The UN Environmental Programme has released a report stating that climate change is emerging as the latest threat to the world''s dwindling fish stocks.
The report 'In Dead Water' suggests that at least three quarters of the globe's key fishing grounds may become seriously impacted by changes in circulation as a result of the ocean's natural pumping systems fading and falling.
These natural pumps, dotted at sites across the world, including the Arctic and the Mediterranean, bring nutrients to fisheries and keep them healthy by flushing out wastes and pollution.
The report also states that the impacts of rising emissions on the marine world are unlikely to end there. Higher sea surface temperatures over the coming decades threaten to bleach and kill up to 80 per cent of the globe's coral reefs, natural sea defences and also nurseries for fish.
Meanwhile there is growing concern that carbon dioxide emissions will increase the acidity of seas and oceans. This in turn may impact calcium and shell-forming marine life including corals, but also tiny ones such as planktonic organisms at the base of the food chain.
"The worst concentration of cumulative impacts of climate change with existing pressures of over-harvest, bottom trawling, invasive species infestations, coastal development and pollution appear to be concentrated in 10-15 per cent of the oceans," says the report.
This 10-15 per cent of the oceans is far higher than had previously been supposed and is "concurrent with today's most important fishing grounds" including the estimated 7.5 per cent deemed to be the most economically valuable fishing areas of the world, it adds.
Other key findings of the report include:
• Half the world's catch is caught along Continental shelves in an area of less than 7.5 per cent of the globe's seas and oceans.
• An area of 10-15 per cent of the world's seas and oceans cover most of the commercial fishing grounds.
• 80 per cent to 100 per cent of the world's coral reefs may suffer annual bleaching events by 2080 under global warming scenarios.
• Those at particular risk are in the Western Pacific; the Indian Ocean; the Persian Gulf; the Middle East and in the Caribbean.
• Over 90 per cent of the world's temperate and tropical coasts will be heavily impacted by 2050. Over 80 per cent of marine pollution comes from the land. Marine areas at particular risk of increased pollution are Southeast and East Asia.
• Up to 80 per cent of the world's primary fish catch species are exploited beyond or close to their harvesting capacity. Advances in technology, alongside subsidies, means the world's fishing capacity is 2.5 times bigger that that needed to sustainably harvest fisheries.
• Bottom trawling is among the most damaging and unsustainable fishing practices at the scales often seen today.
• Alien invasive species, which can out-compete and dislodge native ones, are increasingly associated with the polluted, over-harvested and damaged fishing grounds. The report shows that the concentration of 'aliens' matches with some precision the world's major shipping routes.
