Cape Town - Wanted: Alive not dead. That’s the whale shark, the world’s biggest fish that has now become a major tourist attraction and a big earner all over the world – particularly in the Maldives, Australia, the Gulf of Mexico and the Seychelles, but also in places closer to home such as Sodwana Bay in the Greater St Lucia Wetland Park and at several highly popular dive sites in southern Mozambique such as Tofo Beach and Ponta do Ouro.
Until now, the impact of what researchers call “this majestic and charismatic animal” on the economy of the relatively poor island nation of the Maldives was largely unknown. But a new study by scientists from the the Maldives Whale Shark Research Programme has revealed that just a small group of whale sharks in a single Maldivian atoll accounts for nearly 3 percent of global shark ecotourism spend and nearly half of that spent in the Maldives.
The Maldives is one of the few known year-round aggregation sites for whale sharks, said James Hancock, research programme director of co-author of a paper about the study that recently appeared in PeerJ – an open access, peer-reviewed scientific journal. “We’ve seen that they have become a major tourism draw to South Ari atoll, but we didn’t expect these big numbers”.
The South Ari atoll Marine Protected Area (Sampa) – first designated in 2009 and at 42km2 the largest protected area in the Maldives – alone attracted 77 000 tourists last year. This equates to $9.4-million in direct income to operators who offer the chance to glimpse the famous “bucket list” animal.
This is the first value that’s been attributed to this burgeoning industry in the Maldives, and it’s also the first time that a valuation for a wildlife viewing experience has been calculated exclusively from observational studies. “Instead of surveying tourists and extrapolating results, we actually went out and counted how many boats and people there were in the water looking for sharks,” said Neal Collins, one of the co-authors.
Fellow co-author Fernando Cagua said when they included the whale sharks from South Ari atoll, they were able to adjust previous estimates of annual “shark-related” tourism expenditure in the Maldives from $12m to nearly $20m. “There are still many mysteries about these whale sharks – we don’t know why they come here or for how long they stay – but bringing the money issue to the table is an important step towards ensuring their conservation.”
Richard Rees, director of the research programme, said: “In a sense the whale sharks here are perfect for wildlife tourism. They are the largest shark in the world and the slow-moving, shallow-swimming behaviour they exhibit in Sampa waters makes them accessible, not just to scuba divers, but also to snorkel excursions.
“This opens up an incredible wildlife experience to just about everyone, which brings with it a degree of risk in terms of the welfare of both sharks and tourists. The encouraging thing is that everyone in the industry we talk to agrees these risks need to be managed and the local communities are receptive to participating in the management of the area.”
In another new study on whale sharks, scientists from the US and Saudi Arabia have shed light on the hitherto largely secret breeding and migratory habits of the species by discovering a juvenile whale shark aggregation in the Red Sea. They say little was known about the sharks’ movements on a daily basis.
In a study published in the journal Plos One, scientists from Woods Hole Oceanographic Institution in Massachusetts and colleagues from the King Abdullah University of Science and Technology and Massachusetts Division of Marine Fisheries reported on the movements of whale sharks tagged at the Red Sea site.
During fieldwork in 2009, the research team found hundreds of juvenile whale sharks gathering on coral reefs near Al-Lith on the central coast of the Saudi Arabian Red Sea.
“The fact that there were so many whale sharks in such a small area gave us an opportunity to begin an unprecedented study to answer some of the basic questions,” said Simon Thorrold, a Woods Hole biologist and co-author of the paper.
The team used three types of satellite-transmitting tags to track the movements of 47 whale sharks between 2009 and 2011. The tags, placed just below the dorsal fins, measure temperature, depth and light levels of the waters the fish swim in. After several months, the tags pop off, float to the surface and beam data via the Argo satellite system back to computers on shore.
Diving data from the tags revealed that the sharks made frequent deep dives to at least 500m, while three of them went deeper than 1 000m and one reached 1 360m.
While most of the sharks stayed in the southern Red Sea throughout the time the tags were on, a few tagged individuals headed into the Indian Ocean. Because most remained relatively close to where they were tagged, this suggests that this area represents a critical juvenile habitat for this population, said Thorrold.
No adult whale sharks were seen at the site, which might serve as a “staging ground” for juveniles before they move on to regional aggregations of larger sharks, the scientists said. Twelve whale shark aggregation sites have been identified globally.
Knowing where they go at different times of the year is critical to designing effective conservation strategies for the species, said Thorrold.
In a third recent study, the largest yet conducted on the genetics of whale sharks, researchers found that the giant fish probably exists in two distinct populations, with minimal connectivity between those in the Indo-Pacific and others in the Atlantic Ocean.
Writing in the scientific journal Molecular Ecology, they said they found a significant population expansion of this species – possibly during the Holocene (the geological epoch that started 11 700 years ago and continues today).
However, this historic trend of population increase may have reversed recently, they warned, citing declines in genetic diversity found over six consecutive years in animals visiting Australia’s Ningaloo Reef.
They suggested these declines may be because of commercial-scale harvesting and collisions with boats in past decades in other countries in the Indo-Pacific, and said their study supported a continued focus on effective protection of the world’s largest fish “at multiple spatial scales”.
Gentle giants are listed as vulnerable
The Whale Shark Rhincodon typus is the sole representative of its genus and also the only member of the family, Rhincodontidae.
Known as the gentle giants of the ocean, these mostly plankton-eating filter feeders can reach a length of 12m and are the largest non-mammalian animals on Earth, with adults weighing on average around 18-19 tons – more than many dinosaurs did.
According to Wikipedia, the largest confirmed individual was 12.65m long and weighed more than 21.5 tons. But there are unconfirmed reports of individual whale sharks as big as 14m-plus and weighing at least 30 tons.
Preferring tropical and warm temperate waters, whale sharks do venture as far south as Cape Town.
Generally passive and non-aggressive to divers, a whale shark feeds by swimming along with its massive mouth wide open, scooping up plankton and small fish as it goes.
It was named by army surgeon Dr Andrew Smith after he inspected the carcass of a specimen that had been harpooned in Table Bay in April 1928. It was a “baby”, just 4.5m long.
Whales sharks are listed as “vulnerable” on the International Union for the Conservation of Nature Red List of Threatened Species, mainly because so little is known about them.
They are now protected in many places in the world and are also listed under the Convention on the International Trade in Endangered Species Appendix II, but they continue to be hunted illegally in parts of Asia, such as the Philippines.
Like other sharks and large rays, whale sharks probably have small litters of pups and are slow to reach sexual maturity.