It is, of course, impossible for scientists to count every single fish in the sea. Instead, they collect as much information as they can from three main sources: landings at ports, fishers, and research vessels surveys.
The collected data is then used to estimate the size of commercial fish populations such as cod, haddock, and hake, and the estimates are used by ICES to give advice to international commissions and governments on the sustainable exploitation of these fish populations.
Our newly published brochure "Fish stocks: counting the uncountable?" explains how fish stocks are assessed in the Northeast Atlantic and gives insight into the types of science and information that goes into scientists' stock estimates. It also describes the ICES advisory process and sheds light on the efforts in integrating ecosystem considerations into fisheries advice.
Join ICES at the Science in the City festival in Copenhagen on Sunday, 22 June, where Advisory Programme Professional Officer Anne Cooper will give a presentation on this very topic. The presentation How do scientists count the number of fish in the sea? takes place in Dance Halls in Carlsberg City at 13:00 and at 15:00.