Changes in growth patterns of wild Arctic charr (Salvelinus alpinus (L.)) in response to fluctuating environmental conditions

Several studies have revealed relationships between annual size-at-catch and various climatic factors for anadromous Arctic charr (Salvelinus alpinus) captured as part of the commercial fishery at Nain, Labrador (Nunatsiavut), Canada. Here, changes in growth patterns are examined among cohorts subject to differing lifetime temperature regimes, thereby considering the cumulative effects of past climate conditions instead of only annual fluctuations in temperature. An anomalous cold period, occurring in the Labrador region during the 1990s, was associated with a reduction in mean size-at-age for cohorts passing through this period. The physiological effect of temperature on growth was further exacerbated by a coincident change in the regional availability of preferred prey species. Mean sizes-at-age for cohorts experiencing a subsequent warm period, however, were not significantly larger than those observed for cohorts experiencing average cumulative lifetime temperatures. The latter result may be indicative of broader changes in ecosystem dynamics, exploitation rates and behaviour that coincided with the increase in temperature. The growth changes observed for the Nain Arctic charr stock complex indicate that climatic fluctuations can have both direct physiological effects on Arctic charr growth patterns as well as indirect effects through changes in ecosystem dynamics such as prey availability.