Earlier this month, fishermen on Florida's Singer Island came under fire for pulling a hammerhead shark onto a local swimming beach. A 2012 regulation change has seen these animals gain much-needed protections in Florida state waters, and bringing them ashore is strictly prohibited. Footage of the incident has circulated widely in the weeks since, and it's ignited some intense debate online.

[The following video contains profanity and may be considered NSFW.]

There's no question that the fishermen involved in this incident broke the law (holding a protected species for the purposes of photographing it is also illegal), but some commenters have stepped up in support of the men, claiming no damage was done because the animal was ultimately released. Others have strongly condemned the behaviour, calling for "justice to be served" for an endangered shark. We've seen these angry debates play out before on many occasions, and they tend to follow a now-familiar pattern: lines are drawn, invectives are hurled in both directions, and a bullying back-and-forth erupts over the morality of sport fishing.

This dialogue is tired, divisive and, in the end, accomplishes very little. So let's put personal opinions aside for a moment, and create something useful instead: a resource for anyone who wants to learn more about hammerhead sharks. What makes landing these fish so bad? And what can fishermen do to help? (Not a fisherman? Don't like sport fishing? Keep reading anyway! Knowing the facts is just as important for anyone who supports shark conservation. Maybe something in this article will prepare you for a productive conversation down the line – no pun intended).

The hypersensitive hammerhead

It might seem inconsistent that some sharks – but not all – are illegal to bring on land for the purposes of removing a fishing hook. Indeed, many anglers caught in the act of doing this actually believed they were behaving in the best interest of the animal. 

Great hammerheads like the one in the Singer Island video are listed as endangered by the IUCN, and that's often the first thing pointed out by opponents of this kind of fishing. However, there are actually other reasons behind the no-landing rule.

While many sharks can handle stress well, research has shown that hammerheads do not fall in this category. Marine biologist Dr Austin Gallagher, who has done extensive work on fishing stress in sharks along with colleagues at the University of Miami, explains that hammerheads go into a "downward spiral" when caught on the line. "And they really can't get out of it," he notes.

Hammerheads are notoriously hard fighters on the line, and can easily work themselves up to complete exhaustion. Image: Shutterstock

In potentially dangerous situations, humans get a surge of the hormone adrenaline as our bodies prime themselves to rumble or to run. This "fight or flight" response might seem inherently human, but we have our ancient ancestors to thank for it (and sharks have been on this planet almost 500 million years longer than we have).

"When a fish is caught, it also gets the 'fight or flight' response," notes Gallagher. A surge of hormones in the shark's brain triggers the release of sugar and energy to the rest of the body – a boost to help the shark operate in overdrive. 

"So now the animal is fighting, right? You have all this new, mobilised, beautiful energy to the muscles," he explains. "You need it because moving and escaping really fast is demanding. The whole point of a stress response is to be quick ... The reaction is immediate, but the trouble is, it's not designed to be prolonged."

Hammerheads are notoriously hard fighters, and there's a problem with that spirited survival instinct: they can fight themselves to complete exhaustion very easily. 

Built for speed not distance

Despite being one of the most agile sharks, hammerheads are quite bulky, which means it takes a lot of energy for them to hit top speed. What's more, their mouths are quite small in relation to their large bodies, which limits the amount of oxygenated water that can move over the gills. To keep their energy consumption in check, the sharks usually rely on quick bursts of speed when they need to get up and go.

"Hammerheads are [built] for speed not distance, and that's the problem," says Gallagher. "We're analysing drone footage now of hammerheads hunting, and what we're finding is that they really only have four to five seconds going full speed before they have to stop, chill out and replenish their cells."

But when their fight-or-flight response is triggered, hammerheads will battle their way to complete exhaustion. They reach a point when there isn't enough oxygen or energy left in the body to keep up: the blood becomes loaded with carbon dioxide and lactic acid floods the muscles. These potentially lethal effects are amplified when the fish are dragged ashore in this state.

"In these situations, you're bringing an animal that's already at a high risk of metabolic collapse out of the water where it can't breathe," notes Gallagher. "That adds another stressor to the animal." Without the support of water, the shark's organs can also be crushed under their own weight. 

"Now the shark is in full-blown survival mode – so it's still firing some of those muscles, trying to escape," adds Gallagher. "And at that point, it's very hard for some animals to come back." It's estimated that as many as 40 or 50 percent of hammerheads will die after release following 40 minutes on a fishing line. (A figure of 90 percent is sometimes cited, but this comes from research focusing on commercial fishing practices). 

Removing large hammerheads from an already declining population can have devastating effects: the biggest animals are also the ones that contribute most to the population. "These impressive animals are the ones that have been 'road tested'," says Gallagher. "Those are the genes you want in the gene pool!"

This is true whether or not you're fishing in an area where hammerheads have been been granted legal protections. Science is telling us that there are negative consequences to putting these animals under stress.  

Turning the tide 

The story of the deadly impacts on hammerhead sharks has been known for years, and yet the landings persist and many similar cases have gone unenforced by state agencies. But the point here is not to present all sport fishing in a negative light. In fact, most scientists support sustainable shark fishing, and many anglers already collaborate with them on conservation projects. 

"I know a lot of land-based anglers who are really passionate about these sharks, and passionate about their conservation," notes Gallagher.

In the end, it's going to be up to the sport-fishing community to turn the tide on harmful practices – so alienating it is completely counterproductive.

"Some of the folks who get caught doing this don't know about the science or aren't part of communities that are well informed," Gallagher adds. "We have to turn these unfortunate events into learning opportunities – not blame games – if we're going to conserve the future of these animals. And in many cases, fishermen handle these situations the right way."

What is the right way?

Pick smart bait. Hammerheads are especially attracted to stingray prey, and typically go for live bait (some anglers have been known to cut rays in half while still alive to evoke a hammerhead's natural hunting response). Use something else instead. Many published fishing forums contain lists of the best bait options. 

Keep an eye out. Hammerheads are easily recognised by their tall, narrow and pointed dorsal fins. If you see one in the shallows, choose to fish in a different spot.

Cut the line immediately if you've caught a hammerhead by mistake. Sharks have incredible healing abilities, and experts overwhelmingly agree that a hook will do less damage than prolonged stress on the line. This is true for boat-based fishing as well: "Hammerheads tend to bang their heads around the side of a boat," notes Gallagher, which means that promptly cutting the line could reduce the risk of injury. "It's in the animal's best interest to keep it in the water, and reduce the additive stressors that continue to pile up."

Forgo the photo. Cutting the line often means giving up the chance to measure or photograph a shark, but if we want to be able to interact with these incredible animals for years to come, that's a necessary sacrifice. "Anglers want to get those pictures, they want to see the shark and celebrate it, which I understand," says Gallagher. "But science is telling us that for certain species, that just isn't the best way to interact with them from a fishing perspective." 

Share accurate information. For those of us who don't fish, there are ways to help, too – whether you support the sport or not. Avoid out-of-context, misleading data, and don't ignore the efforts of many responsible fishermen. This sends important conversations underground.

Bookmark this article (and this one from shark scientist Dr David Shiffman). The idea that shark fishing and shark conservation are at war is misguided. If a video gets your hackles up, don't get sucked into an ugly blame game. Instead, share accurate information and highlight good examples of responsible fishing.

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Top header image: USFWS Headquarters/Flickr