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Lake Sturgeon Status
Survey in Michigan Waters of Lake Huron
as Reported by Commercial Fishers
March 1999
Tracy Hill
Fishery Biologist
U.S. Fish and Wildlife Service
Fishery Resources Office
Alpena, Michigan
tracy_hill@fws.gov
Provisional data, not to be cited without permission.
Introduction
Lake Sturgeon, Acipenser fulvescens, inhabit large river and lake systems primarily in the Mississippi River, Hudson Bay and Great Lakes basins (Harkness and Dymond 1961; Scott and Crossman 1973). It has and continues to represent an important biological component of the Great Lakes fish community. By the early 1900's many populations of lake sturgeon throughout their range had been greatly reduced or extirpated as a result of overfishing, habitat loss, the construction of dams, and pollution (Ono et al. 1983). Lake sturgeon are listed as either threatened or endangered by 19 of the 20 states within its original range in the United States (Auer 1991). The American Fisheries Society considers lake sturgeon a threatened species in North America (Williams et al. 1989). This ancient family of fishes has been recognized since the Upper Cretaceous period (136 million years ago), at a time when dinosaurs were at the height of their development.
Lake sturgeon are the only sturgeon species endemic to the Great Lakes basin and are the largest freshwater fish indigenous to that system. Lake sturgeon are late-maturing, slow-growing, long-lived fish that reach ages of 100-150 years (Guenette et al. 1993). Hill and McClain (1998) provide more detailed historical information on lake sturgeon populations.
The U.S. Fish and Wildlife Service-Alpena Fishery Resources Office (FRO) began investigating the Lake Huron lake sturgeon population in 1995. The purpose for the study was to gather critical information on Lake Huron lake sturgeon necessary for determination of federal listing and development of recovery plans.
Study Site
Lake Huron is the second largest (by surface area) of the Great Lakes with a total surface area of 59,596 km2. It is a deep oligotrophic lake, with a mean depth of 59 m and depths greater than approximately 30 m over two-thirds of its surface (Berst and Spangler 1973). Lake Huron lies in the center of the Great Lakes and receives discharge from both Lakes Superior and Michigan (Eshenroder et al. 1992).
Most of the lake sturgeon collected for this study came from Saginaw Bay, Lake Huron. Saginaw Bay is one of the largest bays in the Great Lakes. It is a shallow, well-mixed extension of the western shoreline of Lake Huron. Total area of the bay is 2,771 km2, and total water volume is 24.5 km3. Bottom substrates in Saginaw Bay range from silt to mostly cobble and rock.
Methods
Lake sturgeon monitoring continued in 1998 for the fourth straight year. Similar to previous years, all lake sturgeon were collected by commercial fishers as by-catch in their trap net fishery (Hill and McClain 1998). Michigan state-licensed commercial fishers use large commercial trap nets to capture fishes. Lake whitefish Coregonus clupeaformis, yellow perch Perca flavescens, and channel catfish Ictalurus punctatus are the species primarily targeted by the trap net fishery. Lake sturgeon are often encountered as by-catch during normal operation of the trap net fishery in Lake Huron. Total length (TL), fork length (FL), and girth were measured for all captured lake sturgeon. The leading (marginal) ray of the left pectoral fin was removed from each fish to provide estimates of age. All fish were tagged in the left operculum with a serially numbered Monel self-piercing animal ear tag (National Band and Tag CO., Newport, Kentucky). All lake sturgeon were handled by the commercial fishers, including data collection and fish tagging. All materials necessary to collect the biotic information was provided by the Alpena FRO (Figure 1). Each fisher was provided a box containing instructions for fish tagging and fin ray removal, tags and an applicator, fin ray removal pliers, data note book and cards, fin ray envelops, a soft measuring tape and a disposable camera. New to the study in 1998, was the collection of genetic material. The distal portion of the fin ray is being utilized for genetic analysis. Abiotic data recorded for each lake sturgeon captured included; date, latitude/longitude, water depth and temperature, and bottom type. In addition, tag type, agency, and identification number of tag applied to or observed on the fish was also recorded.
To maximize the information being collected on Lake Huron lake sturgeon, the Alpena FRO has been working closely with the Ontario Ministry of Natural Resources-Lake Huron Management Unit (OMNR-LHMU). Coordination between OMNR-LHMU and the Alpena FRO resulted in standardized data collection for lake sturgeon. This coordination enhanced the chances of recovering tag information from both sides of the lake and allowed a better understanding of the seasonal movement patterns of Lake Huron lake sturgeon.
Results and Discussion
Assistance from commercial fishers has been invaluable to the success of this study. Eleven commercial fishers (operating 18 boats) are providing information on by-caught lake sturgeon, eight of these fishers operate in Saginaw Bay. One new fisher began assisting with the project in 1998 (Table 1). Biological data were recorded for 38 lake sturgeon in 1998. The total number of lake sturgeon tagged declined slightly in 1998; this may be due to high water temperatures and low water levels experienced in Saginaw Bay (personal communication, Sandra Whyte). A total of 129 lake sturgeon have been tagged by commercial fishers since 1995.
Table 1. Number of lake sturgeon tagged by participating commercial fishers in Lake Huron trap net fishery since 1995. Dash indicates the fisher was not participating in the program.
Number of sturgeon tagged |
||||||
| Fisher | 1995 | 1996 | 1997 | 1998 | Total Tagged |
|
| Barbeaux Fishery | - |
1 |
7 |
0 |
8 |
|
| Bay Port Fish Company | 13 |
7 |
10 |
8 |
38 |
|
| Beardsley Fish Company | - |
- |
0 |
0 |
0 |
|
| Cederville Fish Company | - |
- |
1 |
7 |
8 |
|
| Gauthier-Spaulding Fishery | 2 |
0 |
2 |
2 |
6 |
|
| Lentz Fishery | 0 |
6 |
6 |
10 |
22 |
|
| Lixey Fish Company | - |
- |
- |
0 |
0 |
|
| M & W Fish Company* | 0 |
1 |
4 |
4 |
9 |
|
| Serafin Fishery | - |
7 |
17 |
3 |
27 |
|
| Warren Beers Fishery | 0 |
0 |
0 |
0 |
0 |
|
| Whytes Fishery | 0 |
3 |
4 |
4 |
11 |
|
| Total by Year | 15 |
25 |
51 |
38 |
129 |
|
*Formally Sam’s Fishery
Fork length of lake sturgeon captured in 1998 ranged from 67 cm to 171 cm with a mean fork length of 112 cm (Table 2). Age of these fish ranged from 4 to 59 years with a mean of 14 years. A summary of morphological data for lake sturgeon captured during the four years of this study are shown in Table 2. Figures 2 and 3 illustrate the length frequency and age frequency, respectively, of lake sturgeon collected during the course of this study. Biotic parameters were collected to assist with data exchange among other agencies involved in lake sturgeon status surveys. Several relationships were developed with these parameters to aid information exchange between the agencies. Figures 4 and 5 illustrate total length-fork length and girth-fork length relationships, respectively. These relationships are similar to information collected by OMNR-LHMU for Ontario waters of Lake Huron (Lloyd Mohr, personal communication).
Table 2. Summary of morphological data collected on lake sturgeon by commercial fishers in Michigan waters of Lake Huron. Dash indicates data was not collected.
1995 |
1996 |
1997 |
1998 |
|
| Mean Fork Length (cm) | 111 |
92 |
101 |
111 |
| Median Fork Length (cm) | 111 |
90 |
99 |
109 |
| Fork Length Range (cm) | 71 - 155 |
50 - 135 |
42 - 185 |
67 - 171 |
| Mean Age (years) | - |
- |
17 |
14 |
| Median Age (years) | - |
- |
13 |
12 |
| Age Range (years) | - |
- |
4 - 72 |
4 - 59 |
Figure 2. Length frequency of 149 Lake Huron lake sturgeon captured as by-catch in the trap net fishery, 1995-1998.
Figure 3. Age frequency of 58 Lake Huron lake sturgeon captured as by-catch in the trap net fishery, 1997-1998.
Figure 4. Fork length to total length relationship for Lake Huron lake sturgeon captured as by-catch in the trap net fishery, 1995-1998.
Figure 5. Fork length to girth relationship for Lake Huron lake sturgeon captured as by-catch in the trap net fishery, 1995-1998.
Weight information is limited for the lake sturgeon collected during this study. However, biologists working with lake sturgeon in Ontario waters of Lake Huron have developed an equation to predict weight of sturgeon based on total length and girth measurements. The equation is as followsLog (Weight)=Log (Total length) X 2.44499+Log(Girth) X 1.00584 - 21.1645
where weight is in kg and total length and girth are in mm.
Overall, the age distribution of lake sturgeon caught in 1997 and 1998 is dominated by sturgeon older than 11 years with a total of 25 year-classes represented (Figure 3). Lake sturgeon younger than 8 years old represent 10% of the sturgeon sampled in the trap net fishery. This may be due to poor recruitment, gear selectivity, or distribution of young sturgeon. It may indicate that Saginaw Bay is a staging area for sub-adult lake sturgeon.
Four previously tagged lake sturgeon were recaptured in 1998. One fish was found dead, one was harvested by an Ontario commercial fisher and tag numbers were not collected on the other two. One of the recaptured fish had lost a tag and had a new tag attached. Another recaptured fish was caught during rough seas and it was not possible to obtain the tag number. Lake sturgeon number 4043 was tagged by Serafin fishery on 25 August 1997, this sturgeon was found dead off Grand Bend, Ontario on 28 August 1998. Cause of death was unknown. Lake sturgeon number 4087 was tagged by Bay Port Fish Company on 4 October 1998 in Saginaw Bay, it was recaptured and harvested by Purdy Fisheries six days later in southern Lake Huron.
Data collected on Lake Huron lake sturgeon are biased by the fishing locations selected by the fishers seeking target species. There are, however, temporal differences in habitat overlap between lake sturgeon and the commercially targeted species. The greatest overlap occurs in the spring and fall period. Lake sturgeon are captured most frequently in May and October (Figure 6). This temporal information may prove useful in developing sampling protocol for assessment activities targeting lake sturgeon.
Figure 6. Number of lake sturgeon captured by Lake Huron commercial fishers, 1995-1998.
Summary
The cooperation and assistance provided by Lake Huron commercial fishers provided crucial information on the lake sturgeon populations in Saginaw Bay and northern regions of Lake Huron. Lake sturgeon appear to be less abundant in U.S. waters of Lake Huron than in Canadian waters based on by-catch return data. This is not surprising given that historically important spawning streams in Michigan have been blocked by hydro-power projects. A number of large streams with available spawning habitat are still free-flowing in Ontario, providing some degree of sustainability for lake sturgeon populations.
Increasing participation by commercial fishers should result in an escalation of lake sturgeon reports over the next few years. With more fishers involved in the tagging operation, additional information on seasonal movement should result from increased recaptures of previously tagged fish. In addition, collaboration between OMNR-LHMU and the Alpena FRO on the lake sturgeon project has begun to define movements of tagged sturgeon between the different basins of Lake Huron.
Despite the limited number of tagged lake sturgeon (129), a few discernible biotic and abiotic trends are developing. Personal discussions with the fishers indicate that small lake sturgeon have been observed in years prior to the initiation of this project. Although the mean age of captured lake sturgeon is 15 years, this mean was calculated from a small number of fish and may not represent the true age structure of the sturgeon population. Continued collection of age information should provide evidence of local recruitment in Michigan waters of Lake Huron if it is occurring. In addition, a few clusters of lake sturgeon captures are identifying areas that should be more closely examined for their habitat value to existing lake sturgeon populations and the possibility of supporting successful lake spawning stocks.
Expansion of the Alpena FRO and OMNR-LHMU efforts for lake sturgeon status surveys in the next few years will aid in understanding the current status, and the potential for a successful lake-wide recovery effort for this important native species.
Acknowledgements
The information presented in this report was collected entirely though the voluntary assistance of Barbeaux Fishery, Bay Port Fish Company, Beardsley Fish Company, Cederville Fish Company, Gauthier-Spaulding Fishery, Lentz Fishery, Lixey Fish Company, M&W Fishery, Serafin Fishery, Beers Fishery, and Whytes Fishery. Their cooperation, interest, and enthusiasm continues to be invaluable in defining the current status and trends of this native Lake Huron fish species. The author wishes to thank the Michigan Department of Natural Resources for initiating the mailing of data cards to the state-licensed commercial fishers, and Scott Koproski for his assistance with coordinating this project.
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Berst, A.H., and G.R. Spangler. 1973. Lake Huron-the ecology of the fish community and man?s effects on it. Great Lakes Fishery Commission Technical Report 3, Ann Arbor, Michigan.
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Scott, W.B., and E.J. Crossman. 1973. Freshwater fishes of Canada. Fisheries Research Board of Canada. Bulletin 184. Ottawa, Ontario.
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