Catch and release sportfishing will kill endangered bluefin tuna


If you go to the UK coast and look out to sea you may be lucky and spot one of the world’s largest and most spectacular fish. The remarkable bluefin tuna has returned to UK coastal waters after an absence of over half a century and they can once again be seen leaping from the water as they chase schools of fish at the surface. Tourists are already enjoying this unique spectacle on eco-safaris in Cornish waters.

Surfer watches a giant bluefin tuna leaping out of the water at Watergate Bay in Newquay. Credit: Megan Hemsworth.

Bluefin tuna are classed as charismatic megafauna but unfortunately they are also one of the world’s most exploited fish species. From the 1960s until the mid-2000s Atlantic bluefin tuna populations were in decline and as a result are now an IUCN Red List endangered species.

Following the establishment of drastic management measures, the North Atlantic stock has started to recover recently and, as a result, stakeholders have raised catch quotas by fifty-percent for the period 2017–2020. However, stock assessments still omit the natural, long-term variability in the species distribution.

An international group of UK and French scientists recently showed that the return of bluefin tuna to UK waters is a result of a warming climate due to the influence of the current positive phase of the Atlantic Multidecadal Oscillation (AMO). The scientists showed that a cyclical switch between negative (cool) and positive (warm) phases of the AMO over the last 400 years (the period for which records were available) had a major influence on bluefin tuna distribution to create a seesaw like northerly (warm phase) and southerly (cool phase) movement of bluefin tuna in the North Atlantic.

The scientists study provided a new insight into both the dramatic and sudden collapse of the Nordic bluefin tuna fishery circa 1963 and the recent increase in bluefin tuna abundance in the Northeast Atlantic. Their results demonstrated how climatic variability could alter the distribution of a large migrating species to generate rapid changes in its regional abundance. They concluded by arguing that climatic variability must not be overlooked in stock management plans for effective conservation.

Inevitably, the climate-induced reappearance of bluefin tuna in UK waters after such a long absence has sparked considerable interest, not least among British recreational anglers eager to fight and dominate one of the oceans largest and most powerful fishes.

Unfortunately however, the physiology of bluefin tuna is unsuited to a long fight on the end of a line and so all recreational fishing has an associated death toll. When hooked, the considerable size and power of bluefin tuna means a long and arduous fight ensues and inevitably, some don’t survive the struggle.

Bluefin tuna unlike other fish can raise and maintain their body temperature (almost ‘warm-blooded’) and this is what enables them to exploit colder waters, but this physiology also means that if they are forced to exert themselves for an extended length of time they can ‘cook’ themselves to death.

Although anglers that wish to create a recreational fishery will cite only low mortality rates of <5% for catch and release fishing, such low figures are for optimal conditions and catch and release has been shown to exert considerable mortality levels. Studies of the southern bluefin tuna recreational fishery have shown that recreational catch and release mortality rates can vary between 17% and 40% depending upon the tackle used.

If bluefin tuna were an endangered land animal we would not even consider catching and releasing them for fun if some would go on to die. Imagine going on safari and for every 100 rhinos photographed, one died as a result. Would we still photograph rhinos? Of course we wouldn’t.

Bluefin Tuna breach in Mount's Bay Cornwall. Credit: Marine Discovery 

Should we not rather just be delighted bluefin tuna have returned to our waters and take the opportunity to watch them in their habitat rather than harm them for our own fun?

There is a considerable economic opportunity for eco-safaris to benefit from the spectacle of bluefin tuna, and this harmless activity has untapped potential for tourist revenue equal or greater than recreational fishing could achieve and no endangered bluefin tuna need die. We have dramatic coastlines and good wildlife; entrepreneurs could create eco-safaris like those seen in some southern hemisphere countries, safaris like those run by Pennicott Wilderness Cruises in Tasmania that not only thrill but also inspire people about the marine world.

In the last weeks, lobbying for a recreational fishery has gathered pace.

However, it should be pointed out that we have no existing fishery and so, there are no current jobs at risk and a catch and release recreational fishery is purely an opportunistic activity that will introduce a new level of mortality upon a fish that is already endangered.

The Angling Trust is among those lobbying for a revival of recreational bluefin tuna fishing. We should be careful that the loudest voices or rather, all the information, shouldn’t just come from vested interests such as the angling community.

While the Angling trust describes in their press release why bluefin tuna have returned to UK waters their article also reveals why we should be cautious in their exploitation. They say: “Those long term climatic cycles have since around 2000 been shifting back into a ‘warm phase’, and PERHAPS aided by a marked recovery in stocks over the last ten years, Atlantic bluefin are once again regular seasonal visitors to the waters of the far NE Atlantic, including the UK.”

The key word is ‘perhaps’. Any mortality as a result of the new addition of recreational angling in UK waters will put additional pressure on the stock unless mortality is eased elsewhere.

Indeed, climate-induced range changes may require a new look by ICCAT at quota allocation across the geographical distribution of Atlantic bluefin tuna, before additional quota is allocated, i.e. a redistribution of quota in light of range changes rather than additional quota in new areas.

While some scientists advocate for recreational angling of bluefin tuna, they are usually associated intimately with a requirement for anglers to assist them in procuring fish for research involving scientific tagging to study migration patterns etc. While that research is valid, it shouldn’t be used as a trojan horse for an expanded bluefin tuna recreational fishery. For example, in the Bahamas the recreational fishery catch now exceeds the commercial catch.

Now that bluefin tuna have returned to UK waters we should question why our attitude towards endangered wild marine animals is so different to endangered wild land animals. We should leave recreational fishing for bluefin tuna as an archaic pastime of yesteryear rather than renew an activity that will inevitably cause harm and death to this remarkable and endangered species.

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Blue Planet Society is a global pressure group campaigning to protect the world’s ocean. By utilising effective activism, minimising the use of resources and applying the highest ethical standards, we believe our approach is the future of marine conservation advocacy.