Myopathy and Blunt Force Trauma most likely cause of death of a Hammerhead Shark

If it was not for the senseless tragedy of this scene, the above image would be an amazing capture of an incredible keystone species.

Instead, it is of a dead immature male Hammerhead Shark, one of most common dead sharks that we find in the ocean around popular sports shark fishing sites.

The undeveloped claspers indicative of an immature male.

The reason for the high rate of finds of dead Hammerheads is that they are more prone to post release mortality due to a combination of factors.

Myopathy

Physiologically, they succumb to myopathy, a malignant post exertion stress condition. During the ‘fight’ of landing Hammerheads, they produce the highest level of lactic acid of all shark species, making them extremely vulnerable to post release fatalities.

Anatomy

The lacerations around the eye are typical in hammerheads which regularly sustain blunt force trauma to their eyes while struggling out of water on rocks.

Due to the structure of their head and the placement of their eyes, handling during hook removal often results in blunt force trauma to their eyes, especially when landed and handled on rocks. They are either blinded or have impaired vision as a result.

Handling Time

Again, due to the structure of their head, often the duration out of water while removing the hook is, on average, longer than other species of sharks, further amplifying their physiological stress.

A Lethal Combination of Factors

Once released into the water, the lactic acid build-up, damaged eyesight and oxygen deprivation, result in them being in an extremely weakened condition which results in them dying either from myopathy or being preyed on by larger sharks.

The result of 455 million years of evolution threatened by a recreational past time.

Lessons from the Wildlife Industry

In the game industry, the capture and release of wildlife is a precise procedure mostly with a vet in attendance.

With the dramatic decline in global shark populations, it may well be time for improved handling and care of sharks by fishermen when landing and returning sharks to the ocean.

Hammerheads are specialized to feed off the seabed, targeting buried crustaceans, mollusks and small skates.

Improving Landing Protocols

Avoiding landing on rocks, providing a protective layer of shade cloth (or something similar) and striving to reduce handling time out of water should be standard best practice, even if it means forgoing the ‘Brag’ photo session.

I have watched completion anglers employ higher standards of care of game fish than what is practiced on sharks. It can be done and will contribute to the sustainability of not only shark populations, but the marine biodiversity of which they are vital keystone species.

Measuring up a Brag Photo. The cost – the death of the keystone species. The consequence – the loss of vital ecological services.