Oceans losing oxygen at unprecedented rate, experts warn

Sharks, tuna, marlin and other large fish at risk from spread of 'dead zones', say scientists

Oxygen in the oceans is being lost at an unprecedented rate, with "dead zones" proliferating and hundreds more areas showing oxygen dangerously depleted, as a result of the climate emergency and intensive farming, experts have warned.

Sharks, tuna, marlin and other large fish species were at particular risk, scientists said, with many vital ecosystems in danger of collapse. Dead zones - where oxygen is effectively absent - have quadrupled in extent in the last half-century, and there are also at least 700 areas where oxygen is at dangerously low levels, up from 45 when research was undertaken in the 1960s.