Characterisation and monitoring of one of the world's most valuable ecotourism animals, the southern stingray at Stingray City, Grand Cayman

Abstract

Southern stingrays (Hypanus americanus) represent a multimillion dollar ecotourism operation in Grand Cayman, interacting with over a million visitors annually. Over 30 years of stingray provisioning by tour operators has provided a predictable aggregation at the Stingray City Sandbar (SCS). Despite potentially negative effects of provisioning and concerns about declining stingray numbers at SCS, there has never been a formal assessment of the aggregation. In the present study we analysed tagging data from 2002 to 2015 and established structured censuses monitoring the aggregation. The consistently female-dominated aggregation declined between 2008 and 2012, from >100 to <60 stingrays, but has increased since 2012, stabilising at ~90 stingrays. Female site fidelity was high, with ~20% of females resident for ≥10 years, compared with only 3 years for most males. Stingrays were also found to have growth rates similar to those in captivity. The results of the present study suggest the SCS aggregation is highly dependent on individuals arriving from the island-wide stingray population, susceptible to perturbation, and that successful management of activities at SCS will benefit from regular monitoring of the stingray aggregation. We chronicle the historical status of this well-known and economically valuable marine resource and provide suggestions applicable towards sustainable human–marine wildlife interactions for similar resources.

Seasonal patterns in stable isotope and fatty acid profiles of southern stingrays (Hypanus americana) at Stingray City Sandbar, Grand Cayman

“…Differences in growth rates can affect stable isotope turnover and tissue discrimination and higher growth rates reduce nitrogen discrimination 62 . While male southern stingrays do exhibit faster growth rates than females in this sexually dimorphic species 39 , animals sampled in this study were within reported ranges for maximum disc width for adult males and females. This suggests that these animals had reached maturity were not likely actively growing and δ 15 N values would not be greatly affected by this variable.…”

“…North of the sandbar is an adjacent patchwork of deeper reefs and habitat to the south is primarily seagrass beds. There are over one million visitors to the SCS site annually, where they interact with approximately 100 stingrays, 80% of which are large mature females (personal communication Cayman Islands Department of Environment, 39 ). Stingrays at SCS show very high fidelity to the feeding site, with females resident for an average of 10 years, and males resident for an average of 3 years 39 , demonstrating chronic provisioning of the animals.…”

Linking local movement and molecular analysis to explore philopatry and population connectivity of the southern stingray Hypanus americanus

“…Size–frequency distribution of Hypanus americanus individuals captured between January 2015 and May 2017 at Cape Eleuthera, Bahamas ( n = 200, females = 155, males = 45). Size threshold for maturity is ≥750 mm for females and ≥ 470 mm for males, indicated by grey scale according to the legend males (Ramirez Mosqueda et al ., 2012; Vaudo et al ., 2018). () Immature and () mature…”

“…The disc width, body length and total length were measured to the nearest millimetre. Sex was identified by the presence/absence of male reproductive organs, and maturity was confirmed by the disc width, with threshold being 750 mm for females and 470 mm for males (Ramirez Mosqueda et al ., 2012; Vaudo et al ., 2018). Neonates would be expected to measure 200–340 mm disc width (Henningsen, 2000).…”

“…One dasyatid ray that is ubiquitous within this region is the southern stingray ( Hypanus americanus , Hildebrand & Schroeder, 1928), which is distributed throughout the coastal areas of the Caribbean Sea, the Gulf of Mexico and the northeast coast of South America. They are a valuable subject of ecotourism activities and attract more than a million visitors annually to the Stingray City Sandbar, Grand Cayman (Vaudo et al ., 2018). Meanwhile, fisheries in the southern Gulf of Mexico targeting the southern stingray are most likely responsible for a decrease in abundance (Shepherd & Myers, 2005).…”