Stream restoration: a key to the survival and recovery of the Endangered Western Brook Lamprey (Lampetra richardsoni), Morrison Creek population

Stream remediation - key for the survival and recovery of species at risk

Abstract

Aquatic ecosystems and species are increasingly threatened by anthropogenic activities. Stream restoration has therefore
become a necessary conservation strategy to improve habitat quality and quantity, which are key components of productive, healthy, resilient aquatic ecosystems. The Morrison Creek watershed on Vancouver Island, British Columbia has been impacted by anthropogenic activities resulting in the degradation of aquatic habitat. For an Endangered, range-restricted species like Western Brook Lamprey (Lampetra richardsoni), Morrison Creek population, which only occurs in this one watershed, any habitat-related impacts have the potential to cause population level declines, thereby increasing the risk of extinction. Stream and riparian restoration were therefore undertaken to ameliorate the species’ Critical Habitat, which no longer supported spawning and early rearing. Effectiveness of restoration was determined through the use of restored areas for spawning, increased hydraulic complexity, and reduced sedimentation. Lamprey (adults and larvae) and salmonids (Oncorhynchus spp.) had not been observed in this habitat since 2005; however, following habitat restoration in 2021, 10 different lamprey nests were observed being tended in the restored habitat in 2022. Salmonids were also observed using the newly created habitat for spawning in fall 2021 and fry and smolts used pools and riffles for rearing the following spring and summer. Our work demonstrates specific types of habitat restoration that are effective for lamprey conservation and validates that complex restoration activity can occur when there is effective collaboration.