© Frank Gregersen, Nofima
Crowding is one of the most critical steps in the successful handling of farmed salmon. It typically occurs when fish are being moved or treated and involves temporarily increasing fish density and reducing available water volume.
The purpose of the handbooks – one for net pens and one for tanks – is to support fish farmers in monitoring and hopefully improving the crowding process. The authors have updated existing frameworks and toolboxes to monitor and measure welfare before, during, and after crowding. They also provide schemes and metrics for monitoring crowding above and below water and introduce the first version of a novel underwater crowding intensity risk scale designed for use by ROV operators, based upon work led by the Institute of Marine Research.
These handbooks were developed as part of the CrowdMonitor project, funded by FHF – Norwegian Seafood Research Fund. Cermaq Norway and Grieg Seafood have also contributed valuable practical experience to the project and the handbooks.
While the recommendations in the handbooks do not guarantee positive outcomes during crowding, they are intended to serve as guidance and support for operators performing and monitoring such procedures.
“We have received many inquiries about this from the industry in Norway and abroad, so there is clearly a need for more information,” said project manager, Chris Noble, in a press release.
Noble encourages fish farmers to visit the project where they can find recordings of the webinar where the handbooks were presented, and soon, the handbooks, practical posters and fact sheets. The handbooks are currently available in English and will be translated into Norwegian this winter.
Together with Lars Helge Stien from the Institute of Marine Research, Noble will host a new webinar in April 2026 to gather feedback on the handbooks and release a revised version if needed.
