According to the DIVE magazine Cranfield University and the Marine Biological Association of the UK demonstrated that small-spotted catsharks possess impressively quick learning ability. They were also able to determine that the sharks possess a memory of between a day and a few weeks; significantly more than the 7-seconds that is, often incorrectly, associated with fish.
Sharks use a sense called electroreception to detect bio-electric fields emitted by their prey. The researchers recreated these electric fields to measure and analyse the behavioural response of the sharks, using experimental manipulation and food rewards. The rewarded sharks showed an impressive learned response of finding and biting the source of the electric fields significantly more quickly and intensely than their unrewarded counterparts. They would, however, forget these learned adaptations, after three weeks when experiments were repeated.
It is thought these skills are adaptive and are ideally suited to a predator living in a complex, variable and unpredictable environment allowing them to adapt behaviour, ultimately improving their feeding efficiency. Certainly there can be differences between the capabilities of the different shark species, but it seems we should treat these animals as intelligent predators. Sadly they aren't smart enough to escape from fishing nets, even the small-spotted catsharks are often caught, and some of the largers shark species are threatened.