Growth of five landlocked Arctic charr stocks under hatchery conditions

Abstract

Growth dynamics of five stocks of Arctic charr, were compared from the fry stage in June 1986 until December 1987. Each stock originated from a different lake in Sweden: Hornavan; Nfickten; Torr/Sn; Rensj6n and Visj6n. Hornavan charr reached the highest final mean weight (237 g), but they were not significantly heavier than VisjSn charr (206 g). Growth of fish of the three remaining stocks was similar but less rapid. The superior growth performance of Hornavan charr was most pronounced during autumn. Coefficients of variation for individual size within stocks was between 30 and 54%, with Hornavan and N~ckten charr displaying least variability. Charr from Lake Visj6n had a significantly lower proportion of mature males (6%) than the other stocks (19-29%) at the end of the experiment. The results demonstrate that differences in growth potential exist between stocks of charr, and these differences may be related to differential seasonal rhythms in growth. Variations in early growth, size distributions and sexual maturation seemed to be subordinate factors affecting overall growth performance.

A comparison of growth patterns between a stunted and two large predatory Arctic charr populations under identical hatchery conditions

“…LP2 charr were clearly the largest at the egg stage, but both SP and LP2 charr had grown to a corresponding body size during the first few months of exogenous feeding (by August). This is in line with the previous observations on different species of salmonids (Springate and Bromage 1985;Näslund and Henricson 1996;Heath et al 1999;Berrill and McCarthy 2008), indicating that the possible size advantage due to larger egg size disappears during early stages of growth.…”

“…In addition to fish density, sexual maturation among 2+ fish needs to be considered as a potential factor affecting population-specific growths patterns. Although maturation is known to be accompanied by a slowing growth rate and an increasing size variation (Papst and Hopky 1983;Jobling et al 1993;Damsgård et al 1999), it seemed to have relatively limited effects on overall growth and size dispersion in our study (see also Näslund and Henricson 1996).…”

“…This may represent the natural growth variability of the species Näslund and Henricson 1996), as well as reflect the effects of social factors, i.e., the formation of a dominance hierarchy, which leads to disproportionate feed intake and growth between dominant and subordinate individuals (Noakes 1980;de March 1997;Olsen and Ringø 1999). Resulting from different post-hatching mortalities, populations were exposed to somewhat divergent stocking densities, which may have impacted their size means and dispersions especially during the first summer.…”

“…In addition to sympatric morphotypes occupying a single lake and showing differences, e.g., in growth patterns, morphology and life history traits (Sandlund et al 1992; have traditionally been grouped into two separate categories, 'small charr' and 'large charr', or alternatively, 'dwarf' and 'normal charr', based on the attainable adult size (Griffiths 1994). The genetic isolation of allopatric charr forms a prerequisite for local adaptations (Taylor 1991;Adams and Maitland 2007;, which might reflect in differences in intrinsic growth potential as well (e.g., Adalsteinsson et al 1992;Näslund and Henricson 1996). Although growth and the closely associated life history traits may, indeed, involve a significant amount of heritable variation in charr (Nilsson 1992;Thériault et al 2007), they are primarily plastic characters, being adjusted in response to the state of environment (Nordeng 1983;Hindar and Jonsson 1993;Griffiths 1994).…”

The Arctic charr story: development of subarctic freshwater fish farming in Sweden

“…1). In addition, in a later trial, the Hornavan predatory strain was found to have higher growth capacity than other strains of charr in Sweden (Näslund & Henriksson, 1996). For these reasons, in 1986, we choose the predatory morph from Lake Hornavan to be the starting population for a selective breeding programme.…”