Date of Award

8-2008

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Ecology and Environmental Sciences

Advisor

Gayle B. Zydlewski

Second Committee Member

Michael T. Kinnison

Third Committee Member

Joseph Zydlewski

Abstract

Atlantic sturgeon (Acipenser oxyrinchus) and shortnose sturgeon (Acipenser brevirostrum) overlap throughout most of their distribution along the Atlantic coast of North America from southeastern Canada to Florida, USA (Moser and Ross 1995). Both species are found in major coastal rivers, estuaries, and move into marine waters to varying degrees (Gilbert 1989). Atlantic sturgeon are an anadromous species throughout their range. Adults spend many years at sea before returning to reproduce in freshwater, and juveniles spend from two to six years in riverine and estuarine habitats before migrating to the marine environment (Bain 1997). In the southern part of their range, shortnose sturgeon are described to be "estuarine anadromous" (National Marine Fisheries Service 1998). In northern rivers their behavior is described as "freshwater amphidromy" (Bain 1997), which means that "migration from fresh water to the salt water, or vice-versa, is not for the purpose of breeding although it occurs regularly at some point(s) in the life cycle" (McDowall 1987). The Gulf of Maine distinct population segment (GOM DPS) of Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) is at moderate risk of becoming endangered in the next twenty years based on the status review conducted in 2005. No listing recommendation was provided by the review team for the GOM DPS because they determined there was insufficient data to allow a full determination of this population (Atlantic Sturgeon Status Review Team 2007). The shortnose sturgeon (Acipenser brevirostrum) was listed as endangered in 1967 and remains listed under the ESA to the present. The initial listing was range wide, but the National Marine Fisheries Service (NMFS) has since recognized 19 distinct population segments (DPSs) occurring from New Brunswick, Canada to Florida, USA. There is little known about both species in the northern part of their range in the United States, and the Penobscot River is the largest river in this region that lacks recent documentation of sturgeon presence or status.

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