Introduction
The smalltooth sandtiger shark (Odontaspis ferox (Risso, 1810)), also known as the bumpytail ragged-tooth shark, is classified as a mackerel shark species within the order Lamniformes. It belongs to the Odontaspididae family, commonly called sandtiger or bumpytail ragged-tooth sharks (Ebert et al., Reference Ebert, Dando and Fowler2021). This species has a global but patchy distribution, predominantly inhabiting warm-temperate and tropical deep waters (Bonfil, Reference Bonfil1995; Fergusson et al., Reference Fergusson, Graham and Compagno2008). It has been recorded at depths ranging from 10 to 1,015 m (Ebert et al., Reference Ebert, Dando and Fowler2021) in diverse habitats, including submerged ridges (Barcelos et al., Reference Barcelos, Azevedo, Pollerspöck and Barreiros2018; Fergusson et al., Reference Fergusson, Graham and Compagno2008), seamounts (Fergusson et al., Reference Fergusson, Graham and Compagno2008), upper slopes, and both insular and continental shelves (Barcelos et al., Reference Barcelos, Azevedo, Pollerspöck and Barreiros2018; Barría et al., Reference Barría, Colmenero, Del Rosario and Del Rosario2018; Fergusson et al., Reference Fergusson, Graham and Compagno2008).
Odontaspis ferox is distinct from other ragged-tooth species (Carcharias taurus and O. noronhai) due to its long conical snout and unique dentition (Ebert et al., Reference Ebert, Dando and Fowler2021; Tavares et al., Reference Tavares, Sánchez and Briceño2019). Its moderately large teeth have prominent, narrow cusps with two or three pairs of lateral cusplets (Tavares et al., Reference Tavares, Sánchez and Briceño2019). Notably, this species features five medium to long gill slits positioned anterior to the pectoral fins, a slightly larger first dorsal fin closer to the base of its pectoral fins than to the origins of the pelvic fins, and a long angular mouth (Ebert et al., Reference Ebert, Dando and Fowler2021; Tavares et al., Reference Tavares, Sánchez and Briceño2019). The smalltooth sandtiger shark’s body coloration varies from grey to brownish grey dorsally, lighter ventrally, and often displays dark dusky spots laterally (Ebert et al., Reference Ebert, Dando and Fowler2021; Tavares et al., Reference Tavares, Sánchez and Briceño2019).
The maximum total length (TL) recorded for the smalltooth sandtiger shark is 450 cm in a female specimen, while males reach a maximum size of 344 cm TL (Fergusson et al., Reference Fergusson, Graham and Compagno2008). Males are estimated to reach maturity between 200 and 250 cm TL and females between 300 and 350 cm TL (Fergusson et al., Reference Fergusson, Graham and Compagno2008; Higgs et al., Reference Higgs, Hoffmayer, Driggers, Jones and Hendon2022). The species has low fecundity, usually two pups around 100–105 cm TL at 2-year intervals (Barría et al., Reference Barría, Colmenero, Del Rosario and Del Rosario2018; Ebert et al., Reference Ebert, Dando and Fowler2021; Fergusson et al., Reference Fergusson, Graham and Compagno2008). It is considered viviparous, with nourishment through uterine cannibalism, though the exact mechanism of nourishment is still uncertain, with possibilities of lamniform oophagy or embryophagy (Abel and Grubbs, Reference Abel and Grubbs2020; Barcelos et al., Reference Barcelos, Azevedo, Pollerspöck and Barreiros2018).
Commercial fishing activities do not explicitly target this species (Barría et al., Reference Barría, Colmenero, Del Rosario and Del Rosario2018), but it is known to be captured incidentally (by-catch) by diverse types of fishing methods (e.g., trawling, longlining, and gillnetting) (Barría et al., Reference Barría, Colmenero, Del Rosario and Del Rosario2018; Fergusson et al., Reference Fergusson, Graham and Compagno2008). Due to its low fecundity, presumed small population size, and susceptibility to incidental capture across multiple fishing techniques, this species is expected to have a reduced capacity to recover from fishing pressure (Barría et al., Reference Barría, Colmenero, Del Rosario and Del Rosario2018; Finucci et al., Reference Finucci, Rigby, Charles, Dicken, Giovos, Gordon and Soldo2024). Such factors place the smalltooth sandtiger shark at heightened risk, potentially leading to local extirpation (Barría et al., Reference Barría, Colmenero, Del Rosario and Del Rosario2018; Fergusson et al., Reference Fergusson, Graham and Compagno2008). As of its last assessment in 2023, the smalltooth sandtiger shark is classified as Endangered in the IUCN Red List of Threatened Species, and its population size is decreasing (Finucci et al., Reference Finucci, Rigby, Charles, Dicken, Giovos, Gordon and Soldo2024).
There is limited information on the biology, ecology, distribution, species diversity, and fishing patterns of shark species in Puerto Rico (Franqui-Rivera, Reference Franqui-Rivera2020). Furthermore, only a few individuals of the smalltooth sand tiger shark have been studied worldwide. Commercial fisheries in Puerto Rico operate on a relatively small scale, with fishers active throughout the entire archipelago, encompassing the main island of Puerto Rico, along with Vieques, Culebra, and the fishing banks near the islands of Mona and Desecheo. Unfortunately, deep-water sharks, such as smalltooth sandtiger shark, are highly susceptible to the longlines employed by fishers (Finucci et al., Reference Finucci, Rigby, Charles, Dicken, Giovos, Gordon and Soldo2024; Franqui-Rivera, Reference Franqui-Rivera2020). This documented occurrence of the incidental capture of an O. ferox is the first recorded sighting of a smalltooth sandtiger shark on the west side of Puerto Rico.
Materials and methods
On December 30, 2020, a local commercial fisher, Mr. José Chaar was targeting queen snapper (Etelis oculatus) using a cala, a vertical longline with 9–15 hooks attached to a floating buoy, in the northwest region of Puerto Rico. During that day, an uncommon shark species, later identified as smalltooth sandtiger shark, was incidentally captured at a depth of 325 m, approximately 3 miles north of Monito Island (Figure 1). Given the rarity of such an occurrence, Mr. Chaar promptly documented the specimen by taking photographs (Figure 2) and collected a small tissue sample, which was preserved under refrigeration for further analysis.
Location corresponding to the capture of Odontaspis ferox at Mona Passage.
Lateral view of Odontaspis ferox. Photo: Jose Chaar.
Molecular methods, specifically DNA barcoding using the mitochondrial gene Cytochrome Oxidase Subunit 1 (CO1), were employed to aid in identifying the specimen. Genomic DNA was extracted from a small tissue sample, previously preserved in 95% ethanol, using the QIAGEN DNeasy kit (QIAGEN Inc., Valencia, CA, USA). A fragment of approximately 355 base pairs (bp) from the CO1 region was amplified through the polymerase chain reaction (PCR) protocol, employing the primer set HCOI and LCOI (Folmer et al., Reference Folmer, Black, Hoeh, Lutz and Vrijenhoek1994). The PCR thermal conditions consisted of an initial denaturation step at 94 °C for 3 min, followed by 35 cycles of denaturation at 94 °C for 40 seconds, annealing at 50 °C for 40 s, extension at 72 °C for 1 min, and a final extension at 72 °C for 7 min, with a final cooling step at 4 °C for 5 min (Fariña et al., Reference Fariña, Quinteiro and Rey-Méndez2014). The amplified product was then sent to MCLAB genomic facility (San Francisco, California) for DNA sequencing. Afterward, the CO1 sequence was cleaned and aligned using Geneious Prime and MEGA11 software. In order to verify the species, a BLAST search was performed against the National Center for Biotechnology Information (NCBI) database. After cleaning and trimming, the resulted sequence was reduced to a shorter consensus fragment of high quality.
Results
The unidentified shark photos were carefully analysed, using Ebert et al. (Reference Ebert, Dando and Fowler2021) to identify species-specific distinctive characteristics such as a long conical snout, large teeth, and coloration. The CO1 sequences (355 bp) from the Puerto Rican shark specimen showed a 100% match with the CO1 sequence of O. ferox (GenBank: KY909459.1), which confirmed the identification of the Puerto Rico specimen as a smalltooth sand tiger shark (GenBank: PP198108), with a high level of confidence.
Discussion
This is the first confirmed record of a smalltooth sandtiger shark in Puerto Rico. It is a noteworthy contribution to the island’s known shark diversity (Franqui-Rivera, Reference Franqui-Rivera2020) and provides valuable insights into the species’ distribution within Caribbean waters. Although this species exhibits a broad distribution in the Atlantic, documentation in tropical regions remains limited. Since 1989, occurrences of this species have been recorded in the western North Atlantic Ocean, with sightings reported inter alia from the Yucatán Peninsula (México; Bonfil, Reference Bonfil1995), North Carolina, South Carolina, Florida, and Alabama in the Gulf of México (Ross and Quattrini, Reference Ross and Quattrini2007; Sheehan, Reference Sheehan1998; Sulak et al., Reference Sulak, Brooks, Luke, Norem, Randall, Quaid, Yeargin, Miller, Harden, Caruso and Ross2007). Furthermore, observations have been documented in Colombia (Anguila et al., Reference Anguila, Nieto-Alvarado and Hernández-Beracasa2016), Caribbean Venezuela (Tavares, 2008), Brazil (Garla & García-Junior, Reference Garla and García-Junior2008; Long et al., Reference Long, Sala, Ballesteros, Caselle, Friedlander, Klapfer, Blum and Constable2014), France, Spain, Madeira, Azores Islands, Canary Islands, Cape Verde Islands (Wirtz et al., Reference Wirtz, Brito, Falcón, Freitas, Fricke, Monteiro, Reiner and Tariche2013), and more than 30 additional countries (Finucci et al., Reference Finucci, Rigby, Charles, Dicken, Giovos, Gordon and Soldo2024). Most recently, in February–March 2023, three deceased individuals were discovered in the United Kingdom and Ireland, signifying at the time the highest geographic range extension in the North Atlantic Ocean (Curnick et al., Reference Curnick, Deaville, Bortoluzzi, Cameron, Carlsson, Carlsson, Dolton, Gordon, Hosegood, Nilsson, Perkins, Purves, Spiro, Vecchiato, Williams and Payne2023).
This species is found at depths ranging from 10 to 1,015 m, with most documented specimens being observed between 200 and 600 m (Ebert et al., Reference Ebert, Dando and Fowler2021; Fergusson et al., Reference Fergusson, Graham and Compagno2008). They exhibit a habitat preference for the deep-water zone near the seabed and continental shelves (Finucci et al., Reference Finucci, Rigby, Charles, Dicken, Giovos, Gordon and Soldo2024), where water temperatures range from 6 °C to >20 °C (Ebert et al., Reference Ebert, Dando and Fowler2021). In the case of the Puerto Rico specimen, it was found at a depth of 325 m during the winter season.
Pelagic and deep-water sharks are not intentionally targeted by the small-scale fisheries around Puerto Rico, but incidental capture and discard of sharks occurs. Formulating and implementing effective catch limits and shark management strategies is difficult without specific capture data for sharks, including the small-toothed sandtiger shark. To address this knowledge gap, collaborative efforts with fishers are indispensable for acquiring species-specific catch data.
Acknowledgements
We extend our heartfelt gratitude to the fisher Mr. José Chaar from the west coast of Puerto Rico for his invaluable cooperation, which was crucial for the successful completion of this report. Additionally, we express our appreciation to Mr. Wilson Santiago (port sampler) of the Department of Natural and Environmental Resources (DNER) for providing essential photographs and facilitating the collection of the tissue sample from Mr. José Chaar.
Author contributions
GFR conducted genetic analysis, analysed photographs, reviewed literature, and completed the manuscript draft. GRF interviewed the fisher and contributed to the draft. NS provided laboratory materials, revised, and edited the last versions of manuscript. All authors edited and approved the final submission of the manuscript.
Funding
We extend our sincere gratitude to the Save Our Seas Foundation for their generous financial support, which facilitated the genetic analyses that significantly contributed to this study.
Competing interests
None.
