Canada, with over five million square kilometres of ocean area, is one of the countries to put forward a new ocean action agenda on Wednesday.

Boris Worm of Dalhousie University - who has also been a diver for decades - says the seahorses, spotfin butterfly fish and bluespotted cornetfish would once have been considered a rarity in Nova Scotia.

Though adult members of the critically endangered species can be as long as a city bus, their movements remain difficult to track.

The big problem with plastic bags is that they never go away.

Researchers using surveillance technology that can peer down on vessels from space have for the first time shed light on the extent and locations of transshipments, an innovation going back to the 1960s that has also been linked to illegal fishing, drug smuggling and human rights abuses.