Restoring River-Runs of Landlocked Atlantic Salmon in Lake Champlain

Landlocked Atlantic salmon (Salmo salar) were extirpated from Lake Champlain in the early 1800s.  Management actions, including sea lamprey control and stocking yearling smolts, provide for a popular salmon fishery in the lake.  However, spawning runs of salmon to rivers (i.e., river-runs) have remained low.  In 2010, we initiated a long-term adaptive management experiment focused on increasing river-runs of salmon to enhance in river fisheries and restore natural populations.  Examples of ongoing experiments include: (1) identifying indicators of smolting to optimize timing of stocking to periods when fish are likely to imprint on rivers and (2) evaluating alternative hatchery rearing methods.  We identified gill Na⁺/K⁺ ATPase activity during the spring as a potential indicator of smolting for landlocked salmon but activity levels were much lower than observed in anadromous populations.  We also observed a large impact of alternative hatchery rearing on adult returns to a focal river in 2013.  There was a fourfold increase in adult return rate of smolts reared in river water with an ambient temperature profile compared to smolts reared on well water with an increased temperature profile.  Our results demonstrate potential for rapid increases in river-runs using hatchery smolts combined with targeted research and adaptive management.