Identification of potential wintering habitat for threatened Atlantic sturgeon Acipenser oxyrinchus oxyrinchus in Saco Bay, Maine, USA

Abstract

The identification of habitats critical to wintering, foraging, and spawning is imperative to the management and recovery of imperiled fishes such as the Atlantic sturgeon Acipenser oxyrinchus oxyrinchus. Atlantic sturgeon are threatened in the Gulf of Maine, and endangered throughout the rest of their range along the United States East coast. While the distribution of Atlantic sturgeon in freshwater and estuarine habitats has been well documented, data on use of marine habitat, particularly in winter months, remains relatively unknown. To better understand the habitat utilization of Atlantic sturgeon during winter, 6 individuals captured at the mouth of the Saco River Estuary (SRE) were fitted with both an external mark report pop-off archival satellite tag (mrPAT) and an internal acoustic transmitter (Vemco V16). Pop-off dates for mrPATs were staggered to occur in pairs on 15 and 30 January and 15 February 2017, with tags recording daily maximum and minimum temperatures while at liberty. All tags lasted the duration of scheduled deployment. Five Atlantic sturgeon appeared to aggregate in Saco Bay within 5 km of their original capture location, while 1 fish moved offshore, where the tag detached 33 km from the mouth of the SRE. The data presented herein suggest that Saco Bay and the surrounding marine environment may serve as wintering habitat for adult Atlantic sturgeon; this is the first direct documentation of such behavior in the Gulf of Maine.