Shark nets kill sharks
** This is a repost of a blog I wrote for SheSapiens **
When I say shark nets, what I referring to are nets that are deployed across stretches of coastline near popular beaches in order to keep water users safe from being bitten by a shark. Marketed as a necessity, shark nets are plugged to the public as a something to keep people safe from dangerous, human-eating sharks. It is assumed that without these nets, hungry sharks would have easy access to vulnerable swimmers and we’d either not be able to go in the water, or go in at our peril. This is a lie.
Shark nets do not prevent sharks from getting close to beaches. Firstly, they do not form a barrier to sharks. They are suspended in the water column, and there is a gap above them, below them, and between them on both sides. Sharks can literally go over, under, or around the nets if they want to. What’s even more interesting is that in Kwa-Zulu Natal, South Africa, the majority of the sharks caught in the nets are caught on the shoreward side. Therefore, the sharks had made it past the nets and were caught in between the beach and the net when swimming back out to sea (away from swimmers). Secondly, the design of nets is not to act as a barrier, but to entangle, catch and kill large sharks.
Calling these lethal devices shark nets is the first big marketing win. They are actually gill nets. As in, fishing nets. Gill nets are used by commercial fishermen, and shark nets are the same nets: just on bigger scale for a bigger fish, like a great white shark. If beaches that have shark nets advertised that they have gill nets, we would avoid a lot of misconception (i.e. that these nets form a barrier).
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| Source: Cape Town SharkSpotters |
Another important point to touch on is the non-target nature of gill nets. By this what I mean is, non-target species are also often caught in the net. This is known as by-catch: when you catch something that you didn’t intend to. Turtles, whales, dolphins and smaller sharks all get caught and die in these nets. These are animals that pose no threat to human life. Their only mistake is living in the ocean and being in the wrong place at the wrong time. Some critically endangered and endangered species have fallen victim to shark nets, such as the humpback dolphin in Kwa-Zulu Natal, South Africa (Atkins et al. 2016).
One of the biggest issues surrounding shark nets is that people are largely unaware this is happening. However, the managers of beaches that sign off on these nets are not technically lying to us. If you look for the correct information about shark nets – i.e. they’re are designed to catch and kill sharks, do not form a barrier to shark, and the majority of sharks are caught swimming back out to sea – you’ll find it. But you have to look. You have to be deliberately searching for this information, and so you basically have to already know it to find it. They may not be lying, but they are not forthcoming with the truth.
I think this is deliberate. It’s not exactly a good look for them to promote that they kill sharks, along with lots of other species. But this omission of truth means that the public opposition that I imagine would be there, is missing. Campaigns to end this culling, and to promote human safety AND shark conservation, a coexistence of both, are either not there or not loud enough to be heard.
Conservation-wise, the biggest issue with these shark nets is that they violate internationally agreed responsibility to protect endangered species. In Australia, the use of these nets goes against the Environmental Protection and Biodiversity Act. Several species of so-called ‘dangerous’ sharks are endangered, and much of the by-catch is too. Furthermore, sharks carry out critical ecosystem functions as apex predators. Removing them from the system could have cascading consequences for marine life and ecosystem services (natural processes that directly or indirectly benefit humans).
One of the biggest issues surrounding shark nets is that people are largely unaware this is happening. However, the managers of beaches that sign off on these nets are not technically lying to us. If you look for the correct information about shark nets – i.e. they’re are designed to catch and kill sharks, do not form a barrier to shark, and the majority of sharks are caught swimming back out to sea – you’ll find it. But you have to look. You have to be deliberately searching for this information, and so you basically have to already know it to find it. They may not be lying, but they are not forthcoming with the truth.
I think this is deliberate. It’s not exactly a good look for them to promote that they kill sharks, along with lots of other species. But this omission of truth means that the public opposition that I imagine would be there, is missing. Campaigns to end this culling, and to promote human safety AND shark conservation, a coexistence of both, are either not there or not loud enough to be heard.
Conservation-wise, the biggest issue with these shark nets is that they violate internationally agreed responsibility to protect endangered species. In Australia, the use of these nets goes against the Environmental Protection and Biodiversity Act. Several species of so-called ‘dangerous’ sharks are endangered, and much of the by-catch is too. Furthermore, sharks carry out critical ecosystem functions as apex predators. Removing them from the system could have cascading consequences for marine life and ecosystem services (natural processes that directly or indirectly benefit humans).
BALANCING HUMAN SAFETY WITH SHARK CONSERVATION
You might be reading this and be conflicted. Yes, killing sharks for just existing in their natural space seems harsh, but if people want to continue recreationally using the water in areas these sharks exist, which encourages tourism and thus has huge direct and indirect economic benefits, then we do need to do something to keep people safe.
So what can we do?
Firstly, it’s important to understand that sharks do not attack people. Sharks bite people sometimes, but incredibly rarely. And these bites are not a calculated malicious attack. The primary theory of why this happens is curiosity on behalf of the shark. Sharks cannot come up and ask us what we are, or touch us to figure it out. Their way of identifying objects or creatures is to bite them and see. There is also a theory that sharks mistake humans (often on surf boards in wetsuits) for seals. That’s why humans are rarely eaten by sharks: they bite us, realise we are not at all what they wanted, and leave. It’s just unfortunate for us that the force of a curious bite from a great white shark could take your leg off.
Sometimes sharks are just aggressive, particularly juveniles. But again, it’s incredibly rare. If you consider how many people have encountered sharks and not been bitten, or the number of people who have swam at beaches where sharks frequent and not been bitten, you get some idea of just how unlikely being bitten is.
Finally, there are shark management strategies that are harmless to sharks, but keep people safe. The Shark Spotters Programme in Cape Town is the most notable and successful to date. A spotter sits at a high vantage point (Cape Town is ideal for this kind of programme with mountains situated adjacent to popular surfing beaches). They use a flag system to signify level of risk or shark activity. If a shark is spotted, the white flag is raised and an alarm goes off notifying everyone to get out of the water. The water is evacuated until the spotter deems it safe for people to return. The flag flying also indicates how recently a shark has been spotted, and how good the spotting conditions are.
There are other options too if you don’t have a conveniently placed mountain. New technologies are in the works, including cameras that detect movement in the water. They use machine learning technology to identify sharks based on how they move, so they would be able to tell if the motion they detect is a shark. There are wetsuits you can buy that are supposed to camouflage you into the water column based on a sharks visual system, and individual shark repellent devices you can attach to yourself.
There is also such thing as an exclusion net! A net that actually does form a barrier to sharks AND does not kill them! These nets form a complete barrier from the water surface to the sea floor, creating an enclosed space for swimmers which marine life cannot enter. The mesh of the net is small (45mmx45mm) and square which reduces entanglement risk. An example of this is also found in Cape Town, at Fish Hoek beach, where a section of the bay is enclosed from sharks. The net is retrieved every evening and deployed every morning, to minimise environmental impact.
So what can we do?
Firstly, it’s important to understand that sharks do not attack people. Sharks bite people sometimes, but incredibly rarely. And these bites are not a calculated malicious attack. The primary theory of why this happens is curiosity on behalf of the shark. Sharks cannot come up and ask us what we are, or touch us to figure it out. Their way of identifying objects or creatures is to bite them and see. There is also a theory that sharks mistake humans (often on surf boards in wetsuits) for seals. That’s why humans are rarely eaten by sharks: they bite us, realise we are not at all what they wanted, and leave. It’s just unfortunate for us that the force of a curious bite from a great white shark could take your leg off.
Sometimes sharks are just aggressive, particularly juveniles. But again, it’s incredibly rare. If you consider how many people have encountered sharks and not been bitten, or the number of people who have swam at beaches where sharks frequent and not been bitten, you get some idea of just how unlikely being bitten is.
Finally, there are shark management strategies that are harmless to sharks, but keep people safe. The Shark Spotters Programme in Cape Town is the most notable and successful to date. A spotter sits at a high vantage point (Cape Town is ideal for this kind of programme with mountains situated adjacent to popular surfing beaches). They use a flag system to signify level of risk or shark activity. If a shark is spotted, the white flag is raised and an alarm goes off notifying everyone to get out of the water. The water is evacuated until the spotter deems it safe for people to return. The flag flying also indicates how recently a shark has been spotted, and how good the spotting conditions are.
There are other options too if you don’t have a conveniently placed mountain. New technologies are in the works, including cameras that detect movement in the water. They use machine learning technology to identify sharks based on how they move, so they would be able to tell if the motion they detect is a shark. There are wetsuits you can buy that are supposed to camouflage you into the water column based on a sharks visual system, and individual shark repellent devices you can attach to yourself.
There is also such thing as an exclusion net! A net that actually does form a barrier to sharks AND does not kill them! These nets form a complete barrier from the water surface to the sea floor, creating an enclosed space for swimmers which marine life cannot enter. The mesh of the net is small (45mmx45mm) and square which reduces entanglement risk. An example of this is also found in Cape Town, at Fish Hoek beach, where a section of the bay is enclosed from sharks. The net is retrieved every evening and deployed every morning, to minimise environmental impact.
CONCLUDING THOUGHTS
Overall, it’s safe to say I do not agree with lethal shark management. I believe it is not only possible, but essential, to promote coexistence with sharks. These days there are ways to recreationally use the oceans and let sharks live. Some beaches, such as in Cape Town, lend themselves easily to shark spotters or exclusion nets. I acknowledge that this is not the case everywhere, and more work is needed to figure out universal solutions or technologies.
But, an ocean without sharks is no ocean at all, and to kill these animals for our own enjoyment of their home is senseless. It’s time to leave shark nets in the past.
But, an ocean without sharks is no ocean at all, and to kill these animals for our own enjoyment of their home is senseless. It’s time to leave shark nets in the past.
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