Ecology and comparative population dynamics of anadromous Arctic charr, Salvelinus alpinus (Linnaeus 1758), in northern Labrador

Dempson, J. B. (1982) Ecology and comparative population dynamics of anadromous Arctic charr, Salvelinus alpinus (Linnaeus 1758), in northern Labrador. Masters thesis, Memorial University of Newfoundland.

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Abstract

Biological characteristics and population dynamics of northern Labrador anadromous Arctic charr (Salvelinus alpinus) were investigated. Univariate and multivariate statistical analyses were performed on nine meristic and thirteen morphometric characters of charr samples from various northern Labrador areas. Variation in meristic characters was slight, although significant differences between samples indicated the discrete nature of the stocks. Differences in growth rate, age at maturity, and movement patterns of tagged fish corroborated results of morphological analyses. -- Biological characteristics including age, growth, movement patterns and aspects of reproduction were examined in Fraser River Arctic charr. No consistent differences in growth rate were found between male and female charr. Upstream migration from the sea began in mid-July with a tendency for larger fish to enter the river first. Average size and age of upstream migrants were 45.1 cm and 8.3 years respectively. -- Biological characteristics of commercially exploited and unexploited Labrador charr populations were examined. Mean age of charr increased with latitude. Commercial exploitation has reduced the proportion of charr greater than 2.3 kg (gutted head-on weight) in commercial catches. Mean length of catches, however, has remained relatively constant in several areas. Total instantaneous mortality rates varied from 0.48 to 0.83 in exploited areas to 0.28 and 0.29 in unexploited populations. -- Comparisons between northern Labrador Arctic charr and charr from other regions are discussed with respect to movement patterns, size, age and reproductive characteristics. Labrador· charr migrated to sea for the first time at smaller sizes (7.8-19.1 cm) but comparable ages (3-7 years) with Arctic charr from other regions. Egg production in Fraser River charr was intermediate between charr from eastern and central Arctic regions, and those from the Western Arctic. Female Fraser River charr were estimated to produce 245 eggs 100g⁻¹. Commercially exploited Labrador Arctic charr populations were generally smaller and younger than exploited charr stocks in the Northwest Territories.

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