So how to do you find a fish in the middle of an ocean?
Just following this story through and, as usual, wondered how they knew the lat and long of the fish. If you follow a few leads you discover the page which says the fish are 'precisely located' (love that phrase, esp when you see what's coming next!)...
The tag's processors monitor sunrise and sunset and therefore noon and hence calculate longitude using the tag's internal clock ("very accurately" the article says). Latitude is a bit more tricky and is based on day length. So not the 'precise' levels of positioning that I'm used to - probably within the nearest mile? - but not bad for a fish.
It goes back to what you can do with the materials you have. I was talking with a director yesterday and said surely 'rough-and-ready' was better than nothing at all; as long as you knew how inaccurate the advice you were giving was. Given the choice between no position or an approximate one which would you take?