Kejimkujik National Park in Nova Scotia has decided to halt its annual brook trout census due to the detrimental 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 by counting, weighing, and measuring the fish they caught, has been temporarily stopped this year.
Parks Canada revealed that the pause in the census is a result of the overwhelming presence of chain pickerel, which accounted for 90% of the fish caught in the national park in western Nova Scotia in 2025. The agency explained that the current number of brook trout reported in the census is insufficient for statistical accuracy due to the invasion of chain pickerel, which were first detected in the park in 2018 after being illegally introduced to Nova Scotian waters in 1945.
Efforts to control the spread of chain pickerel, known for their voracious appetite that threatens native fish populations, have faced challenges. Despite attempts by Kejimkujik staff to install fish barriers, these measures proved ineffective due to flooding. However, the agency remains committed to mitigation strategies, having already removed over 5,300 chain pickerel with the help of volunteers.
While the brook trout census is on hold, Parks Canada will continue monitoring the species through alternative methods such as the angler diaries program and deploying fyke nets annually in various waterbodies within Kejimkujik. Conservationists are advised to shift focus to areas where chain pickerel have not yet invaded to prevent further ecological disruption.
Chain pickerel, being ambush predators, pose a significant threat to the biodiversity of aquatic ecosystems. Trevor Avery, a biology and mathematics professor at Acadia University, emphasized the need for effective population management strategies, ranging from targeted fishing to more extreme measures like the use of rotenone, a natural fish pesticide.
While Nova Scotia boasts renowned brook trout fisheries, the presence of chain pickerel also offers recreational opportunities for anglers due to their strong fighting abilities. Andrew Lowles, a resource manager at the Nova Scotia Department of Fisheries and Aquaculture, highlighted the historical significance of the region’s fishing heritage and the evolving challenges posed by invasive species like chain pickerel.
In conclusion, the invasion of chain pickerel in Kejimkujik National Park underscores the importance of ongoing conservation efforts to protect native fish populations and preserve the ecological balance of the region.