The influence of climate change on growth of Arctic charr (<i>Salvelinus alpinus</i>).

Abstract

The Arctic is warming at an unprecedented rate and with longer growing seasons, greater rainfall, and less snowfall. Cold-adapted ectotherms, such as the Arctic charr, <i>Salvelinus alpinus</i> (Linnaeus 1758), are likely to experience changes to growth as a result. Anadromous Arctic charr (charr, hereafter) are of great importance for northern communities, providing a source of income from commercial fisheries and food security from subsistence harvest. Initially, warming is expected to increase the growth of charr, benefitting subsistence and commercial fisheries in the short term. However, over longer time scales, temperatures exceeding the optimum for growth will likely result in metabolic stress, slowed growth, and higher mortality. Thus, the long-term consequences of climate change will likely be negative. We assessed anadromous charr growth from 1984 to 2013 in three stocks around Cumberland Sound using otolith measurements as proxies for age-specific growth. Trend analyses indicated growth had increased in pre-migratory ages over the years. We used mixed models to investigate changes to growth for ages 1-10 in relation to climate variables, finding that growing degree days had the greatest positive influence on ages 1-6 while annual precipitation had an overall negative effect on growth in ages 1-2 and 6-10. Contrary to previous assessments on these stocks, our results suggest charr have indeed experienced changes to growth with climate change. These findings emphasize the need for more thorough long-term growth studies in the management of fisheries as altered growth will affect food security and the economy across the Canadian Arctic.