Thursday, November 30, 2017

The Deep Ocean has no Borders


Journey with Diva Amon, a deep-sea biologist who has explored the deep ocean in Antarctica, the Atlantic and the Pacific. She has experience in chemosynthetic habitats and anthropogenic impacts on the deep sea. You can find out more via her Twitter (https://twitter.com/DivaAmon) and her website (https://divaamon.com/).

We now know that the seas around Trinidad and Tobago boast unique and ecologically important deep-sea methane seeps. It is useful that we have taken the first steps to answer the most basic of questions about the Caribbean deep ocean, “What lives there?” But what about even more complex questions such as “How do species find and colonize these relatively small and patchy chemosynthetic habitats in the huge expanse of the deep ocean?”
To get between islands, birds can fly, reptiles can raft over on flotsam, and many shallow water marine animals (fish, marine mammals, turtles, etc.) can swim the long distances, but what about deep-sea animals like the Bathymodiolus mussels, Alvinocaris shrimp and Lamellibrachia tubeworms that inhabit chemosynthetic habitats? Recent studies have shown that many of the species found at the deep-sea sites off Trinidad and Tobago have also been observed at sites on Kick’Em Jenny off Grenada, off Barbados, in the Cayman Trench and even as far as the Gulf of Mexico. But if many of these methane-seep inhabitants are unable to move, how do these far-ranging sites have these species in common?
The adults may be permanently attached (or sedentary) but their offspring are not! Many of the seep species release their young into the water column, where they hitch a ride in the currents. The Caribbean region boasts a predominantly easterly-north-easterly current suggesting that the seeps off Trinidad and Tobago may be a source of species for the more northerly chemosynthetic sites of the Caribbean. But how long would the epic journey from Trinidad and Tobago to the Gulf of Mexico take for a juvenile mussel? And is that even possible?! Well, that depends on the depth that the larvae travel at and the duration of the larval life span, of which very little is known. However, a recent study reported that the larvae of a seep mussel (Bathymodiolus childressi) and a seep snail (Bathynerita naticoidea) migrate into shallow waters (<100m depth) allowing them to take advantage of faster surface currents that may facilitate long-distance dispersal. Amazingly, it is estimated that B. naticoidea is able to disperse for 7–12 months, whereas B. childressi could migrate for up to 16.5 months. Additionally, it is thought that deep-sea larvae originating around Trinidad and Tobago had the potential of colonizing virtually the entire Caribbean area and even the southeastern Gulf of Mexico.
As some of the deep-sea animals found off Trinidad and Tobago have been found across the Caribbean and as far north as the Gulf of Mexico, having a regional understanding is essential. It reminds us that there are no borders in our deep ocean and is key to comprehending our current and future impacts in these areas. As a result, I will be exploring the deep sea of the Gulf of Mexico in the hope that we can gain a better understanding of those habitats and in turn that it will help to improve our knowledge of the Trinidad and Tobago and Caribbean deep sea. But even more excitingly, I hope that you will join me for the journey!
NOAA Ship Okeanos Explorer berthed at the NOAA Ford Island facility located in the middle of Pearl Harbor, Hawaii. The ship will be leaving from Key West, Florida for the upcoming expedition. Image courtesy of NOAA Office of Ocean Exploration and Research.
My upcoming expedition utilizes an incredible technological innovation called telepresence. Telepresence uses satellite technology to transmit live images and data from ships and ROVs at sea, providing a real-time portal into the excitement of deep-sea exploration and research for scientists, stakeholders, and members of the public (like you!) onshore. Yes, that’s right, every day from 30th November to the 20th December you can be a deep-sea explorer! We will be sending the ROVs Deep Discoverer and Seirios from the NOAA Ship Okeanos Explorer down into the depths to explore areas of the Gulf of Mexico that have never been visited, and beaming the images to you in your home, at work or anywhere you have an internet connection. There will be 21 dives including at potential methane seeps, shipwrecks, coral gardens and even some deep-sea canyons! Will they yield new and exciting life forms and landscapes? You’ll just have to follow along to find out!
Please visit www.oceanexplorer.noaa.gov for the live video stream and more information about the expedition. ROV dives with live streaming will be conducted every day from approximately 8am to 4pm from 30th November to 20th December. You can also find the live video stream on NOAA Ocean Explorer Facebook and Youtube.
Bathymodiolus mussels (both dead and alive) are seen underneath a carbonate overhang. Also visible under this overhang is methane hydrate. Between the mussels, urchins and sea stars can also be seen. This site looks remarkably similar to seeps seen off Trinidad and Tobago. Image courtesy of the NOAA Office of Ocean Exploration and Research, Gulf of Mexico 2014.

 

Thursday, November 23, 2017

Healthy marine systems for Tobago's business and tourism model

Anjani Ganase, marine scientist, calls upon business to claim its share of ocean wealth while helping to conserve and manage Tobago’s offshore resources. This feature was first prepared for Contact, the magazine of the Trinidad Chamber of Industry and Commerce; and is reprinted in the Tobago Newsday on November 23, 2017

We think of the ocean and its resources as vast and endless. Goods and services provided by the ocean for humans have been estimated to be about 24 trillion USD in assets (World Wildlife Fund, 2015) more than the economy of most nations. These goods include fishing, harvesting of materials and procurement of medicine, as well as services through shoreline protection, wave energy extraction, shipping and tourism. This asset value is grossly underestimated, as it doesn’t consider the crucial roles of the ocean in regulating climate, the air we breathe and stabilising temperature, nor does it consider the intrinsic cultural value that we place on the ocean (WWF 2015). But the resources of the ocean have been depleted more in our lifetime than ever. 

Today, statistics show that humankind’s grasp has outreached the resource capacity of the ocean. Over 90 % of all the big fish stocks are gone, and by 2050 there will be more plastic in the ocean than fish if trends continue. Over the last 40 years, the biodiversity of marine life has dropped by 39 %, while marine habitats are declining at alarming rates. Mangrove ecosystems are being removed faster than the forests, and many coral reefs in the Caribbean have been reduced to about 20 % of original cover (WWF 2015). In the Pacific, the Solomon Islands have lost five islands due to climate related rising sea levels; the government of Kiribati has already bought land in Fiji to relocate their citizens, refugees of climate change. The Caribbean region is already being affected by severe weather patterns, more intense hurricanes, and warming ocean waters.

Fortunately, some countries have found long-term sustainable solutions to save valuable ocean resources through the use of marine protected areas. The designation of marine sanctuaries, such as coral reefs, mangroves and offshore seamounts, has been shown to increase the abundance of marine life both inside and outside the protected areas. This has boosted the stock in the fishing areas, despite the concern of the local fishers. The tourism industry also benefits from marine sanctuaries, as snorkelling and diving sightseers are attracted to larger fish and marine life within the sanctuaries. Protected mangrove ecosystems buffer coastlines from storms, and act as nurseries for juvenile marine life. With proper enforcement, the recovery of marine areas along with profitable returns has occurred in as little as five years after the establishment of the marine sanctuaries. Communities on island nations worldwide, including Fiji, The Philippines, Bahamas, St Lucia and the Netherlands Antilles, have reported improved fisheries and tourism with long-term sustainability through the use of marine sanctuaries.
 
Englishman’s Bay, Tobago: by preserving ecosystems both above and below the water, we can maintain the natural beauty for all to enjoy. Photo by Anjani Ganase

Tobago is a hub of marine biodiversity. Tobago’s waters support the development of coral reefs along most of its sheltered coastline, while the nutrients in the water column also provide food for an array of marine life. Located between the Caribbean Sea and the Atlantic Ocean, Tobago is on migration routes for many marine mega fauna, including sharks, whales and dolphins. The exclusive economic zone (EEZ) for Trinidad and Tobago is 16 times greater than the combined landmass of the two islands, most of it around Tobago. The waters and coastal habitats of Tobago can be used to enhance and diversify Tobago’s economy with adventure and educational tourism. However, it is crucial to conserve the product, the natural habitats and the marine life.

Tobago has a real chance of benefitting from conservation; and there are small businesses with environmental goals already showing the way. Businesses that explore the coral reefs, such as dive centres – Environmental Research Institute Charlotteville (ERIC) and Frontier Divers at Store Bay - seek to provide educational experiences, where visitors acquire diving skills and learn about coral reef ecology. Visitors become involved in local conservation activities, such as coral health monitoring surveys, garbage removal dives or guided hunts of the invasive lionfish. Tobago has shown entrepreneurship in eco-tourism through the development of low impact accommodation with limited land clearing, sustainable water usage and alternative energy supplies: examples can be found in Man O’ War Bay Cottages in Charlotteville, and in Castara where the entire village participates in the Castara Tourism Development Association. These examples ensure sustainability, incorporating the services of local operators in community-run enterprises.

Investments in conservation business should include services, such as field research facilities and technical support staff for managing Tobago’s numerous ecosystems. By providing lab and field technical support to visiting groups, we continue to learn about our own ecosystems, adding to the repertoire of Tobago’s natural wonders. However, there must be a mandate for protection and enforcement of marine and terrestrial sanctuaries at all levels – community, business and government. The government’s role includes creating policy that is pro-environment, actively enforcing management of protected area, as well as establishing green infrastructure – proper waste (sewerage) management facilities, recycling centres and renewable energy supplies. Jobs in the public sector can be created through the training of Tobagonians for eco-tourism. The Main Ridge Forest Reserve is a living example. We can do the same for protected areas of the marine EEZ. These jobs regulate tourist traffic, provide information (visitor centres and shops), oversee the use of the areas and continually update regulation as we learn more about our ecosystems. Above all, there is a need for the government to invest in appropriate infrastructure, technology and education. Businesses can be built on skill development in ecosystem research and management. Together, we can all support Tobago’s brand: clean, green, safe and serene.


References:
Albert, S., Leon, J., Grinham, A.R., Church, J. A., Gibbes, B. R., Woodroffe, C. D. (2016) Interactions between sea-level rise and wave exposure on reef island dynamics in the Solomon Islands. Environmental Research Letters, 11, 054011.

World Economic Forum (2016),The New Plastics Economy; Rethinking the future of plastics
Hoegh-Guldberg, O. et al. (2015) Reviving the Ocean Economy: the case for action – 2015. WWF International, Gland, Switerland, Geneva, 60 pp.


Thursday, November 16, 2017

The Secret Lives of Coral Reef Fish

Anjani Ganase, marine biologist, looks into the world of coral reefs at some of the residents in these undersea cities. Down there, she says, it’s noisier than you think!

When we dive along coral reefs, we glimpse moments in the lives of the fish and marine creatures bustling about on their daily routines in underwater coral cities. At first glance, movements may appear arbitrary, but as you observe for a minute or two we start to recognise the activity the fish is carrying out, whether it is foraging or simply hiding out. However, for more rare activities or seasonal movements, such as at dawn or dusk or during mating season, this would require longer, more consistent times spent looking into the secret lives of fish. Here are a few observations of some reef fish behaviours:

Hunting buddies, the grouper and the moray eel

Grouper (Plectropomus pessuliferus) and Giant Moray Eel (Gymnothorax javanicus) make an excellent partnership for hunting on the coral reefs. How this partnership came about is not clear but it appears that the different strategies of the grouper and the moray eel compliment each other and therefore make for highly successful cooperative hunting of prey. Groupers tend to cruise over the coral reefs during the day, hunting fish that have strayed a bit too far off the reef. Moray eels are able to weave in between the reef framework, bombarding fish and backing them into tight corners. Morays also prefer to hunt at night, where low visibility gives them an advantage.

The grouper often initiates the hunting partnership, which is more likely to occur after an unsuccessful hunt when the grouper is hungry. The grouper will swim to a known resting spot of a moray eel, near to where it may have lost its prey. The grouper will then gesture to the eel in the form of a rapid shaking of the head in front of the eel’s face. The eel responds by swimming out on to the reef together with the grouper. If the uncaught prey is nearby, the grouper will then attempt to guide the eel to the location, usually a hole, where the prey previously escaped. The eel then uses its method of hunting. For the prey to escape the moray it may head to open water, where the grouper will be waiting. Alternatively, if the eel corners the prey, then the eel will have it for itself. Researchers have found that the grouper and moray eel could spend over half an hour hunting together, and both the grouper and the eel still benefitted overall from these arrangements, even though they did not share the meals (Bshary et al. 2006). On the occasions where the eel fed on the prey, the grouper did not appear to act aggressively towards the eel. Further research may be needed to determine whether the grouper will approach the same eel in the future. Groupers have also been observed gesturing for the aid of other predators. In an area of the reef where the prey is hiding, the grouper will remain near the opening and perform a headstand and shake its head to signal to others. Predators, such as napoleon wrasses, groupers and even moray eels may come over to assist in the hunt (Bshary et al. 2006).

Close up of a giant moray eel on Opal Reef, The Great Barrier Reef. Photo by Richard Vevers, The Ocean Agency, XL Catlin Seaview Survey.

Tool use by the wrasses

Only recently, certain species of wrasses, such as the black spot Tuskfish (Choerodon schoenleinii), yellowhead wrasse and sixbar wrasse, were recorded using corals as anvils to the crack the shells of cockles (Jones and Gardner 2011; Bernardi 2011). Tool use in the wild is associated with complex problem solving that extends the use of something other than a body part. The wrasses would uncover a bivalve, such as a cockle, by wafting the sand away with its fins. The wrasse would then pick the bivalve up using its mouth, swim over to a coral boulder and then pitch the bivalve towards the coral through sideways movement of its head. This action would be repeated multiple times until the shell of the bivalve is cracked and the fish could eat the insides (Bernardi 2011)


A school of Bumphead parrotfish hovers over a coral reef bommie. Photo by Richard Vevers, The Ocean Agency, XL Catlin Seaview Survey
Head butting bumphead parrotfish

On almost every dive along the northern Great Barrier Reef we would encounter schools of bumphead parrotfish, cruising along the shallows and foraging on corals. These fish may look intimidating with their bulbous head and chicklet smile but generally are not aggressive fish. Despite the frequent encounters, I’ve never experienced bumphead head-butting each other to win the favour of a female. This was the experience of scientist Roldan Muñoz and others, while diving in a remote marine reserve in the western Pacific: male bumpheads were observed repeatedly head-butting each other in an epic battle for the right to mate. The sounds that are produced from these repeated head bumps were quite loud and metallic. Encountering this aggressive behaviour also suggested that the marine reserve was also a spawning ground for bumphead parrotfish (Muñoz et al. 2012).

Perfect flatmates – the pistol shrimp and the goby

Living at the sandy edges of coral reefs, the goby sits beside a hole keeping a watch for predators. Meanwhile, his roommate, the pistol shrimp, busily maintains the burrow that they both share, by relocating sand and setting up coral and shell reinforcements along the sides and the opening of the burrow. The pistol shrimp is blind and therefore relies on movements of the Goby’s tail nearby to let it know when danger is around so that it can retreat back into the hole. The pistol shrimp has an enlarged claw that acts as another line of defence. When the claw clamps down, it sounds like a pistol blast, making it the noisiest animal in the ocean (relative to its size), beating even the sounds of whales and other large marine animals. The goby feeds on organisms, such as crustaceans and amphipods that live among the sand particulates stirred up by the shrimp. The shrimp, on the other hand, feeds on mostly detritus, some of it from cleaning the goby. After sunset, both shrimp and goby retreat back into the burrow, which becomes closed in by the end of the night either intentionally, or just from lack of maintenance overnight. In the morning, the goby pushes through the sediment and both goby and shrimp each begin their job of look out and excavator. The survival of the Goby and the shrimp is dependent on due diligence by the two creatures.

References:
Bshary R, Hohner A, Ait-el-Djoudi K, Fricke H (2006) Interspecific Communicative and Coordinated Hunting between Groupers and Giant Moray Eels in the Red Sea. PLoS Biol4(12): e431. https://doi.org/10.1371/journal.pbio.0040431

Jones, A.M., Brown, C. & Gardner, S. Coral Reefs (2011) 30: 865. https://doi.org/10.1007/s00338-011-0790-y

Karplus, I. (1987), The Association between Gobiid fishes and burrowing alpheid shrimps. Oceanogr. Mar. Biol. Ann. Rev., 25, 507 562

Muñoz RC, Zgliczynski BJ, Laughlin JL, Teer BZ (2012) Extraordinary Aggressive Behavior from the Giant Coral Reef Fish, Bolbometopon muricatum, in a
Remote Marine Reserve. PLoS ONE 7(6): e38120. doi:10.1371/journal.pone.0038120



Thursday, November 9, 2017

Do you know where your seafood comes from?


Anjani Ganase, marine biologist, alerts us to the risks in eating seafood of unknown origins. These are some of the questions she suggests that we ask before we purchase.

Growing up in Trinidad and Tobago, I’ve had the luxury of eating freshly caught fish straight off the fisherman’s boat or caught by a family member or friend. We learned to identify the common species of fish that live in our local waters, identify their flavours and how to cook the different fish species. Other countries and cities are not as fortunate as fish is brought from great distances and often pre-packaged and frozen. Unfortunately, more and more fish are being bought in the supermarkets with fewer visits to the local fish depot; and there are fewer occasions of a friend handing over a fresh catch.

It may be that this is still happening. But, according to the FAO (Food and Agriculture Organization of the United Nations) since 2002, the import of fish to Trinidad and Tobago began to exceed local catch and exports. In 2014, we spent about 52.5 million USD to import seafood, which is almost four times the amount earned from our local fisheries (FAO). With more people eating imported fish, there is a need to understand the global fishing industry and how it affects you and your local economy and environment. Here are questions that you should ask about the fish that you eat.

What is it? 

A study done by Oceana revealed that globally, 1 in 25 fish being sold is mislabelled, where the mislabelling can occur at any level along the chain of supply until it reaches the consumer. There are severe consequences to this, especially among fish species that have very different life histories. Knowing what you eat is better for multiple reasons.

Firstly, your health. Consider the higher diversity of fish and other marine life in the ocean: the diets and habits of the fish in the ocean are just as varied - if not more so - as land animals. The top predators – the lions and tigers of the ocean – are the sharks, tunas and swordfish, to name a few, which have very different lifestyles and feed on different prey. Being on top of the food chain, these species of fish build up a significant storage of toxins and organic chemicals that were passed up the food chain. Methylmercury is one of the chemicals that bio-accumulates in the fatty tissues. Health officials have warned that long-term consumption of these fish species can also lead to a build up in your body over time and result in mercury poisoning; symptoms include tremors, numbness or pain in parts of your body, changes in vision and hearing. Species of fish that are high in mercury and should not be consumed include: swordfish, shark, king mackerel, Spanish mackerel, grouper, marlin and Chilean sea bass. There are many other fish species that have low mercury content and are still rich in the necessary fatty acids.

Sustaining fish stocks goes hand in hand with being selective about what you eat. Much of the fish species that are longer-lived predators usually take four to five years to reach maturity and become reproductive. The rapid rates at which humans are removing these fish put them at great risk of a rapid population crash. The biomass of predator fish globally has declined by two thirds over the last 100 years with the majority of this loss occurring in the last forty years (Christensen et al 2014). Furthermore, many fish that are mislabelled turn out to be species that are already overfished and therefore threatened with extinction. For example, an overfished rockfish species was being sold as Pacific Red Snapper in California (Logan et al. 2008). This mislabelling does not help consumers that are trying to do the right thing.

Trinbagonians – as well as others - need to avoid the complacency of not knowing the type of fish we eat. In Australia, for example, the basic term “white fish” is often accepted when purchasing fish from a fish and chips shop. This is a general term where the flesh of the fish is white. Think about this for a second: if you are given a meat pie and you ask what meat is inside, and the response is"red meat," how do you feel?


A fishing net draped over a coral reef is used to catch the fish we eat but it also entraps other marine organisms and damages the surrounding habitat. Fishing practices need to be more sustainable, targeting only the seafood that we want without destroying the habitat or other ecologically important marine life.

 


Where is it from?

When we buy fish straight off the boats near a beach or at fish markets, we are usually assured of fish that is fresh from our coastal and offshore waters. In the freezer department of the supermarket, however, what fish is available? Where is it from?

Fish farms have been growing in numbers over the last decade to balance the demand of fish with the decline in stocks of fish worldwide. The quality of the fish farms depends on the species of fish and how well they do in captivity and the amount of antibiotics being used to to prevent disease. Over the years, the technology behind of fish farms has improved dramatically; the farms can be set up to be environmental friendly and sustainable.

The best quality seafood farms are those dedicated to rearing crustaceans, such as oysters, clams, mussels and scallops. These sedentary filter feeders strain out particulates from the surrounding water column. The majority of these filter feeders are farmed in coastal bay areas, where they are suspended so the concerns you should have will be related to the run off from the land and the pollution in the water column. It is crucial that these farming habitats are regulated to maintain healthy conditions. Of all the farmed seafood these have the lowest environmental impacts as they simply feed on the plankton already existing in the water column and it is the preferred purchase by environmentally conscientious consumers.

If caught in the wild, then how was it caught?

There are many pros and cons to wild caught fish, with the biggest con being the lack of regulation resulting in the rapid depletion of fish stocks. Although some countries have regulations governing pelagic fish, there is no global regulation on what can be caught and how much. The methods used to fish can also be devastating to the marine ecology. The most detrimental of all is shrimp trawling. This method involves collecting shrimp by scraping the bottom habitats and gathering everything into a net. The method destroys the whole ecosystem that is home to the shrimp as well as many other organisms. This includes fish species (mostly inedible), sea turtles, dolphins, corals and other benthic invertebrates. Most of the shrimp trawling for Trinidad occurs in the Gulf of Paria. A study done in 1991 estimated that for every kilo of shrimp being caught, at least 20 kg of demersal fish were caught and discarded. An estimated total of 1,500,000 kg of by-catch, which included demersal fish and other invertebrate life, were estimated to be discarded over the ten-month study period (Maharaj and Recksiek, 1991). Ironically, the Gulf has been a growing industrial coastline over the last thirty years with a considerable amount of pollution run off. I wonder how much viable catch is collected today.

In Tobago, fishing takes place from relatively small-scaled artisanal craft, with significant cultural value to the local communities. While choosing local is always the preferred choice for a greener future, it is also imperative that consumers demand sustainable practices.  For the sake of our health, we must insist that fishermen and consumers alike be educated about the seafood we eat; and the ecological roles they have in maintaining our ecosystems (our surroundings) in the long-term.

References:
Christensen, V., Coll, M., Piroddi, C., Steenbeek, J., Buszowski, J., & Pauly, D. (2014). A century of fish biomass decline in the ocean. Marine Ecology Progress Series, 512, 155-166.

Maharaj, Vishwanie and Recksiek, Conrad (1991) The By-catch From the Artisanal Shrimp Trawl Fishery, Gulf of Paria, Trinidad.Marine Fisheries Review, 53(2), pp. 9-15.

Cheryl A. Logan, C. A., Alter, S. E., Haupt, A. J., Tomalty, K., Palumbi, S. R. (2008) An impediment to consumer choice: Overfished species are sold as Pacific red snapper. Biological Conservation, 141, 1591 – 1599.
FAO website: www.fao.org/fi/oldsite/FCP/en/tto/profile.htm

More information on Oceana seafood fraud campaign:
oceana.org/our-campaigns/seafood_fraud/campaign


Thursday, November 2, 2017

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.