It has been recently brought to attention that the observed behaviors of sharks around the world has drastically changed. While scientists and researchers have not narrowed the reason of these behavioral changes to one specific cause, many theories have been explored in attempts to explain and further understand them.
It has gotten to a point where the increasing aggressiveness of great whites led to the call to ban cage diving in the New Zealand Ocean. While it is not advantageous to get in the water with knowledge that predators are more aggressive than ever, cage diving might be actually contributing to the increased number of shark encounters. Through chumming, a technique used to attract and lure sharks close to the cages by dispensing blood and fish parts into the water, sharks may be starting to recognize that where there is human, there is food. People have always been told to not feed wild animals, especially predators, because sooner or later it will condition them to associate humans with food, and that might be exactly what is going on with the sharks recently.
There is also a possibility that sharks are not necessarily targeting humans on purpose when feeding. Commonly known, sharks are not man-eaters, and shark attacks are mostly the unfortunate consequence of humans being mistaken for their natural prey. As the severity of climate change escalates, ocean temperatures increase while its ph decreases. These changes in the ocean are proved to be causing a decrease in the efficiency and ability of sharks’ hunting. Going hand in hand with ocean acidification, the abundance of carbon dioxide found in the water decreases the ability of sharks when it comes to locating prey by slightly handicapping their olfactory sense.
Sharks being blinded, in a sense, by ocean acidification helps explain why the number of shark attacks on humans has increased lately. With their predominant hunting sense hindered, attacking humans instead of fish or seals becomes more likely thus resulting in a perceived increase in aggressiveness towards humans. Not meant to discredit the theory of sharks becoming collectively more aggressive, the higher counts of shark attacks could be the outcome of both associating humans with food and the impairment of their olfactory system.
Along with the changing of hunting behavior seen in sharks, their migratory patterns are also exhibiting a change. Scientists speculate that this can also be a result of climate change and how it affects the oceans. There are three main and overall reasons behind migration of sharks: temperature, food, and reproduction.
Since most sharks are cold-blooded, they rely on warm and tropical waters in order to maintain a healthy metabolic rate, meaning that they migrate to warmer waters during the colder seasons. Consequently, food and reproduction-directed migration also rely on the temperature of the water. For example, some sharks migrate to places where tuna or other species of fish are going to, and those fish that are soon to be prey are migrating due to changes in water temperature. Similarly, sharks sense when it is time to breed by a change in the water temperature.
There is also the idea that sharks are migrating differently because of over-exploitation of the ocean. Illegal fishing and too many nets being cast out are extremely harmful to marine biodiversity and could be causing dramatic decreases in specific fish populations. Due to fewer food supplies, sharks are migrating to places that they usually do not go to, or are moving to certain areas during different seasons than before. This lack of food could also help explain why there have been more shark attacks.
In response to all of these changes in shark behavior, a lot of people are trying to advocate for a population control by mass killing sharks. Of course, this is not the acceptable approach to this, but instead, further studies and researches need to be conducted in order to accurately define what the causes of these behavioral changes are. Upon finding what is triggering these abnormal behaviors, the human population will be able to minimize the stimuli leading to such changes. In the mean time, it would be wise to take precautionary measures and fight global warming in order to prevent further rising in temperature and acidity in the oceans.
