Development of an assessment approach for remnant lake salmonin populations: The Crean Lake example

Aquatic Ecosystems, Saskatchewan Research Council, Division and Environmental Engineering, University of Saskatchewan, 125 – 15 Innovation Boulevard, Saskatoon, SK Canada S7N 2X8

Corresponding author: melville@src.sk.ca

Received: 13 May 2005
Accepted: 18 July 2005

Abstract

This research investigates a status assessment approach for remnant lake salmonin populations, using the lake charr (Salvelinus namaycush Walbaum) of Crean Lake (105 km²) as an example. A mark-recapture program was implemented employing small-mesh gill nets to ensnare charr by the teeth at spawning. Prior to sampling, potential spawning sites were designated primary or secondary based on habitat. Most charr were caught on three primary reefs, with some spawners moving between reefs. The spawning period peaked at day 2, enhancing spawning synchrony, and lasted up to 10 days. Results produced very low sampling mortality (5.7%), consistent estimates of the number of spawning charr (60 y⁻¹) and a very low (<2000) estimate of the total number of mature charr in Crean Lake. The approach offers an effective means of assessing remnant salmonins with minimal impact on their populations.