What effect has global warming had on shark populations?

I can only speculate but I wouldn't imagine global warming would have had much of an impact on global shark populations to date. Water takes a lot of energy to heat up and changes to global oceanic temperatures are less noticable than atmospheric temperatures. Sharks are cold-blooded so changes in the oceans' temperatures could potentially affect their metabolisms but I would suspect sharks would simply migrate to a more suitable area if one location became unfavourable. Most of the effects of global warming on oceanic ecosystems is through increased concentrations of CO2 in the water which can reduce the ability of invertebrate, such as corals and shellfish, to produce shells made from calcium carbonate. The main threat to shark populations is overharvesting by humans. I heard a statistic a few years ago (so don't know how correct it still is) that shark populations in the Mediterranean were ~3% of their historical size due to overfishing. I'm confident any impact of global warming is fairly irrelevant to the killing of sharks for foods such as shark fin soup.