Sixty-one of the world’s 64 Large Marine Ecosystems (LME) show a significant increase in surface temperature, a new UN report says. LMEs with the sharpest increase included the Baltic Sea, the North Sea and the Mediterranean.
The change in surface temperature had led to smaller catches in some fisheries, and bigger in some other, according to the report from the United Nations Environment Programme (UNEP).
LMEs are large coastal ocean waters adjacent to continents. “The large majority of these ecosystems are shared by two or more countries, underscoring the need for regional cooperation to advance sustainable management,” said Dr. Kenneth Sherman, director of the National Oceanographic and Atmospheric Administration’s (NOAA) Large Marine Ecosystem program.
The NOAA, an agency in the US Department of Commerce, was a key contributor to the study.
“The added stress of increasing sea surface temperatures makes it that much more important that nations cooperate to sustainably manage large marine ecosystems, the areas where most marine fisheries are produced and caught”, ha added.
The temperature changes were measured over the last 25 years. Warming waters have brought about an increase in zooplankton, a vital fish food, and catches have been growing in several northern Atlantic LMEs, including the Norwegian Sea, the Faroe Plateau and the Iceland Shelf. Catches are declining, however, in several other European LMEs, including the North Sea, the Celtic Biscay Shelf and along the Iberian Coast, the report showed.
It also showed that 70 per cent of global fish stocks within LMEs are overexploited, reducing the availability of fish for food. This is especially critical in LMEs off the coasts of Africa, Asia and Latin America, where fish is a major protein source.
On another beat, the report highlighted a problem that has been much publicized around the Baltic in recent years: algae blooms. During the algal blooms, small plankton consume excessive amounts of available dissolved oxygen, sink to the bottom and deprive fish and shellfish of the oxygen they need to survive, beside the seasonal problem this causes for vacationers. The U.N. report said that an unprecedented volume of nitrogen effluent running into coastal waters is causing a greater frequency and extent of harmful algal blooms, oxygen depletion events and dead zones.
The effort to reverse the degraded status of LMEs “will take time, well-focused and creative policies, and funding,” said Achim Steiner, U.N. under-secretary general and executive director of UNEP.