Murray et al (2021). The average sea lice numbers per fish per year can be summarised as follows: Year Average sea lice count 2013 0.54 2014 1.15 2015 1.30 2016 1.33 2017 0.90 2018 0.612 2019 0.741 2020 0.623 Following the introduction of The Fish Farming Businesses (Reporting) (Scotland) Order 2020 on 29 March 2021, Aquaculture Production Businesses which farm fish (other than at freshwater sites) will be required to report average weekly female sea lice numbers per site per week, one week in arrears to Scottish Ministers.