Climate impacts on albacore and bluefin tunas migrations phenology and spatial distribution

North Atlantic albacore and eastern Atlantic bluefin tunas perform feeding migrations to productive areas of the northeast Atlantic Ocean during the summer. Climate change is likely to influence the timing and even the spatial distribution of albacore and bluefin tunas during this event. Thus, tuna catches during their feeding migration to the Bay of Biscay have been analyzed from 1967 to 2005 for albacore tuna and from 1981 to 2005 for bluefin tuna. The results indicate that tuna arrive now earlier to the Bay of Biscay, with albacore tuna arriving about 8 days earlier than 40 years ago and bluefin tuna arriving 14 days earlier than 25 years ago. This represents a rate of change of 2 and 5.6 days per decade, respectively. Besides, albacore tuna mean catch latitude showed an increasing trend over time. Statistical analyses provided the first evidence of the North Atlantic regime shift, as well as climate variability, influencing changes in migration phenology and spatial distribution of albacore and bluefin tunas.