The Prince of Wales has warned of the "dire social and economic consequences" of failing to manage the world's fish stocks sustainably.
Charles, known as the Duke of Rothesay in Scotland, spoke of the need to improve knowledge of marine ecosystems as he addressed the sixth World Fisheries Congress in Edinburgh on Tuesday.
He established the International Sustainability Unit (ISU) to build consensus on how to resolve some of the key environmental challenges facing the world.
The ISU's marine programme has looked at ways to manage fish stocks more sustainably to ensure there are more fish, more jobs and better economic returns.
Charles told an audience at Edinburgh International Conference Centre that there was a "direct link" between the health of ecosystems and food security.
He said: "It is a serious social and economic issue. If fish stocks fail, then the social and economic consequences will be dire. Just think of all those thousands of coastal communities in Africa and around the world whose livelihoods and futures depend on fish. Where will they go? What will they do?"
Charles said there was a disparity between how much was known and how much should be known about the state of fish stocks.
He said: "I am no expert, but it does seem to me that, under these circumstances, our chances of keeping stocks healthy, and oceans thriving so they can continue to maintain food security, are going to be severely compromised unless we dramatically - and I would suggest, rather urgently - improve our knowledge."
Charles went on to warn that even the British tradition of fish and chips could disappear unless action is taken.
He said: "I remember one occasion buying fish and chips from a shop in Inverness. It never occurred to me then that I was eating food that had such a reliance on how we treat a wild natural resource."
The World Council of Fisheries aims to encourage and promote sustainable management practices, excellence in fisheries research and the wise use of fishery resources.
The congress is held every four years, with the last one taking place in Yokohama in Japan in 2008.
Charles, who arrived in Edinburgh by train, was greeted by the Scottish Government's Environment Secretary Richard Lochhead as he arrived at the conference centre.
Following his speech, the Prince visited Marine Scotland's research vessel Scotia in Leith harbour. He viewed the facilities on board and met fish and chip fryers and representatives from leading fish wholesale companies.
Speaking at the conference, he said he was "delighted that some pioneering fish and chip shop owners are making the connection" between how fish was harvested and how much would be left in the ocean to catch next time.
He said: "The simple fact is that fish and chip shops rely on there being plenty more fish in the sea, and that is only going to be the case if we take care of fish stocks now and plan for them to be there long into the future.
"If their businesses are to remain viable in the long-term, fisheries management, accompanied by sound science, really matters to them too."