Kejimkujik National Park in Nova Scotia has decided to halt its traditional brook trout census due to the detrimental impact of an invasive species on the local ecosystem. Since the 1990s, volunteers, mainly fly fishers, have been participating in the census by catching, weighing, and measuring brook trout to aid Parks Canada in monitoring the species.
This year, the census has been put on hold as chain pickerel, an invasive species, have become the dominant catch at the park. According to Parks Canada, chain pickerel accounted for 90% of the fish caught in the park in 2025, making the brook trout count insufficient for the monitoring project’s statistical requirements.
The introduction of chain pickerel to Nova Scotian waters in 1945 led to their proliferation throughout the province, with their first appearance at Kejimkujik National Park noted in 2018. Once established, chain pickerel rapidly dominate the ecosystem by preying on various species, including fish, reptiles, and even young ducklings.
Efforts by Kejimkujik staff to contain chain pickerel through fish barriers have been hindered by flooding, rendering the barriers ineffective. However, ongoing mitigation strategies involve removing chain pickerel with the help of volunteers. To prevent their spread, chain pickerel caught at the park must be retained, while native fish species, such as trout, are released back into the water.
The park will continue monitoring brook trout populations through alternative methods, including the angler diaries program and deploying fyke nets annually to track native fish populations. While conservationists focus on managing the invasive species, experts suggest directing efforts towards areas not yet affected by chain pickerel to prevent further ecological damage.
Trevor Avery, a biology and mathematics professor at Acadia University, has been studying chain pickerel in Kejimkujik since their introduction. He highlights the challenge of managing the population, suggesting options from using fish pesticide to targeted fishing as potential solutions.
Despite the threat posed by chain pickerel, Nova Scotia remains renowned for its brook trout fisheries. Andrew Lowles, a resource manager at the Nova Scotia Department of Fisheries and Aquaculture, acknowledges the historical significance of the region as a prime fishing destination. He notes that while chain pickerel offer an angling opportunity due to their aggressive nature, they also pose a threat to the ecosystem.
In conclusion, the invasive chain pickerel’s impact on Kejimkujik National Park’s ecosystem has led to the suspension of the annual brook trout census. Efforts are ongoing to mitigate the spread of these predators while maintaining the park’s biodiversity through innovative monitoring and management strategies.
