Sharks are part of a group of fish called Chondricthyes or ‘cartilaginous fishes’ that also includes Skates, Rays and Chimaeras. The earliest sharks appeared on Earth over 400 million years ago and during this time they have endured all five major extinction events in history. They were here before the dinosaurs and, as one of the earliest vertebrate animals; have remained almost unchanged when most other life forms perished. Today they have evolved into around 450 different species ranging in size from the deep sea Dwarf Lanternshark (Etmopterus perryi), at roughly 17cm, right up to the world’s largest fish, the Whale Shark, (Rhincodon typus), at around 12m. They have also diversified into every sea and ocean and several species frequent depths of around 2,000m (6,600ft).
Sharks are particularly vulnerable to over-exploitation due to their biological characteristics of having few young, maturing late (up to 25 years), and being long lived. This is known as a ‘k’ life history strategy and is distinct from an ‘r’ life history strategy (many young, quick maturation and relatively short lives). As a result, when their numbers are reduced significantly, even if fishing stops, they will take many years to recover, if at all.
Unfortunately, sharks are under considerable threat from over-exploitation on more than one front. It is estimated that between 75 and 100 million sharks are killed every year. Slightly more than 50% of these deaths is the result of bycatch (accidental catch) from fisheries targeting other species such as tuna. Many of the methods used by fisheries, such as purse seines and long-lines, are not species specific and catch anything that comes into contact with them. Furthermore, there now exists an incredibly lucrative industry for shark fins. The vast majority of this demand comes from Asia for a delicacy called shark fin soup. The cartilaginous nature of shark fins provides texture to the soup but is in fact, flavourless. The demand for shark fin soup (or fish wing soup in China) has grown enormously over the last 50 years.
To add to the problem, marine concerns receive far less publicity than terrestrial ones because sharks are not exactly the typical ‘cuddly’ animals that capture the imagination of the public. For most people sharks are nothing more than a triangular fin and a huge mouth full of razor-sharp teeth. Despite relatively little biological understanding of sharks in general, there is an abundance of anecdotal, emotional and misleading information available about the minor phenomenon of shark attacks. This misinformation has come from films such as ‘JAWS’ and the sensationalised media coverage of the few attacks that do occur. In fact, between 1959 and 2009 nearly 85 times more people were killed in US coastal states by lightening than by sharks.
However, the main problem is that international waters are unregulated and there is no comprehensive global regulation in place for managing shark fishing or finning; so beyond national boundaries, sharks are a target for anyone and everyone.
The importance of sharks and why we should care
Sharks are ecosystem engineers and have helped shape life in our oceans. Their carnivorous predatory behaviour has given rise to schooling, camouflage, speed, size and communication amongst smaller prey animals. By preying on weak and sick animals, sharks act as controlling agents, like lions or tigers. Over time this engineering activity creates better genetically and evolutionarily capable species and influences both biological diversity and ecosystem function.
There are direct and indirect effects of fishing at the single-species level. The direct effect is that exploitation can result in changes in abundance, life-history patterns and can also lead to extinction. The indirect effects involve changes to the levels of the food chain that species have evolved to exist, also known as trophic levels. Without a proportionate number of sharks to keep prey populations in check, an ecological imbalance could cause a top-down trophic cascade, with potentially disastrous repercussions throughout the world’s oceans.
Trophic cascades can result in substantial changes to the composition and structure of communities. Sharks (and other apex predators) provide a vital stabilization role in the oceans and the removal of these controlling agents allows meso-consumers at the mid-trophic level (predators or herbivores) to increase in abundance and furthermore, can impact populations at lower trophic levels such as the plankton-eating species. If plankton starts to become affected, then we could detrimentally affect the base of almost all marine food chains and also the planet’s most important source of oxygen.
Our understanding of these consequences is not nearly good enough but the possible outcomes should be taken very seriously. We need far more attention to be focused on this poorly studied area to gain a better understanding of trophic interactions and the long-term consequences an imbalance in trophic levels can have on marine ecosystems.
In addition, the awful practice of removing a shark’s fins whilst still alive and then discarding the trunk back into the ocean where it will drown, starve, or be eaten by other predators is a major welfare concern which should appall everyone.
The solution: what we can do
The most difficult and large-scale solution would be to make shark finning illegal by international law. However, this would create enormous enforcement problems and would be difficult to implement, costing substantial sums of money. In addition, the shark finning industry is extremely lucrative and there is already an extensive black market; an international ban may simply expand it. Nevertheless, this should be the ideal and if sharks arrived at docks with their fins attached, species identification and biological data could be captured to monitor populations. If enforced properly, this would also address the welfare concerns.
The most effective way to stop the cruel, wasteful practice of shark finning is to reduce the market for the fins. If fewer people ate shark fin soup, there would be less of a demand. While the vast majority of the demand comes from Asia, there are many places in the UK, particularly in China Town (London), that sell shark fin products and shark fin soup. The first thing that we can do is boycott these shops and restaurants and encourage others to do the same.
All of this goes hand in hand with the greater need to raise awareness, educate people and dispel myths associated with sharks. There are also cultural barriers. Asian countries uphold ancient traditions that many westernized countries consider cruel and unsustainable. At what point is it appropriate to interfere with another nation’s culture? When unsustainable practices affect us on a global scale, there is the need for international collaboration and commitment from all cultures, religions and disciplines. It goes without saying that, if travelling in Asia, we should not order shark fin soup or other shark-derived products. Furthermore, if you feel comfortable doing so, talk to shop owners, restaurateurs about the issue. There is no need to be aggressive or tell people what they are doing is wrong. You might be surprised how many people are simply unaware of the problems facing sharks and the cruel methods used to obtain fins.