|
> Conserving
Fisheries new __________ |
Preliminary evaluation of the current status of lake sturgeon (Acipenser fulvescens)
in Michigan waters of Lake Huron--
A progress report for 1995 and 1996.January 1997
Jerry R. McClain
U.S. Fish and Wildlife Service
Alpena Fishery Resources Office
Federal Building, Rm 204
145 Water Street
Alpena, MI 49707
jerry_mcclain@fws.gov
Provisional data, not to be cited without permission.
INTRODUCTION
Historically, the lake sturgeon Acipenser fulvescens was an important component of the Lake Huron fish community. Considered part of the nearshore, coolwater community, the species was important to Native American tribes inhabiting the Lake Huron basin as a food source in the pre-European settlement period (Kinietz 1940). Lake sturgeon were considered a nuisance by early commercial fishers, both, for lack of a market and the damage the fish did to nets when entangled. In the mid-1800’s markets began developing for lake sturgeon that would place immediate and extensive pressure on the stability of this long-lived species. In 1860 a sturgeon processing plant was established in Sandusky, Ohio that began marketing smoked sturgeon on a large scale (Harkness and Dymond 1961). Later the roe was being processed for caviar and isinglass was produced from the swim bladders. The rapid increase in exploitation led to similarly rapid decreases in abundance. In Lake Huron, lakewide commercial landings exceeded 453,000 kg in 1885 but declined by 56% in the seven years between 1893-1900 (Harkness and Dymond 1961). This over-exploitation coupled with the construction of dams on rivers historically used for spawning were the key contributors to the current depleted status of lake sturgeon in Lake Huron (Ono et al. 1983).
The lake sturgeon is listed as either endangered or threatened by 19 of the 20 states encompassing the original range within the United States - Wisconsin is the only exception (Auer 1991). Protection in Canada is provided under the Federal Fisheries Act by the province where the sturgeon population is located (Houston 1987). Protection of sturgeon in the Ontario waters of Lake Huron consists of closed seasons, size limits, creel limits, and gear restrictions. Currently commercial harvest in Ontario is controlled by a quota system. No commercial harvest of sturgeon is permitted in Michigan waters and sport harvest is limited to one fish per year.
Although sturgeon are occasionally reported by sport and commercial fishers and recreational divers, essentially no qualitative information is available on the current status of the species in Lake Huron. Inland populations of landlocked remnants of Lake Huron have been studied (Baker 1980) but no work exits that would aid in the development of recovery plans for the species in Lake Huron.
In 1995 the Lake Huron Committee (LHC) published the Fish-Community Objectives for Lake Huron in which the stated objectives for lake sturgeon were 1) to increase the abundance of lake sturgeon to the extent that the species is removed from its threatened status in U.S. waters, and 2) to maintain or rehabilitate populations in Canadian waters (DesJardine et al. 1995). To address these objectives the Lake Huron Technical Committee (LHTC) completed an update on the present status of the principal fish stocks in Lake Huron, including the lake sturgeon (Krueger et al. 1995). Unfortunately, very little is known regarding the current status of this species in either U.S. or Canadian waters of Lake Huron, making development of plans for recovery very difficult.
The State of Michigan has listed the lake sturgeon as a Threatened species and it has been previously identified as a Candidate for listing by the U.S. Fish and Wildlife Service (Service). In an attempt to begin assembling information on the status and trends of Lake Huron lake sturgeon, necessary for final determination of federal listing status, the Alpena Fishery Resources Office (FRO) initiated a project in 1995. This report summarizes those activities in 1995 and 1996.
METHODS
Although there have been occasional reports of large sturgeon from commercial fishers and divers in northern Lake Huron, all major streams thought to have supported sturgeon spawning (Cheboygan, Thunder Bay, Au Sable, etc.) have been blocked by one or more hydro-power projects and provide little if any spawning habitat. Discussions with commercial fishers from Saginaw Bay indicated that sturgeon are frequently encountered as by-catch in trap net fisheries there. In addition to the probability that the Saginaw River and its major tributaries probably supported some degree of sturgeon spawning, there are published reports of reef spawning activities in Saginaw Bay (Organ et al. 1979; Goodyear et al. 1982).
In 1995, in cooperation with the Michigan Department of Natural Resources (MDNR) and commercial fishers in Saginaw Bay, the Alpena FRO initiated a tagging program to begin piecing together information on relative abundance, movement, and life history on these lake sturgeon. Beginning in the spring of 1995 and continuing through the 1996 season, the Bay Port Fish Company (BPFC), Bay Port, Michigan agreed to collect biological data on lake sturgeon encountered as by-catch in their trap net fishery. In addition, to ensure minimal stress to the fish, fishers from BPFC agreed to apply tags to the fish immediately upon removal from the nets. In 1995 and through August 1996, Floy (Model FT4) Cinch-up tags were applied to all sturgeon encountered by BPFC. The tags were inserted through the musculature posterior to the dorsal fin. In 1996 (September) we switched to a Monel self-piercing animal ear tag that was attached to the operculum. To assist in the collection of biotic data on Saginaw Bay lake sturgeon and to enhance the chances of tag recaptures, self-addressed data return cards were distributed to several state licensed commercial fishers by MDNR personnel regulating the fishery. Fishers were asked to cooperate by filling out the data cards and forward them to the Service’s Alpena FRO.
Biotic data collected by the fishers includes; total length (T.L.), fork length (F.L.), girth, and weight when possible. Abiotic data include; latitude/longitude, water depth, date, and gear and mesh size. In addition, the tag type, agency, and identification number of tags applied or observed are also recorded.
To maximize the level of information being collected on the Lake Huron lake sturgeon, a similar effort was initiated in Ontario waters by the Ontario Ministry of Natural Resources - Lake Huron Management Unit (OMNR-LHMU) in 1995. Coordination between OMNR-LHMU and the Alpena FRO has been excellent and data collection has been standardized to allow for exchange of information. This coordination, transferred through the respective commercial fishers, will enhance the chances of recovering tag information from both sides of the lake and allow for a better understanding of the seasonal movement patterns of Lake Huron lake sturgeon.
RESULTS
Abiotic Summary
Table 1 summarizes the number of commercial fishers who participated in the sturgeon data recovery project in 1995 and 1996, and the number of sturgeon they each encountered. A total of 53 lake sturgeon have been sampled since the project was initiated. Of this total, only three of the sampled fish have come from outside Saginaw Bay. In 1995, 6 Lake Huron fishers returned data cards for 22 lake sturgeon, 11 of which were tagged by the BPFC and 2 by Gauthier-Spaulding (Rogers City). In 1996, 6 fishers returned data cards for 31 lake sturgeon, with 6 fish tagged each by BPFC and Serafin Fisheries, and 1 by Barbeaux Fishery (DeTour). Data cards from nine different commercial fishers have been returned since 1995 (Table 1.) Only a single recapture was reported in 1996 of a fish tagged in 1995. In 1996 the tagging operation was expanded to include additional fishers who expressed an interest in assisting in the project. However, tagging supplies were not provided to the fishers until October 1996 and, with the exception of Serafin Fishery, no additional fish were tagged by the new participants. A majority of the sturgeon are captured in small-mesh (4.8-7.6 cm) trapnets fished in the shallower regions of the inner Saginaw Bay. The average depth of the net sets where the reported sturgeon were recovered was 7.0 meters. Depths ranged from 2.1 meters to 31.4 meters (one fish caught in the DeTour area by Barbeaux Fishery in whitefish gillnet early in 1996). These depths are consistent with those reported by others as general depth of distribution (Priegel and Wirth 1977; Ono et al 1983; Houston 1987).
Although areas of Saginaw Bay where sturgeon have been encountered as by-catch are dictated by where the participating fishers are fishing, there appear to be some areas where the encounters are more frequent. Figure 1 illustrates lake sturgeon captures by statistical grid, as determined by reported latitude/longitude on the data return cards, or by physical description of capture site when coordinates are not available.
Table 1. Summary of commercial fishers participating in tagging and/or data collection , and the number of lake sturgeon encountered as by-catch in Lake Huron trap net fisheries in 1995 and 1996. (*) indicates fishers who have agreed to participate in sturgeon tagging for 1996 and beyond.
NO. of STURGEON NO. TAGGED TOTAL TOTAL FISHER 1995 1996 1995 1996 STURGEON TAGGED BAY PORT FISH COMPANY * 11 6 11 6 17 17 BARBEAUX FISHERY * 0 1 0 1 1 1 WARREN BEERS 2 0 0 0 2 0 GAUTHIER-SPAULDING * 2 0 2 0 2 2 LENTZ FISHERY * 4 8 0 0 12 0 BRETT MORGAN * 1 0 0 0 1 0 SAM'S FISHERY * 0 3 0 0 3 0 SERAFIN FISHERIES * 0 9 0 6 9 6 WHYTE'S FISHERY * 2 4 0 0 6 0 TOTAL 22 31 13 13 53 26
Grids 1509 and 1608 account for 50% of the total sturgeon returns, and are the two grids closest to the location cited by Organ et al. 1978 as a documented lake spawning site for the species in the early 1900’s. The other area of interest is located in grid 1507 where Lentz Fishery has captured and collected data on 11 sturgeon over the last two fishing seasons. As an attempt to define the location of capture on a greater level of resolution, capture sites (as recorded for the net set) were manually plotted in Figure 2. Some clustering of capture coordinates is noted, especially in grid 1509 near Sand Point and in the northeast corner of grid 1507. While some recapturing of untagged sturgeon could be occurring in 1507, the cluster observed near 1509 was composed entirely of tagged fish with no recaptures reported. Trends such as this will be used in future years to assist in identifying focal points for more extensive sampling and for collection of habitat data.
Figure 1. Recovery of by-caught lake sturgeon, by statistical grid, as reported by Lake Huron commercial fishers (U.S.) in 1995 and 1996.
Figure 2. Location of Saginaw Bay, Lake Huron lake sturgeon captures as reported by commercial trap-net fishers during 1995 and 1996 fishing seasons. Locations (x) plotted manually based on coordinates provided by data return cards.
Although previous authors have referenced seasonal movement patterns that may reflect temperature selection (Ono et al 1983), or possible links to prey abundance (Houston 1987), no such trends are discernible from data we have collected to date. Data collected to date on the Saginaw Bay lake sturgeon are biased by the fishing locations selected by the fishers seeking their target species. There are, however, temporal differences in habitat overlap between lake sturgeon and the commercially targeted species. The overlap is greatest in the spring and fall period, with May and October being the months when sturgeon are most frequently encountered (Figure 3). Again, this temporal information may prove useful is developing sampling protocol for assessment activities targeting lake sturgeon.
Figure 3. Number of lake sturgeon captured, by month, as by-catch in Saginaw Bay commercial trap-net fisheries in 1995 and 1996.
Biotic Summary
A total of 53 lake sturgeon were reported by Lake Huron commercial fishers (U.S.) for the 1995 - 1996 period. Biological data were recorded for 52 sturgeon with all fish being returned to the lake in good condition. Tags were attached to 26 sturgeon by participating fishers. The mean total length for all sturgeon was 110 cm with sizes ranging from 70 - 173 cm. Figure 4 illustrates the length-frequency distribution for the 52.
Figure 4. Length-frequency distribution of lake sturgeon sampled as by-catch from Lake Huron commercial fisheries (U.S.) in 1995 and 1996.
sturgeon for which biological data were collected No weight data were collected, nor were structures collected for aging purposes. Pectoral fin rays were collected by OMNR-LHMU in the Canadian portion of the Lake Huron status survey and have been aged, providing a point of reference for estimating the age range for the sturgeon from U.S. waters (Figure 5).
Figure 5. Growth curve for Lake Huron lake sturgeon as determined from pectoral fin ray aging of fish sampled in Ontario commercial fishery (North Channel and southern Main Basin combined) in 1995 (from Mohr 1996).
Based on the total length at age relationship developed by Mohr (1996) for Ontario waters of Lake Huron, it is estimated that the sturgeon collected in this study range in age from 5 to over 35 years with a mean age of approximately 15 years.
Several biotic parameters were collected to provide for ease of data exchange between agencies involved in lake sturgeon status surveys. In addition to total length; fork length and girth were collected by the fishers as part of the data reporting requirements of this project. Figures 6 and 7 provide total length - fork length and total length - girth relationships, respectively.
Figure 6. Total length to fork length relationship for lake sturgeon sampled as by-catch from Lake Huron commercial fisheries (U.S.) in 1995 and 1996.
Figure 7. Girth to total length relationship for lake sturgeon sampled as by-catch from Lake Huron commercial fisheries (U.S.) in 1995 and 1996.
Standardization of data parameters analyzed in this and the Ontario portion of the survey allow for exchange and application of the various morphological relationships with some degree of confidence. Data collected in Ontario waters of the three basins of Lake Huron were consolidated to form the length to age relationships, therefore making application to Saginaw Bay relatively reliable. Sturgeon girth to weight relationships will also be possible as weight data are available from many of the Ontario fish.
DISCUSSION
The excellent cooperation and assistance being provided by the Michigan commercial fishers is providing important information on the lake sturgeon populations in the Saginaw Bay area of Lake Huron. Lake sturgeon appear to be considerably less abundant in U.S. waters than is being reported through by-catch return data in Canadian waters through a similar effort. This is not surprising based on the fact that the 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 sturgeon populations there.
Increasing participation by Michigan licensed commercial fishers in Saginaw Bay should result in an escalation of sturgeon reports over the next few years. With more fishers now involved in the tagging operation, more information on the seasonal movement should result from increasing recaptures of previously tagged fish. In addition, the collaborative effort in U.S. and Canadian waters of Lake Huron should begin to define the movement of tagged sturgeon among the different basins of the lake.
In spite of the limited number of sturgeon returns to date (53), a few biotic and abiotic trends are beginning to develop that are of interest. Although the mean age of Saginaw Bay sturgeon appears to be somewhere in the range of 10 to 20 years, a few smaller (younger) sturgeon were reported in 1996 and in personal discussions with the fishers, small sturgeon have been observed in years immediately prior to the start-up of this project. Continued collection of information over the next few years will determine whether there is evidence of local recruitment in the Michigan waters of Lake Huron. In addition, a few clusters of sturgeon captures are beginning to highlight 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 effort for lake sturgeon status surveys in the next few years will assist in the development of a better understanding of the current status, and the potential for a successful lake-wide recovery effort for this important native species.
ACKNOWLEDGEMENTS
The information presented in this progress report was collected entirely through the voluntary assistance of the Bay Port Fish Company, Barbeaux Fishery, Warren Beers, Gauthier-Spaulding Fishery, Lentz Fishery, Brett Morgan, Sam’s Fishery, Serafin Fisheries, and Whyte’s Fishery. Their interest, cooperation and enthusiasm has been (and continues to be) invaluable in taking this first step toward defining the current status and trends of this native Lake Huron fish species. The assistance of the Michigan Department of Natural Resources in initiating the project through the mailing of data return cards to licensed commercial fishers and requesting cooperation is greatly appreciated.
LITERATURE CITED
Auer, N.A. 1991. Conservation of the threatened lake sturgeon. Mich. Dept. Nat. Resour., Nongame Wildl. Fund and Living Reour. Small Grants Prog. Final Rep. 23p.
Baker, J.P. 1980. The distribution, ecology, and management of the lake sturgeon (Acipenser fulvescens Rafinesque) in Michigan. Mich. Dept. Nat. Resour., Fish. Research Rep. No. 1883, Ann Arbor, Michigan.
DesJardine, R.L., T.K. Gorenflo, and N.R. Payne, and J.D. Schrouder. 1995. Fish -community objectives for Lake Huron. Great Lakes Fish. Comm. Spec. Pub. 95-1: 37 p.
Goodyear, C.S., T.A. Edsall, D.M. Ormsby-Dempsey, G.D. Moss, and P.E. Polanski. 1982. Atlas of the spawning and nursery areas of Great Lakes fishes. Vol.5: Lake Huron, U.S. Fish Wildl. Serv. Washington, DC FWS/OBS-82/52.
Harkness, W.J.K., and J.R. Dymond. 1961. The lake sturgeon: the history of its fishery and problems of conservation. Ontario Dept. Lands and Forests, Fish and Wildl.Branch. Toronto.
Houston, J.J. 1987. Status of the lake sturgeon (Acipenser fulvescens) in Canada. Can.Field-Nat. 101:171- 185.
Kinietz, W.V. 1940. The Indians of the western Great Lakes, 1615-1760. Ann Arbor Paperbacks, Univ. Mich. Press. 427 p.
Krueger, K.M., K.S. Schrouder, J.P. Baker, M.P. Ebener and J.R. McClain. 1995. Status of cool-water fishes in 1992, p.73-85. In M.P. Ebener [ed.] The state of Lake Huron in 1992. Great Lakes Fish. Comm. Spec. Pub. 95-2.
Mohr, L.L. 1996. 1995 Lake Huron lake sturgeon assessment. A progress report to the Lake Huron Technical Committee, St. Clair, MI, 23 January, 1996.
Ono, D., J.D. Williams, and A. Wagner. 1983. Vanishing fishes of North America. Stone Wall Press, Washington.
Organ, W.L., G.L. Towns, M.O. Walter, R.B. Pelletier, and D.A. Riege. 1979. Past and presently know spawning grounds of fishes in the Michigan coastal waters of the Great Lakes. Mich. Dept. Nat. Resour. Fish Div. Tech. Rep. 79-1.
Priegel, G.R. and T.L. Wirth. 1977. The lake sturgeon: It’s life history, ecology and management. Wisc. Dept. Nat. Resour., pub. 4-3600(77). 20 p.
