Kejimkujik National Park in Nova Scotia has decided to halt its annual brook trout census due to the negative impact of an invasive species on the local ecosystem. Since the 1990s, volunteers, mainly fly fishers, have been conducting the census by counting, weighing, and measuring brook trout caught to aid Parks Canada in species monitoring.
The interruption of this year’s census was deemed necessary because chain pickerel, accounting for 90% of the fish caught in 2025 at the park in western Nova Scotia, have significantly affected the brook trout population. This invasive species was illicitly introduced to Nova Scotian waters in 1945 and made its way to the park in 2018, rapidly dominating the ecosystem by preying on various species, including fish, reptiles, and amphibians.
Parks Canada expressed concern that the dwindling number of brook trout reported in the creel census does not provide sufficient statistical power for effective monitoring due to the overwhelming presence of chain pickerel. Efforts to mitigate the spread of chain pickerel by creating fish barriers were hindered by flooding, making it challenging to protect Kejimkujik entirely from this invasive species.
Despite the setback, Parks Canada remains committed to conservation efforts. With the assistance of volunteers, over 5,300 chain pickerel have been removed from the park. Furthermore, chain pickerel caught by anglers must be retained, while native fish species, such as trout, are to be released back into the water.
Alternative methods, including the angler diaries program and deploying fyke nets in various water bodies of Kejimkujik, will be used to continue monitoring the brook trout population. However, conservationists like Ken Donnelly suggest shifting focus to areas where chain pickerel have not invaded, emphasizing the importance of early intervention in managing invasive species.
Trevor Avery, a biology and mathematics professor at Acadia University, highlighted the predatory nature of chain pickerel and proposed management strategies, such as targeted fishing, to help control their population. While Nova Scotia boasts renowned brook trout fisheries, the presence of chain pickerel also presents opportunities for anglers, offering a different fishing experience.
The ongoing battle against invasive chain pickerel underscores the challenges faced by conservationists in maintaining the delicate balance of ecosystems like Kejimkujik National Park.