Atlantic bluefin Tuna, Thunnus thynnus is a giant of the fish world growing to a maximum size of 3meters and weighing up to 250 kilos. The largest species of tuna in the world these torpedo shaped fish are built for speed and power and travel huge distances in the open ocean. Unlike most fish they are warm blooded with heat generated in their powerful swimming muscles that enable them to accelerate rapidly, and gives them improved cognitive power and reactions. They are incredible top predators and are at the top of the oceanic food chain.
Atlantic bluefin tuna are a fast simming and wide ranging species that has always occasionally ventured into UK waters but they became an extremely rare sight through the latter half of the 20th century when this higly valuable species was fished near to extinction. Thanks to improved international management stocks appear to have recovered. Atlantic bluefin tuna began reappearing in UK coastal waters in 2014 and since then they have been regularly sighted in increasing numbers around the coasts of Cornwall, and further along the south coast into Devon and Dorset waters.
The return of this incredible species is most likely due to the increase in their prey in our waters, small pelagic fish such as sardines. Bluefin tuna appear in Cornish waters in mid-summer and are seen well into autumn.
From 2021 the UK government allowed commercial fishermen who accidentally catch bluefin tuna in trawls or ring nets to land one fish per day per boat and they can be sold for human consumption. In 2023 the MMO announced a limited hook and line fishery for bluefin tuna in UK waters. We hope that this newly opened fishery is well managed and rules are strictly enforced as this is a top predator that is very easily over fished and has only recently recovered from the brink of near extinction.
In 2022, 2 tonnes of Atlantic Bluefin tuna was landed to Cornish ports with a value of over £10,000.
During the first year of the new hook and line fishery, the allocated 39 tonnes was not caught, in part due to poor weather at the start of the season.
Updated January 2024
Cornwall
A commercial hook and line fishery for Atlantic bluefin tuna has been opened in 2023. This is limited trial commercial fishery and we plan to provide a rating for this in winter 2023/2024
Learn moreCornish Waters
Commercial fishers who accidentally catch Atlantic bluefin tuna are allowed to land one fish per boat per day under new rules from MMO 2021
Learn moreCornish waters
Commercial fishers who accidentally catch Atlantic bluefin tuna are allowed to land one fish per boat per day under new rules from MMO 2021
Learn moreCornish Waters
Commercial fishers who accidentally catch Atlantic bluefin tuna are allowed to land one fish per boat per day under new rules from MMO 2021
Learn moreCornwall Good Seafood Guide rates fish on sustainability using a scale of 1 to 5.
1, 2 and 3 are recommended, Fish to avoid are rated 5.
We use the system devised by the Marine Conservation Society (MCS) so our scores are comparable with the scores produced by MCS for the UK and fisheries from all around the world. For more information on scoring click here.
Tuna belong to the mackerel family, Scombridae. They are large, oceanic fish and are seasonally migratory, some making trans-oceanic journeys. Able to tolerate both warm and cool temperatures, bluefin tuna range throughout the entire north Atlantic and adjacent seas, (primarily the Mediterranean Sea) and can frequent depths to 1000m. Despite this thermal tolerance, a recent analysis of present vs. historical ranges concluded that Atlantic bluefin tuna has shown range contractions of 46% since 1960 - more than any other pelagic species . Despite poorly understood movements from east to west, a distinction in populations is made between the two regions. Interestingly, life history characteristics differ greatly between them. In the Mediterranean, bluefin tuna is assumed to mature at approximately 25 kg (age 4), whereas in the Gulf of Mexico in the West Atlantic, maturity occurs at approximately 145 kg (age 9). Northern bluefin grow slowly compared with other tunas and billfish but can reach more than 450cm in length and 680kg in weight with a maximum age of approximately 40 years. Spawning occurs from April to June in the Gulf of Mexico and June to August in the Mediterranean.
There are two stocks of Atlantic bluefin tuna: west Atlantic (western stock), and East Atlantic and Mediterranean (eastern stock). This rating is for the eastern stock. There has been a lot of uncertainty about the size and health of the Atlantic bluefin stock following their recent recovery. It is thought that the high levels of illegal, unregulated and unreported fishing (IUU) has dropped drastically, and the total catches now reflect the TACs that have been set. The recent stock assessment suggests we now have a better understanding of the stock status, which is not subject to overfishing, but the vulnerability of this species following their very recent recovery must be considered.
While it has recently improved, it is not clear whether it has reached sustainable levels. MCS considers there to be concern for the biomass, because it is recovering from an historically low level. The stock is not thought to be subject to overfishing, and so there is no concern for fishing pressure.
Atlantic bluefin tuna are assessed and managed by the International Commission for the Conservation of Atlantic Tunas (ICCAT). The eastern stock was heavily fished from the 1950s until 1996, after which, catch limits and a limit in the size of tuna that could be taken caused catches to drop from 60,000 tonnes to 10,000 tonnes. The stock declined from the 1970s until 1991, staying at a low level and coming close to stock collapse until it began to increase in the mid-2000s. A new stock assessment was produced in 2022/3, still with highly uncertain recruitment estimates, which are highly unstable, and with assumptions made about stock structure and migratory behaviour, which are poorly known. This assessment used three models, and their combined output indicated that the stock is not in an overfished state. Fishing pressure appears to be below the target level of F0.1, which is a proxy for FMSY, and has been set with the aim of maintaining the biomass at B0.1 (BMSY). The stock size is predicted to increase for the next two years (short-term projection) with current TACs. These conclusions must be taken with caution giving the uncertainty of the data.
The average fishing pressure from 2015-2017 is 42.6% of the target level, indicating that overfishing is not taking place. Given the levels of uncertainty, and that the stock is recovering from very low levels, MCS considers that there is still concern for the biomass. The stock is not thought to be subject to overfishing, and so there is no concern for fishing pressure.
Projections on the future of the stock could not be made owing to the uncertainty in the data. However, an analysis of the effect of the current and future catch limits (32,240t in 2019 and 36,000 t in 2020-2022) suggests that there is no cause to change them. The projections from the 2017 advice have been reiterated in the 2020 assessment: a constant catch of 36,000 tons from 2018 onwards would keep fishing pressure below the target level with a probability higher than 60% in 2021 and in 2022.
The introduction of fattening and farming activities into the Mediterranean in 1997 and good market conditions resulted in rapid changes in the Mediterranean fisheries for bluefin tuna, mainly due to increasing but unknown catches of juveniles going into farms. There have been considerable improvements in data quality and quantity over the past few years but important gaps remain in the temporal and spatial coverage for detailed size and catch-effort statistics for several fisheries, especially in the Mediterranean before the implementation of stereo video cameras in farms in 2014.
Since the 2006 Recovery Plan, ICCAT states that the fishing pressure on juvenile fish (ages 2-5), and on large fish (over 10 years in age) has declined. This is likely to have played a key part in their recovery.
It still remains unclear how much of the Eastern Atlantic stock mixes with and supports the Western Atlantic stock.
In 2021 the IUCN changed the status of Atlantic bluefin tuna from Critically endangered to Least concern. Read more here.
Bluefin tuna commercial trial fishery 2023 MMO
CHART - CEFAS Scientific Catch And Release sport fishery
IUCN Red List Atlantic bluefin tuna
MMO landings data to Cornish ports.
Cornwall Good Seafood Guide is underpinned by the Marine Conservation Society (MCS) Good Fish Guide. The first UK consumer guide to sustainable seafood. For more information visit www.fishonline.org