If current trends continue, all the world's fish and seafood stocks are projected to collapse by 2048.

Credit: Amir Gur

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SYDNEY: All the world's fish and seafood species are projected to collapse by 2048, an international team of researchers has announced.

In a study published today in the U.S. journal Science, they reported that marine species are disappearing at an accelerating rate, posing a threat to future human health and well-being.

However they pointed out that evidence from protected marine areas suggested it is not too late to reverse trends and restore the valuable ecosystem services provided by the oceans.

The four-year study involved 14 ecologists, economists, and fisheries scientists in a working group at the National Centre for Ecological Analysis and Synthesis in Santa Barbara, California.

"We analysed all existing data on ocean species and ecosystems, synthesising historical, experimental, fisheries, and observational datasets to understand the importance of biodiversity at the global scale," explained co-author Heike Lotze, from Dalhousie University, Canada.

According to the researchers, the loss of marine biodiversity is increasingly impairing the ocean's capacity to provide food, maintain water quality, and recover from disturbances. In place of these essential services are increased harmful algal blooms, oxygen depletion, coastal flooding and species invasions.

However the researchers stressed that, "available data suggest that at this point, these trends are still reversible". The team reported that the restoration of biodiversity in 48 marine protected areas increased productivity fourfold and improved ecosystem stability.

The researchers said they believed that marine biodiversity can be restored "through sustainable fisheries management, pollution control, maintenance of essential habitats, and the creation of marine reserves".

Yet even as authorities act to protect some areas, others are coming under attack for the first time. Co-author Reg Watson from the University of British Columbia in Canada explains: "Now, especially in the southern oceans, there is almost a kind of desperation, as more and sometimes larger fishing vessels … try and find new resources in what is considered the last frontier."

Watson said we need collective action "to prevent the kind of disasters we have had in coastal waters from occurring on the high seas. It will take new levels of cooperation and innovative enforcement for this to succeed."

Apart from the range of ecosystem services our oceans provide, they are also our insurance against the uncertainties of climate change. As Watson put it, "with biodiversity there are new actors waiting in the wings - understudies for when things change.

"With the profound changes we are making to our environments these currently inconsequential organisms may be central to future food webs and indeed our welfare."

Far from seeing a conflict between conservation and long-term economic development, the researchers said they are complementary goals. According to Watson, the study demonstrates the economic value of the natural services our marine systems provide, and the high costs of inaction.