Physiological correlates of seasonal growth patterns in lake trout Salvelinus namaycush

Abstract

Physiological correlates of seasonal growth patterns were measured in lake trout Salvelinus namaycush from two populations with contrasting diets (zooplankton-dominated diet in Louisa Lake; fish-dominated diet in Opeongo Lake). Fish in Opeongo Lake grew faster and were in better condition than fish in Louisa Lake. The most prominent biochemical difference between populations was higher citrate synthase (CS) and cytochrome c oxidase activity in the white muscle of fish from Opeongo Lake, indicating greater sustained swimming activity in this lake. In contrast, lactate dehydrogenase (LDH) activity in white muscle, an indicator of capacity for burst swimming, was similar between lakes. Nucleoside diphosphate kinase (NDPK) activity in white muscle, an indicator of protein synthesis, was higher in Opeongo Lake than in Louisa Lake but only in the autumn. In both lakes, protein concentration and therefore nutritional status increased as the growing season progressed from spring to summer to autumn. Biochemical indicators of growth and activity showed similar seasonal patterns in the two lakes with the spring characterized by high NDPK, high CS and high LDH activities (i.e. high levels of protein synthesis in association with high aerobic and anaerobic activities). These results suggest high foraging effort and allocation to growth early in the growing season in both lakes.

Behavioral responses to annual temperature variation alter the dominant energy pathway, growth, and condition of a cold-water predator

“…First, increased reliance on Mysis and zooplankton would be less energetically efficient than foraging on larger prey fish or benthic invertebrates because predatory fish are more active when forced to feed on numerous, smaller prey (22). This increased energetic cost of feeding on small prey has been illustrated by studies that found predatory fish in lakes without pelagic prey fish had increased muscle activity and greater activity rates than those same species in lakes containing pelagic prey fish (23)(24)(25) and by studies showing that more active fish generally grow more slowly (26). Additionally, in oligotrophic lakes, the littoral zone is often more productive and smaller in volume than the pelagic zone (6,17), and therefore the probability of a lake trout's encountering prey would be higher in the littoral zone than in the pelagic zone, increasing foraging success but also reducing the time required to find prey.…”

Convergence in form and function overcomes non-parallel evolutionary histories in a Holarctic fish

“…6c). These genes are known to be associated with growth rate, body size, and metabolism (Morbey et al 2010;Palstra et al 2014;Flanagan et al 2017), making them strong candidates for underlying ecotype divergence in Arctic charr. Additionally, 19 differentially expressed genes were shared across four ecotype pairs, which included several haemoglobin subunits ( Supplementary Fig.…”

Intermittent breeding in the absence of a large cost of reproduction: evidence for a non‐migratory, iteroparous salmonid

“…For brevity, we do not present other condition metrics such as Le Cren's condition index (K LC ) or residual mass from the regression of logW on logL F (Rennie and Verdon 2008). However, in our system, K F , K LC , and residual mass are highly correlated (Morbey et al 2010). Large year-toyear variation in size-at-age meant it was not useful to generalize growth using standard descriptive models (e.g., von Bertalanffy) or realistic mechanistic models (e.g., generic biphasic growth model; Lester et al 2004, Quince et al 2008a, Quince et al 2008b).…”