January
7, 2019, Secchi Disk Foundation
Bluefin
tuna are back in the sea around the U.K. after decades of absence and a new
study says that warming seas can explain why. Bluefin tuna are one of the
biggest, most valuable and most endangered fish in the oceans. Sportfishermen
excited at the prospect of catching a fish that can grow to over 900 kg have
already launched a U.K. campaign to allow recreational fishing for one of game
fishing's top targets. But should we catch and exploit this endangered species
or should we make U.K. waters a safe space for this species? Why has this
endangered fish suddenly returned to the U.K. after an absence of nearly 40
years? And are bluefin tuna now more abundant, or have they just changed in
their distribution?
New
research by Dr. Robin Faillettaz from the University of Lille (France), his
French co-workers Drs Gregory Beaugrand and Eric Goberville, and Dr. Richard
Kirby from the U.K. report that warmer seas can explain the reappearance of
tuna around the U.K. Their research shows that the disappearance and
reappearance of bluefin tuna in
European waters can be explained by hydroclimatic variability due to the
Atlantic Multidecadal Oscillation (AMO), a northern hemisphere climatic
oscillation that increases the sea temperature in its positive phase, as it is
now.
To reach
their conclusion, the scientists examined the changing abundance and
distribution of bluefin tuna in the Atlantic Ocean over the last 200 years.
They combined two modeling approaches, focusing on the intensity of the catches
over time and on the distribution of the fish's occurrence, i.e., when it was
observed or caught. Their results are unequivocal: The AMO is the major driver
influencing both the abundance and the distribution of the bluefin tuna.
Dr.
Faillettaz says, "The ecological effects of the AMO have long been
overlooked, and our results represent a breakthrough in understanding the
history of bluefin tuna in the North Atlantic."
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