Changing our perception of Sharks

Anjani Ganase, marine biologist, proposes greater respect and a different understanding of the place of sharks in ocean ecosystems

When we think of sharks, we imagine them as bloodthirsty creatures, roaming the deep blue seas for unsuspecting beach-goers and swimmers. Growing up, movies such as Jaws and Deep Blue Sea instilled fear in people and children. Yes, sharks are top predators, but they don’t hunt people; and are important in keeping our marine environments in balance.

Sharks are part of a diverse sub-class, known as Elasmobranchii, which also include skates and rays. Being part of the class chondrichthyes, this means that their structure is made up of cartilage rather than bones. A lighter cartilage skeleton and a tough outer skin makes for lightweight and efficient movement through the water column. There are over 400 species of sharks globally, much higher than breeds of dogs (~340), yet we only hear of the larger, more dangerous species. Here in the Caribbean, we have a subset of species with the most commonly encountered sharks being the Caribbean reef shark, which are shy and smaller than the typical apex predator shark. Caribbean reef sharks are about 1.5 m in length and reside along coral reefs. Other common sharks include the Nurse sharks, which are also residents near coral reefs and have very small teeth (they are suction feeders, so are more likely to give you a hickey than a bite!), and Silky sharks (aka Grey Whalers) that inhabit the open ocean and are very common in the tropics. Finally whale sharks are the gentle giants of the shark species, they can get up to 10 m in length and they roam the open tropical oceans feeding on plankton. Attacks by these common shark species in the Caribbean are extremely rare, and their protection is vital to our healthy ocean and reefs.

Juvenile Caribbean reef shark in Bahamas gets in close to investigate the camera. Photo by Anjani Ganase

Growing up, my irrational fear of sharks prompted me to avoid cross-harbour swims or any open water events. By the time I learned to dive, I hardly got the chance to engage or observe shark behaviour, because of the low number of sharks living among Caribbean reefs after generations of overfishing. But when I moved to Australia to study coral reefs that were protected, I had more shark encounters. Reef sharks are predators but they also compete with other meso-predator fish species, altering their feeding behaviour. Therefore changes in the shark population may shift prey choices of their competitors, which in turn influences the benthic community composition (Roff et al. 2016). A high diversity of shark and fish species indicates a healthy reef. These reefs may be more ecologically stable, meaning that following any disturbance, there are higher numbers of species that can refill functional roles (Roff et al 2016). Sharks also benefit from coral reefs, as reefs provide a diverse foraging habitat for sharks, as well as act as nursery habitats. Unfortunately, in many Caribbean reef systems, sharks and other meso-predators are scarce because of over-fishing.

The first day I snorkelled in the Southern Great Barrier Reef, I was fearful, for I knew I would encounter sharks, even though shark attacks on these reefs were extremely rare. The first shark I met while snorkelling on the reef flat was a Black tip reef shark; and I quickly came to realise that the shark met me with the same fear and curiosity. Most of the sharks I encountered while living on Heron Island came up when I would swim laps in the harbour after work. Swimming up and down this natural pool, I would see sharks seeking shelter from strong currents, escaping the receding tide by dashing off the reef flat into the deeper harbour water, and even chasing fish through the bait ball that gathered at the edge of the wreck.

Whenever I approached the shark, it always kept a safe distance. At times they would come up to investigate and swim away once their interest was met. Four years later, every encounter I’ve had with a shark underwater has been one of cautious curiosity – including a bull shark and an oceanic white tip accompanying us on our dive safety stops; a hammerhead cruising by as if humans were old news; and schools of silver tips, waiting for us as we rolled back for each dive. (All these dives were done in crystal clear and calm waters during daylight hours).

When I surveyed the Caribbean in 2013, there was a stark contrast to Australia’s Great Barrier Reef. The lack of protection over generations essentially meant that sharks were a rarity on Caribbean reefs. The only places frequented by sharks were in Bahamas, which banned long line fishing since the early 1990s (over 25 years), as well as actively protected their habitats. Shark protection has given good returns to Bahamas, as the country earns about 114 million USD annually from tourism based on sharks. Shark diving is the main activity for viewing reef sharks; while swimming and snorkelling with stingrays, and film and television production and research also add to the profits (Haas et al 2017). Sharks are worth much more to the Bahamians alive than as food.

This industry offers bigger benefits to the smaller communities present on more remote islands (Haas et al. 2017). Tourist divers mainly view Caribbean reef sharks; and only at specific locations, such as around the Bimini islands, where the great hammerhead, Oceanic white tip and Tiger sharks congregate (Haas et al. 2017). Globally, shark watching (including whale sharks, great white sharks, tiger sharks and reef sharks) is expanding and soon the economic value of keeping sharks alive, especially along marine protected areas, will outweigh the value of sharks that are killed in fisheries, a trend that may be declining or eventually outlawed. The development of more marine sanctuaries for sharks at Caribbean islands, such as St. Maarten, the Cayman Islands, Grenada and Curaçao means that the shift in the perception of sharks as bad beasts is changing.

Here, in Trinidad and Tobago we also need to change our relationship with sharks. Shark is a known local food delicacy, but this tradition is not sustainable. Traditions have changed in the past through education and understanding that conditions of our ocean have changed. To adapt means to survive, especially with the changing economy of Trinidad and Tobago and our waning natural resource of oil and gas. It is more crucial than ever to change our ways, just as other Caribbean and Pacific Island nations have done. It is time for us to become stewards of our lands and oceans rather than consumers. This is crucial for our children and future generations.

Surveying reefs dominated by reef sharks, Osprey reef 2012. Photo by Richard Vevers, The Ocean Agency/XL Catlin Seaview Survey.

SAFETY AGAINST SHARK ATTACKS

Being educated on the behaviour of sharks and their hunting regimes will significantly reduce your already slim chance of being bitten by a shark.

1. Fishing and spearfishing activities automatically increase your chances of being bitten by a shark, if you are in the water. These are provoked attacks, as sharks are highly stimulated by fish blood and struggling fish.

2. Avoid swimming in areas where there is a lot of baitfish as these also attract sharks.

3. Do not swim at night or at sunset and sunrise; sharks are more active during these times.

4. Avoid murky waters or strong surf as sharks can bump into and mistake people for fish and then can accidentally bite.

5. Shiny jewellery can resemble silver baitfish underwater so remove all jewellery before swimming.

6. Follow all the typical safety rules when swimming by a beach or as indicated by lifeguards.

REFERENCES

Roff, G., Doropoulos, C., Rogers, A., Bozec, Y.M., Krueck, N.C., Aurellado, E., Priest, M., Birrell, C., Mumby, P. J. The Ecological Role of Sharks on Coral Reefs, In Trends in Ecology & Evolution, Volume 31, Issue 5, 2016, Pages 395-407,

Haas, A. R., Fedler, T., Brooks, E. J. The contemporary economic value of elasmobranchs in The Bahamas: Reaping the rewards of 25 years of stewardship and conservation, In Biological Conservation, Volume 207, 2017, Pages 55-63.