Monitoring of smolt outmigration by capture-marking-recapture to assess striped bass predation on salmonicultural productivity in the Matapedia River

Description: For the last few years, the presence of an important population of striped bass in Matapédia River has preoccupied local communities, fishers and managers of the territory. Few comprehensive analyses exist on the impact of striped bass in Québec salmon rivers. It has already been shown that striped bass’ opportunistic diet does not target salmon parrs specifically, but where an abundance of striped bass is present in watercourses for a long period, its impact on juveniles is not known. Striped bass has been present in Matapédia River since 2018. Its abundance varies each year, but an upsurge has been noted for 2 years. In 2023, schools of striped bass including several hundreds and even thousands of individuals entered the river in June and hundreds of them were still there in September (according to CGRMP snorkel survey’s data). Fishers seem very preoccupied and some of them even leave the river. Traffic on the river has decreased significantly after the arrival of striped bass. One of the available options to validate the health condition of the salmon population in Matapédia River is to evaluate its abundance during the smolt downstream migration and to compare the results with counting data of 2015-2016-2017. That monitoring would help determine if striped bass has negative impacts on salmon young life stages and help to observe the downward trend as the case may be. If it is the case, management procedures can be put in place to avoid the decline of the species.