Nutritional correlates of spatiotemporal variations in the marine habitat use of brown trout (Salmo trutta) veteran migrants

Abstract

The brown trout (Salmo trutta) is an iteroparous, anadromous salmonid that exhibits a complex continuum of feeding migration tactics, ranging from freshwater residency, to potamodromy, to estuarine migration, as well as short- to long-distance coastal migrations. While anadromous migrants are believed to play an important role in the species’ population dynamics, little is known about the factors driving differences in the extent of individual marine habitat use. In this study, 32 brown trout veteran migrants were acoustically tagged prior to their seaward migration and sampled for indices of their nutritional state. Our findings suggest that (i) body condition factor differed among fish adopting different migratory tactics, with outer fjord migrant being in poorer condition; and (ii) within migratory groups, plasma triglyceride concentration was negatively correlated with the duration of marine residency. Results support the idea of condition-dependent migration in veteran migrants, with individual variation in nutritional state influencing the spatiotemporal aspects of marine habitat use. Furthermore, overall marine minimum survival during the summer feeding migration was 86%, the highest reported estimate for this life stage.

Potential of a no‐take marine reserve to protect home ranges of anadromous brown trout (Salmo trutta)

“…The latter is in line with findings by Flaten et al (2016) and Bordeleau et al (2018), showing that female sea trout migrating to the outer fjord areas were larger than females migrating to inner fjord areas in Norwegian fjords. The latter is in line with findings by Flaten et al (2016) and Bordeleau et al (2018), showing that female sea trout migrating to the outer fjord areas were larger than females migrating to inner fjord areas in Norwegian fjords.…”

“…Variation in how sea trout use marine habitats is substantial and ranges from spending only a few weeks at sea (Eldøy et al, 2015) to spending two or more years at sea (Jonsson & Jonsson, 2002;Klemetsen et al, 2003). Seaward migration can occur as a response to reduced energetic surplus available for growth (Forseth, Naesje, Jonsson, & Hårsaker, 1999) and is also more likely for individuals with a lower body condition (Bordeleau et al, 2018). Seaward migration can occur as a response to reduced energetic surplus available for growth (Forseth, Naesje, Jonsson, & Hårsaker, 1999) and is also more likely for individuals with a lower body condition (Bordeleau et al, 2018).…”

“…In addition, there is great variation in habitat use in marine regions, with some sea trout spending most of their time in fjords and some venturing out to the open seas (Bordeleau et al, 2018;del Villar-Guerra, Aarestrup, Skov, & Koed, 2014). Seaward migration can occur as a response to reduced energetic surplus available for growth (Forseth, Naesje, Jonsson, & Hårsaker, 1999) and is also more likely for individuals with a lower body condition (Bordeleau et al, 2018). Decisions made regarding staying in fjord habitats or moving to the open sea are made shortly after entering the fjord (del Villar-Guerra et al, 2014).…”

Patterns of Iteroparity in Wild Snake River Steelhead

“…Kelts in poor nutritional condition (low condition factor and plasma triglyceride concentrations) tend to stay in salt water longer (Bordeleau et al. ). For Snake River steelhead, we infer an even greater proportion of kelts were attempting a years recovery than the percentage of skip spawners indicates.…”

Environmental influences on life history strategies in partially anadromous brown trout (Salmo trutta, Salmonidae)

“…This may be because females do not exhibit alternative spawning tactics (sneaking versus fighting) as males do (McLean, Bentzen, & Quinn, 2004). Thus, females are more likely to migrate to more food rich areas and stay there for longer periods of time to grow larger before spawning (Bordeleau et al, 2018;Cucherousset et al, 2005;Ferguson, 2006;Northcote, 1992). Thus, females are more likely to migrate to more food rich areas and stay there for longer periods of time to grow larger before spawning (Bordeleau et al, 2018;Cucherousset et al, 2005;Ferguson, 2006;Northcote, 1992).…”