The Role of Culture, Conservation Stocking, and Ecological Insights in Mitigating the Decline of the American Eel (Anguilla rostrata)

The American Eel is showing universal declines. Conservation stocking of eels was conducted experimentally from 2006-2010 in the upper St. Lawrence River in an attempt to mitigate recruitment declines. Microhabitat associations of recently stocked age-one eels electrofished 2008-2010, along with otolith isotopic thermography and controlled rearing experiments, provided ecological insights that can improve stocking success. Otolith δ¹⁸O temperature estimates indicate that microhabitat associations and cover (small rock rubble) are more important than thermal conditions; otolith temperature was 1.5^oC cooler than habitat. Young elvers were reared in three replicate controlled temperature experiments over a range (10^oC-37^oC) simulating midsummer temperatures across the species range. Eels retain a high optimum temperature (28^oC) despite living at suboptimal temperatures in the northern part of the range. Microhabitat associations are more important to recently stocked eels than seeking optimal temperatures for growth. Culture enhances survival and stocking provides increased opportunity to study important ecological associations and requirements while maintaining a presence, profiling the need for continued conservation efforts. Culture now plays a major role in worldwide eel production; stocking to enhance fisheries can be compatible with conservation. Importantly, culture and conservation stocking can result in greater habitat utilization, potential for increased escapement, and increases in recruitment.