Anadromous salmonids—fish such as salmon, char, and trout that live at sea and return to freshwater to spawn—are central to recreational and subsistence food fisheries in Newfoundland and Labrador as well as the Arctic. But little is known about the relative habitat use of these species in areas where their distributions overlap, particularly in the North. Predicted effects of climate change, such as reduced migration, altered growth, and changing species composition have increased the need to understand this comparative ecology.

The first component of this project focused primarily on Arctic char and Atlantic salmon—species historically divided by resource and habitat preferences. The work was carried out by the Ocean Tracking Network (OTN) in several nearshore river systems in northern Newfoundland and Labrador. The distributions of these animals are shifting due to climate change, with the southern salmon pushing north into char habitat. 

Using acoustic and archival geolocation tag technology, the project characterized overwinter movements, activity patterns, thermal habitat use and dispersal rate of char. This revealed char movement corresponded with daylight, temperature and body size. 

In Newfoundland, salmon movement patterns, residency, feeding ecology and survival were quantified for the first time in relation to their life stage and spawning history. The studies provided insight into how climate change may affect individual fitness and on the relative competitive abilities of these salmonids. 

The second project component focused on understanding the patterns and consequences of char dispersal in the Arctic region of Cambridge Bay, Nunavut. Char are the most northerly distributed freshwater fish and are culturally significant to Inuitand important for food security.  

Key findings revealed clear preferences of char for coastal surface waters when in the marine environment; regular and lengthy forays into estuaries throughout the summer; extensive stock mixing, including in freshwater; and use of the largest (and most heavily fished) lake in the region as an overwintering area for fish from many rivers in the region. 

These findings are critically important for maintaining char stocks as well as a guide for future management for these species in the region, particularly given the invasion of southern species seeking colder waters.