References:

Schneeberger, P., M. Toneys, R. Elliott, J. Jonas, D. Clapp, R. Hess, and D. Passino-Reader.1998.Lakewide assessment plan for Lake Michigan fish communities.Lake Michigan Technical Committee Report.Great Lakes Fishery Commission, Ann Arbor, Michigan.

Table 1.–Lake-wide assessment plan (LWAP)lake trout survey summary from 2010.

Port / Number of nets / Depth strata (ft.) / Number of lake trout
Arcadia / 2 / <50 / 1
2 / 50–100 / 16
2 / 100–150 / 40
2 / >150 / 11
8 / All / 68
Grand Haven / 2 / <50 / 11
2 / 50–100 / 10
2 / 100–150 / 22
2 / >150 / 26
8 / All / 69
Saugatuck / 2 / <50 / 65
2 / 50–100 / 25
2 / 100–150 / 40
2 / >150 / 27
8 / All / 157
South Haven / 2 / <50 / 91
2 / 50–100 / 42
2 / 100–150 / 69
2 / >150 / 18
8 / All / 220

Table 2.–Summary of mixed-model analyses of the relative abundance (gillnet catch-per-unit effort) of lake trout captured in annual surveys from four regions of Lake Michigan.MM designations are lake trout management units (Figure 1); “–” indicates missing data.

Modeled region
North / Grand Traverse Bay / Frankfort to Leland / Arcadia to Holland
Year / (MM1/2/3) / (MM4) / (MM5) / (MM6/7)
1981 / 0.55 / 1.49 / 2.34 / 3.13
1982 / 0.19 / 1.36 / 2.30 / 1.80
1983 / 0.48 / 1.51 / 2.16 / 3.26
1984 / 0.30 / 1.41 / 1.94 / 1.09
1985 / -0.04 / 1.01 / 2.74 / –
1986 / 0.02 / 1.43 / 3.74 / 2.21
1987 / 0.43 / 1.87 / 2.15 / 2.66
1988 / 1.04 / 2.62 / 2.18 / 1.60
1989 / 1.04 / 2.15 / 2.63 / 1.95
1990 / 1.11 / 2.22 / –
1991 / – / – / – / –
1992 / – / 1.81 / – / –
1993 / – / 1.51 / – / –
1994 / – / 1.87 / – / –
1995 / – / 1.70 / – / –
1996 / – / 1.74 / – / 0.71
1997 / – / 1.64 / 3.27 / 1.42
1998 / 0.33 / 2.25 / 0.99 / 1.90
1999 / 0.49 / 1.22 / 1.27 / 2.01
2000 / 0.79 / 1.68 / 2.11 / 2.08
2001 / 0.94 / 1.51 / 2.30 / 2.00
2002 / 0.45 / 1.36 / 2.23 / 2.03
2003 / 0.66 / 1.53 / 2.48 / 2.35
2004 / 1.07 / 1.79 / 2.54 / 2.01
2005 / 0.87 / 1.64 / 2.35 / 2.08
2006 / 0.66 / 2.42 / 2.47 / 2.29
2007 / 1.00 / 2.04 / 2.45 / 2.36
2008 / 1.36 / 2.28 / 2.32 / 2.56
2009 / 1.35 / 1.71 / 2.43 / 2.16
2005–09 average / 1.05 / 2.02 / 2.40 / 2.29

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