He was speaking at an event held to celebrate the world's first international treaty specifically aimed at tackling Illegal, Unreported and Unregulated (IUU) fishing.
The treaty requires foreign vessels to submit to inspections at any port of call and for port states to share information on violations. An improvement on prior rules requiring countries to control the activities of their own fishing fleets, the new agreement is designed to raise the cost of IUU fishing as it blocks improperly caught fish from being brought to land and entering markets.
The treaty went into force last month and more than 30 nations as well the European Union on behalf of its 28 members have acceded to the treaty. More countries have initiated the accession process.
However, Mr Graziano da Silva said implementation of the agreement may prove challenging for some nations, especially developing and small island states, due to resource and capacity constraints.
It is estimated that globally IUU fishing accounts for annual catches of up to 26 million tonnes, with a value of up to $23 billion. IUU not only jeopardises marine ecosystems but also threatens the livelihoods and food securities of millions of fishers around the world, Mr Graziano da Silva said.
"While the agreement constitutes a powerful and cost-effective tool, it cannot eliminate IUU fishing on its own," and must be flanked by other tools and efforts, Mr Graziano da Silva said.
