The negative association of sea lice from fish farms on recreational fishing catches of Atlantic salmon

The question of whether and to what extent sea-louse (L. salmonis) infestations from salmon farms influence wild Atlantic salmon survival has been subject to sustained scientific debate and political controversy. Documenting the population-level effects of sea lice on wild salmon remains inherently challenging. We employ comprehensive sea-lice data and recreational catch data from Norway to assess the impact of farm sea-louse infestations on wild salmon catches in different production areas (PAs). Our analysis finds a significant correlation between declines in wild Atlantic salmon catches and increasing amounts of adult female sea lice per km2. The effect is most pronounced in PA 4 on the west coast of Norway, an area within the government’s ”traffic light” management system where out-migrating salmon smolts are deemed to face high exposure to louse-induced mortality risk. Our model predicts below-average catches when the total sea louse load exceeds the government’s limit of 0.1 avera..., The data pertains to the total number of sea lice (L. slamonis) in salmon farm production areas and wild Atlantic salmon catch statistics for Atlantic salmon in Norway.
1. We employ comprehensive sea-lice (L. salmonis) data from salmon farms in Norway and recreational river catch data of Atlantic salmon from Norway to assess the impact of farm sea-louse infestations on wild salmon catches in different production areas (PAs). 
2. We have estimated the total amounts of lice within each corresponding PA for each year. To facilitate a comparison of relative lice levels across PAs, we factored in the size of PAs and computed the total number of female sea lice per km2, denoted as the farm sea-louse load.  
3. The official government statistics of salmon catches in Norway document the nominal river catches of adult Atlantic salmon, caught by rod.  We aggregated the catches for each Sea-winter class (SW) from all rivers within each PA. The aggregated values were then standardized (subtracting ..., , # The negative association of sea lice from fish farms on recreational fishing catches of Atlantic salmon

[https://doi.org/10.5061/dryad.905qftttr](https://doi.org/10.5061/dryad.905qftttr)

## Description of the data and file structure

The dataset consists of 6 columns of data: 

1. Catch: The dataset comprised official government statistics that documented the nominal river catches of adult Atlantic salmon, caught by rod, spanning the period 2006 to 2022 (Norway, 2021). Catch statistics offer insights into total catches in terms of both numbers and kilograms, encompassing catch and release data from 2009 onwards. As a substantial proportion of released fish are not recaught (Thorstad et al., 2020a), we used total catch as a metric to describe annual riverine catch. The age of the fish was inferred from the size categories that were registered in the catch data, where a fish < 3 kg was assumed to have spent one winter at sea (1 SW), and one between 3-7 kg was assumed to have spent...