Publications by authors named "K Helgesen"
Background: Vaccination of farmed salmonids has been an integral part of preventing infectious diseases in Norway's aquaculture industry. In Norway, vaccine usage is regulated by the government. There is a need to monitor vaccine usage for both regulatory and research purposes, at local and national scales.
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- - Parasitic salmon lice significantly hinder the growth of salmon farming in Norway, leading to stagnation in production as regulations aim to limit their impact on migrating wild salmon.
- - A study found that to meet regulatory targets for louse levels, the number of female lice on farms needs to be halved in spring, using virtual models to simulate the necessary reductions to protect wild salmon.
- - Implementing coordinated production strategies and reducing the density of farmed fish through measures like stocking larger fish or using closed systems can help control louse infestations and maintain sustainable aquaculture.
The effective control of ectoparasitic salmon lice, Lepeophtheirus salmonis, in fish farms is challenged by the salmon lice having developed resistance towards several antiparasitic drugs and by the effectiveness of non-medicinal treatments being limited by considerations of fish welfare. When new antiparasitics are introduced to the market, these should be used sparingly to slow resistance development. Using a population model for salmon lice parameterised for salmonid fish farms in Norway, we quantified how reduced treatment effectiveness influences treatment frequency and lice abundance.
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- Norway produces over one million tonnes of salmonids annually in open-water net pens, with recent government plans to boost production raising concerns about sustainability.
- Increased salmonid farming can result in higher sea lice populations, which negatively impact fish health, particularly when production is scaled up.
- Simulation results indicate that doubling or quintupling production could raise sea lice abundance by up to 7.1%, and while stricter control measures could mitigate this risk, they would significantly increase operational costs and mortality rates among the fish.
The salmon louse Lepeophtheirus salmonis has been a substantial obstacle in Norwegian farming of Atlantic salmon for decades. With a limited selection of available medicines and frequent delousing treatments, resistance has emerged among salmon lice. Surveillance of salmon louse sensitivity has been in place since 2013, and consumption of medicines has been recorded since the early 80's.
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