Yup--nice data set. Unfortunately, the data they report from is from items such as "nettings", "tournament catches", etc. In other words, the data collection was not intended to address the primary endpoint of the study. In the medical world, this is what is known as "observational", and has little correlation to the primary endpoint. In other words, you are studying headaches, for instance, and you happen to notice some patients had waxy ears. Yes, ears are on the head, and waxy ears may be set a patient up for headaches, etc, but it is not directly related to what endpoint you are looking for. All I know is this--my good friend is a marine scientist here in northern New England--he and his crew, when out in his boat, see great whites in all 4 seasons of the year. Now that in itself is "anecdotal". Bottom line is this: nobody really knows yet, although studies such as the one you posted are circling around the answer and we will know sooner or later. Right now, based on other biological species, sharks do migrate south to release pups--that much we know. Females give birth (hahahaha) not males; the males whereabouts are still unknown. Thanks for posting that--it was interesting.
