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STUDY PLAN FOR COORDINATED EVALUATION OF STRAIN PERFORMANCE, EARLY LIFE STAGE STOCKING, AND MOVEMENT OF LAKE TROUT IN LAKE HURON

2nd Edition

 

Edited for the Lake Huron Technical Committee by:

Jerry McClain
U.S. Fish & Wildlife Service
Alpena Fishery Resources Office
Alpena, Michigan
jerry_mcclain@fws.gov

Jim Johnson
Michigan Department of Natural Resources
Alpena Great Lakes Fisheries Research Station
Alpena, Michigan
johnsoje@michigan.gov

Chuck Bowen
Mary Burnham-Curtiss
U.S. Geological Survey - Biological Resources Division
Great Lakes Sciences Center
Ann Arbor, Michigan

March 1999

Provisional data, not to be cited without permission.

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CONTENTS

INTRODUCTION
1.  SIX FATHOM BANK - CWT
2.  NORTHERN REFUGE - CWT
3.  MOVEMENT STUDY - CWT
4. FISH QUALITY STUDY - CWT
5. OWEN SOUND LAKE TROUT - BACKCROSS STUDY - CWT
6.   MICHIPICOTEN/SLATE ISLAND STRAIN COMPARISON STUDY - CWT
7.  EGG STOCKING-   EARLY LIFE HISTORY EXPERIMENTS
8.  LARVAL FISH STOCKING - EARLY LIFE HISTORY EXPERIMENTS
9.   CWT DATABASE MANAGEMENT
LITERATURE CITED
APPENDIX 1

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INTRODUCTION

In 1985 studies were initiated in U.S. waters of Lake Huron to evaluate comparative plantings of several strains of lake trout. The experimental lots of trout were reared in federal (U.S. Fish and Wildlife Service) hatcheries, marked with coded-wire tags (CWT) for later analysis of differential performance, and stocked at specified locations. By stocking various strains and comparing their performance, it was hoped that a strain(s) could be identified which performs better than others, both in terms of establishing spawning populations on historically important reefs and surviving the presence of sea lamprey.

Two locations were chosen for the experiments, a mid-lake reef complex called Six Fathom Bank and a nearshore site along the south shore of Drummond Island in northern Lake Huron (Figure 1). Both sites contain extensive areas of habitat suitable for lake trout reproduction. To eliminate bias associated with harvest, the sites had to be relatively free of fish extraction. The remoteness of Six Fathom Bank (approximately 35 miles from the nearest shore access) provided such protection. To provide similar protection for the fish, Drummond Island was designated as a Refuge closed to all harvest. As the lake trout population has grown and expanded at Six Fathom Bank additional protection was warranted. In 1997 the State of Michigan and Ontario Ministry of Natural Resources designated the site as the first international lake trout refuge in the Great Lakes.

While fish for the two sites were marked and reared similarly, the objectives of the two experiments were different. The Northern Refuge lies in the region of Lake Huron experiencing the greatest degree of sea lamprey induced mortality. A strain of lake trout from the Finger Lakes region of New York state (Seneca Lake strain), having demonstrated a superior ability to withstand sea lamprey attacks (Royce 1950; Schneider 1985; Schneider et al. 1983), was chosen as a test strain. The Lake Superior strain of lake trout that has been the mainstay of the hatchery programs was chosen as the reference strain for this study. These strains are being stocked to test their ability to withstand sea lamprey attacks, or to mature prior to reaching a size when fully vulnerable to attacks, better enabling them to successfully reproduce. Additionally, this comparison will allow better evaluation of sea lamprey control measures applied to the St. Marys River.

Although lake trout were extirpated from the area, Six Fathom Bank was a historical spawning reef that continues to provide what is believed to be suitable spawning habitat. Strain comparison studies in this area of the lake were conducted to compare several lake trout genotypes in terms of growth, survival, and reproductive success relative to the ability of different strains to re-establish reproducing resident populations on a historic spawning reef.

This document is an attempt to establish clearly defined objectives, strategies, responsibilities, and time lines for efficacious execution of the studies. The first version of this document was completed in 1995 and is being updated with this second edition. As new studies are added to the program, or significant changes are made in the protocol of any individual component of this document, subsequent editions will be produced.

1.  SIX FATHOM BANK - CWT

It was the recommendation of the Lake Huron Technical Committee (LHTC) that three strains of lake trout (60,000 of each strain) be coded-wire tagged and stocked at specified locations on Six Fathom Bank annually through 1998. Recommended strains, as previously developed by the federal hatchery system, included the Lewis Lake, Seneca Lake, and Superior strains. Stocking coordinates were selected and provided to the federal hatchery system (Table 1).

Study Objectives:

To compare growth, sea lamprey wounding rates, survival, age composition, movement/distribution, and reproductive success of three strains of lake trout, which could result in selection of a preferred strain for the rehabilitation effort in this area of Lake Huron.

Principal Null Hypothesis:

There is no significant difference in the contribution of the respective genotypes being stocked to the genetic variation of lake-produced YOY lake trout at Six Fathom Bank.

Methods:

A variety of sampling techniques will be employed to recover data necessary for analysis of study results.

1. SPRING/SUMMER GILLNETTING will be conducted using standardized protocol allowing use of the site as a primary index station for lakewide trend analysis. Three gangs of nets tied together will be set cross contour (14 to 40 m) on the southern reef at Six Fathom Bank. A gang of nets consists of 300-ft panels of 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5 and 6.0 inch mesh stretched measure multi-filament nylon (210/2 twine; 6 ft high) that will be fished overnight at predetermined locations at each of these sites. Beginning and ending depths for each mesh size fished will be obtained from the ship’s sounder as each gang of net is set. Water temperature profiles from surface to lake bottom, will be recorded using an electronic bathythermograph at each location at the time of sampling. Sampling will take place during the last two weeks in June before thermocline becomes established and affects the distribution of lake trout. Catch per unit effort (CPUE) will be standardized to 1000 feet of net. Biological data, including length, weight, age, sex, maturity, stomach analysis, and sea lamprey wounding will be collected from all lake trout, along with information available through recovery of CWTs. All lake trout will be sacrificed for tag recovery and data collection. Mean length at age for fish captured during the sampling period will be used to monitor growth rates. The following information will be provided by this phase of the assessment program:

- relative abundance (CPUE)
- age class composition
- growth (mean length at age)
- survival
- food habits
- sea lamprey wounding rates (AI-AIII)
- maturity schedule
- distribution (among habitat types, depth)
- origin (hatchery/wild)

2. SPRING/SUMMER ASSESSMENT activities on and near the reef complex will use various methodologies for collection of juvenile and young-of-the-year (YOY) lake trout. Beam (3 meter) trawls will be fished across the tops of the northern, central, and southern reefs in the Six Fathom Bank Refuge to estimate the densities of wild lake trout from the sac fry to the fingerling stage. Special rock-hopping (13 meter) bottom trawls will be fished in deep waters (>150 ft) adjacent to all three reefs at Six Fathom Bank to estimate the densities of wild yearling lake trout. Sampling will take place during the last two weeks in June and July when sac fry have gone through swim-up and are more available to the trawl. Trawl catches will provide density estimates of wild age-0 lake trout on offshore spawning reefs. Catches of age-0 lake trout will be adjusted to number caught per hectare swept (Bronte et al. 1995). In addition to the collection of young lake trout, composition of forage species and predator-prey interactions will be analyzed. Stomachs of all predators, including lake trout, will be analyzed. All YOY lake trout will be preserved according to established procedures (Marsden et al. 1989) allowing for genetic analysis. Genetic analysis of naturally produced lake trout will be necessary to determine the strain of origin, which will provide critical information necessary for measurement of comparative performance of the strains being tested.

In addition to the biological data on the fish inhabiting the reef complex, the spring and summer cruises will be employed to collect physical data on the reef itself. Specifically, habitat found to be most heavily frequented by spawning lake trout the previous fall will be extensively examined.

3. FOOD WEB DYNAMICS of lake trout and burbot will be examined through concurrent studies at the Six Fathom Bank Refuge during the spring/summer assessment cruises. The objectives of this study are to understand the community interactions involving lake trout over present and historic spawning areas, in particular the critical, early life history stages of lake trout in a protective setting. Specifically this study will: (1) compare the food habits of offshore lake trout and burbot stocks for evidence of competition, (2) compare the food habits of offshore and nearshore burbot and lake trout stocks to determine if temporal or bathometric changes in diets have occurred, and (3) analyze the stomach contents of fishes for evidence of predation on early life-history stages of lake trout (egg, sac fry, fingerling).

Historically the food web dynamics in the U.S. waters of the central basin of Lake Huron, and in particular, the mid-lake reef area, was dominated by two top predators, lake trout and burbot, and their prey. However, major changes in fish species composition have occurred since the lake trout was extirpated from Lake Huron in the mid-1950s and managers are concerned that interactions with new species inhabiting these reefs could be an impediment to lake trout restoration. For example, offshore reefs are again inhabited by resident burbot populations that have increased dramatically during the late-1980s and could act as potential competitors with or predators on lake trout. Diets of both burbot and lake trout also change and may overlap only at certain life stages or time of year. Moreover, alewife (Krueger et al. 1995) and slimy sculpins and burbot (Savino and Henry 1991) can act as predators and could conceivably inhibit first year survival of, wild lake-produced young of lake trout (Jones et al. 1995).

Fish will be processed according to standard operating procedures (Brown and Eck 1994, Elliott et al. 1996). Biological data, including weight, sex, maturity, stomach analysis, and sea lamprey wounding will be collected from all adult lake trout, and the age, stocking site, and strain will be determined from coded wire tags. Similar biological information (length, weight, sex, maturity, stomach analysis, and sea lamprey wounding) will be collected from obtained burbot. Mean length at age for fish captured during the June-July sampling period will be used to measure growth rates. Diet information will be transformed to biomass eaten through our length-weight regressions available in other Center data archives.

Analysis of variance for unbalanced designs will be used to determine factors (year, site, taxa) that contribute significantly to diet in burbot and lake trout (Proc GLM, SAS, 1989a). Percent volumes will be rank transformed and numbers eaten will be natural log + 1 transformed for analyses. Significant effects from multiple comparisons will be determined with Tukey’s studentized t statistic. To interpret trends in diets, groupings of diet categories will be determined by cluster analysis (as in Hudson et al. 1995), using the option to minimize the root-mean-square difference between the data and the corresponding cluster means (Proc Fastclus, SAS 1989b). The number of clusters designated will be varied in an iterative process until clusters reflect major prey types.

4. FALL SPAWNING ASSESSMENT will be conducted on the reef complex for further analysis of strain differences. Four-hundred foot gangs of gillnets consisting of 100-foot panels of 4.5, 5.0, 5.5 and 6.0 inch stretch mesh multi-filament nylon will be used. Three gangs of nets will be fished at selected sites (established coordinates) annually. Effort will consist of overnight sets. An attempt will be made to conduct two to three sampling trips to the reef between mid-October and early November in years when weather permits, to examine possible bias associated with the time of spawning by the respective strains. All lake trout will be sacrificed for recovery of tags and data collection. Again, tissue samples will be collected from all CWT fish to assist in development of "learning samples" necessary for mixed stock analysis. The following information will be provided by this phase of the assessment program:

- relative abundance of the respective strains
- spawning time by strain
- depth distribution of spawners by strain
- age composition of spawners by strain
- spawner abundance (CPUE)
- spawning habitat/temperature selection by strain
- sea lamprey wounding rates
- incidence of unmarked/unclipped (presumably wild) spawners
- sex composition and maturity.

The Kolmogorov-Smirnov two-sample test will be used to test for differences in length-frequency distributions of the various groups of lake trout of a given strain and age (Conover 1971). Length-weight regressions will be developed for each strain; and differences in the regression lines will be determined using analysis of covariance (ANCOVA) (Neter and Wasserman 1974). Contingency tables will be used to test for differences in sex ratios (Conover 1971). Catch curves will be used to estimate lake trout survival (Ricker 1975); and ANCOVA will be used to detect significant differences in survival between lake trout strains. We will use probability analysis to determine sea lamprey attack rates on lake trout (Finney 1971); and we will used relative potency testing to determine differences in lamprey wounding (AI-III) rates among various lake trout strains (Finney 1971). Additionally, we will use probability analysis to determine maturity schedules for both male and female lake trout; and we will test for differences in maturation rates between strains using relative potency testing. Growth for each of the lake trout strains will be modeled using the von Bertalanffy curve (Ricker 1975); and differences in growth rates will be tested using multivariate techniques (Gallucci and Quinn 1979; Bernard 1981; Cerrato 1990).

5. GENETIC ANALYSIS of both stocked lake trout and unmarked fish resulting from natural reproduction will be necessary to fully evaluate the survival and reproductive contribution of respective strains. Genetic markers (nucleic acids or proteins) can be employed to identify possible parental stocks of lake-produced lake trout. Allozymes have effectively been used in mixed stock analysis of lake-produced Lake Ontario lake trout (Marsden et al. 1989) and Lake Superior rainbow trout (Krueger et al. 1994). The advantage of allozyme analysis is that both the maternal and paternal components of the stock can be surveyed for fixed differences at one or more protein-coding loci.

In a mixed stock analysis, genotype frequencies from parental stocks and populations of wild offspring are used in combination with the statistical technique of maximum likelihood estimation to estimate the most probable strain origins of the young. The information necessary as input includes genotype frequencies of protein coding loci of hatchery raised lake trout stocked into Lake Huron and genotype frequencies of wild-produced young lake trout. The "learning sample" needed as baseline input for 1985-1992 year classes for the maximum likelihood estimation will be determined from adult lake trout caught in spring/summer and fall gill net assessments (from which no samples were collected from the hatchery). Since all of the fish stocked for this study are marked with CWTs, strain and year class can be determined for the adult fish caught. Current and future year classes (1993+) will be represented by 80-100 fingerlings of each strain stocked, randomly sampled from raceways at the production hatchery.

Sampling Strategy
1. In each year hatchery fingerlings are stocked at Six Fathom Bank, a sample of 80-100 fingerling lake trout should be randomly sampled for each strain stocked. Whole fish should be preserved in liquid nitrogen or on dry ice and sent to U.S. Geological Survey, Biological Resources Division - Great Lakes Science Center (BRD-GLSC) where they will be processed within 3 months. These will provide information on genotypic frequencies for the "learning sample" or baseline sample.

2. Spring/summer/fall gill net assessments: sample various tissues for allozyme analysis as follows:

white muscle tissue -- 1-5 grams taken from dorsal area anterior to dorsal fin
eye -- save intact eyeball(s)
liver -- save 1-5 grams (same as white muscle). This tissue will also be sampled and archived for nucleic acid analyses (nuclear DNA, mitochondrial DNA)
kidney -- if possible, a sample of some kidney tissue should be taken for complete allozyme analysis.

Tissue samples are easiest to package in 1.5 or 2.0 milliliter cryotubes or microcentrifuge tubes, with all tissues from a single fish gathered in a "whirl-pak" type bag. Ideally, samples should be flash frozen in liquid nitrogen or placed on dry ice and transported as soon as possible for processing. Each fish sampled should be given a unique identification number which can be cross-referenced to collection data and CWT information.

3. Allozyme analysis: Tissues will be stored frozen a -80�C for allozyme surveys to be conducted at the NBS-GLSC. Allozyme analysis procedures, staining recipes, and nomenclature will follow May et al. 1979. Tissues, enzymes, and buffer systems will be run as outlined in Krueger et al. 1989 with slight modifications as necessary to accommodate lab conditions. An attempt will be made to document distribution and frequencies of 102 biochemical loci in the learning sample for comparison with results of Marsden et al. 1989. At least 18 loci (shown to be polymorphic in lake trout) will be surveyed from lake-produced young lake trout.

The following enzyme systems will be surveyed for all fish: AAT-1,2; ACP-1; FH-1,2; GPI-1; G3PDH-1; LDH-B3; sMDH-B3; sMDH-B-4; mMEP-2; PEP-D-1; PEP-D-2; PGK-1; PGM-2; PGM-3; sSOD-1. Additional enzyme systems will be investigated to complete data (102 loci) for the learning sample.

4.    Mixed Stock Analysis (MSA): YOY lake trout will be placed, individually, in plastic vials on ice for transfer to NBS-GLSC. Allelic or genotype frequencies will be used to describe the parental populations of lake trout contributing to a mixed sample of offspring in the areas of interest. This information will be used as input for MSA program (Grant et al. 1980) modified with an infinitesimal jackknife (Millar 1987) as used in Marsden et al. 1989. In this algorithm, the potential parents of wild offspring are identified rather than the actual stock composition of the wild offspring, as the offspring mixtures may comprise both pure-bred (intra-strain cross) and hybrid (inter-strain cross) fish.

6. DISPERSAL PATTERNS of fish stocked on Six Fathom Bank will be analyzed by comparing spring and fall CWT recoveries from near-shore and off-shore assessment sites, and sport and commercial recoveries. As part of the overall analysis of dispersal patterns, two approaches will be applied: 1) The incidence of CWT fish in assessment catch at Six Fathom Bank and near-shore sites (pooled) will be compared statistically with Chi-square or other non-parametric analyses to determine the degree of dispersal from the stocking site. 2) Analysis of CWTs recovered from fish at Six Fathom Bank, the near-shore sport and commercial fishery, and assessment catch will allow for comparison of strain dispersal patterns. For the purposes of analysis two null hypotheses will be tested:

Null Hypothesis 1: There is no significant difference in the incidence of CWT fish in the catch at Six Fathom Bank and the near-shore sites.

Null Hypothesis 2: There is no significant difference between strains in the proportion of lake trout caught at the near-shore sites.

Responsibilities:

Due to the remote location of the reef complex, safety of operation requires that a work platform capable of accommodating Great Lakes weather changes be employed. The R/V Grayling will be employed for the spring and summer cruises, as has been the case for the last several years. Fall spawning surveys on the reef will be conducted by the U.S. Fish and Wildlife Service - Alpena FRO from the M/V Togue. Staff assistance for the fall survey will be supplied by the BRD-GLSC. Recovery of CWTs, data analysis, and reporting will be accomplished collaboratively by BRD-GLSC and the Alpena FRO. Genetic analyses will be conducted by geneticists at BRD-GLSC. The nearshore spawning assessments, creel census and CWT collection programs necessary for evaluation of the dispersal patterns of Six Fathom Bank fish, will be conducted by Michigan Department of Natural Resources (MDNR) with assistance from USFWS (Alpena FRO). Alpena FRO will extract and read CWTs recovered from the MDNR assessment, sport and commercial fisheries.

Time Line:

Stocking five consecutive year classes of the same strains from the same facility should be considered the baseline for strain comparison using CWTs. At the end of the fifth year, re-evaluation of the plan is recommended. While lake trout representing the 1985-1997 year classes, inclusively, have been stocked on Six Fathom Bank, these plants have been from three different hatcheries and consisted of, both, fall fingerling (1985 year class) and yearling (1986-1997 year classes) fish. Additionally, the strains used for these plants have not been consistent. The Superior strain has been stocked each of the years identified. The second strain used prior to 1992 (1991 year class) was the Jenny Lake strain. Genetic analysis of that strain demonstrated that a lack of variability, produced by a "bottleneck" of some sort, made it less desirable than the Lewis Lake strain for the Great Lakes program (Leary et al. 1983). In 1992 (1991 year class), stocking of the Lewis Lake strain was established as the Wyoming strain of choice at the Six Fathom Bank Refuge. In 1990 (1989 year class) the transition was made from the Seneca Lake strain to the Lake Ontario feral strain (Ontario) due to a lack of the former in the federal hatchery system. Seneca Lake strain fish were not re-established in the program until the 1993 year class. Although genetically the Ontario and Seneca Lake strain are very similar, there appear to be differences that do not allow for direct comparison. Therefore, stocking of the 1993 year class should be considered the "first" of the five consecutive.

A thorough evaluation of the differential strain performance of those five year classes would require that the study be carried out until the last of the year classes is fully mature at age 8 (in 2005). At that point, obvious trends, or lack of, would be apparent and allow for recommendations regarding the future direction of the hatchery broodstock program.

The 1997 year class stocked in the spring of 1998 was the final year class of CWT marked lake trout for this study. Beginning in 1999 (1998 YC) lake trout stocking in this region of the lake will be shifted to Yankee Reef with the lakewide fin clip only.

Collection of tissue samples necessary to develop the "learning sample" began in 1994 when BRD-GLSC established the genetics laboratory. Annual samples of the hatchery fish being stocked at the Six Fathom Bank Refuge will be taken and forwarded to the lab for analysis. Appropriate tissue samples are also being collected from the spawning population (beginning with the fall spawning survey in 1994). Genetic analysis of F1 progeny should continue for the duration of the study phase (through 2005).

Evaluation of seasonal nearshore/offshore movement of Six Fathom Bank trout should continue for the duration of the study phase (through 2005).

2.  NORTHERN REFUGE - CWT

It is the recommendation of the LHTC that two strains of lake trout (60,000 of each strain) be marked with CWTs and stocked at specified locations in the Northern Refuge annually. Recommended strains, as previously developed by the federal hatchery system, are to include the Seneca Lake/Lake Ontario, and Superior strains. Stocking coordinates were selected and provided to the federal hatchery system (Table 1). If changes in stocking coordinates are required they will be provided to the federal hatchery system by the Lake Huron Committee at least 30 days prior to the anticipated stocking date.

Study Objectives:

1) To document trends in sea lamprey wounding and monitor effects of St. Marys River control efforts on lake trout stocks.
2) To compare vulnerability and survivability of two strains of lake trout to sea lamprey predation in northern Lake Huron where sea lamprey populations are largest.
3) To compare growth, sea lamprey wounding rates, survival, age composition, movement/distribution, and reproductive success of the two strains.

Principal Null Hypothesis:

There is no significant difference in survivability and vulnerability of the two strains to sea lamprey predation.

Methods:

A variety of sampling techniques will be employed to recover data necessary for analysis of study results.

1. SPRING GILLNETTING with 5,400 ft. gangs of net will be conducted at three locations within the refuge in May of each year. Each gang will consist of 54 one-hundred foot panels of 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5 and 6.0 inch stretch mesh multi-filament nylon gill nets. Each net is 6 ft. high and twine diameter is 210/2 (0.23mm) in the 2.0 to 4.5 inch mesh gill nets and #69 (0.28 mm) in the 5.0 to 6.0 inch mesh gill nets. These nets have plastic floats for buoyancy and 3/lb leads to keep them on the bottom. Each 100 ft. panel is numbered from 1 to 54 by writing that number on the first two floats at each end of a net. A 100 ft. panel of each mesh size is placed into a single net box and six net boxes are set during the spring. Individual 100 ft. panels are randomly arranged in each net box by drawing a piece of paper with the mesh size written on it from a coffee can. This procedure is repeated for each box of nets. The boxes of nets are set in the lake in no specific order. The number of each 100 ft. panel is recorded as they are set and the depth of water at the beginning and end of each 100 ft. panel. Typically fishing is conducted in water 70 to 160 ft. deep. All gangs are lifted after one night in the water. The purpose of this survey is to target both juvenile and adult lake trout. Catch per unit effort (CPUE) is standardized to 1000 feet of net. Biological data, including length, weight, age, sex, maturity, stomach analysis, fin clips, and sea lamprey wounding will be collected from all lake trout, along with information available through recovery of CWT. Mean length at age for fish captured during the May sampling period will be used to measure growth rates. All adipose clipped lake trout will be sacrificed for tag recovery and data collection. The following information will be provided from this phase of the assessment:

- relative abundance (CPUE)
- age class composition
- growth (mean length at age)
- survival
- food habits
- sea lamprey wounding rates
- maturity schedule
- distribution (among habitat types, depth)
- origin (hatchery\wild)

2. FALL INDEX GILL NETTING will be conducted at 13 sites within the refuge during October of each year. Single 800 ft. gangs of 4.5, 5.0, 5.5 and 6.0 inch mesh gillnets are set in waters of 3 to 50 ft. deep at ten sites during this survey. The 800 ft. gang contains two 100 ft. panels of each mesh size randomly arranged in a net box as described for the spring assessment surveys. These nets are all 6 ft. high and have a twine diameter of #69 and have no floats or leads. Float line and lead line is used on these nets. There is one float at each end of each 100 ft. panel with a number from 76 to 100 written on it. The net number and water depth at the beginning and end of each 100 ft. panel is recorded when the gangs are set. The purpose of the shallow water sets is to target adult, spawning-size lake trout.

In addition to the shallow sets, a single 2,000 ft. gang of 2.0, 2.5, 3.0, 3.5 and 4.0 stretched mesh gill nets is set at three sites in waters of 90 to 150 ft. during the October survey. The 2,000 ft. gang contains four 100 ft. panels of each mesh size randomly arranged in each box. These nets are the same as those used in the spring survey and are 6 ft. high, have a twine diameter of 210/2 (0.23 mm), and have floats and leads. The number of each 100 ft. panel is recorded as the nets are set, as is the water depth at the beginning and end of each panel. The purpose of these deep sets are to target immature, juvenile lake trout that are spatially segregated from the adult spawning-size fish during October.

The following information will be provided by this phase of the assessment:

- relative abundance of the two strains
- age composition of spawners (by strain)
- sea lamprey wounding rates
- spawner abundance (CPUE)
- spawning time (by strain)
- origin (hatchery\wild)
- sex composition and maturity

All lake trout captured in both the spring and fall surveys will be sacrificed for tag recovery and data collection. Length, weight, fin clip, sex, stage of sexual maturity, and sea lamprey marking is recorded for each fish. In addition, 10 stomachs from each of five size classes of each predator species; i.e. lake trout, burbot, chinook salmon, and walleye. The size classes are <200 mm, 200-399 mm, 400-599 mm, 600-799 mm, and >799 mm. Snouts are removed from all adipose clipped fish and placed in numbered plastic bags. A scale sample is collected from each fish species, except for unclipped lake trout >800 mm long and walleyes >500 mm long. Otoliths are collected from lake trout >800 mm and the first dorsal spine from walleyes >500 mm long.

Responsibilities:

Spring and fall assessment, as described above, will be conducted by Intertribal Fisheries and Assessment Program (ITFAP) personnel. Trout heads containing a CWT will be forwarded to the Alpena FRO for extraction and data recovery. Recovered data will be forwarded to NBS-GLSC for database storage, consolidation, and reporting.

Time Line:

This study has no clear end point. A primary objective of the strain evaluation study is to compare the success of two strains of lake trout (test and reference) in response to sea lamprey predation. It is the recommendation of this committee that this study continue until further evaluation warrants the definition of a single strain to be used in the Refuge study area.

3.  MOVEMENT STUDY - CWT

Calculation of Total Allowable Catch (TAC) in northern Lake Huron has suggested that there is substantial south to north movement of stocked lake trout from MH-2 to MH-1. Such movement significantly complicates mortality and TAC estimates. In an effort to quantify movement patterns, the LHTC requested four lots of CWT fish (60 K each) from the federal hatchery system. In the spring of 1992 lots of 60,000 lake trout (1991 year class) were stocked at Adams Point, Middle Island, Sturgeon Point, and Point Aux Barques (Figure 1). Stocking coordinates were selected and provided to the federal hatchery system (Table 1). Three additional year classes of similarly marked fish were stocked in alternate years at those locations as replicates of the 1992 study fish. Stocking of the 1997 year class in the spring of 1998 was the fourth and final replicate for this study.

Study Objectives:

1) To determine the extent of immigration to MH-1 from MH-2 and beyond.
2) To better define movement for improved delineation of management units.
3) To better define seasonal inshore/offshore movement patterns of hatchery lake trout.

Principal Null Hypothesis:

For lake trout marked with coded-wire tags and stocked at the four index locations, there is no difference in north and south movement of fish stocked at each site where movement is distance over time.

Methods:

Extend study initiated with 1991 year class, whereby 60 K lots were marked with CWTs and stocked in previously selected nearshore sites. The Lewis Lake strain will be used for the study to maintain continuity of the data set and all lots will be reared at the same hatchery. Distribution and movement patterns of these specially marked fish will be monitored through recovery of tags from assessment sampling and sport and commercial harvest in U.S. and Canadian waters.

Spring assessment conducted by MDNR at four of the five index stations (Figure 1), will be expanded, beginning in 1995, to sample north and south of the stations, as well as at the standard coordinates. This expanded coverage will enhance recoveries and provide better definition for the degree of movement.

Recovery of CWT from spring and fall surveys at the index stations and from the sport fishery will provide the best information for statistical analysis of movement patterns. Information will be compiled on the degree (distance) and direction of movement from the stocking site for each lot. In addition, as the lots of CWT fish age, a comparison of movement behavior between ages will be evaluated.

Increased effort for the recovery of CWTs from sport harvested lake trout will be undertaken through increased involvement of the charter industry, and by increased efforts at major sport fishing ports by agency personnel as budget and staffing allows. The 1991-97 year classes stocked for this study began returning to the creel in 1994 and has increased annually. Also, recovery of CWT from commercially harvested lake trout in U.S. and Canadian waters will supplement data collected through the sport fishery. Data recovered through commercial harvest will not be structured adequately to provide for sound statistical analysis, however it will provide information on distance and direction of movement.

Responsibilities:

Ongoing interagency assessment activities (MDNR, ITFAP, OMNR, BRD, USFWS), creel surveys, and increased involvement of the charter industry will provide the bulk of the CWT returns. Alpena FRO will be working with the charter industry to encourage their assistance in increasing tag recoveries. The MDNR Alpena Great Lakes Research Station will employ a seasonal "head-hunter" position through the duration of this study to provide coverage at principal fishing ports for recovery of CWTs, and to collect heads from drop-off stations along the Michigan shore. Alpena FRO will provide assistance to MDNR for enhanced coverage at major fishing ports, especially during tournaments. A significant number of tag returns are provided by Ontario Ministry of Natural Resources, primarily from the commercial fishery. These tag return data will be provided to BRD-GLSC for database entry. Routine screening of commercially harvested lake trout in the tribal fishery, conducted by ITFAP staff, will provide access and recovery of CWTs in the northern region of the lake. The Alpena FRO will receive lake trout heads carrying CWTs from assessment, sport, and commercial harvest for recovery, analysis, and data entry. Data analysis and reporting for this study will be conducted by the Alpena FRO with assistance from the Alpena DNR office.

Time Line:

A total of four alternate year classes of fish were marked and released for this study (1991, 1993, 1995 and 1997). Distribution and movement patterns should be monitored for ten (10) years or until the last year class (1997) is no longer present in the catch.

4. FISH QUALITY STUDY - CWT

The federal hatchery system has altered its program to improve the quality of lake trout stocked in the upper Great Lakes. To improve the quality of the product fewer fish are being held in the hatcheries, and they are being fed optimum rations throughout the hatchery cycle. As a result of the change 35 percent fewer yearling fish are available for stocking in each of the lakes. It is hoped that improved quality will result in significantly better survival, and consequently in no net loss to lakewide abundance. The proposal was made to Lake Huron Technical Committee in July 1994 and the endorsed recommendation passed on to the Lake Huron Committee where it was approved. To evaluate the change, the Technical Committee has designed a study to compare the new hatchery product with the historical "standard". The study is part of the movement study previously discussed.

Study Objectives:

1) To compare the post-stocking performance of the new, enhanced quality (larger) fish with the historical "standard" produced in the federal hatchery system.

Principal Null Hypothesis:

There is no net loss of fish to the fishery; that is, we should expect that survival of the enhanced quality (larger) fish will be at least 35 % greater than the standard quality (smaller) fish.

Methods:

Beginning with the 1995 year class, modify the movement study to incorporate the stocking of two 30,000 fish lots at each of the four movement study sites. One lot will be reared and stocked at the current standard of quality and size (approximately 20 fish/lb), and the second lot will be reared under more optimal hatchery conditions and consequently stocked at a larger size (approximately 10 fish/lb). All lots will be reared at the same hatchery and marked with coded-wire tags for purposes of analysis. Prior to release the LaCrosse Fish Health Center (USFWS) will conduct a fish health/condition assessment of each lot according to procedures developed by Goede and Barton (1990). Data collected through this assessment will provide baseline information on stocked fish, and allow statistical comparison of the two treatments at release. Monitoring of post-stocking performance will be accomplished through recovery of tags from interagency assessment sampling and sport and commercial harvest in U.S. and Canadian waters.

The expanded assessment (MDNR), at and adjacent to the index stations, previously mentioned in the movement study will provide enhanced data recovery for this study as well.

Increased effort for the recovery of CWTs from sport harvested lake trout will be undertaken through increased involvement of the charter industry, and by increased efforts at major sport fishing ports by agency personnel (MDNR, USFWS) as budget and staffing allows.

Relative abundance of the two treatments in the returns will be used as an indicator of survival. Other means of comparing short-term relative performance of the treatment groups will include growth rates, movement patterns, and sea lamprey wounding rates. Scale samples will be collected from assessment catches and back-calculation of growth will be performed to compare annual rates of growth by each group. Overall evaluation of the efficacy of the program change will be addressed by comparing relative abundance of the treatment groups in the assessment catch through age 4 or 5. In light of current mortality constraints being imposed on the Lewis Lake strain by sea lamprey, it is doubtful that an adequate sample size of experimental fish older than age 5 would be available for assessment.

Responsibilities:

Ongoing interagency assessment activities (MDNR, ITFAP, OMNR, BRD, USFWS), creel surveys, and increased involvement of the charter industry will provide the bulk of the CWT returns. Alpena FRO will be working with the charter industry to encourage their assistance in increasing tag recoveries. The MDNR Alpena Great Lakes Research Station will employ a seasonal "head-hunter" position through the duration of this study to provide coverage at principal fishing ports for recovery of CWTs, and to collect heads from drop-off stations along the Michigan shore. Alpena FRO will provided assistance to MDNR for enhanced coverage at major fishing ports, especially during tournaments, as long as budget and staffing at the two offices allows. A significant number of tag returns are provided by Ontario Ministry of Natural Resources, primarily from the commercial fishery. These tag return data will be provided to NBS-GLSC for database entry. Routine screening of commercially harvested lake trout in the tribal fishery, conducted by ITFAP staff, will provide access and recovery of CWTs in the northern region of the lake. The Alpena FRO will receive lake trout heads carrying CWTs from sport and commercial harvest, as well as ITFAP assessment activities for recovery, analysis, and data entry. Data analysis and reporting for this study will be conducted by the Alpena FRO with assistance from the Alpena DNR office.

In the years that the test fish are stocked (1996 and 1998), condition of the two treatments at release time will be compared by the LaCrosse Fish Health Center (USFWS), analyzed statistically if possible, and reports provided to the Lake Huron Committee at the following year's annual meeting. These data will provide the baseline information needed to monitor the groups over the next several years, as well as assist in establishing sample size necessary for comparing post-stocking performance.

Time Line:

Two alternate year classes of lake trout will be stocked for analysis of this study (1995 and 1997). Monitoring of these experimental lots will continue for a minimum of ten years, or until they are no longer present in the catch.

5. OWEN SOUND LAKE TROUT - BACKCROSS STUDY - CWT

Ontario Ministry of Natural Resources is currently in the final phase of a study to evaluate the differential performance of paired plants of lake trout and backcross in the Owen Sound region of Lake Huron.

Study Objectives:

1) To determine if differences exist between lake trout and backcross in survival, contribution to the fishery, and success of natural reproduction.

Principal Null Hypothesis:

There is no significant difference in performance, in terms of survival, contribution to the fishery, and contribution to the spawning population, between lake trout and backcross stocked in Owen Sound.

Methods:

For 5 years (1986-1990), 100,000 lake trout and 100,000 lake trout backcross were marked with coded-wire tags and stocked as yearlings in Owen Sound. The fish were reared at the Chatsworth Fish Culture Station; lake trout were Lake Manitou strain and backcross were Lake Manitou strain eggs crossed with highly selected splake males. The population of lake trout and backcross in Owen Sound was also contributed to by other stocking. Backcross were stocked in Owen Sound from 1979 to 1985, and in other areas of southern Georgian Bay from 1991 to 1995. Other lake trout were stocked in southern Georgian Bay in 1991 and each subsequent year. Standard annual index netting started in Owen Sound in 1984, and was used to evaluate this study. Index nets used were multi-filament nylon of 2250 feet total length, containing mesh sizes of 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 and 5.0 inches. The 1.5 inch panels were 150 feet, with the remaining seven panels being 300 feet each.

Coded-wire tags were recovered through the assessment sampling, as well as returns from sport and commercial fisheries.

Responsibilities:

OMNR Lake Huron Management Unit is responsible for data recovery, analysis, and report preparation.

Time Line:

Although the assessment netting was officially completed in 1994, data will continue to be added to the data set as long as tags are being recovered.

6.   MICHIPICOTEN/SLATE ISLAND STRAIN COMPARISON STUDY - CWT

A strain comparison study was initiated by OMNR in Owen Sound in 1994. In 1996 stocking was moved to the nearby Cape Rich location due to constraints in the assessment budget. This study, using coded-wire tagging, was initiated to compare the relative performance of two lake trout genotypes. The last year of stocking for this study was 1998.

Study Objectives:

1) To determine if differences exist between two strains of stocked lake trout in terms of survival, contribution to the fishery, and reproductive success.

Principal Null Hypothesis:

There is no significant difference in the performance, in terms of survival, contribution to the fishery, and reproductive success, of Michipicoten and Slate Island strains of lake trout stocked in southwestern Georgian Bay.

Methods:

Annual spring releases of 100,000 lake trout yearlings of each strain were coded-wire tagged in lots of 10,000 fish and stocked in Owen Sound or at Cape Rich. At the Owen Sound location, paired stocking over three different water depths was conducted in 1994 and 1995 to test for differential performance relative to stocking habitat. Annually three lots (30,000) of each strain were stocked at the surface over a 16 foot dept, four lots (40,000) of each over a 50 foot depth, and three lots (30,000) of each over a 98 foot depth. In 1996, 1997, and 1998 all fish were released over the same depth (approximately 30 feet) at Cape Rich. Assessment netting for this study utilizes the standard OMNR Lake Huron graded mesh monofilament gill nets. In addition to the recovery of data from assessment netting, data are anticipated from sport and commercial catches.

Responsibilities:

OMNR Lake Huron Management Unit is responsible for data recovery, analysis, and report preparation.

Time Line:

The experiment had a five year stocking protocol with annual releases occurring from 1994 through 1998. The Cape Rich assessment site is a long term OMNR project with annual summer gill netting planned to continue indefinitely. Data collection and analysis will continue as long as the tagged fish occur in the various fisheries.

7. EGG STOCKING -  EARLY LIFE HISTORY EXPERIMENTS

A joint study developed by the Technical Committees for Lakes Huron and Michigan was initiated in 1992. The study calls for the stocking of up to 4.0 million lake trout eggs, using protocol developed by Swanson (1982), on historical spawning reefs in the two lakes. Egg stocking was alternated between the two lakes, with Lake Huron receiving the eggs in 1993, 1995 and 1997. Beginning in 1998 the artificial turf incubation study was moved to Lake Michigan and will remain there, annually, through 2000. In 2001 the experiment is scheduled to return to Lake Huron. The experimental use of lake trout eggs will be in lieu of any fall fingerling stocking in the lakes unless/until the availability of eggs exceeds the needs of the early life-history work.

Study Objectives:

1) To evaluate the efficacy of stocking lake trout eggs in artificial turf incubators on historically important reefs for the establishment of spawning populations of lake trout.

Principal Null Hypothesis:

The artificial-turf technique is not effective at establishing spawning populations of lake trout on historically important spawning reefs.

Methods:

Using procedures developed by Swanson (1982) and modified by Holey (1993) and McClain (1994), stock up to 4.0 million green or eyed lake trout eggs on Spectacle Reef where suitable habitat exists. Techniques and procedures will be modified annually based on logistical impediments identified the previous year. Eggs will be shipped from the federal hatcheries to sites specified by the ITFAP in late October (green) or early November (eyed). Using staff and volunteer assistance, the eggs will be packaged and transported to the stocking site for deployment. The incubators will be retrieved the following spring in May or June. Upon retrieval, the incubators will be transported to Sault Ste. Marie where they will be disassembled and cleaned for future use. Twenty percent of the incubators will be randomly selected for evaluation of hatching success. Selected incubators will be carefully examined during disassembly, with dead eggs and/or alevin counted and converted to a percentage of the estimated number contained in each incubator. A mean survival will be calculated to represent the overall "swim-up" success of that year's operation.

1. FALL GILL NETTING will be conducted at 3 sites on the reef during October of each year. Single 800 ft. gangs of 4.5, 5.0, 5.5 and 6.0 inch mesh gillnets will be set across the reef during this survey. The 800 ft. gang contains two 100 ft. panels of each mesh size randomly arranged in a net box as described for the spring assessment surveys at the Northern Refuge. These nets are all 6 ft. high and have a twine diameter of #69 and have no floats or leads. Float line and lead line is used on these nets. There is one float at each end of each 100 ft. panel with a number from 76 to 100 written on it. The net number and water depth at the beginning and end of each 100 ft. panel is recorded when the gangs are set. The purpose of the shallow water sets is to target adult, spawning-size lake trout to determine if spawning is currently occurring on that reef.

In addition to the shallow sets, a single 2,000 ft. gang of 2.0, 2.5, 3.0, 3.5 and 4.0 stretched mesh gill nets will be set in the deeper water off the reef. The 2,000 ft. gang contains four 100 ft. panels of each mesh size randomly arranged in each box. These nets are the same as those used in the spring survey at the Northern Refuge and are 6 ft. high, have a twine diameter of 210/2 (0.23 mm), and have floats and leads. The number of each 100 ft. panel is recorded as the nets are set, as is the water depth at the beginning and end of each panel. The purpose of this deep set is to target juvenile lake trout, burbot and chubs in this region of Lake Huron.

Responsibilities:

The ITFAP will be responsible for the scheduling, coordination, and execution of the deployment phase of the project. Retrieval of the artificial turf incubators will be accomplished with the assistance of tribal commercial fishers. The retrieval phase of the project will be conducted in mid-May, in conjunction with spring assessment activities in that region of the lake if possible. Data analysis and report preparation, for the evaluation of this project, will be conducted by ITFAP personnel. All fall spawning surveys will be conducted by ITFAP as well.

Time Line:

Three year classes (1998, 2000 and 2002) of lake trout will be stocked as eggs at this site using the artificial turf technique. Spring, summer, and fall assessment activities will continue annually through 2007 to evaluate the efficacy of the program. During the 10-year assessment phase, modifications will be made as needed to improve the efficiency of the gear, and annual updates will be provided. At the end of the 10-year assessment phase a decision will be made regarding the future of the program.

8. LARVAL FISH STOCKING - EARLY LIFE HISTORY EXPERIMENTS

The development of spawning populations of lake trout and the production of offspring in Lake Huron has, with few exceptions, been unsuccessful. There are constraints on both processes: the development of spawning populations can be constrained by exploitation, maturation, location and use of appropriate spawning shoals, and the behavior of naive mature trout; recruitment can be constrained by environmental conditions on the shoals and nursery habitats, and by the phenology of incubation and emergence. In a large lake, the location of appropriate spawning shoals and nursery habitats by lake trout may be more of a roulette game than in small inland lakes. If imprinted mature planted fish can be induced to return to appropriate shoals in sufficient numbers for spawning, this bottleneck may be overcome.

Study Objectives:

1) To evaluate the efficacy of stocking larval lake trout on historically important spawning shoals for improved homing of sexually mature adults to these "natal" shoals.

Principal Null Hypothesis:

Lake trout planted as larvae on historically important spawning shoals will show no more fidelity to the "natal" shoal than lake trout planted as yearlings.

1.   ONTARIO WATERS

Methods:

Up to 1 million pre-swimup lake trout fry will be stocked on an alternate year basis at White Shingle reef, a historically important reef in the Bruce archipelago north of Tobermory, Ontario. The fry will be stocked in May of 1995, 1997, 1999, and 2001. The stocking will be accomplished by gravity feeding the fry through a flexible hose that is dragged along the bottom at depths of 10-17 feet. Approximately 500 fry will be retained in 10 containers on the reef and retrieved after 1 week to determine post stocking mortality.

Up to 50,000 lake trout yearlings will be stocked at the same reef in May of 1994, 1996, 1998, and 2000. The yearlings will be fin clipped and marked with a coded-wire tag.

All lake trout used in this study will be the Michipicoten strain from Lake Superior. Eggs and fry will be incubated at ambient lake temperature at the Blue Jay Creek Fish Culture Station.

Assessment of this study will entail various techniques employed from year 4 through year 12.

1. SUMMER ASSESSMENT around the stocking site will consist of 10 overnight sets of multi-mesh gill nets in August of each year. At the present time, the gear is 2250 foot multi-filament gill nets with mesh sizes of 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5 and 5.0 inch. The 1.5 inch panels are 150 feet, with the remaining seven panels being 300 feet each. Transition is currently being made to mono-filament nets, with the possible inclusion of trap nets as part of the assessment gear.

2. FALL SPAWNING ASSESSMENT will start in the fifth year of the study and continue each successive fall. Current plans call for the use of trap nets set on the spawning shoal to assess the spawning population. The exposed nature of the shoal may preclude the use of trap nets and require reversion to multi-mesh gill nets.

Responsibilities:

OMNR's Lake Huron Fisheries Research team will be responsible for coordinating and completing all aspects of this project. The vessel Atigamayg will be used to stock lake trout and set assessment gear.

Time Line:

Five year classes (1993, 1995, 1997, 1999, 2001) of lake trout will be stocked as either fry or yearlings from 1994 to 2001. Summer and fall assessment activities will continue annually through 2005 to evaluate the relative contribution of the fry and yearlings to the spawning stock at White Shingle shoal.

2.  MICHIGAN WATERS

Methods:

Up to 1 million pre-swimup lake trout fry will be stocked on an alternate year or annual basis at Thunder Bay Shoal north of Alpena or at other sites as determined. In the spring of 1999, 2000, and 2001 when the bulk of the available eggs are used for artificial turf incubation experiments in Lake Michigan, some fry will be stocked at Spectacle Reef rather than at Thunder Bay Shoal. The number stocked will be dependent upon total availability and the extent of the artificial turf experiment in Lake Michigan. The stocking will be accomplished by gravity feeding the fry through a flexible hose that is dragged along the bottom at depths of 30-40 feet.

Incubation will be retarded to provide pre-swimup fry in April by a combination of chillers and ambient Videan Creek water at the Pendills Creek NFH. Thermal marking will applied to eyed-eggs and/or fry to provide differentiation from hatchery and naturally produced lake trout. Strains used for the study will be determined by hatchery availability in the years of stocking.

Assessment of this study will entail various techniques employed from year 4 through year 12.

1. SPRING/SUMMER ASSESSMENT will be conducted annually at the site of fry stocking using nine hundred foot nets consisting of one-hundred foot panels of 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5 and 6.0 inch stretch mesh multi-filament nylon, fished overnight at varying depths. CPUE will be standardized to 1000 feet of net. Biological data, including length, weight, age, sex, maturity, stomach analysis, and sea lamprey wounding will be collected from all lake trout. Aging of unclipped lake trout will be conducted using scale and otolith samples. Year class strength of unclipped lake trout will be compared with fry stocking histories using statistical methods to explain annual variations. Mean length at age for fish captured during the May - July sampling period will be used to measure growth rates. In addition, tissue samples (as described previously) will be collected from unclipped fish for MSA..

2. FALL SPAWNING ASSESSMENT will start in the fifth year of the study and continue each successive fall. Four-hundred foot gillnets consisting of 100 foot panels of 4.5, 5.0, 5.5 and 6.0 inch stretch mesh multi-filament nylon will be used for this portion of the assessment. Nets will be fished overnight at various locations on the reef, providing representation of a variety of depths and habitat types. Tissue samples (as described previously) will be collected to assist in the development of "learning samples" necessary for MSA.

Responsibilities:

The Alpena Fishery Resources Office (USFWS) will be responsible for stocking of the fry with the use of the M/V Togue. Spring/summer and fall assessment netting will be conducted through collaboration between the MDNR, ITFAP and the Alpena FRO.

Time Line:

Five year classes (1998 - 2002) of lake trout fry will be stocked for this study. Spring/summer and fall assessment activities will continue annually from 2002 through 2010 to evaluate the relative contribution of the fry and yearlings to the spawning stock at Thunder Bay Shoal, Spectacle Reef, or alternate sites chosen during this study.

9.   CWT DATABASE MANAGEMENT

The Lake Huron lake trout CWT database is currently being maintained by NBS-GLSC. All CWT data should be provided to the center in a timely manner by those recovering and reading the tags (MDNR, OMNR, USFWS). Once the data have been entered (annually) a collated listing of the recovery information will be provided to each of the agencies and interested offices. Dissemination of the information in this manner will allow each office involved in or directing a particular study to analyze their own data and prepare the appropriate reports. It is anticipated that the report will be available for distribution by the winter meeting of the LHTC. This protocol will continue until further notice to the LHTC. Once the Alpena FRO is more adequately staffed a decision will be made between NBS and USFWS as to whether the database will be transferred to that office.

The Alpena FRO has worked with the USGS-GLSC to standardize the input data and provide that guidance to all agencies involved in data collection. Previous input inconsistencies resulted in missing data for specific agencies and years that impede effective analysis of data provided by this database. This new standardized format should eliminate many of the previous problems with this database.

LITERATURE CITED

Bronte, C. R., J. H. Selgeby, J. H. Saylor, G. S. Miller, and N. R. Foster. 1995. Hatching, dispersal, and Bathymetric distribution of age-0 wild lake trout at the Gull Island Shoal complex, Lake Superior. J. Great Lakes Res. 21(Supplement 1):233-245.

Brown, E.H., and G. W. Eck. 1994. Quality assurance project plan for lake trout and forage fish sampling for diet analysis and/or contaminant analysis in Lake Michigan. Prepared for the Environmental Protection Agency, Great Lakes National Program Office, Chicago, IL (May 1994). 22 p. + 10 p. appendices.

Elliott, R. F., P. J. Peeters, M. P. Ebener, R. W. Rybicki, P. J. Schneeberger, R. J. Hess, J. T. R. Francis, G. W. Eck, and C. P. Madenjian. 1996. Conducting diet studies of lake Michigan piscivores- A protocol. Prepared by the Lake Michigan Technical Committee for the Lake Michigan Committee. Report No. 96-2.

Goede, R.W., and B.A. Barton. 1990. Organismic indices and an autopsy-based assessment as indicators of health and condition of fish. American Fisheries Society Symposium 8: 93-108.

Grant, W.S., G.B. Milner, P. Krasnowski, and F.M. Utter. 1980. Use of biochemical loci variants for identification of sockeye salmon (Oncorhynchus nerka) stocks in Cook Inlet, Alaska. Canadian Journal of Fisheries and Aquatic Sciences. 37:1236-1247.

Holey, M.E. 1993. Deployment of lake trout eggs in artificial turf incubators in Lake Michigan, 1992. U.S. Fish and Wildlife Service Progress Report, March 1993. 6pp.

Hudson, P.L., J.F. Savino, and C.R. Bronte. 1995. Predator-prey relations and competition for food between age-0 lake trout and slimy sculpins in the Apostle Island region of Lake Superior. J. Great Lakes Res. 21 (Suppl. 1): 445-457.

Jones, M.L., G.W. Eck, D.O. Evans, M.C. Fabrizio, M.H. Hoff, P.L. Hudson, J. Janssen, D. Jude, R. O’Gorman, and J.F. Savino. 1995. Limitations to lake trout (Salvelinus namaycush) rehabilitation in the Great Lakes imposed by biotic interactions occurring at early life stages. J. Great Lakes Res 21(Suppl. 1): 253-259.

Krueger, C.C., J.E. Marsden, H.L. Kincaid, and B. May. 1994. Genetic differentiation among lake trout strains stocked into Lake Ontario. Transactions of the American Fisheries Society. 118:317-330.

Krueger, C.C., D.L. Perkins, R.J. Everett, D.R. Schreiner, and B. May. 1994. Genetic variation in naturalized rainbow trout (Oncorhynchus mykiss) from Minnesota tributaries to Lake Superior. Journal of Great Lakes Research. 20(1):299-316.

Krueger, C.C., D.L. Perkins, E.L. Mills, and J.E. Marsden. 1995. Predation by alewives on lake trout fry in Lake Ontario: role of an exotic species in preventing restoration of a native species. J. Great Lakes Res. 21 (Suppl. 1): 458-469.

Leary, F.R., F.W. Allendorf and K.L. Knudsen. 1983. Electrophoretic analysis of Lewis and Jenny Lake lake trout, Salvelinus namaycush. University of Montana Population Genetics Laboratory Report 83/10. 12pp

Marsden, J.E., C.C. Krueger and B. May. 1989. Identification of parental origins of naturally produced lake trout in Lake Ontario: Application of mixed-stock analysis to a second generation. North American Journal of Fisheries Management 9:257-268.

May, B., J.E. Wright, M. Stoneking. 1979. Joint segregation of biochemical loci in Salmonidae: Results from experiments with Salvelinus and review of the literature on other species. Journal of the Fisheries Research Board of Canada. 36:1114-1128.

McClain, J.R. 1994. Deployment of lake trout eggs in artificial turf incubators in Lake Huron, 1993. U.S. Fish and Wildlife Service Progress Report, March 1994, 8 pp.

Millar, R.B. 1987. Maximum likelihood estimation of mixed stock fishery composition. Canadian Journal of Fisheries and Aquatic Sciences. 44:583-590.

Royce, W.R. 1950. The effect of sea lamprey attacks upon lake trout in Seneca Lake, New York. Transactions of the American Fisheries Society. 79:71-76.

SAS 1989a. SAS/STAT User’s Guide, Version 6, Fourth Edition, Volume 2, pp. 891-996. Cary, NC: SAS Institute Inc.

SAS 1989b. SAS/STAT User’s Guide, Version 6, Fourth Edition, Volume 1, pp. 823-850. Cary, NC: SAS Institute Inc.

Savino, J.F., and M.G. Henry. 1991. Feeding rate of slimy sculpin and burbot on young lake charr in laboratory reefs. Environ. Biol. Fishes 31: 275-282.

Schneider, C.P. 1985. Assessment of adult lake trout stocks in Lake Ontario, 1984. Report of the Lake Ontario Committee, Great Lakes Fishery Commission, Ann Arbor, MI. 15 p.

Schneider, C.P., D.P. Kolenosky, and D.B. Goldwaite. 1983. A joint plan for the rehabilitation of lake trout in Lake Ontario. Report of the Lake Trout Subcommittee of the Lake Ontario Committee, Great Lakes Fishery Commission. Ann Arbor, MI. 50 p.

Swanson, B.L. 1982. Artificial turf as a substrate for incubating lake trout eggs on reefs in Lake Superior. Prog. Fish-Cult. 44(2):109-111.

APPENDIX 1

Table 1. Stocking coordinates for experimental lots of lake trout used in coded-wire tagging (CWT) studies in Lake Huron.

 

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