Research Document 2021/022

Harvest, catch-effort, and biological information of Arctic Char, Salvelinus alpinus, collected from a long-term subsistence harvest monitoring program in Tatik Lake (Kuujjua River), Northwest Territories

By Gallagher, C.P., Howland, K.L., Papst, M., and Harwood, L.

Abstract

Data collected from a fishery-dependent monitoring program between 1992 and 2015 and supplemental information collected in 1978 and 1987 were used to inform a population assessment of anadromous Arctic Char (Salvelinus alpinus) from the Kuujjua River, Northwest Territories. The stock is important for the subsistence and economy of residents from the hamlet of Ulukhaktok in the Inuvialuit Settlement Region. Arctic Char from the Kuujjua River stock are harvested during summer when feeding along the coast in a mixed-stock fishery, and during winter (under-ice) while overwintering in Tatik Lake. The monitoring program conducted during the winter fishery employed subsistence fishers from Ulukhaktok to collect harvest, catch-effort, and biological data for the majority of the duration of the fishery. Catch-effort in Tatik Lake varied without trend although the frequency of relatively high values (> 125 Arctic Char/100 m/24 hours) increased from 2006 to 2015. The biological data reveal the winter fishery harvests Arctic Char mainly between 500 and 700 mm, 1,000 and 3,500 g, and 8 and 12 years of age. Mean length and weight increased from 533 to 633 mm and 1,893 to 3,354 g, respectively, between 2008 and 2012, and have been relatively stable through 2015. Mean age increased from 8.3 to 10.3 years between 2010 and 2012 and was then stable through 2015 with the consistent presence of fish ≥ 15 years of age. The von Bertalanffy growth parameters of Arctic Char from Tatik Lake were L∞= 703, K= 0.42, and t₀= 2.61, with no statistically significant difference between sexes. The mean length of fish 9 to 12 years of age increased beginning in 2008 and continued through 2015. Over the time-series, mean length and weight, and length-at-age followed a quasi-cyclic pattern. Condition factor remained relatively high (K ≥ 1.2) and stable from 2008 to 2015, which suggests feeding opportunities were favorable for growth during this period. The annual mortality rate between 2011 and 2015 was stable (~ 30%). Where comparisons were possible, some similarities were observed between the biological data collected from the 1992-2015 monitoring, and data collected from this same fishery in 1978 and 1987. Collectively, the catch and monitoring data through 2015 indicate that the Kuujjua River population is not experiencing overfishing and the current stock status is healthy.

Research Document 2021/022 (PDF, 6,087 KB)

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.