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 average fishing pressure from 2015-2017 is 42.6% of the target level, indicating that overfishing is not taking place. ![]() ![]() Fishing pressure appears to be clearly 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. ![]() Nonetheless, compared to 2017, the extra data now available confirm a recent stock biomass increase, although the magnitude of the increase remains difficult to quantify. A new stock assessment was produced in 2020 but depends on recruitment estimates, which are highly unstable, and is also closely related to assumptions made about stock structure and migratory behaviour, which are poorly known. 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. 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 10,00 tonnes. Spawning occurs from April to June in the Gulf of Mexico and June to August in the Mediterranean.Ītlantic bluefin tuna are assessed and managed by the International Commission for the Conservation of Atlantic Tunas (ICCAT). 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. 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). Interestingly, life history characteristics differ greatly between them. Despite poorly understood movements from east to west, a distinction in populations is made between the two regions. historical ranges concluded that Atlantic bluefin tuna has shown range contractions of 46% since 1960 - more than any other pelagic species. Despite this thermal tolerance, a recent analysis of present vs. 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. They are large, oceanic fish and are seasonally migratory, some making trans-oceanic journeys. Tuna belong to the mackerel family, Scombridae. In 2021, 1.3 tonnes of Atlantic Bluefin tuna was landed to Cornish ports with a value of over £4000. 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. Fish have to be carefully handled and released alive and it is illegal for tuna to be retained and landed by anglers. ![]() A sport fishing Catch and Release programme has been established but anglers have to be licenced to target blue fin tuna. Bluefin tuna are known to be accidentally caught in fishermen’s nets particularly when ring netting for sardines. From 2021 the UK government allowed commercial fishermen who accidentally catch bluefin tuna to land one fish per day per boat and they can be sold for human consumption. Bluefin tuna appear in Cornish waters in mid-summer and are seen well into autumn. 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. 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. Thanks to improved international management stocks appear to have started to recover. 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.
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