First report of the whitesaddled catshark Scyliorhinus hesperius (Springer 1966) in Guatemala’s Caribbean Sea

Abstract

Background

The present study represents the first record of Scyliorhinus hesperius in Guatemala’s Caribbean Sea.

Methods

Five male whitesaddled catsharks, S. hesperius, were captured in 200 m deep waters of Guatemala’s Caribbean coast.

Results and Conclusion

All specimens were male with total lengths ranging from 420 mm to 510 mm. These fish represent the first record of mature male S. hesperius, the first record for this species in Guatemalan territorial waters, and a range extension in the Western Central Atlantic.

Background

Scyliorhinidae (catsharks) constitute the largest shark family with at least 160 species distributed across 17 genera (Ebert et al. 1996). These species are broadly distributed throughout temperate and tropical waters, inhabiting the bottom of shallow and deep waters over 100 m (Nakaya 1975). Catsharks are small, demersal species, and relatively poor swimmers (Compagno et al. 2005).

The genus Scyliorhinus Blainville 1816, is comprised of 16 species distributed in cold, subtemperate to tropical waters (Ebert et al., 2015; Soares et al., 2016) including the eastern and western Atlantic and the Mediterranean (Rodríguez‐Cabello et al. 2007; Ebert et al. 2015). In the western Atlantic, Scyliorhinus is most diverse and at least six species of Scyliorhinus are distributed in the Caribbean (Compagno, 1984) with three species occurring throughout the Central America Caribbean: Scyliorhinus boa Goode and Bean 1896, S. retifer Garman 1881, and S. hesperius Springer 1966 (Compagno, 1984).

S. hesperius was described by Springer (1966) based on an immature female holotype of 415 mm total length (TL). Additionally Springer (1966) examined 12 specimens, sex not specified, ranging in total length from 177–460 mm. All specimens were captured between 274 m and 530 m depth in the Western Caribbean near Jamaica and Honduras and southward towards Panama and Columbia (Springer 1966). Later, Ross and Quattrini (2009) reported sightings of three individual sharks S. hesperius resting on thick coral rubble between 580–604 m depth, off of Jacksonville, Florida, while conducting deep water dives on deep reefs along the southeastern US continental shelf slope.

Maximum size for this species is based on a singular female S. hesperius (470 mm), with no information on its biology (Leandro 2004). Compagno (1988) reports two immature specimens from Nicaragua, one female and one male, 159 mm and 356 mm respectively. Size range of specimens reported in this study was 420–510 mm TL, all adult male sharks. This study represents the first report of adult male S. hesperius and also the largest S. hesperius specimen collected to date, based on morphometric data of specimen Rf. 252.

The whitesaddled catshark S. hesperius is currently listed by the International Union for the Conservation of Nature’s Red List as Data Deficient due to insufficient information available to assess the species population status (Leandro 2004). No current information exists for this species’ biology, and distributional limits are poorly known. This paper reports the first record of S. hesperius in Guatemalan waters, representing a range extension in Central America and the Caribbean.

Methods

On March 20^th 2016, five whitesaddled catsharks were captured by artisanal fishermen of El Quetzalito, Izabal Department, in Guatemala (Fig. 1). These specimens were captured with a 1000 m wide bottom trammel net, consisting of one panel with 3.5 in. mesh size, set at 200 m depth.

Fig. 1

Study area with location (X) of capture in relation to the fishing village of El Quetzalito

All specimens were initially kept on ice prior to preservation in formaldehyde (10%) for 3 weeks and transferred to ethyl alcohol (70%) for final preservation. The specimens were donated to the Laboratory of Biological Science and Oceanography, Centro de Estudios del Mar y Acuicultura (CEMA) of the Universidad San Carlos de Guatemala (USAC). The specimens are part of the collection registered to the Consejo Nacional de Áreas Protegidas (CONAP) under the reference numbers (Rf) 252, 253, 254, 255 and 256.

The five specimens were sexed and measured after being preserved. A total of 91 morphometric measurements were taken (Table 1) as proposed by Compagno (2001). Measurements are expressed as percentages of total length (%TL). All specimens were examined and identified using identification guides developed by Compagno (1984, 2001). Maturity for males was determined by the full calcification of claspers.

Table 1 Morphometric measurements (mm) of individuals of five male specimens of Scyliorhinus hesperius

Results

Systematic account

Family Scyliorhinidae Gill, 1862

Scyliorhinus Blainville, 1816

Scyliorhinus hesperius Springer, 1966

Common name: Whitesaddled catshark.

Material examined

Rf 252 specimen: male, mature, 510 mm TL (Fig. 2a); Rf 253 specimen: male, mature, 455 mm TL (Fig. 2b); Rf 254 specimen: male, mature, 429 mm TL (Fig. 2c); Rf 255 specimen: male, mature, 435 mm TL (Fig. 2d); Rf 256 specimen: male, mature, 420 mm TL (Fig. 2e).

Fig. 2

Scyliorhinus hesperius (a. Rf. 252, b. Rf. 253, c. Rf. 254, d. Rf. 255, e. Rf. 256)

All specimens were caught approximately 15 Km north of El Quetzalito, Izabal, Guatemala (15° 49.776 N,–88° 12.340 W), at approximately 200 m, based on known length of net deployed.

Description

Color pattern variable, of seven to eight dark saddles with large light spots concentrated in the saddle marks. Background coloration is light brown on the dorsal surface and paler on the ventral surface. First dorsal fin originates behind pelvic fins, and larger than second dorsal fin (Fig. 2). Lower labial furrows present (Fig. 3).

Fig. 3

Scyliorhinus hesperius (head-ventral view; a. Rf. 252, b. Rf. 253, c. Rf. 254, d. Rf. 255, e. Rf. 256)

Discussion

This study provides multiple first records for S. hesperius with the largest of the species described based on Reference 252 and also the first mature males. This study further supports the extension of the known range of S. hesperius in the Caribbean while including a first record for the species in Guatemala. Although the whitesaddled catshark has been recorded in the Western Central Atlantic in Honduras, Panamá and Colombia (Kyne et al. 2012), Ross and Quattrini’s regional study (2009) and this study suggest that the species’ range may be more extensive than originally thought.

Knowledge of S. hesperius basic biology is limited. By comparison, considerable literature exists on S. canicula, a relatively abundant catshark species distributed throughout the Eastern North Atlantic and Mediterranean (Sims et al. 2001; Rodríguez‐Cabello et al. 2007; Ebert et al. 2015). In south-west Ireland, an acoustic tagging study of four S. canicula revealed that two tagged females exhibited alternative behavioural strategies compared to the tagged two males, a difference resulting in spatial segregation of the sexes by habitat (Sims et al. 2001). Sims (2003) further reports that sexual segregation in this species occurs primarily as a consequence of male avoidance by females. In the western Mediterranean, segregation between juveniles and adults occurs for S. canicula where juveniles are found in depths greater than 100 m while adults almost exclusively occupy shallower depths Massutí and Moranta (2003). By comparison, in the Northern Aegean Sea, the pattern of vertical distribution of S. canicula showed that individuals did not exhibit any sexual segregation and juveniles and adults were found together in the bathyal zone, often located swimming near the benthos D’Onghia et al. (1995). Considering the range of behavioral strategies demonstrated by members of the genus Scyliorhinus, it is currently unclear if S. hesperius exhibits sexual and size segregation in the Caribbean. This study’s record of male-only specimens raises the question if S. hesperius segregate by sex in waters 200 m deep in Guatemala’s Caribbean waters. According to artisanal fishers interviewed, this species is rarely captured in the fishery and never utilized due to the species’ small size. These results suggests a further need for fisheries-independent studies to elucidate habitat preferences and distribution by sex and size of S. hesperius.

Conclusions

This paper provides noteworthy multiple firsts records of S. hesperius in Guatemalan waters, that represents a range extension in Central America and the Caribbean, the largest S. hesperius and the first mature males collected to date. Future studies are needed to identify the behavior and ecology of S. hesperius in the Caribbean in light of increasing fisheries effort.