Endangered ocean species

I've been looking at ocean biodiversity. That's the diversity of species that live in the world's oceans. Biologists still don't know how serious the threat to their survival is for each individual species. So a body called the Global Marine Species Assessment is now creating a list of endangered species on land. So they consider things like the size of the population, how many members of one species there are in a particular place, and then they look at their distribution in geographical terms, although this is quite difficult when you look at fish, because they're so mobile. And then thirdly they calculate the rate at which the decline of the species is happening. So far only 1,500 species have been assessed, but they want to increase this figure to 20,000. For each one they assess, they use the data they collect on that species to produce a map showing its distribution. So finally, what can be done to retain the diversity of species in the world's oceans? Firstly, we need to set up more reserves in our oceans, places where marine species are protected. We have some, but not enough. In addition, to preserve species such as leatherback turtles, we need to create corridors for migration so they can get from one area to another safely.