Life history contrasts in nutritional state and return probability of post-spawned Atlantic salmon

Abstract

Using nonlethal tissue biopsies, we investigated somatic energy, lipid composition, and condition in post-spawned Atlantic salmon (Salmo salar) (kelts, n = 69) returning to sea in the spring and explored contrasts as a function of previous migration and spawning history, length and sex. Using mark–recapture analysis, we also explored linkages between spawning history and probability of future repeat spawning. Lipid density was significantly higher in previously spawned individuals compared to first-time spawned fish and in females compared to males. Fatty acid composition differed significantly among spawning histories. Return rates to consecutive spawning the following year were consistent with spawning history-dependent differences in lipid density, as first-time spawned kelts had lower return rates compared to consecutive repeat spawned kelts. We suggest that spawning history related contrasts in nutritional state in post-spawned Atlantic salmon may be a carry-over effect of differences in the feeding habitat as affected by spawning-history-dependent migration strategies. Alternatively, it may represent an adaptive response to increased survival and recovery potential with age.