Canadian scientists have devised a new scale for measuring ocean change – the fish. They have used the changing make-up of the global fisheries catch to detect the signature of global warming.
In a warming world, fish that find the sea temperatures too hot for comfort could move north or south, away from the tropics, or to deeper and therefore cooler waters.
Although oceans are warming, and the chemistry of the seas gradually changing, William Cheung and colleagues at the University of British Columbia report in Nature that it has not been easy so far to detect any evidence of change for these reasons: because over-exploitation of the traditional fishing grounds, and greater pressure on more distant and deeper waters, made it difficult to identify any climatic effect.