Researchers are tracking shark, snapper and grouper populations to monitor the health of predators on Cayman’s reefs.
An ongoing study by a team from the Department of Environment and Marine Conservation International is focusing particularly on Caribbean reef sharks, tiger sharks and Oceanic whitetip sharks.
A new phase of the research will also look at mutton and lagoon snapper and tiger grouper. The study is independent of the Guy Harvey Research Institute’s tagging and monitoring of Oceanic whitetip sharks, but the two teams will share data.
Mauvis Gore of Marine Conservation International said the study team has been collecting data on shark populations since 2009.
She said preliminary results from this year’s efforts suggest shark numbers are declining in Cayman’s waters.
Researchers use a variety of methods, including monitoring reefs with baited cameras, to estimate shark populations at more than 30 test sites around all three islands.
Other methods include diver surveys, catching, photographing and releasing sharks and monitoring their movements using tags.
The combination of approaches allows researchers to get an accurate picture of the number of sharks in Cayman’s waters.
The information can be used to help inform a species monitoring plan, required as part of the new National Conservation Law for protected species.
The study has already yielded some interesting results. One Caribbean reef shark was recorded on reefs around Little Cayman, Cayman Brac and off East End in Grand Cayman, challenging previous assumptions that these sharks remain “resident” on specific reefs.
Ms. Gore says further research is important to assess the impact of conservation plans.
“We don’t just need a few sharks for the system to work, we need a lot of them. You need apex predators to keep the reefs healthy,” she said.
“For example, sharks play a key role in keeping secondary predator numbers in line so that the reef fish, such as parrot fish, can continue to keep our reefs healthy by scraping off the algae.”
Beyond their environmental value, sharks have a quantifiable value to Cayman’s tourism-based economy, according to the research team.
Using surveys and questionnaires, the researchers came up with an estimated dollar value based on what tourists were willing to pay to have sharks on the reefs.
“The value of having sharks on the reef is about US$54 million per year. By contrast, catching and killing sharks was worth only US$1.6 million per year. Neighbouring Bahamas earn about US$78 million per year from sharks on their reef,” the Department of Environment and Marine Conservation International said in a joint statement about the research, principally funded by the Darwin Initiative.
“Of course, once a shark is dead, its value is used up,” noted Department of Environment Director Gina Ebanks-Petrie, “whereas a live shark continues to play a valuable role on the reef and provides economic worth to our economy year after year after year.”
The project is also working on population surveys of tiger grouper and mutton and lagoon snapper, analyzing the food these fish are living on and where they reproduce.
Ms. Gore said, “We are looking at the next step down the chain. We are trying to build liaison groups with fishermen to work towards sustainable fishing for everyone.”
The Department of Environment is asking fishermen to assist with samples from snapper or grouper. The researchers also ask that anyone who sees or catches a fish with any sort of tag to call them on 949-8469.
For more information about this research and reward program, visit www.doe.ky.