September 21, 2021 — Fish can drown. They require oxygen to breathe, and use the oxygen dissolved in water rather than that in the air. When there’s too little oxygen in the water, they have to move or suffer ill effects.

Unfortunately, oxygen concentrations are dropping throughout the oceans. The new research, published in Global Change Biology, spans 15 years of surveys and measurements. The authors stress the importance of accounting for the findings in fishery management and conservation, or risk implementing strategies wildly out of step with conditions under the waves.

“This study finds that oxygen is declining at all the depths we surveyed: from 50 meters (164 feet) to 350 meters (1,148 feet),” says lead author Erin Meyer-Gutbrod, “and so fish seem to be moving up to shallower regions to get to an area where the oxygen is relatively higher.” Now an assistant professor at the University of South Carolina, Meyer-Gutbrod started this analysis as a postdoctoral scholar at the University of California, Santa Barbara.

Oxygen concentrations are decreasing for a number of reasons, including changes in ecology, seasons, and storms. But perhaps the most significant reason is that warmer water holds less dissolved oxygen.

Read the full story at Futurity