Atlantic Salmon Movement Patterns and Habitat Use during Colonization of Novel Habitat

Abstract

AbstractAllowing reproductive individuals to colonize novel habitat or recolonize previously occupied habitat is increasingly being considered as a tool for recovery of depleted populations of anadromous salmon. Successful application of these techniques requires thorough understanding of how adults use the riverscape during colonization to ensure that programs achieve desired outcomes. We examined the movements and habitat use of adult Atlantic Salmon Salmo salar during colonization of novel habitat in an eastern Canadian river using a novel combination of acoustic telemetry, remote sensing, ground surveys, and continuous records of river temperature and discharge. Females moved less than males, regardless of river temperature or discharge, whereas males engaged in more extensive movements except at elevated temperature and discharge. Probability of movement was lower during the summer, coincident with individuals holding in pools during high‐heat/low‐discharge events. River temperature, discharge, and day of year were influential in predicting whether salmon held in pools, and size was the most important physical characteristic identifying “suitable” holding pools. Observed movement patterns may reflect different evolutionary strategies employed by each sex to maximize reproductive fitness. Because spawning behavior is highly conserved within salmonids, these findings may (1) provide a generalized picture of how Atlantic Salmon use space during colonization of unoccupied habitat and (2) be used to optimize future reintroduction and assisted migration programs.