Interactive effects of life history and season on size‐dependent growth in juvenile Atlantic salmon

Abstract

Size‐dependent growth (SDG) is an important process in structuring populations as well as determining life history outcomes. Despite its importance, there have been few investigations from observational studies focusing on the interaction between life history decisions and SDG. In this study, we used data on individually tagged Atlantic salmon from both the laboratory and the field to investigate differences in SDG among two life history groups, parr and smolts. In the laboratory, we found little evidence of SDG in parr but seasonally dependent SDG in the smolt group. Smolts showed at strong compensatory response over the winter months just prior to the smolt transformation window. In the field, we found little evidence of SDG early in ontogeny (i.e., age 0+ fall and winter). There was some evidence of depensatory growth (positive SDG) during the age 1+ spring among both life history groups that may reflect random habitat variation or the monopolisation of resources. After the age 1+ spring, we found that smolts were more likely to show a compensatory effect (negative SDG) than parr. This effect was strongest, as they approached the smolt window in the spring of their age 2+ year. These results suggest (i) SDG is common in Atlantic salmon; however, the form and extent of life history depends on (ii) season and (iii) life history. For individuals that adopt a smolt life history, trade‐offs between freshwater survival and sea survival may lead to a convergent growth pattern, as they approach the smolt migration window.

Associations between metabolic traits and growth rate in brown trout ( Salmo trutta ) depend on thermal regime

“…in winter months when temperatures are sub-optimal and food availability reduced) but could have been most beneficial in the spring, when temperatures are closer to optimal ranges [ 67 , 68 ]. Consideration of life history might also be important here because metabolic rate tends to be positively related to migratory propensity/timing in salmonids, with individuals showing compensatory growth in the period prior to smolting [ 69 ]. In general, metabolic phenotype, growth rates, and life-history traits likely coevolve in relation to abiotic and biotic drivers that vary across space or through time [ 60 , 70 ].…”

The influence of nutrients from carcasses of sea lamprey (Petromyzon marinus) on larval growth and spawner abundance

“…Nutrients from carcasses of sea lamprey stimulate productivity during spring, a critical period of temperature-driven increases in metabolism for fish facing potential limitations in resources (Hall, 1972;Weaver et al, 2015;Weaver et al, 2016). Therefore, salmon parr that are subsidized directly and indirectly by these resources may benefit from a compensatory growth as fish approach the smolt stage (Guyette et al, 2013;Sigourney et al, 2013). This enhanced growth could potentially increase survival and reduce the number of years spent in freshwater before the young salmon successfully migrate to the ocean (Horton et al, 2009).…”

Three Visualization Approaches for Communicating and Exploring Passive Integrated Transponder Tag Data

“…For example, we identified variation in Atlantic Salmon body size (Letcher and Gries ), growth (Sigourney et al. , ), survival (Letcher et al. ; Horton et al.…”

“…Over the course of the study, we have conducted analyses and modeling exercises to identify drivers of population dynamics and life history patterns, resulting in 43 publications to date. For example, we identified variation in Atlantic Salmon body size (Letcher and Gries 2003), growth (Sigourney et al 2012(Sigourney et al , 2013, survival (Letcher et al 2002;Horton et al 2009), and morphometry (Letcher 2003;Pearlstein et al 2007) for fish with different eventual freshwater life histories. Fish with earlier smolt ages (2+ versus 3+) and males that were mature or not in the stream were different sizes and shapes as early as their first year.…”