GROWING NUMBERS OF BLUEFIN TUNA

Growing numbers of bluefin tuna appearing in UK waters – Increasing numbers of bluefin tuna are now appearing in UK waters because of the warming impact of a long term ocean current, according to researchers.

Scientists say that their recent rise is connected to the Atlantic Multidecadal Oscillation (AMO), according to a report today by the BBC.
Now in a warm phase, the current makes UK waters more hospitable for the species.

The scientist report is published in the journal Science Advances. The team looked at the changing abundance and distribution of bluefin tuna in the Atlantic over the past 200 years.

They’ve concluded that the major factor influencing the movement of bluefin is the AMO.

“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,” said lead author Dr Robin Falllettaz from the University of Lille.

He believes that while current numbers of sightings of the UK may indicate that the species is doing well, this may not be the case everywhere.
“When water temperature increases during a positive AMO, bluefin tuna move further north. However, the most positive (warming) phases of the AMO also have a detrimental effect upon recruitment in the Mediterranean, which is currently the most important spawning ground, and that will affect adult abundance a few years later.”

“If the AMO stays in a highly positive phase for several years, we may encounter more bluefin tuna in our waters but the overall population could actually be decreasing.”