Sea lice infestations are an increasing challenge in the ever-growing salmon aquaculture sector and cause large economic losses. The high salmon production in a small area creates a perfect habitat for parasites. Knowledge of how salmon lice planktonic larvae disperse and spread infection between farms is of vital importance in developing treatment management plans to combat salmon lice infestations. Using a particle-tracking model forced by tidal currents, we show that Faroese aquaculture farms form a complex network. In some cases as many as 10% of the infectious salmon lice released at one farm site enter a neighboring fjord containing another farm site. Farms were characterized as emitters, receivers or isolated, and we could identify 2 clusters of farms that were largely isolated from each other. These farm characteristics are a valuable input for the development of management plans for the entire Faroese salmon industry.

No abstract

No abstract

Managing salmon louse Lepeophtheirus salmonis outbreaks is a crucial part of salmon aquaculture in sea cages. Treatment management strategies can be optimized with the aid of salmon-louse population dynamic models. These models, however, need to be calibrated and validated with biologically meaningful parameters. Here, based on a time-series of lice data, we estimated 2 essential model parameters: the external infection pressure and the salmon-louse population growth rate for each active salmon farm site in the period 2011 to 2018 in the Faroe Islands. External infection pressure was found to vary between farm sites and ranged on average from 0.002 to 0.1 lice salmon-1 d-1. Further, external infection was significantly correlated with the total number of gravid lice in the Faroese farm network. Salmon-louse population growth rates were found to vary between farm sites and ranged on average from 1.7 to 5.4% d-1. These model parameter estimates are crucial in developing a salmon-louse population dynamic model for the Faroe Islands, and the method to estimate these parameters may be applicable in other aquaculture regions.