|Scientific Name:||Acipenser brevirostrum|
|Species Authority:||Lesueur, 1818|
|Red List Category & Criteria:||Vulnerable A2ce; B1ab(iii) ver 3.1|
|Assessor(s):||Friedland, K.D. (University of Massechusetts) & Kynard, B. (U.S. Geological Survey)|
|Reviewer(s):||St. Pierre, R. & Pourkazemi, M. (Sturgeon Red List Authority)|
Shortnose sturgeon is a relatively small species, sympatric in U.S. and Canadian Atlantic Coast rivers and estuaries with the larger Atlantic sturgeon (A. o. oxyrhinchus). Historically the two species were harvested commercially for flesh and caviar, but no species differentiation was recorded in the landings data.
Although some shortnose sturgeon may still be harvested incidental to Atlantic sturgeon in Canada, there are no legal fisheries or by-catch allowances in U.S. waters. Principal threats to the survival of this species are habitat related resulting from loss or degradation. Direct mortality is known to occur from impingement on cooling water intake screens, dredging, and incidental capture in other fisheries (NMFS 1998).
Shortnose Sturgeon stocks appear to be stable and even increasing in a few large rivers but remain seriously depressed in others, particularly southern populations. Previous Red Lists listed the species as Vulnerable. Since that earlier listing, a Recovery Plan has been developed and is being implemented and genetically distinct population segments have been identified. Although exploitation is no longer a serious concern, effects of habitat alteration and degradation and water quality (contaminant) concerns remain. Thus, the shortnose sturgeon should continue to receive a Vulnerable listing. This is based, in part, on an estimated population reduction of greater than 30% over the past three generations with some irreversible habitat losses and continued concern about impacts of pollutants and water-based development activities on population health. We also note extreme fluctuations in the number of mature individuals between rivers, from a few hundred or less in the Chesapeake Bay to perhaps 10,000 or more in the Hudson.
|Range Description:||Shortnose sturgeons occur in many of the large coastal rivers of eastern North America. From survey and tagging data, the National Marine Fisheries Service now recognizes 19 distinct population segments. The Shortnose Sturgeon Recovery Team considered sturgeon populations from two general regions, northern rivers and southern rivers. The largest populations in the northern region appear to be in the Saint John, NB, Canada (Dadswell 1979), Delaware, NJ-PA (Hastings et al. 1987), Kennebec, ME (Squiers et al. 1982), and Hudson, NY rivers (Bain et al. 1995).
See the NatureServe Explorer database for a more detailed description of this species’ range.
Native:Canada (New Brunswick); United States (Connecticut, District of Columbia - Regionally Extinct, Florida, Georgia, Maine, Maryland, Massachusetts, New Hampshire - Possibly Extinct, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island, South Carolina, Virginia - Regionally Extinct)
|FAO Marine Fishing Areas:||
Atlantic – northwest; Atlantic – western central
|Range Map:||Click here to open the map viewer and explore range.|
The estimate of the total current population size for the Hudson River indicates a 95% confidence interval of 26,000 to 55,000 individuals. The Saint John, Kennebec, and Delaware subpopulations appear to be on the order of 5,000 to 15,000 fish each. Estimates of other northern populations are the Connecticut River (CT-MA) — about 1,200 fish, and the Merrimack River (MA) of less than 100 individuals (Kieffer and Kynard 1993, Kynard 1997, Savoy 2004). Though many rivers in the southern region have been documented to contain shortnose sturgeon, few have had population estimates conducted. Only abundance in the Ogeechee and Altamaha rivers of Georgia have been estimated and both appear to be on the order of 1,000 fish each (Rogers and Weber 1994). Shortnose sturgeon occur only rarely in Chesapeake Bay and its tributaries and no breeding population has been confirmed here.
Walsh et al. (2001) analyzed shortnose sturgeon populations from two drainages in Maine and the Hudson River for genetic diversity. They noted significant differences between the Kennebec and Androscoggin stocks and even greater separation when compared to the Hudson stock. These data support the putative stock structure and distinct population segment designation adopted for shortnose sturgeon.
|Habitat and Ecology:||
Shortnose sturgeon use of saltwater is generally amphidromous throughout most of the species' range, although far northern populations are anadromous (Kynard 1997). Spawning takes place in upper freshwater areas, while feeding (summering) and wintering occurs in both fresh and saline environments. This species typically spends its entire life history in the natal river and estuary and only rarely moves any great distance in near-coastal marine waters. There are no naturally land-locked populations of the species, but two rivers have populations that are segmented by dams.
This species typically attains an adult size of 75–100 cm total length, though the maximum recorded size for a Canadian-caught female was 1.43 m and 23.6 kg (Dadswell et al. 1984). Maximum ages determined for female and male shortnose sturgeon (again in Canada) were 67 and 32 years, respectively (Vladykov and Greeley 1963). Prespawning migrations in northern populations are triggered by increasing water temperatures of 7–10°C, and during spawning, males are attracted to females by a female pheromone (Kynard and Horgan 2002a). Spawning occurs at water temperatures of 7–15°C. Spawning habitat is a substrate of rock or large gravel (usually rubble), and water depth during spawning is highly variable. Spawning suitability windows follow day length of 13.9–14.9 h, water temperature of 6.5–15°C, and river discharge that provides 30–120 cm/sec (mean 70 cm/sec) bottom velocity. All spawning windows must be open simultaneously for spawning to occur. Yearling shortnose sturgeon initiate the major dispersal that moves young fish to join older juveniles and adults in fresh or salt water foraging concentration areas. Yearling and older juveniles use the same summering and wintering habitats as adults (Kynard et al. 2000).
In southern waters, shortnose males may mature in 2-3 years and females in 4-6 years. In northern portions of the range, maturation may not occur for 10-15 years (maximum). Spawning periodicity is poorly understood but in the northern part of the range, females are highly variable (2-9 years) and males spawn at 1-5 year intervals depending on fish age and foraging conditions. Some males in northern populations spawn annually.
|Major Threat(s):||Although some shortnose sturgeon may be harvested incidental to Atlantic sturgeon in Canada, there are no legal fisheries or by-catch allowances in U.S. waters. Principal threats to the survival of this species are blockage of up- and downstream migrations at dams, habitat loss or degradation due to dams and dam operations, river channel dredging, and pollution. Southern populations are particularly at risk due to water withdrawal from rivers and groundwaters and from eutrophication that directly degrades river water quality causing loss of habitat. Direct mortality is known to occur from impingement on cooling water intake screens, dredging, and incidental capture in other fisheries (NMFS 1998).|
The shortnose sturgeon was listed as endangered under the inaugural U.S. Endangered Species Act (ESA) in 1967. At that time, very little information was available regarding life history and behavior of this species. Since then, considerable work has been accomplished to determine habitats and migrations important to each life stage, population status, genetic assessment, use of fish passage and fish protection structures, and fish culture. The Shortnose Sturgeon Recovery and Management Plan (NMFS 1998) identifies recovery actions that would help to establish population levels that would allow de-listing of the shortnose sturgeon.
Captive broodstock and several generations of progeny are currently being held at federal fish hatcheries operated by the U.S. Fish and Wildlife Service and at a research laboratory of the U.S. Geological Survey. Additionally, several years of research on spawning has produced larvae from natural mate selection and spawning of adults in an artificial spawning stream, a process that appears to produce superior young fish for conservation stocking.
It is listed on CITES Appendix I.
|Citation:||Friedland, K.D. (University of Massechusetts) & Kynard, B. (U.S. Geological Survey) 2004. Acipenser brevirostrum. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 20 December 2014.|
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