Elasmobranchs observed in deepwaters (45-330m) at Isla del Coco National Park, Costa Rica (Eastern Tropical Pacific)

: Isla del Coco is an oceanic island 500km off the Pacific coast of Costa Rica. It is a National Park and its marine fauna has been relatively well protected. The island is famous for its elasmobranch (sharks, rays and skates) sightings in shallow waters. Here we present a catalogue of the deepwater elasmobranchs observed with the DeepSee submersible. Five species of sharks, six species of skates and one ray have been observed between 45 and 330m depth. Triaenodon obesus , the white tip reef shark, was commonly observed between 80 and 301m, but only in the afternoons. Sphyrna lewini , the scalloped hammerhead shark, was observed as deep a 303m, but commonly between 45 and 90m, and close to the island. Odontaspis ferox , the smalltooth sand tiger shark, was observed between 82 and 316m. Echinorhinus cookei , the prickly shark, was observed between 91 and 320m. Rhincodon typus , the whale shark, was observed only close to the island, between 77 and 80m. Taeniura meyeni , the marbled ray, was observed only close to the island, between 45 and 90m. A Dasyatis sp., similar to the the diamond stingray, was observed only once close to the island at 60m; this is the first report of this genus at Isla del Coco National Park. Manta birostris , the giant manta, was only observed close to the island at 90m. Mobula tarapacana , the sicklefin devil ray, was observed between 60 and 326m, extending its maximum depth almost 10 times what has been reported. Aetobatus narinari , the spotted eagle ray, was observed only close to the island between 60 and 82m. Torpedo peruana , the Peruvian torpedo ray, was observed only once at 313m, and is the first record of this species from Isla del Coco National Park. Citation: Cortés, J., A. Sánchez-Jiménez, J.A. Rodríguez-Arrieta, G. Quirós-Barrantes, P.C. González & S. Blum. 2012. Elasmobranchs observed in deepwa-ters (45-330m) at Isla del Coco National Park, Costa Rica (Eastern Tropical Pacific). Rev. Biol. Trop. 60 (Suppl. 3): 257-273. Epub 2012 Dec 01.

Isla del Coco (also known as Cocos Island) is the only point above sea-level of the Coco volcanic Cordillera that originates in the Galápagos Hotspot in the Eastern Tropical Pacific (Alvarado 2009, Rojas & Alvarado 2012).It is part of the Isla del Coco National Park and located more than 500km from mainland Costa Rica (Cortés 2008).The 24km 2 island is surrounded by an insular platform that deepens to around 180m, with an area of about 300km 2 , then drops to several thousand meters deep (Lizano 2001(Lizano , 2012)).This submerged platform consists of rocky outcrops and sandy bottoms (Cortés & Blum 2008).
The island has been explored down to 450m with the DeepSee submersible since 2006.Below 50m deep (the average depth of the thermocline) the environments and organisms are different than at surface (Cortés & Blum 2008).In this paper we present the sharks, skates and rays that have been photographed between 45 and 330m deep around Isla del Coco National Park.Images and species description and distribution (spatial and temporal) are presented.

MATERIAL AND METHODS
videos are taken with a high-definition digital camera mounted on the DeepSee submersible (Cortés & Blum 2008), at several localities around Isla del Coco National Park (Fig. 1).videos were recorded on mini-Dv tapes and then digitized to a .movformat.Image grabs of organisms, substrates and objects on the bottom were made in the laboratory using Imovie and FinalCut software.A total of 811 dives have been made, and 130 hours of the video have been recorded from 2006 to 2012.For this project 570 dives have been processed; of those, sharks, skates or rays were recorded and 397 video grabs were obtained from 87 dives.Several species were observed in only one dive, e.g.Torpedo peruana and a Dasyatis sp., while others were observed in numerous dives, such as Mobula tarpacana in 36 dives.The following was recorded for each image: dive number, dive site, date, time of day, and depth.

RESULTS AND DISCUSSION
Five species of sharks and seven of rays have been observed in deepwaters at Isla del Coco National Park (Table 1).Images of the species are included together with a brief description of the species, its distribution, observations at Isla del Coco National Park (location, depth, date, time of day), previous reports of the species at Isla del Coco National Park,).Two species are reported for the first time: Dasyatis sp. and Torpedo peruana.Other species were commonly seen.Several species  Long et al. (2011) and the second by López-Garro et al. (2012).With the species reported here, the number of sharks and rays from Isla del Coco National Park increased to 20 species.Starr et al. (2012) observed Carcharhinus falciformis in deepwaters at PNIC but we did not see it in this study.to develop this project.The vicerrectoría de Investigación and the Centro de Investigación en Ciencias del Mar (CIMAR), Universidad de Costa Rica, for their financial and logistic support.The Consejo Nacional de Rectores de las Universidades Públicas (CONARE) for its financial support.We appreciate very much the time taken by the following ichthyologists to help us with the identification of the elasmobranchs and/or the review of this paper: Peter J. Auster, Felipe Galván-Magaña, Ginger Garrison, John E. McCosker and D. Ross Robertson.JC thanks Nicholas Polunin and Newcastle University, Newcastle, United Kingdom, for the oportunity to spend time there as visiting Professor.
Description: Tips of first dorsal fin and upper caudal lobe white (Bussing & López 2005).Brownish grey, with a few scattered grey spots on body, and a yellow cast ventrally (Robertson & Allen 2008).Short snout and small smooth-edged teeth with strong cusplets in both jaws.Size: up to 213cm.Depth: 1-330m, usually 8-40m (Compagno 1984).WorlDWiDe Distribution: Tropical Indo-Pacific to Eastern Pacific; in the Eastern Tropical Pacific, from Nicaragua to Colombia (Garrison 2005), including all oceanic islands except Clipperton (Robertson & Allen 2008).observations at isla Del coco (DeepSee): Commonly observed between 80-301m, at Everest (80m) and The Wall 0475 (301m) during the afternoon.White tip reef sharks have been observed in deep waters year round mostly in the afternoons.previous reports: This is the most abundant species in the shallow waters of Isla del Coco (Garrison 2005).This is one of the two species that register more sightings per dive in the shallow waters of Isla del Coco (Sibaja-Cordero 2008).White tip shark prefer certain areas of the bays and apparently do not travel far from them (Zanella et al. 2012).This species has groups courtship and its mating behaviour has been reported in Isla del Coco (Whitney et al. 2004).Whitney and Motta (2008) described the interaction between these sharks and swarms of amphipods, at Manuelita , probably related with a cleaning process.Comments: In the Eastern Tropical Pacific, reported between 2 and 300m, in an area of approximately 517,482km 2 (Mejia-Falla & Navia 2011).Classified as Near Threatened in the IUCN Red List.This means is not in danger of extinction, since it has relatively large and stable populations, as is the case in Isla del Coco National Park.
Triaenodon obesus (Rüppell 1837).White tip reef shark / Tiburón punta blanca de arrecifes, tiburón cazón coralero.Description: Robust body, head with long conical snout; eyes moderately large, without nictitating membranes; gray on back, light gray below; sometimes with reddish spots on the body (Compagno 1984), young with black tips on dorsal fins.Size: up to 410cm (Robertson & Allen 2008).Depth: 10-530m in the Eastern Pacific (Mejía-Falla & Navía 2011).WorlDWiDe Distribution: Circumglobal, predominantly in subtropical waters; Eastern Pacific from southern California to Malpelo (Robertson & Allen 2008).observations at isla Del coco (DeepSee): Observed at a depth range of 82-316m; at Everest (82-85m), mornings and afternoons; at The Arch (90-95m) in the morning hours, and at The Wall 0475 (316m) in the afternoons.Not commonly observed.previous reports: Cortés and Blum (2008) first reported the occurrence of this species in Isla del Coco National Park, at The Arch; a group of five, females and males.comments: The first observations in their natural habitat occurred in the eastern Pacific, in Isla Malpelo, with movements that seem related to the thermocline and a preference for cold waters between 18ºC and 21ºC (Bessudo & Caballero 2003).Classified as vulnerable in the IUCN Red List.
Odontaspis ferox (Risso, 1810).Smalltooth sand tiger shark / Tiburón solrayo.Description: Large sharks with robust bodies, depressed head and small dorsal fins.Grey-white, white around snout and mouth.Size: 400cm (Robertson & Allen 2008).Compagno (1984) reported this species from 11 to at least 424m; additional captures have extended the range up to 650m and possibly around 1000m (Dawson & Starr 2009).WorlDWiDe Distribution: Subtropical to temperate Pacific (Robertson & Allen 2008).Underwater observations from Galápagos Islands, Isla del Coco National Park and northern Peru confirm its continuous occurrence in the Tropical Eastern Pacific (Long et al. 2011).In the Eastern Pacific, from Oregon to Chile, and Malpelo, the Revillagigedos and Isla del Coco (Robertson & Allen 2008).In Central America: El Salvador (Rojas et al. 2006), Nicaragua (Sánchez 1997) and off the coast of Costa Rica (Bussing & López 2009).observations at isla Del coco (DeepSee): At a depth range of 91-320m.At The Wall 0475 (300-320m) and Piedra Drop (301-311m), mornings and afternoons.At Everest (80m) and Piedra 165 (160m) in the afternoon and at The Arch (91m) only in the mornings.Observed year-round and most commonly at Piedra Drop and The Wall 0475.previous reports: Underwater observations confirm the occurrence of this species in Isla del Coco National Park (Cortés & Blum 2008, McCosker & Rosenblatt 2010, Long et al. 2011).comments: E. cookei presents a wide range of depth in the eastern Pacific, despite the clear distinction of deep-water records that mostly correspond to low latitudes and the records of shallow waters that correspond mainly to high latitudes (Long et al. 2011).Classified as Near Threatened in the IUCN Red List, which means is not in danger of extinction.Description: Rhincodon typus is the largest fish in the world (Bussing & López 2005.With mouth wide, transverse; five massive gill slits and two dorsal fins (Robertson & Allen 2008).Flat head and a large mouth with numerous teeth.A checkerboard pattern with spots of soft colors , grey horizontal and vertical stripes (Compagno 2001).Size = up to 21m.Depth: 0-700m (Compagno 2001).WorlDWiDe Distribution: Circumglobal in tropical and subtropical seas (Garrison 2005, Robertson & Allen 2008), including throughout the Tropical Eastern Pacific (Robertson & Allen 2008).observations at isla Del coco (DeepSee): Between 77 and 80m at Everest, morning and afternoon.Observed only a few times in 2007 and 2010.previous reports: In shallow waters (Garrison 2005, Sibaja-Cordero 2008), Roca Sucia and Isla Manuelita (Garrison 2005).comments: Observed only at Everest in deep waters and in shallow waters, primarily around Isla Manuelita.Is known about numerous reports in Cabo San Lucas, Acapulco and the Gulf of Mexico in the eastern Pacific, with preference to areas of upwelling and temperatures of 17ºC or less, optimal sites for the production of their food (plankton) (Compagno 1984).Classified as vulnerable in the IUCN Red List, which means it is a threatened species.
Rhincodon typus Smith, 1828.Whale shark / Tiburón Ballena.Description: Disc wider than long, rhomboid; tail slightly longer than disc, tail fin with a small upper ridge on top and a deep fold.Greyish-blue on back with dark spots (Bussing & López 2005).Size: 300cm long, 75cm wide.Depth: 5-500m (Robertson & Allen 2008).WorlDWiDe Distribution: Indo-West Pacific Ocean, oceanic islands in the Tropical Eastern Pacific (Garrison 2005); resident in the Galápagos Islands and Isla del Coco (Robertson & Allen 2008).observations at isla Del coco (DeepSee): Everest, 45-90m, morning hours.Description: Tail shorter than disc, whip-like; maximum disc width, 3m (Garrison 2005).Head relatively long, with short horns; large triangular fins strongly curved backwards; mouth on underside of head.Dorsal surface olive-green, underside white at front, grey posteriorly (Robertson & Allen 2008).Size: up to 300cm (McEachran & Nortarbartolo di Sciara 1995).Depth: up to 30m (Feitoza et al. 2003).1991-1992and 1997-1998, during El Niño years. Reported by Starr et al. (2012) from waters deeper than 50m.comments: Depth range expanded to 326m, more than ten times the maximum depth stated by Feitoza et al. (2003).Classified in the IUCN Red List as Data Deficient, which means there is not enough knowledge to determine whether it is threatened or not.However this species may well be as threatened as the giant manta due to fishing pressure.

Fig. 1 .
Fig. 1.Location of sites at Isla del Coco National Park where the submersible DeepSee has acquired videos of elasmobranchs since 2006.

Fig. 3 .
Fig. 3. School of white tip reef sharks at Everest, 50m, in the afternoon of 30 April 2009.

TABLE 1
List of sharks and rays observed from the DeepSee at Isla del Coco National Park, Costa Rica.With common names and IUCN Red List status (IUCN 2012): EN = Endangered, vU = vulnerable, NT = Near Threatened, DD = Data Deficient