Kejimkujik National Park in Nova Scotia has decided to halt its annual brook trout census due to the harmful impact of an invasive species on the local ecosystem. The census, which began in the 1990s with volunteer fly fishers assisting Parks Canada in monitoring brook trout populations, has been put on hold this year.
Parks Canada revealed that the chain pickerel, an invasive species, dominated the fish caught in the national park in western Nova Scotia, accounting for 90% of the catch in 2025. The agency explained that the presence of chain pickerel has significantly reduced the brook trout numbers reported in the census, making it challenging to maintain the statistical power required for the monitoring project.
Notably, chain pickerel were illegally introduced to Nova Scotian waters in 1945 and were first detected in Kejimkujik National Park in 2018. Once established, these predators rapidly consume various aquatic life, including other fish, reptiles, frogs, dragonflies, and even ducklings.
Efforts to control the spread of chain pickerel included the installation of fish barriers, but these were ineffective due to flooding. Despite the challenges, Parks Canada remains committed to mitigation actions and, with the assistance of volunteers, has removed over 5,300 chain pickerel to date. Anglers are required to retain any chain pickerel caught, while native fish species must be released back into the water.
Parks Canada will continue to monitor brook trout populations through alternative methods such as the angler diaries program and deploying fyke nets annually in various water bodies within Kejimkujik. Conservationists emphasize the importance of early intervention in areas where chain pickerel has not been introduced to prevent further ecological disruptions.
Trevor Avery, a biology and mathematics professor at Acadia University, has been studying chain pickerel in Kejimkujik since their arrival. His research team examines the stomach contents of captured chain pickerel, highlighting their predatory nature and rapid consumption habits.
While challenges remain in managing chain pickerel populations, options such as targeted fishing and population control measures are being explored. Nova Scotia’s rich fishing history, known for its brook trout fisheries, faces new opportunities and challenges with the presence of chain pickerel, offering anglers a different fishing experience.