Identifying ‘firebreaks’ to reduce marine parasite spread

Parasite and disease outbreaks are a common issue for many aquaculture industries around the world, and efficient strategies to control the spread of them are scarce. The Atlantic salmon aquaculture industry is growing globally, with Norway producing the most salmon worldwide. However, salmon lice infestations hinder the growth of the industry and can have negative welfare outcomes. Salmon lice larvae are released from and transported among salmon farms by ocean currents, which create inter-farm networks of louse dispersal. Dr Francisca Samsing along with researchers from the University of Melbourne, Deakin University, and Institute of Marine Research investigated if introducing no-farming areas or ‘firebreaks’ could disconnect dispersal networks of salmon lice. Using a model to predict louse movement along the Norwegian coastline and analysis to identify potential firebreaks to dispersal, she identified one firebreak that split the network into two large unconnected groups of farms. She also found farms that should be removed during spring to prevent wild salmon migrating out into the ocean from getting bombarded with high infestation pressures. If applied to the industry, her model should help lower infestation pressure both at farms and in wild salmon populations.

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