Seasonal patterns of growth in Arctic Charr (Salvelinus alpinus L.): differences between morphs of Cumberland Sound populations

Abstract

Arctic Charr (Salvelinus alpinus L.) are phenotypically variable with multiple life history eco-morphotypes. The mechanism determining life history trajectory remains undiscovered. At maturity, anadromous individuals have greater seasonality in their growth and feeding relative to their resident conspecifics. To determine if lifelong seasonal and annual growth patterns differ between resident and anadromous individuals I measured otolith increment widths with a semi-automated method. I found that there has been a linear increase in growth in Arctic Charr between 1990 and 2015. Additionally, anadromous Arctic Charr have greater growth and seasonality in their growth relative to their resident conspecifics and these patterns are consistent at all ages. Finally, a probable life history trajectory can be assigned to Arctic Charr based on the seasonal growth pattern in the first year of life. In conclusion, further studies examining factors influencing early development are essential to elucidate the mechanism behind life-history trajectory in Arctic Charr.