Unfortunately, the way in which dolphins have adapted to survive in the cold sea has made them a very sought after meal for other creatures living in the same environment. Dolphins have a very high fat content which makes them an excellent source of calories for those living in the harsh conditions of a maritime habitat. This is, of course, if you can succeed in catching a dolphin, which isn’t the easiest of tasks for any sea creature and is the main reason why dolphins don’t have that many natural predators.
Dolphins are only really naturally threatened by sharks, and it is only the larger species of shark which stand any chance in succeeding to attack one. Researchers have found dolphin remains in the stomachs of killer whales, but this doesn’t necessarily mean that the killer whales were responsible for hunting fellow dolphin species. It could just be that they capitalized on the hunting methods of another predator and chose to reap the rewards of a different animal’s efforts. There is no other evidence to suggest that killer whales gang up on other pods of dolphins to attack them.
Today, the main real enemy of the dolphin is the human. Although there are very few cultures which would kill dolphins to eat them in modern society, unsustainable fishing methods often kill dolphins accidentally as collateral damage. Dolphins can get caught up in trawling nets even if they were not the fishermen’s primary target. The tuna fishing industry is one which regularly takes dolphins as unwitting victims. The nets are incredibly strong to withstand the movement of thousands of fish which means that once a dolphin gets caught up in one, they stand no chance of escaping. It is a common occurrence because dolphins will often be feeding from the same groups of fish which are being targeted by human fishermen.
Sometimes dolphins are specifically targeted to be killed for this exact reason. The dolphins threaten the fish stocks which are some people’s only source of food or income. Some fisherman cannot afford for this to happen and so have been known to target and kill whole pods of dolphins to stop them from depleting their fishing stock.
There are some cultures in which dolphin meat is seen as a delicacy. In Japan, sushi restaurants sell dolphin meat for a small fortune and in other areas of the world where other species are running out, dolphin is replacing staple fish stocks in markets.