4 tuna species are showing signs of recovery. Here's what that tells us about the future of fisheries 

Four commercially-fished tuna species are on the path to recovery, according to the updated International Union for Conservation of Nature's (IUCN) Red List of Threatened Species.

Seven of the most commercially fished tuna species were assessed in the update, with four of them showing signs of recovery:

The IUCN explains that these recoveries are the result of greater enforcement of more sustainable fishing quotas and work to combat illegal fishing.

“These Red List assessments are proof that sustainable fisheries approaches work, with enormous long-term benefits for livelihoods and biodiversity. We need to continue enforcing sustainable fishing quotas and cracking down on illegal fishing,” said Dr Bruce B Collette, Chair of the IUCN SSC Tuna and Billfish Specialist Group. “Tuna species migrate across thousands of kilometres, so coordinating their management globally is also key.”

It's vital that all fisheries - not just tuna - are carefully managed, explains Gemma Parkes of the Friends of Ocean Action at the World Economic Forum. This management should be done in a consistent and precautionary way - and based on the best available scientific advice.

The IUCN's update is not all good news for tuna species, though. Although there are positive signs on a global level, there are regional disparities, with many stocks still severely depleted.

The larger, eastern population of Atlantic bluefin, which originates in the Mediterrean, has increased by at least 22% over the past four decades. But, the smaller, native western Atlantic population, which originates in the Gulf of Mexico, has declined by more than half in that period.

And the updated list showed bad news for other ocean species. More than a third of the world's shark and ray species are now threatened with extinction - with all these threatened species overfished. Many are also affected by loss and degradation of habitat and climate change.

But, as Dr Bruno Oberle, IUCN Director General, explains, "[The] IUCN Red List update is a powerful sign that, despite increasing pressures on our oceans, species can recover if states truly commit to sustainable practices."

Tackling the issue of overfishing and its impact on marine life, as well as other challenges like climate change, is a key part of the United Nations' Sustainable Development Goals (SDGs).

SDG 14 'Life Below Water' is focused on just this. Explanatory notes for the goal say that "careful management of this essential global resource is a key feature of a sustainable future". And target 14.4 focuses specifically on the need for effective regulation to end overfishing and for science-based management plans in order to restore fish stocks.

All of this matters because of the crucial role a healthy ocean plays - as a food source, for livelihoods and as a key weapon in the fight against climate change.

Because, as Peter Thomson, UN Special Envoy for the Ocean and Co-Chair of Friends of Ocean Action told the World Economic Forum in August, "you can't have a healthy planet without a healthy ocean".