Seasonal Distribution and Movements of Shortnose Sturgeon and Atlantic Sturgeon in the Penobscot River Estuary, Maine

Abstract

Relatively little is known about the distribution and seasonal movement patterns of shortnose sturgeon Acipenser brevirostrum and Atlantic sturgeon Acipenser oxyrinchus oxyrinchus occupying rivers in the northern part of their range. During 2006 and 2007, 40 shortnose sturgeon (66-113.4 cm fork length [FL]) and 8 Atlantic sturgeon (76.2-166.2 cm FL) were captured in the Penobscot River, Maine, implanted with acoustic transmitters, and monitored using an array of acoustic receivers in the Penobscot River estuary and Penobscot Bay. Shortnose sturgeon were present year round in the estuary and overwintered from fall (mid-October) to spring (mid-April) in the upper estuary. In early spring, all individuals moved downstream to the middle estuary. Over the course of the summer, many individuals moved upstream to approximately 2 km of the downstream-most dam (46 river kilometers [rkm] from the Penobscot River mouth [rkm 0]) by August. Most aggregated into an overwintering site (rkm 36.5) in mid-to late fall. As many as 50% of the tagged shortnose sturgeon moved into and out of the Penobscot River system during 2007, and 83% were subsequently detected by an acoustic array in the Kennebec River, located 150 km from the Penobscot River estuary. Atlantic sturgeon moved into the estuary from the ocean in the summer and concentrated into a 1.5km reach. All Atlantic sturgeon moved to the ocean by fall, and two of these were detected in the Kennebec River. Although these behaviors are common for Atlantic sturgeon, regular coastal migrations of shortnose sturgeon have not been documented previously in this region. These results have important implications for future dam removals as well as for rangewide and river-specific shortnose sturgeon management.

Dispersal and productivity of Chinook (Oncorhynchus tshawytscha) and coho (Oncorhynchus kisutch) salmon colonizing newly accessible habitat

“…), lamprey (Petromyzontidae), and sturgeon (Acipsenser spp.) demonstrate their capability of exploiting opportunities to recolonize spawning habitat (Burdick and Hightower 2006;Fernandes et al 2010;Pess et al 2014), similar to the salmon in our study.…”

Characterization and expression of cytochrome P4501A in Atlantic sturgeon and shortnose sturgeon experimentally exposed to coplanar PCB 126 and TCDD

“…Shortnose sturgeon is amphidromous and were believed restricted to their natal estuary for their entire life history (Kynard, 1997). However, recent evidence suggests that they may foray into coastal waters more frequently and for greater distances than previously thought (Fernandes et al, 2010; Wirgin et al, 2010). Thus, young life-stages of both species are likely to be highly exposed to contaminants within some natal estuaries and are potentially susceptible to their toxic effects.…”

Post-tagging behaviour and habitat use in shortnose sturgeon measured with high-frequency accelerometer and PSATs

“…Along the east coast of North America, most shortnose sturgeons remain in their natal river and estuary [34,35]. Their abundance is less than the minimum estimated for a viable population [35] mainly due to anthropogenic impacts such as bycatch and poaching, blockage of spawning runs by dams and the regulation of river flows [35,36]. Thus, they are listed as endangered under the Endangered Species Act 1973 [35] throughout their US range.…”