Why do sharks breach

Over millions of years, Great White Sharks have adapted their hunting techniques to include breaching as an effective means to hunt certain species of prey. Great White Sharks rely on stealth, camouflage and speed when hunting, and the breaching technique is most effective as it provides the Great White Sharks with an element of surprise as they explode from the water with explosive speed to capture their prey.

There are numerous different breaching techniques which Great White Sharks use while hunting for prey, but the 3 main breaching techniques which we will focus on include:. But why? This seems like an obvious point, but when you look closer at where attacks are taking place there are some clues as to what might be going on.

The large human populations along the southern coast of Australia and the eastern coast of the US mean large numbers of people enjoying the water. But southern Australia has also seen rising numbers of fur seals along its coastline, the favourite prey of great white sharks in the region. The resurgence in seal populations on Cape Cod on the east coast of the US has led to rising numbers of great white sharks in areas popular with people Credit: Getty Images. This has led to increased numbers of great whites in the area too during the warm summer months as they look to feast on the seals that pull themselves out to bask on the beaches.

Sadly, last autumn, Massachusetts suffered its first fatal shark attack in 82 years and growing numbers of shark sightings have led to a string of beach closures. But there is no real evidence that sharks are actively hunting humans, according to the scientists who study them. Great whites in the North Atlantic, for example, show seasonal movement patterns, migrating thousands of miles to warmer waters further south during the winter months.

Some mature adults will venture out into the open ocean for months at a time , covering tens of thousands of miles and diving to depths of 1,m as they seek prey. But despite being potentially such an easy meal, sharks are really not that interested in hunting humans.

I think if people knew how frequently they were in water with sharks, they would probably be surprised. However, Naylor believes that the official statistics on shark attacks are probably an underestimate. Most reports come from highly developed countries with large populations and highly active news media. Attacks on remote islands or in less developed communities probably go unreported.

Looking at the statistics for the number of shark attacks last year can reveal some fascinating trends. Just four of these were fatal according to the International Shark Attack File, although another database of shark attacks records seven deaths. So far in , there have been four fatal shark attacks. Tiger sharks are one of the three main species responsible for attacks on humans but much of the time they ignore people in the ocean Credit: Getty Images.

The reason for the fall — which bucks the overall trend of growing numbers of attacks — has been attributed to a sharp decline in the number of black-tipped sharks. These sharks account for many of the bites around the south-eastern US, migrating down the coast of Florida due to rising sea temperatures that have led their prey to become more dispersed. The findings highlight one of the key challenges in understanding why sharks bite humans.

There are dozens of different species responsible for bites , each with their own unique behaviour, hunting strategies, prey and preferred habitat — although in many cases the species can be misidentified or not identified at all.

The majority of unprovoked attacks on humans where a species is identified involve three large culprits: the great white, tiger and bull sharks. Great white sharks are considered to be the most dangerous species in the oceans today, but we still know very little about their life cycle and behaviour Credit: Getty Images. Bull sharks, for example, tend to hunt in shallow, murky water that will require them to rely less on vision and more upon their sense of smell and electroreception, which allows them to detect minute electrical fields produced by their prey.

There is also some evidence that shark teeth may also function as mechanosensory structures — similar to touch — to help the animals learn more about what they are biting. Chapman believes there may be a complex set of reasons for why unprovoked attacks on humans appear to have risen in recent decades. In , for example, there was a sudden spate of shark bites off the coast of Recife, Brazil — an area that had no unprovoked attacks for the entire previous decade.

Chapman believes that heavy commercial port construction in the area damaged large areas of reef and mangrove, potentially displacing species like bull sharks , which moved to new areas like Recife in search of prey. Bull sharks are aggressive animals that typically hunt in water with reduced visability Credit: Getty Images.

Since , there have been 11 fatal attacks on Reunion , mainly on surfers. Those who survive often lose limbs. Researchers have found that around two-thirds of the Reunion attacks have occurred in turbid water and swells of more than two metres — the favoured environment for bull sharks, which are thought to be responsible for most of the attacks.

Madrigal, Alexis C. Great white breaks the ocean surface — from Alex Steyn via Unsplash So if a breach attack is so difficult to pull off, how are great white sharks able do it, and why do they do it? Great white shark mid-breach — from Alex Steyn via Unsplash According to a paper by Martin and Hammerschlag , who spent 13 years studying great white predation in South Africa, breach attacks allow great whites to play to their strengths and maximize stealth.

Great white shark chases decoy prey from behind — from Sharkcrew via Wikipedia Commons As great whites are less agile than seals, maximizing stealth and minimizing the time seals have to react is imperative.

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