Observations of American Shad
 Alosa sapidissima
 Approaching and Using a Vertical Slot Fishway at the Head‐of‐Tide Brunswick Dam on the Androscoggin River, Maine

American Shad Alosa sapidissima have historically supported an important fishery along the Atlantic coastal waters of North America. However, the construction of dams reduced populations and restricted landings. Fishways are intended to mitigate obstacles to anadromous fish migrations, but a thorough evaluation of their efficiency is warranted. We analyzed data collected from video recordings, hydropower turbine operations, and telemetry conducted by the Maine Department of Marine Resources to evaluate American Shad behavior while approaching and using a vertical slot fishway at the head-of-tide Brunswick Dam on the Androscoggin River in Maine. American Shad passage at the dam has been poor, ranging from 0 to 1,100 fish per year, relative to passage at other facilities in the region. Additionally, our observations indicate that there are relatively high numbers of American Shad present downstream in the river (averaging 50,000) compared with the entrance of the fishway or its pools (<8,000). On average, the rates of observed American Shad on the side of the river near the fishway entrance were significantly higher (6.5–8.6 individuals/min) when the turbine closest to the entrance of the fishway was not operating compared with when it was operating (4.1 individuals/min). Most of the radio-tagged American Shad remained in the river below the dam or went undetected. Eleven of 57 tagged fish were detected at the fishway entrance and of those only five were detected in the lower fishway. Individuals that were detected were observed making multiple attempts at entering the fishway, but movements were restricted to the lower pools. Our results suggest that this fishway is not conducive to the passage of American Shad. Examining the relationship between hydropower operations and other environmental variables on the behavior and passage of migrating anadromous fish remain an area for further study. American Shad Alosa sapidissima is an anadromous species requiring connectivity between marine and freshwater habitats to complete their lifecycle. Historically, populations of American Shad supported recreational, subsistence, and commercial fisheries along the Atlantic coastal waters of North America with annual landings ranging in the millions of pounds (Hightower et al. 1996; ASMFC 2007). However, overfishing, pollution, and habitat loss resulting from dams, restricted passage, and human development have reduced populations and subsequently total landings (Limburg et al. 2003; ASMFC 2007; Limburg and Waldman 2009). Many state and federal agencies have prioritized the management of American Shad by supporting research and monitoring programs aimed at conserving and restoring populations (ASMFC 2007). Dams threaten anadromous fish populations by severing the migration of populations between marine and *Corresponding author: daniel.weaver@maine.edu Received January 17, 2019; accepted July 5, 2019 North American Journal of Fisheries Management © 2019 American Fisheries Society ISSN: 0275-5947 print / 1548-8675 online DOI: 10.1002/nafm.10330