The first global treaty aimed at stamping out illegal fishing has come into force, making tighter controls at fishing ports central in efforts to detecting illegal fishing and stopping ill-caught fish from being offloaded and sold.

Illegal fishing is estimated to siphon up to $20bn annually from the global economy, damage marine habitats and make fishing harder for law-abiding fishing boats.

Seven years after it was first agreed, the treaty has now been ratified by 29 countries and the European Union.

"We hail those countries that have already signed on to the agreement and who will begin implementing it," the UN's Food and Agriculture Organisation Director General Graziano da Silva said in a statement.

"We invite governments who have yet to do so, to join the collective push to stamp out illegal fishing and safeguard the future of our ocean resources."

The treaty requires foreign fishing vessels to request permission in advance before visiting ports and forces them to provide detailed information on their identities, activities, and the fish they have onboard.

It also stops the ships from unloading their fish at ports where are no inspectors.

Not enough

Activists have welcomed the new treaty but say It doesn't go far enough.

"Alongside the better port controls the treaty will bring, many flag states need to get better at monitoring and controlling vessels that fly their flags and coastal states need more transparent and sustainable licensing regimes to control access to their waters," Max Schmid, deputy director of the Environmental Justice Foundation told Al Jazeera.

Under the treaty, ships suspected of being involved in illegal, unreported and unregulated fishing can be denied entry into ports.

Countries are also required to share information on these vessels globally.

"To help make the global seafood industry more transparent, there is also a need for a Global Record that would allow governments and industry to see the history of a vessel before they license it or source fish from it," says Schmid.

Insurance industry

Despite efforts by international watchdogs to name rogue fishing vessels, new research from the University of British Columbia has revealed that many of the ships are still able to get insurance.

"Restricting access to insurance could play a major role in ending illegal fishing, and right now, it's a largely overlooked method," said lead author Dana Miller.

Miller says insurance companies should be required to check lists of known illegal vessels before issuing insurance and that refusing it would have a significant impact on the number of illegal vessels.

These lists include vessels identified by regional fisheries organisations and those INTERPOL is seeking information on.

Activists say although significant port states such as the US, EU, South Korea and Thailand have signed the treaty, more nations need to do so.

"States that suffer from high levels of illegal, unreported and unregulated fishing in regions such as the West and Central Pacific Ocean, the Indian Ocean or Africa would greatly benefit from tighter controls over the activities of fishing fleets," Sebastian Losada, senior Ocean Political Adviser at Greenpeace International, told Al Jazeera.