Shark populations in Cayman Islands’ waters could be at risk from overfishing, including shark finning, researchers have warned.
Scientists conducting the first ever “shark census” in the territory’s waters found 12 different species around Grand Cayman and the Sister Islands.
But they warned there are far fewer sharks in Cayman’s waters than they expected, based on what is seen elsewhere in the Caribbean and along the coast of Central America. They expected to see at least 11 additional species and higher numbers of the sharks that they did find.
The researchers also found evidence of some shark finning taking place in the Cayman Islands. They suggest, based on the relatively low shark populations across the three islands, that the level of shark fishing may be higher than previously imagined.
And they warn the potential cost of failing to protect Cayman’s sharks could run to millions of dollars.
They estimated that sharks are worth around US$1.6 million to the islands annually in terms of their consumptive value as a “fishery”. Their “non-consumptive” value, including their impact on tourism and SCUBA diving, was estimated at up to $60 million. In other words, a shark is worth 40 times as much to the Cayman Islands economy alive in the water as it is dead on a boat, according to the research.
Project leader Mauvis Gore said the amount and frequency of sharks encountered during the course of the project paled in comparison with what is seen elsewhere in the region.
The researchers will return to Little Cayman on Wednesday, in part, to evaluate whether numbers have declined even further since they began surveying sharks in 2008.
Ms Gore said: “The numbers were not what we would expect for a healthy reef system. When you compare the numbers to elsewhere in the Caribbean, they are not in order. A major reason for that is over fishing.”
A photograph taken in 2011 and passed to the research team showed several shark fins hanging on a boat docked in George Town. [*see Editor’s note below] It is not clear how widespread shark finning is in the Cayman Islands, but there is currently no law against this or any other type of shark fishing.
A worldwide campaign against shark finning, which often involves fishermen slicing the fin from the shark and throwing the body back into the water, has led to bans in several countries.
Sharks take a long time to mature and produce few pups, making it difficult for the species to recover from over fishing.
The Cayman Islands National Conservation Bill, in its draft form, included protection for sharks, but the bill has yet to be debated in the Legislative Assembly, despite being on the books for almost a decade.
The only current, relevant legislation is a ban on feeding sharks.
Moves to protect sharks have been hampered by an old-fashioned perception that they are indiscriminate killers, with no value to the reefs.
Ms Gore, co-director of Marine Conservation International, who leads the Save our Seas Foundation team on the Cayman project in partnership with the Cayman Islands Department of Environment, says apex predators are essential to the health of the entire marine ecosystem.
“The vast majority of sharks around the Cayman Islands are reef sharks. They are shy of humans and have an essential role in keeping the ecosystem in balance.
“You can’t underestimate the value of apex predators. Think of it like this, if you took all of the lions out of an African national park, you would see a huge explosion in antelope. The antelope would eat all the grass then starve, creating a complete imbalance in the ecosystem,” she said.
Another potential avenue for the researchers to explore in the coming months is the question of whether sharks could eventually begin to feed on lionfish. The invasive species, which has no natural predators in the Atlantic, is a major threat to many species on the reefs and scientists are currently testing the idea that sharks could be part of the solution.
So far the project has focused on gathering and disseminating information that could potentially inform conservation efforts.
The research team has used underwater cameras, with a scent plume to attract sharks in the vicinity, to log sightings at specified points around the three islands.
They have also caught, counted and tagged sharks using “scientific long lines”, which use round hooks to avoid hurting the sharks.
The movements of the tagged sharks suggest that while open water species like tiger sharks and hammerheads roam the Caribbean and the waters as far west as central America, reef sharks stay local, foraging between the three islands.
“Until we started this, we didn’t know what sharks were here, how many, what areas they used and at what time of year. We now have a considerable amount of information on this.”
Ms Gore said reliable up-to-date information was helpful to inform public debate.
She would like to see the conservation bill come into force to ban shark fishing completely, but she believes that a public education programme will be required alongside enforcement.
“The shark population really does need management. It can’t just be about a ban. There is no point putting a ban in place if people feel it is unfair or they don’t understand it. People need to know what this means for them.”
The species of shark observed by the research team included: Caribbean reef shark, black tip reef shark, nurse shark, lemon shark, great hammerhead, scalloped hammerhead, tiger shark, silky shark, oceanic white tip shark, blue shark, shortfin mako shark and whale shark.
[*] Editor’s note: Story changed in the annotated paragraph to reflect the fact that shark fins were hanging on a boat docked in George Town.