Sharks on the Move

Well maybe sharks should just stay home with their dying reefs then, right? It may not be the ideal habitat they've always known, but they can learn to tough it out? Well, sadly that may be wrong.

Photo Courtesy of CBS News

A recent study has shown that many sharks, including our Australian friend the black tip shark, are behavioral thermoregulators.5 This means that these sharks maintain their body temperature not by using internal processes such as sweating or shivering, like we humans do. No, behavioral thermoregulators maintain their internal body temperature by moving to ideal surroundings. They may depend upon certain temperatures to aid them in optimum efficiency in digesting their food or maintaining their metabolism levels. So, with the climate shifting, sharks may end up having to move to even exist.



Studies have shown that the rate of migration to more ideal climates may depend on several factors, including the species physiology.6 The more the temperature affects the internal workings of a creature, the more important it is for that creature to move when the climate changes. Sharks, as behavioral thermoregulators, are VERY dependent on the temperature. To add insult to injury the same paper states that creatures that need an ideal habitat, such as our sharks with their reefs, end up moving slower since it's harder for them to find a suitable new home. A shark's physiology says they should move quickly, but their need for reefs will not allow it. 

I know you may be saying something like "Hey, climates have been changing all along. They'll just adapt or something." While it is true that historically temperature changes do happen, it's also true that the speed of temperature change has been ramping up.7 This paper states that while species have been able to keep up with climate change and adapt so far, this sped up climate change may likely be enough to outpace evolution. To make it even worse, sharks are already having troubles adapting to changes as it is, since they can only give birth once every other year or so.