A resident population of stingrays has made the North Sound Sandbar their long-term home, population data from the latest stingray census indicates.
Volunteers and scientists working with the Guy Harvey Research Institute counted 96 stingrays, including 84 females and 12 males, in the latest census at the popular tourism attraction last week. A total of 90 stingrays were counted in the previous two surveys at the site.
Researchers at the institute analyzed the January 2016 data alongside figures from 10 previous population counts. They conclude, in a report on the census data, that while there are frequently new arrivals to the Sandbar, the vast majority of the population can be found at the site year after year.
“The observation that the largest proportion of stingrays in the January 2016 census had already been tagged indicates remarkable site fidelity,” according to the summary report.
Of the 96 stingrays counted over the three-day census, only seven had not been fitted with tags in previous surveys.
The researchers say the continued occurrence of untagged stingrays during the biennial census demonstrates a “continuous immigration of new individuals” to the site, despite the broader trend of site fidelity.
The report is authored by Mahmood Shivji of Nova Southeastern University, Brad Wetherbee of the University of Rhode Island, Mr. Harvey and Alexandra Prebble of the Guy Harvey Research Institute.
Stingrays are typically solitary animals and nocturnal foragers that patrol large areas of reef looking for food. The aggregation at the Sandbar is an anomaly and, as such, a unique study opportunity for scientists.
Mr. Harvey said the long-term monitoring of life at the Sandbar is also essential to providing the basis for management, sustainability and conservation decisions at the attraction.
His research institute, which carries out the work in partnership with Nova Southeastern University in consultations with the Department of Environment and part-sponsored by Dart Cayman Islands, first surveyed the Sandbar in 2002. Consistent surveys began taking place in 2012 after concerns were raised that numbers had dipped.
Since the first census in 2002, when around 160 rays were counted, a total of 314 individual rays have been observed at the site, 244 female and 70 male. The lowest counted in any one census was 57 in July 2012.
The team will return to the site in July this year.