Introduction
Diseases and parasites are main concerns in Norwegian Atlantic salmon farming. In 2023, over 100 million fish died from various causes throughout the various production stages. The most common cause of death was infection disease which accounted for 38%. This situation is not acceptable, and all parties related to the industry agree that progress is necessary. Biosafety is therefore a central concern in Norwegian salmon farming. World Organization for Animal Health has defined biosafety as “a set of management and physical measures designed to mitigate the risk of introduction of pathogenic agents into, or spread within, or release from, aquatic animal populations.".
Farming of Atlantic salmon can be divided into two main activities; on-land smolt production and sea-based grow-out. This project focuses on smolt production and delivery of smolt to sea-based farms. Reasons for this are both the high number of mortalities in smolt production and the uncertainty related to whether disease and mortality in sea-based grow-out originates from infections carried over from smolt production. Biosafety at this stage is thus essential, and there is need for an overview of risk factors and measures related to infection of salmon in these technical solutions and systems for smolt production and transfer to sea.
Material and methods
This project covers results from a study identifying risk factors related to technical solutions at hatcheries with RAS technology (recirculating aquaculture systems) and well boats, and potential measures to reduce risk. Such risk factors and measures are related to the technical solutions’ design, construction, cleaning, maintenance, and how they facilitate operation according to biosafety principles. Both risk factors and potential measures were identified based on literature review of research literature, document study of technical drawings and other documents provided by industry, interviews and observations and discussions during visits at RAS-facilities and vessels.
Results
Risk factors for RAS facilities are divided into four main groups: Introduction to the facility, spread inside the facility, growth inside the facility, and additional risks. Risk factors for well boats are divided into three main groups: Introduction through intake water, spread between fish groups, and infection of external fish. Measures are proposed to mitigate the identified risk factors. The lists are not exhaustive, and risk magnitude is not quantified, so effect of measures is not calculated. Still, the measures’ potential for risk reduction and implementation (cost/benefit) are discussed.
In the presentation, we will suggest key measures for biosafety in RAS hatcheries and well boats for smolt transfer to sea-based farms.