ORCID
- Bryce Stewart: 0000-0001-5103-5041
- Alice Hall: 0000-0002-1048-3101
- Emma Sheehan: 0000-0002-1066-8237
Abstract
Common octopus (Octopus vulgaris) are normally uncommon in UK waters, with a mainly south-westerly distribution linked to the species’ preference for warmer conditions. However, a major population bloom occurred off southwest UK in 2025, comparable to rare historical blooms recorded in 1899–1900, 1932–33 and 1950–51. The species’ rapid growth, high fecundity and short lifespan make its populations highly responsive to environmental conditions. Evidence from fisheries landings, scientific surveys and citizen science confirmed the bloom, with commercial fisheries landings of common octopus in 2025 being almost 65 times higher than recent annual averages. The 2025 bloom and all previous blooms were strongly associated with unusually warm sea and air temperatures, conditions that likely enhanced breeding success, juvenile survival and growth. Observations of lower salinity and ocean current modelling suggests larval transport from the Channel Islands and northern France may also have contributed to the current UK octopus bloom, particularly following a large bloom in Guernsey in 2024. The bloom has had mixed impacts on the UK fishing industry. Predation by octopus appears to have significantly reduced catches of brown crabs, European lobsters and king scallops, with many fishermen reporting negative economic effects, although some temporarily benefited by targeting octopus. Concerns remain about long-term impacts on shellfish stocks. Given increasing ocean warming linked to climate change, future octopus blooms are considered likely. The report recommends expanded monitoring, predictive modelling, improved data collection from fishermen, and research into ecological, economic and social impacts to support fisheries adaptation.
Publication Date
2026-01-27
Publisher
The Marine Biological Association
Deposit Date
2026-02-09
Additional Links
https://plymsea.ac.uk/id/eprint/10535/, https://plymsea.ac.uk/
Keywords
Fisheries, Fishing industry, Shellfish, Crabs, Lobsters, Scallops, Predation, Climate change, Larval dispersal
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License
Recommended Citation
Stewart, B., Thomas, S., Smyth, T., James, M., Sullivan, E., Hall, A., Osmond, T., & Sheehan, E. (2026) 'Common octopus (Octopus vulgaris) blooms off the Southwest of the UK: History, trends, causes and consequences.: Report on Work Package 1: History, causes and consequences of octopus blooms', The Marine Biological Association: Retrieved from https://pearl.plymouth.ac.uk/bms-research/2303
