Protected areas in high seas help fish grow bigger: Study

Older, larger fish lay more eggs, help replenish populations amid overfishing, climate change

- Audrey Tan

Horse-eye jack spotted by underwater cameras. The study's findings point to how the recovery of the world's largest and most endangered fish in pelagic systems requires the creation of highly protected areas in remote locations, including in the high seas. This requires international cooperation, like through the High Seas Treaty, which will come into force after it is formally adopted, signed and ratified by enough countries. 

They may not be as colourful as a coral reef or come to mind as easily as a mangrove, but the remote high seas also play a critical role in safeguarding marine biodiversity - and ensuring humans continue to have seafood on their plates.

A new study has found that establishing no-fishing zones far from densely populated cities - including in international waters can provide open water fish, such as tuna and sardines, with a safe haven to grow older and larger.

The presence of such older, larger fish can help to replenish fished populations and safeguard stocks in the face of overfishing and climate change, said the authors of the study, published on Feb 29 in journal Science.

"Bigger fish lay more eggs. A single 10kg fish lays more eggs than 10 individual fish weighing 1kg each," said the lead author of the study, Dr Tom Letessier from the Zoological Society of London.

Open water species researchers found included shark species. More than 800,000 sea creatures were caught on tape. PHOTO: MANU SAN FELIX

"This means that it's the big old females that are most important in terms of reproductive output, and safeguards should be put in place for protecting those individuals in a population," he told The Straits Times.