Global heating is warming waters, changing salmon and tuna migration – and hurting fisheries

There is little at Shiogama seafood market to suggest that Japanese consumers could one day be deprived of their favourite seafood – from giant crab’s legs simmering in a winter nabe hotpot to spheres of salmon roe resting on a bed of rice wrapped in nori seaweed.

Stalls heave with huge sides of bluefin tuna, expertly transformed into more manageable portions by knife-wielding workers, while early-morning shoppers pause to inspect boxes of squid, flounder and sea pineapples landed only hours earlier.