Managing Sea Lice in a Warming Ocean
A recent article in IntraFish reported that salmon farmers are concerned with this summer’s above average seawater temperatures in Norway. Specifically, the fear is that warmer ocean temperatures will exacerbate sea lice challenges later in the year. And, more sea lice could mean more sea lice treatments.
Sea lice treatments can negatively impact fish. Mechanical injury from delousing is a major contributor to mortality, reduced welfare, and poor growth. In fact, injury from delousing was one of the top reported health challenges for salmon in 2020 (Norwegian Veterinary Institute Fish Health Report).
Luckily, fish farmers have options to navigate ocean-driven stressors on fish welfare (for example stress from sea lice). One major tool in the toolbox is to minimize the cumulative stress from human disturbances and operations when the ocean conditions are tough on fish. In other words, farms can assess the full landscape of the ocean and operational stressors before making a decision that could have an outsized negative impact on fish welfare.
SeaState customers are armed with the Scoot Integrated Welfare Index (SIWI), a daily score of the cumulative stress at a farm site. SIWI is based on the weighted impact of a number of different ocean and operational factors. Farms running SeaState use their SIWI scores to make faster, data-driven decisions about their operations, like the optimal scheduling of sea lice and other treatments.
The example below shows one farm’s daily SIWI scores over the course of three weeks. The SIWI score decreased during a period of low oxygen, a time when the farm held off on handling and operations. In tandem with SeaState’s ocean forecasts, this farm was able to plan treatments around the timing of this low oxygen event and the recovery of the SIWI score.