ORCID

Abstract

Since early 2025, a nearly unprecedented bloom of common octopus (Octopus vulgaris) has occurred off the southwest UK coast. Although native to UK waters, the species is usually rare, making this the largest bloom recorded in at least 75 years. While many octopus have been commercially landed, they have also preyed heavily on economically important shellfish species, including brown crab, European lobster and king scallop. Landings of these species declined sharply in 2025, causing significant hardship for many in inshore fishing communities. In response, a rapid research project was commissioned in August 2025 to investigate the history, causes and impacts of octopus blooms, and to assess methods for monitoring octopus abundance. Work package 1 examined historical and contemporary evidence and was published in January 2026. It highlighted the role of ocean warming and other environmental conditions for producing octopus blooms, and described the effects on the fishing industry. This new report focuses on work package 2, which tested fisheries-independent monitoring methods. Methods deployed included scientific trawl surveys, baited remote underwater videos (BRUVs), cameras attached to shellfish pots and citizen science surveys involving divers and snorkelers. The survey of divers and snorkelers was particularly successful, providing extensive observations on octopus abundance, distribution, behaviour and reproduction at very little cost. BRUVs also successfully detected octopus and provided valuable information on habitat use, behaviour and condition, making them a promising long-term monitoring tool. Pot-mounted cameras showed potential for studying octopus interactions with fishing gear, although no octopus were recorded during trials. Trawl surveys failed to capture octopus, likely due to limited survey scale. Key recommendations include continued BRUV surveys, wider use of pot cameras, development of a national octopus reporting app, improved age, growth and dietary studies, acoustic tagging research and socio-economic assessments of impacts on fisheries and tourism.

Publication Date

2026-06-05

Publisher

The Marine Biological Association

Deposit Date

2026-06-17

Funding

DEFRA

Keywords

Octopus population dynamics, Fisheries surveys, Baited remote underwater video, Citizen science, Scuba diving, Snorkeling, Climate change

Creative Commons License

Creative Commons Attribution-NonCommercial 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License

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