For as long as I can remember I have loved sharks. Maybe what attracted me to them in the first place was how misunderstood they are – as a teenager this was a trait I could relate to on a personal level. Once they first lure you in with their evolutionary prowess, you quickly become encapsulated by how truly remarkable these animals are.
The group of fish we call ‘sharks’ so often conjures up images of species belonging to the requiem shark family – these are those that have the ‘traditional shark’ morphology, like the bull shark, lemon shark and tiger shark. But there are over 500 species of shark, and with that diversity comes an array of shapes, sizes and oddities. In fact, many of species of shark on the edge of extinction are those that exhibit the largest array of peculiarities, and it’s likely that few of us recognise many of them.
Why are sharks so vulnerable to extinction?
Despite all of the meticulous editing by evolution over millions of years, two of the life history characteristics that make sharks so special in comparison to other classes of fish are also those which make them unequipped to deal with the exceedingly high pressures we put them through via activities like overfishing and habitat loss.
These traits are their low fecundity – a term referring to how many baby sharks they produce with each reproduction cycle – and their late sexual maturity – that is, they can’t reproduce for the first time for 10 – 15 years, or longer, in many cases. If we’re getting really technical about this, sharks are what scientists refer to as a k-selected species. Of course, like with everything in the natural world there are exceptions to this rule.
What does this mean? Species that belong to the k-selected group are those with a longer life expectancy, a larger body size and fewer offspring with each reproduction cycle than those in the r-selected group. For completeness, r-selected species are the opposite – they have rapid growth rates, produce lots of babies with each reproduction cycle and have a early sexual maturity.
“But why is this such a problem for sharks?”, I hear you ask.
A statistic often thrown around in relation to sharks is that an estimated 100 million are thought to be killed annually. Much of this is fuelled by China’s insatiable demand for shark fin soup, which is encouraging the barbaric slaughter of sharks – in many cases their fins are sliced off and the animal is returned to the ocean ALIVE – to keep up with this desire. For the sake of this post, I am not going to delve deeper into the politics of the shark fin trade, but you can check out this article from The Guardian if you’d like to know more.
Another threat to their populations is bycatch – that is their unintentional capture through commercial fisheries for other target species, particularly by methods like longlines, gill nets and trawls. A study published in 2019 featuring the collaborative work of over 150 scientists identified that large pelagic species of shark are especially vulnerable to international commercial fleets in the open ocean due to their shared tendency of aggregating around hotspots of smaller fish species – the prey items of the sharks and the target fish for the fishermen. To put the impact of this into perspective, a statistic published by WWF states that in the Pacific Ocean alone 3.3 million sharks are caught as bycatch by commercial longlines annually.
Not only are these figures staggering, but simply put, for the life history characteristics discussed earlier, shark populations are struggling to recover from this continual onslaught. They have no reprieve and no chance to metaphorically get their act together. They have been thriving in our oceans for millions of years, able to adapt and overcome each challenge to their existence as and when they come, but the obstacles they face as a result of us, human-beings, are now occurring so rapidly that they cannot adjust fast enough.
But why should you care?
Public perceptions toward sharks often hinder their conservation. For far too long we have given in to the rhetoric crafted by Hollywood to create gripping movies and by journalists to sell stories. We often view sharks as an ‘enemy’ rather than an ally. But the reality is that without sharks our lives would look much bleaker. They are silently going about their sharky business in the deep ocean blue and that is directly benefiting both you and I, in far more ways than we regularly give them credit.
As apex predators within the marine environment, sharks regulate the populations of other species below them, often predating on the weaker individuals of other species. This is not only important to keep the populations of other species in check, but it also exemplifies Darwin’s “survival of the fittest”.
For our global community to thrive, we depend on a healthy ocean. Not only is every second breath that we take produced by our seas, but also think about the other services it provides us – food provisioning, carbon capture and storage, coastal protection, improved mental health, spiritual significance, pharmaceuticals… The list goes on and when you really consider how much the ocean touches your life on a daily basis, it can be quite astonishing.
As I’ve outlined above, sharks are integral to the maintenance of a healthy ocean and so it goes full circle – by rapidly depleting shark populations in the manner that we are, we are degrading our marine environments and therefore are also hurting ourselves. As egotistical as our species has been historically, we have also shown remarkable compassion and altruism towards our natural world. It is intrinsically embedded within each and every one of us to share a rich connection with nature; we just have to give it a chance to enter our often frantic 9-5 lives.
Collectively, we can protect sharks across our global ocean, but we have to push for this conservation sooner rather than later. You can start today in a really simple way – changing the way you view sharks and chatting to your friends, family members and colleagues about this whenever sharks come up in conversation. If we foster a more positive public viewpoint of these animals, it is far more likely that governments will respond to calls for their protection in a better light as well. After all, we need policy to translate into the action and enforcement these animals so desperately need to make a difference.
We are in an age where we as the public have the power to drive the political agenda. Over the last few years this has been showcased superbly with the rise of Greta Thunberg’s school strikes for climate action and the increasing demand for single-use plastics to be wiped from our lives, just to name a few examples.
The future of this extraordinary planet we call home rests in our hands, and we morally have a duty to choose the battles that resonate with us personally to secure its future. That may sound daunting, but nothing easy is worth fighting for.
You should be scared if you’re in the ocean and you don’t see sharksDr. Sylvia Earle