Population dynamics and distribution of tench (Tinca tinca) in the St. Lawrence River: managing a problematic invader

SLRRT

May 2019 - November 2020

Tench (Tinca tinca) is an invasive Eurasian freshwater fish that is undergoing a rapid population expansion in the St. Lawrence River (SLR). Introduced to Quebec through the release of live fish into the Richelieu River, it rapidly established self-sustaining populations throughout the SLR and Lake Champlain and has recently been reported in Ontario. Tench is a highly opportunistic fish, which reduces biodiversity, while simultaneously increasing inorganic nitrogen cycling and sediment resuspension, thus compromising water quality and submerged macrophyte beds. An aggressive competitor with native cyprinids for food and space18-20, it is of additional concern in Quebec, where it may adversely affect the endangered copper redhorse. Despite confirmed establishment, little is known about SLR tench populations, aside from increases in reported catches by fisherman. As successful mitigation and management of aquatic invasive species (AIS) requires a clear understanding of establishment, distribution and spread, this project aims to (1) elucidate the scale of the SLR tench invasion and (2) provide a mitigation strategy based on fishery exploitation models.

• Objective (1) will; (i) investigate population dynamics (abundance, size and structure) at multiple SLR sites; and (ii) map movement via acoustic telemetry to assess fish behaviours, distribution, and capacity to clear locks. Objective (2) will use this data to develop predicative exploitation models to provoke a fishery-induced collapse of tench in the SLR. Results from this project will elucidate the scale of invasion, inform mitigation strategies, and improve management and control techniques
• Objective (2) will use this data to develop predicative exploitation models to provoke a fishery-induced collapse of tench in the SLR. Results from this project will elucidate the scale of invasion, inform mitigation strategies, and improve management and control techniques.

• Jaclyn Hill (Fisheries and Oceans Canada) - jaclyn.hill@dfo-mpo.gc.ca
• Olivier Morissette (Ministry Of Forests, Wildlife And Parks)
• Annick Drouin (Ministry Of Forests, Wildlife And Parks)

• Fisheries and Oceans Canada
• Ministère des Forêts, de la Faune et des Parcs du Québec
• Acadia University
• McGill University

• Strategic Program for Ecosystem-based Research and Advice, Ecosystem Stressors and Aquatic Invasive Species (SPERA-AIS)