An 8-billion-U.S. dollar investment annually in rebuilding and "greening" the world's fisheries could both increase fish catches and generate 1.7 trillion dollars in long-term economic returns over the next four decades, according to a new United Nations report whose preview version was released on Monday.

An influx to the fishing sector -- with funding being covered by scaling down or phasing out the nearly 30 billion dollars worth of subsidies in place currently -- is needed to curb the excess capacity of the world's fishing fleets while supporting workers in alternative livelihoods, UN officials said here.

Funding is also vital to reform the management of fisheries through such policies as setting up marine protected areas to allow depleted stocks to recover and to grow, said the Green Economy report in its preview version.

"Fisheries around the world are being plundered or exploited at unsustainable rates," said Achim Steiner, Executive Director of the UN Environment Program (UNEP). "It is a failure of management of what will prove to be monumental proportions unless addressed."

The choices governments make now and in the coming years regarding the fishing industry will impact more than half a billion people, he pointed out.

The final version of the report -- covering 11 sectors, including agriculture, waste and tourism -- will be issued later this year.

In a related development, a new UN-backed project will help strengthen Sierra Leone's fishing sector, which was destroyed by the decade-long, brutal civil war in the West African nation.

Currently, small-scale and subsistence fishing account for 85 percent of the fish landed in Sierra Leone, and the industry has great potential to generate jobs and enhance food security, according to the UN Industrial Development Organization (UNIDO).

"At present, there are two main constraints that are preventing the growth of the industrial fishing sector," said the agency's director-general, Kandeh K. Yumkella.

Firstly, he said, institutions supporting the industry have limited human resource capacity, especially at the middle and junior levels of management, and the second challenge is the lack of local skilled labor, resulting in the reliance on foreign workers.

Under a new scheme financed by Russia, UNIDO will set up a Fishery Training Institute, which seeks to help make the sector more commercial in Sierra Leone.

The agreement to set up the project was signed on Monday in Moscow, with Russia also committing 1.5 million U.S. dollars to improve water quality and reduce the negative impacts of industrial activities in the Volga River basin, as part of another UNIDO initiative, the officials added.