Stingrays at the Sandbar and Stingray City are enjoying a new treat that, as well as giving the animals a more varied diet, is also helping control an invasive marine species.
Water sports operation Ocean Frontiers is now feeding lionfish heads to the stingrays at the popular tourist sites in Grand Cayman to supplement the squid fed to them by visitors and boat operators daily.
Steve Broadbelt, owner of Ocean Frontiers, which has been active in culling lionfish since the invasive species first appeared in Cayman waters nearly five years ago, said his company has been feeding Southern Stingrays the leftover lionfish heads from the fish its divers catch.
Mr. Broadbelt said he has become so accustomed to recycling that it seemed a shame to waste the lionfish heads.
“I thought there has to be something else we can do with them. Knowing the concerns with the stingrays’ diet being predominantly squid in the North Sound and I’ve seen a study that shows the nutrition that the stingrays get from that is less than ideal,” he said.
And while a raw, bony fish head, complete with eyes and brain may not appeal to a human diner, the stingrays seem to be lapping up the new dish and when offered squid or a lionfish head, they invariably opt for the crunchy head, Mr. Broadbelt said.
The natural diet of stingrays in the wild consists of mollusks, fish and crustaceans. The jaws of a stingray have blunt, broad teeth aligned in rows, which enable the animal to crack the shells of it prey.
A group of scientists from the Georgia Aquarium visited the Sandbar in July. Among them was nutritionist Lisa Hoopes, who examined the diet and health of the stingrays.
Commenting on the addition of another foodstuff to the stingray’s diet, Ms Hoopes told the Caymanian Compass in an e-mail: “The main issue with squid from a nutritional standpoint is that it is the sole source of food for these stingrays since they do not forage elsewhere. While we don’t know the specific nutrient requirements for stingrays, we do know that differences can be seen in the blood of stingrays feeding on a wild-diet versus those fed on a primarily squid-diet from the sandbar.
“While it is unclear what the long-term effects of feeding an all-squid diet may be for the stingrays at the sandbar, in my opinion, increasing diet diversity for these stingrays could be a good thing,” she wrote.
Divers have been trying to kill lionfish at the most popular dive sites in the Cayman Islands, as the invasive species can decimate a population of juvenile reef fish among the coral reefs in a few weeks. Lionfish are featuring on more and more menus in restaurants in Cayman as diners get a taste for the white, meaty flesh.
One restaurant that has been serving up lionfish since it first opened is Michael’s Genuine in Camana Bay. Its executive chef, Thomas Tennant, is also working on turning the leftover bits of the lionfish into food for stingrays. He grinds the bones and heads and unused raw flesh of the fish into a paste, which is then cut up into brownie-sized snacks that the stingrays have also been fed.
“It doesn’t have the same crunch as the lionfish heads because it’s been ground, but it has the same nutritional value and it’s potentially easier to package and distribute,” Mr. Broadbelt said.
The chef has made two batches of the all-natural paste, which is frozen to keep it fresh. “It seems they were fairly successful batches. The stingrays enjoyed them, apparently,” Mr. Tennant said.
Making the lionfish paste is not as simple as making sausages, he admitted. “A meat grinder wouldn’t work because of the bones and head. I had to grind them up in a blender,” he said.
Mr. Broadbelt said that if feeding lionfish heads to the almost tame stingrays at the Sandbar catches on and boat operators start taking the heads as well as, or instead of, squid to the Sandbar, then a whole new market for the fish would open up and the demand for lionfish would grow – thus, encouraging people to catch and cull more of them.
However, although the stingrays seem to be more than willing to gulp down lionfish heads, it’s unlikely they’ll become predators of living lionfish, as they are bottom feeders in the wild, foraging for food in the seabed. Lionfish are more commonly found among crevices, rocks and coral on the reefs.
Lionfish have no natural predators in the Caribbean, so the only way to remove them from the wild is for divers and snorkellers to cull them.
The fish, which can spawn 30,000 eggs a month, are the only marine species that can be legally removed from protected marine parks and dive sites in the Cayman Islands.