|Scientific Name:||Acipenser fulvescens|
|Species Authority:||Rafinesque, 1817|
|Infra-specific Taxa Assessed:|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor/s:||St. Pierre, R. & Runstrom, A. (U.S. Fish & Wildlife Service)|
|Reviewer/s:||St. Pierre, R. & Pourkazemi, M. (Sturgeon Red List Authority)|
Acipenser fulvescens was assessed by the IUCN SSC Sturgeon Specialist Group in 1996 as Vulnerable. A more detailed look at the data available for this species has resulted in it being downgraded to Least Concern.
The lake sturgeon occupies the United States and Canadian waters of the Great Lakes and the St. Lawrence River basin; Lake Champlain (Vermont-New York); the Lake Winnebago-Fox River complex (Wisconsin); Canada’s Hudson and James Bay watersheds; the Saskatchewan River (Alberta, Saskatchewan and Manitoba); and the Mississippi River basin area from the headwaters in Minnesota to the northern portion of the state of Louisiana and up the Missouri River into southern South Dakota. Well-regulated sport fisheries occur throughout the northern part of the range and Canada manages modest commercial fisheries in Ontario and Quebec provinces.
Although very little stock assessment is underway, the lake sturgeon subpopulation in the Mississippi and lower Missouri river basins is believed to be stable but relatively small, certainly compared to levels in the late 1800s prior to development of modern locks, dams and reservoirs. Area of occupancy, extent of occurrence and quality of habitats in this part of the species’ range are all diminished compared to historic conditions. Restocking efforts using cultured fish are modest and fragmented among the states but results from Missouri DOC stockings are encouraging. Since there is currently no concerted basin-wide or interstate plan to manage or restore this stock, the Mississippi river basin lake sturgeon subpopulation is considered to be Vulnerable.
The largest proportion of the global population lies in the Great Lakes and the St Lawrence River basin areas where numerous management and recovery plans are in place among and between states and provinces sharing boundary waters. Most threats here are understood and essential conservation measures are being implemented. Populations of lake sturgeon are being monitored and assessed and most segments of the stock appear to be increasing. Based upon all of the above information and IUCN definitions, the species currently is not facing a threat to its survival and is categorized as Least Concern (LC).
|Range Description:||Lake sturgeon spend their entire life cycle in freshwater and are widely distributed in North America. They currently range throughout much of the drainages of the Mississippi River, the Great Lakes, Lake Champlain, the St. Lawrence River, Hudson Bay-James Bay, and the Saskatchewan River (Pflieger 1975, Becker 1983, Ferguson and Duckworth 1997). In the Mississippi basin this species occurs from the headwaters in Minnesota to the northern portion of the state of Louisiana and up the Missouri River into southern South Dakota. There is no known natural exchange of stocks between the Great Lakes and western Canadian provinces and those of the Mississippi River basin, though some stockings in the Mississippi have included lake sturgeon of Great Lakes Basin origin.
For a more detailed description of this species’ range, see NatureServe’s Explorer database.
Native:Canada (Alberta, Manitoba, Saskatchewan); United States (Alabama - Regionally Extinct, Arkansas - Regionally Extinct, Iowa, Louisiana, Minnesota, Mississippi, Missouri, New York, South Dakota, Vermont, Wisconsin)
|Range Map:||Click here to open the map viewer and explore range.|
Lake sturgeon were, and in some cases continue to be, an important component of Native American diet and culture. Up until about 1870, lake sturgeon were primarily considered a nuisance by commercial fisherman and were stacked on the shores to rot (Milner 1874 cited in Becker 1983). Within the next 30 years the value of sturgeon for flesh and the use of roe for caviar became economically important. During heavy fishing years in the late 1800s lake sturgeon harvest from the Great Lakes averaged over 1,814 metric tons (mt) per year. In the peak harvest year of 1885, 4,901 mt were reported of which 2,359 tons came from Lake Erie alone. Sturgeon populations declined dramatically after 1900 and although some incidental harvest was reported until 1977, numbers were extremely low after 1956.
Although lake sturgeon populations in the Great Lakes were greatly reduced due to overfishing during the last several decades of the nineteenth century they appear to be on the rebound throughout the Great Lakes and St. Lawrence basins with spawning populations being documented from 63 locations and spawning size estimates calculated for 17 of these sites. The current status of lake sturgeon populations in most of the Great Lakes Basin, the St. Lawrence River and in Wisconsin’s Lake Winnebago system is stable or increasing.
Lake sturgeon were generally considered to be rare to uncommon in most waters of the Mississippi River basin since the late 1800s. In 1989, this species was declared as threatened by the American Fisheries Society in all Mississippi River states except Louisiana where they are believed to be extirpated (Williams et al. 1989). The Department of Natural Resources in Iowa and Illinois and the Missouri Department of Conservation list the lake sturgeon as endangered in their respective states, and in Minnesota, the lake sturgeon is listed as a species of special concern. The species appears to be extirpated from its former range in Alabama and Arkansas.
The current status of lake sturgeon throughout the Mississippi basin is considered to be severely depressed from historical abundance levels. However, modern population assessment studies are lacking and rate of stock decline or growth is unknown. Native stocks were extremely depressed prior to the stocking program undertaken by the Missouri Department of Conservation. Following the first releases into Mark Twain Lake (Salt River, a Pool 24 tributary) in 1984, then at Louisiana on Pool 24 of the Mississippi River and at several Missouri River locations in 1988, increasing reports of incidental catch in commercial gear and by recreational anglers has been occurring.
|Habitat and Ecology:||
Based on pectoral fin ray sections it has been determined that lake sturgeon can live to be over 100 years old. One individual caught in Lake of the Woods, Ontario in 1953 was estimated to be 152 years old (Priegel and Wirth 1971). Lake sturgeon can reach lengths of 1.9 m, and weigh 91 kg. However, a 141 kg lake sturgeon was reportedly caught in Lake Superior in 1922 and a fish of equal weight was caught in Lake Michigan in 1943. Most fish reported in the literature were less than 35 years old.
Lake sturgeon from Black Lake in Michigan measured 75–193 cm total length (TL) and were 9–64 years old, with most fish less than 20 years old (Baker and Borgeson 1999). In the Lake Winnebago system of Wisconsin, female lake sturgeon reach sexual maturity between 24–26 years of age when they are about 140 cm long. Females spawn only every 3–6 years and can produce up to 700,000 eggs each time. Few male lake sturgeon mature before they are 114 cm long or 14–16 years old. Males spawn every one or two years (Priegel and Wirth 1971, Lyons and Kempinger 1992). In the Sturgeon River of Upper Michigan, male spawning intervals of two, three and four years were observed while females returned to spawn every three to seven years (Auer 1999). In Canadian rivers and lakes, mature male lake sturgeon range in size from 76–98 cm and females 84–117 cm (Houston 1987). Compared to sturgeon from Lake Winnebago and the Great Lakes, relatively little information is available regarding age, growth, maturity and spawning periodicity of lake sturgeon in the Mississippi River basin.
During the spring season, lake sturgeon spawning occurs when water temperatures rise and reach 9–15 °C (Priegel and Wirth 1971, Kempinger 1988). Spawning sturgeon will select shallow areas over hard clean substrate with relatively strong current velocities (Kempinger 1988).
Usual lake sturgeon habitat is the highly productive shoal areas of larger lakes and rivers. They require moderate to swift currents and large rough substrates for spawning and embryo development. Lake sturgeon in the Upper Mississippi River prefer habitat in or adjacent to flow, but with relatively low to moderate current velocity (Knights, B. C., USGS, unpublished data). They are rarely found in backwater habitats without flow. In the Mississippi basin habitat that is in or adjacent to current is generally depositional and has relatively compact silt or silt-sand substrates with presumed high densities of benthic invertebrates. These areas occur at the lower end of navigation pools near the main channel, the mouths of tributaries and large secondary channels, and at some channel border areas. While migrating, presumably en-route to spawning habitats or high use (feeding/home) areas, lake sturgeon will use areas of the river with relatively high current velocities including tailwaters, the main channel in the upper and mid reaches of navigation pools, and tributaries.
Lake sturgeon are known to move great distances to spawning and feeding habitats (Auer 1996). Wisconsin DNR recently reported that a sturgeon originally tagged in Lake Winnebago in October 1978 was recovered almost 19 years later at Locust Point Reef in Lake Erie, a minimum travel distance of almost 1,100 km (R. Bruch, WI DNR, news release).
The life history characteristics of slow growth, late maturation, and irregular spawning periodicity make lake sturgeon subpopulations particularly vulnerable to over-exploitation. Anthropogenic effects such as industrial and municipal pollution, blockage of access to habitats by dykes and dams, channeliszation and elimination of backwater areas, dewatering and water level fluctuations, physical destruction of spawning habitat, and inundation of habitat by reservoirs are known to threaten sturgeon subpopulations (Rochard et al. 1990, Auer 1996, Beamesderfer and Farr 1997, Noakes et al. 1999). Direct mortality of lake sturgeon due to impacts with commercial and/or recreational navigation vessels has been documented.
Dams may be the greatest impediment to lake sturgeon rehabilitation in the Great Lakes. Although there are numerous recorded instances of tagged sturgeon passing through navigation locks, many fish are precluded or delayed from reaching spawning or preferred feeding waters. Dams without locks completely block sturgeon passage and serve as severe impediments to lake sturgeon recovery in the Mississippi basin. Spawning and nursery areas are further degraded from land use problems such as erosion, sedimentation, and adverse discharges from point and non-point sources. Other concerns in the Great Lakes include stream channelization, over-exploitation and/or illegal harvest, lack of public concern and potential adverse impacts of lampricides on sensitive life stages.
Although lake sturgeon harvest from the Mississippi River is prohibited, financial incentive to collect roe for caviar remains. Small population sizes may limit poachers from targeting this species but it is likely that incidental captures are utilized and end up in the black market. With the first stocking of lake sturgeon by Missouri DOC now at age 17, there is increasing concern that poachers will target them as the females reach maturity within the next few years.
Commercial harvest of lake sturgeon is prohibited in all U.S. waters and strictly managed in Canadian waters with closed seasons, size limits and gear restrictions.
Angling in some waters of Michigan is allowed with several restrictions as to season, fish sizes and gear. In Wisconsin, harvest is limited to two separate sportfishing seasons. Spear fishermen must purchase a one-fish sturgeon spear tag and they are allowed to spear a fish from early February until a specified quota is reached. In Lake Winnebago, the 2000 quota was set at 400 adult females, 400 juvenile females and 2,150 males. Once 80% of the quota is reached the fishery is closed after the next day. Typical spear fishing harvest in recent years produced 1,500 to 2,500 fish. Wisconsin’s hook and line fishery allows the catch of one fish per angler per season with a minimum size range of 127–178 cm, depending on location, during early September through 15 October. All anglers must apply for and use a free tag and the fishery produces about 300–400 fish per season.
Sport fishing for lake sturgeon is currently prohibited in the Mississippi River but is allowed in some tributaries in Wisconsin and Minnesota (e.g., Wisconsin, Chippewa, and St. Croix rivers) during a short hook and line season in the fall. Angling in Minnesota has several restrictions as to season, fish sizes and gear and the reported annual sport catch was 2,200–4,200 kg in 1998–2000. Harvest is not allowed in Iowa, Ohio, Kansas, Missouri, Illinois and South Dakota.
According to the CITES Management Authority of Canada (CMAC 2000) sturgeon harvest in Canada consists of aboriginal, commercial and recreational fisheries. The entire North American commercial harvest of lake sturgeon comes from Canada where in 1997, 223 mt were caught in New Brunswick and Quebec, with 90% (200 mt) being taken from the St. Lawrence River. Catch in Ontario during the late 1990s ranged from 5–8 mt. Most of this came from Lake Huron with a small amount from Lake St. Clair. In 1998, international trade in lake sturgeon meat was reported to be 18.2 mt exported from Canada to the U.S. (mostly New York). No caviar exports are reported and no export quotas have been established by range states. Canadian Department of Fisheries and Oceans reported that in recent years total recreational catch from the North and South Saskatchewan rivers in Alberta and Saskatchewan amounted to about 1,000 fish.
Acipenser fulvescens is not listed as a species at risk by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Most subpopulations are thought to be capable of sustaining well-regulated fisheries. Although the species is managed and protected in Canada under the Federal Fisheries Act, regulations differ between provinces and are revised annually. This species is listed under provincial legislation as "threatened" in Alberta, Manitoba, New Brunswick, Newfoundland, Ontario, Quebec and Saskatchewan (CMAC 2000).
In recent years, interest in the restoration of lake sturgeon has increased greatly. Partnerships have been developed throughout the Great Lakes basin between state and federal natural resource agencies, commercial and sport fishers and other water users. Numerous management and recovery plans have been completed for select waters within the lake sturgeon range and are being implemented as resources allow. Their goals include conservation, rehabilitation and enhancement of sturgeon populations, completion of status assessments, harvest restrictions, identification and restoration of critical habitats and elimination of negative effects of dams.
Construction of spawning habitats using coarse stone rip-rapping has been undertaken in some states (particularly Wisconsin) and appears to be highly successful. Artificial culture and restocking of lake sturgeon is under development in Minnesota using wild broodstock. In New York, sturgeon eggs are taken from wild stocks in the St. Lawrence River and cultured fingerlings have been reared and released in several locations since 1995. Survival has been high and populations appear to be recovering. In Missouri over 210,000 lake sturgeon fingerlings have been stocked in the upper Mississippi and lower Missouri rivers since 1986. Survival of stocked fish is considered excellent as tagged lake sturgeon have been recaptured in the Mississippi, Missouri, Gasconade and Osage rivers and commercial fishermen have reported incidental catches reaching nuisance proportions (Hesse and Carreiro 1997). Artificial culture and restocking of lake sturgeon is also under development in Minnesota using wild broodstock. Wisconsin DNR propagates some lake sturgeon for restocking purposes with cultured fish only being placed into the same basins from which broodstock were taken. The Tennessee Valley Authority has stocked thousands of young lake sturgeon within the Ohio River Basin.
A Lake Sturgeon Management Plan has been implemented in Alberta since 1997. This involves a zero catch limit on the North Saskatchewan River; and on the South Saskatchewan, a closed season during the 1 April to 15 June spawning period with a one fish limit (greater than 130 cm) outside that restricted season. There is no aboriginal fishery in Alberta. In Saskatchewan, a self-imposed moratorium on commercial catch of lake sturgeon has been in place since 1996 and sport angling has not been allowed since 1999. A multi-agency study of habitat, fish migration and abundance is currently underway (CMAC 2000). Manitoba reduced its possession limit of lake sturgeon to zero in 1995. The remaining few commercial fisheries closed down during the 1990s but catch and release angling is still allowed in addition to aboriginal subsistence fishing in most rivers. Lake sturgeon population management has been initiated in several Manitoba rivers with involvement of First Nations communities.
In Ontario, a Lake Sturgeon Assessment Program has been implemented for Lake Huron and Lake St. Clair, including population abundance estimation and tagging to identify movements and verify ages. As enough information is developed a management plan for the species will be drafted. Commercial catch quotas of lake sturgeon were established in 1984 and were adjusted periodically - through never achieved. In 1997, the catch quotas amounted to 1,500 kg in Lake St. Clair and 13,124 kg in Lake Huron. Huron catch that year was 5,471 kg, the highest of the previous several years.
Quebec allows the harvest of lake sturgeon with 19–20.3 cm mesh gill nets only during an open season of 14 June through 31 October. A minimum fish length is in effect and quotas are enforced by the requirement that all fish for market must be tagged, and the tag must stay with the fish until it is processed. Quebec sport fishermen may catch and keep one fish per day.
It is listed on CITES Appendix II.
|Citation:||St. Pierre, R. & Runstrom, A. (U.S. Fish & Wildlife Service) 2004. Acipenser fulvescens. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 20 May 2013.|
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