Habitat use and diet composition of juvenile Atlantic salmon in a tributary of Lake Ontario

The habitat use and diet of juvenile Atlantic salmon Salmo salar was examined in the South Sandy Creek drainage that discharges into eastern Lake Ontario. Subyearling salmon were stocked in early May during two consecutive years, and habitat and diet evaluations were made in mid-July and mid-October in 2005 and 2006. Both subyearling and yearling Atlantic salmon occupied deeper and faster areas that had more cover and larger sized substrate materials than was present, on average, within the study reach. Differences in habitat use between subyearling and yearling salmon only occurred in summer. Principal component analysis showed that of the habitat variables examined, the amount of cover and size of substrate were more important to juvenile salmon in summer, whereas depth and velocity were more important in the fall. Trichopteran larvae (mainly hydropsychids) dominated the diet of juvenile Atlantic salmon, and parr were feeding most heavily from the substrate as compared to the drift. The juvenile ecology of this re-introduced population of Atlantic salmon is consistent with that reported in other studies throughout the species native range.

► Cover and substrate were the most important habitat variables to salmon in summer.
► Depth and velocity were the most important habitat variables to salmon in fall.
► Differences in habitat use between salmon year classes were greatest during summer.