AEI prepress abstract  -  DOI: https://doi.org/10.3354/aei00323

Practices to obtain lice counts at Norwegian salmon farms: Status and possible implications for representativity

Trine Thorvaldsen*, Kevin Frank, Leif Magne Sunde

*Email: trine.thorvaldsen@sintef.no

ABSTRACT: The Norwegian aquaculture industry faces several challenges. One such challenge is the prevalence of salmon lice, which adversely affects both wild and farmed salmon. At the core of the current regulatory regime are mandatory lice counts that are manually obtained from fish farms. Thus, the objective of this article is to present knowledge regarding counting practices as well as fish farm employees’ perceptions of the strengths and weaknesses of today's practices and the possible implications of said practices for representativity. For the research, interviews comprised the main method of data collection. The results of this research address 3 phases of the lice-counting process: sampling, sedation, and counting. The organizational factors that may influence the counting, such as training, time, and manning, are also described. Our results show variations in the choice of equipment used for different stages of the lice-counting process, including sampling and crowding time. In the interviews, employees expressed the challenges inherent in identifying different lice species and the associated developmental stages of the lice. The findings presented in this paper demonstrate the importance of documenting actual practices at the fish farms in order to optimize lice counts and should be considered by the aquaculture industry, technology developers and regulators in the future.