Occurrence of atlantic sturgeon in the St. Marys River, Georgia

Abstract

The Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus is an anadromous species that historically has been found along the Atlantic coast of North America from maritime Canada to the St. Johns River, Florida. Decades of overharvest and habitat loss has resulted in range-wide population declines, and in 2012 the species was listed under the U.S. Endangered Species Act as five Distinct Population Segments (DPSs). The extirpation of several populations, including some in the South Atlantic DPS, was identified as an important consideration in the final determination to list this DPS as endangered. In the St. Marys River, Georgia, the second-most southern river within their historical range, Atlantic Sturgeon were thought to have been extirpated for several decades. The objectives of this study were to document the seasonal occurrence of Atlantic Sturgeon in the St. Marys River and to document any evidence of an extant population in the river. During the summers of 2013-2016, we set 533 nets and captured a total of 25 Atlantic Sturgeon, including several age-1, river-resident juveniles. Genetic analyses indicated that these juveniles were descendants of a remnant population that is distinct but more closely related to other populations within the South Atlantic DPS than those in more northern rivers. Using acoustic telemetry, we monitored the movements and habitat use of 14 individual sturgeon in the St. Marys River estuary. Acoustically tagged juveniles resided mainly within the St. Marys River main stem, but we did detect a number of adult migrants using Cumberland Sound on a seasonal basis. Our results indicate that Atlantic Sturgeon persist in the St. Marys River and that the estuary also provides seasonally important habitat for migrating adults from other populations.