Last year, roughly 1 of every 6 fish sold around the world was caught illegally.

That number is now poised to drop precipitously, thanks to the Port State Measures Agreement, the world’s first international treaty designed specifically to tackle illegal, unreported and unregulated fishing.

Under this new agreement, parties are obliged to ensure that any fishing vessel that comes to its port, even for refueling, must announce that it is doing so and submit to an inspection of their log book, licenses, fishing gear and, to be sure, their actual cargo. Port State authorities agree to share information on violations, thus making it harder for rogue fishermen to shift their practices elsewhere.

The treaty, which was adopted by members of the U.N. Food and Agriculture Organization in 2009, marks a big step beyond self-regulation of the seafood sector, from which illicit activity siphons off up to $23 billion a year.

More than 30 countries plus the European Union have formally deposited their instruments of adherence with the FAO, the treaty has now entered into force and a new era has begun.

Those who fish illegally -- who not only profit but also jeopardize coordinated efforts to manage global marine resources in a sustainable manner so that fishing can prosper as a viable activity and people everywhere can enjoy its nutritional benefits -- face higher operating costs and the serious risk of being caught.

To be sure, the treaty today applies only to those countries which gave the required consent. To give the treaty more traction, and accelerate both its effectiveness and impact, more countries must join. As they do, there will be ever fewer port-hopping opportunities for rogue vessels determined to flaunt laws that regulate catch levels, usually to protect biodiversity and stock levels.

But have no doubts. History’s net has been cast. Membership is destined to grow.

I offer my congratulations to the Republic of Korea and the other countries that are already parties to the treaty:

Australia, Barbados, Cabo Verde, Chile, Costa Rica, Cuba, Dominica, the European Union (on behalf of its member states), Gabon, Grenada, Guinea, Guyana, Iceland, Indonesia, Mauritius, Mozambique, Myanmar, New Zealand, Norway, Oman, Palau, Saint Kitts and Nevis, Saint Vincent and the Grenadines, Seychelles, Somalia, South Africa, Sri Lanka, Sudan, Thailand, Tonga, United States of America, Uruguay, Vanuatu.

The agreement makes it harder for improperly caught fish to enter the market, disrupting a critical step in seafood’s complex ocean-to-table supply chain.

Some ships may choose to travel further, already a costly decision and disincentive. Moreover, ports that offer services to such outlaws will not escape notice. Parties to the PSMA will fund capacity-building measures for countries that need it -- and the FAO is offering technical and legal assistance -- and tolerance of rogue behavior will likely increase the burden of eventual compliance.

And let there be no doubt: Compliance is eventually inevitable. Players in the global fish industry are increasingly exploiting their sustainable practices as a marketing asset and catch documentation and eco-labelling schemes gather steam. Adhering to the treaty may enhance a country’s trade opportunities.

As a turning point in the struggle against illegality in the fisheries sector, the PSMA is a concrete step towards healthier oceans, as called for by Goal 14 of the new Agenda 2030 for Sustainable Development.

At the FAO, we emphasize how sustainable development requires an integrated effort and relies on network effects - which in turn can catalyze positive feedback loops. The requisite port state inspections, for example, may indirectly complement other global concerns, including the use of slave labor in fishing-industry, illicit trade in endangered species and better management of Marine Protected Areas.

By Jose Graziano da Silva

Jose Graziano da Silva is the director-general at the Food and Agriculture Organization of the United Nations. -- Ed.