Investigating cottid recolonization in the Cheakamus River, BC : implications for management

Abstract

An estimated 90% of resident sculpin (Cottus asper and C. aleuticus) were impacted by a spill of 45,000 litres of sodium hydroxide, which occurred on the Cheakamus River, British Columbia on August 5, 2005. This study examined sculpin biology, life history, how sculpins are recovering from the impact, and whether they are re-entering the Cheakamus River from the adjacent Squamish and Mamquam Rivers. Sculpins were sampled in the three river systems via minnow trapping and electrofishing. Morphometric data were recorded and fin clips were taken as deoxyribonucleic acid vouchers to validate field species identification and to determine population distinctiveness among the three systems. Populations were not distinct, suggesting recolonization from other rivers is occurring. The data show sculpins will undergo seasonal downstream spawning migrations and also suggest sculpins are opportunistic habitat colonizers. This research bears useful implications for the adaptive management, recovery, and sustainability of sculpins in the Cheakamus River.