Environ Biol Fish DOI 10.1007/s10641-010-9739-1 Spatial and temporal trends in yellow stingray abundance: evidence from diver surveys Christine A. Ward-Paige & Christy Pattengill-Semmens & Ransom A. Myers & Heike K. Lotze Received: 26 November 2009 /Accepted: 31 October 2010 # Springer Science+Business Media B.V. 2010 Abstract Recent concerns about changing elasmo- highest occurrence in the regions surrounding Cuba. branch populations have prompted the need to Overall, sighting frequency declined from 20.5% in understand their patterns of distribution and abun- 1994 to 4.7% in 2007—a standardized decline rate of dance through non-destructive sampling methods. −0.11. However, these trends were not consistent in Since scientific divers represent a small portion of all regions. The strongest decline occurred in the the total number of divers worldwide, the use of non- Florida Keys, the most sampled region, where trends scientific divers could drastically increase the number were similar among all areas, habitats and depths. In of observations needed to monitor broad-scale, long- contrast, sighting frequency significantly increased in term trends. Here, we use 83,940 surveys collected by Jamaica where large fishes are severely depleted. We trained volunteer divers to examine spatial and discuss possible explanations for these changes temporal trends of the most frequently sighted including habitat degradation, exploitation and elasmobranch species in the greater-Caribbean, the changes in trophic interactions. Our results suggest yellow stingray (Urobatis jamaicensis). Despite being large-scale changes in yellow stingray abundance that relatively common and listed as Least Concern on the have been unnoticed by the scientific community. IUCN Red List, little is known about the status of this Thus, our study highlights the value of non-scientific species. In total, yellow stingrays were observed on divers for collecting data that can be used to 5,658 surveys (6.7% sighting frequency) with the understand population trends of otherwise poorly studied species. Ransom A. Myers: deceased. Keywords Citizen science . Elasmobranch Electronic supplementary material The online version of this monitoring . Yellowstingray . Diversurvey. Population article (doi:10.1007/s10641-010-9739-1) contains trend . Trophic interactions supplementary material, which is available to authorized users. C. A. Ward-Paige (*) : R. A. Myers : H. K. Lotze Department of Biology, Dalhousie University, Introduction 1355 Oxford St., Halifax, NS B3H 4J1, Canada e-mail: [email protected] Strong changes in elasmobranch populations have been described in marine ecosystems, with precipi- C. Pattengill-Semmens tous declines in many large sharks that are caught as Reef Environmental Education Foundation, 98300 Overseas Hwy., P.O Box 246, target or bycatch species in commercial fisheries Key Largo, FL 33037, USA (Baum et al. 2003; Baum and Myers 2004; Ferretti Environ Biol Fish et al. 2008) and resulting increases in smaller sharks refuge. Here, non-extractive methods are essential to and rays from predation and competition release provide information on population trends. Underwater (Shepherd and Myers 2005;Myersetal.2007; visual censuses (UVC) conducted by scientific divers Ferretti et al. 2010). Despite improvements to our is an established method that has been used widely understanding of population trends in some species since the 1950’s (Brock 1954) as an alternative to and regions, a large number of elasmobranchs and extractive methods for describing and monitoring fish systems remain unexplored. In the greater-Caribbean, populations. UVC have been used in a range of areas for example, the yellow stingray (Urobatis jamaicen- and habitats and sometimes include elasmobranchs sis) is among the most commonly sighted elasmo- where they are relatively abundant (Friedlander and branch species observed by scuba divers, yet, with the DeMartini 2002; Robbins et al. 2006; Stevenson et al. exception of a study in south Florida (Fahy 2004), 2007; Sandin et al. 2008). Often, however, elasmo- there is little scientific information on the status of branchs are excluded from UVC because they occur this species. According to the World Conservation at low abundance and rarely enter survey boundaries Union Red List (IUCN: www.iucnredlist.org), the (Kimmel 1985). yellow stingray is listed as Least Concern; however, Because elasmobranchs have relatively large home the same source also states that this species is likely ranges, are mobile, and are observed infrequently, affected by inshore fisheries, habitat degradation and they are difficult to study by scientific diver observa- exploitation for the aquarium industry and that tions alone. Even a well designed scientific survey temporal trends are unknown. Because they are would have difficulty describing the broad-scale considered to be abundant and tolerate captivity well distribution and long-term temporal changes to a yellow stingrays are recommended for scientific population of any elasmobranch species because of experiments (Fahy and Sherman 2000) and their logistical reasons and high costs. Similarly, to occurrence in the scientific literature is mostly limited understand general population trends, a wide variety to biochemical, neurological, and physiological of areas, habitats and environmental conditions need experiments (Sulikowski and Maginniss 2001; Barnes to be covered, requiring large amounts of data to et al. 2003; Dwivedi and Trombetta 2006). The reduce the variance and distinguish regional trends. paucity of ecological information may be explained Therefore, it would be ideal to have all divers, with by the fact that yellow stingrays are not economically their wide range of diving interests, reporting elas- important—there is no directed tourism or fishery for mobranch sightings (and non-sightings) from their this species (www.iucnredlist.org). Since yellow daily dive activities. stingrays are relatively small (~76 cm) and often seen A number of volunteer based projects have singly and infrequently it is unlikely that changes in specifically censused sharks at local, regional, and abundance would be noticed even from anecdotal global scales. For example, the Thresher Shark evidence like that reported for other more valuable Monitoring Project (www.malapascua.net) uses recre- species (e.g. groupers: Saenz-Arroyo et al. 2005). ational diver reports of the number of thresher sharks Here, we investigate spatial and temporal trends in seen at Monad Shoal in the Philippines to monitor sighting frequency of the yellow stingray in the local changes in abundance. Examples of more greater-Caribbean. regional organized shark counts include the Great Over the past decade, most studies concerned with Australian Shark Count (www.auf-spearfishing.com.au) trends in elasmobranchs have used catch or bycatch where divers report the sharks they see during their data from fisheries dependent or independent sources daily activities to get estimates of abundance. Also, the to analyze population changes (Baum et al. 2003; Shark Trust asks divers to upload images of opportu- Shepherd and Myers 2005; Myers et al. 2007; Ferretti nistic sightings of any elasmobranch species (www. et al. 2008). However, these are not informative for sharktrust.org) to examine distribution patterns. At the species that are rarely caught and not reported. Also, global scale, ECOCEAN Whale Shark Photo- extractive sampling methods are undesirable for identification Library (www.whaleshark.org)uses censusing rare or declining species and are not photos submitted by all divers to identify individual normally permitted in marine reserves, where vulner- whale sharks to make estimates of absolute abundance. able species, like many elasmobranchs, may find And the Diver Survey portion of the Global Shark Environ Biol Fish Assessment is a citizen science based project that has preferences. We used surveys conducted between been designed to monitor broad-scale changes in January 1994 and December 2007 within the elasmobranch populations (www.globalsharksurvey. greater-Caribbean, which consists of sites within the com). Despite the prevalence of this type of data, only western central Atlantic from northern Florida to a few peer-reviewed publications have been produced northern Brazil, the Gulf of Mexico and the Caribbe- (Arzoumanian et al. 2005; Theberge and Dearden an Sea (Fig. 1)—the described distribution for the 2006; Stallings 2009;Ward-Paigeetal.2010b); yellow stingray (Bigelow and Schroeder 1953). REEF however, volunteer collected data may provide valu- surveyors use the Roving Diver Technique (RDT, able insight into trends that would otherwise go Schmitt et al. 1993)—a method that enlists divers on undetected. their daily dive activities to report the fishes they In this paper, we examine spatial and temporal observe while surveying a variety of habitats within a trends of the yellow stingray in the greater-Caribbean particular site (Schmitt and Sullivan 1996; Schmitt et and demonstrate the power of large amounts of al. 2002). The primary goal of the surveyor is to find observational data obtained from trained volunteer and report as many species as possible. Fish may be scuba divers. We used data collected for the Reef seen at any point during the dive, be any size, located Environmental Education Foundation (REEF: www. anywhere in the water column and within any reef.org), a dataset that is comprised of more than microhabitat, and therefore training primarily focuses