Modelling temperature and fish biomass data to predict annual Scottish farmed salmon, Salmo salar L., losses: Development of an early warning tool.

•Salmon losses increased 2003–2018 as proportion of biomass per month.•Proportion of salmon lost during a production cycle did not increase.•Losses modelled using linear and beta regressions at national and regional levels.•Nationally, 82% and regionally, 62% of losses explained by winter minimum temperatures and biomass.•Development of an early warning tool for managing losses on salmon farms.