Centrophorus uyato has been redescribed and junior synonyms are confirmed as C. machiquensis, C. bragancae, and C. zeehaani (White et al. 2022). It is a smaller species than C. granulosus, and is morphologically similar to the long-snouted complex of C. harrissoni, C. isodon, C. seychellorum, C. westraliensis, and possibly C. tessellatus.

The Little Gulper Shark (Centrophorus uyato) is a small (to 113 cm total length) deep-water shark; known from a widespread yet patchy global distribution in the Mediterranean Sea, Atlantic and Indo-Pacific Oceans. It has been recorded on continental and insular shelves and slopes at depths of 210–1,400 m, and mostly between 400–800 m. The species is caught as target and incidental catch in small scale and industrial fisheries using a variety of fishing gear. The species is retained for its liver oil, which is considered among the most valuable of shark liver oil and is an important marine resource for local communities. Gulper sharks (Centrophorus spp.) are known for their slow life histories and targeted fisheries for the species have collapsed over a relatively short time (<20 years). Much of the species' distribution overlaps with intensive fishing activities, and the species is both estimated and suspected to be declining across much of its range. Globally, the Little Gulper Shark is estimated to have undergone a population reduction of 50–79% over the last three generations (186 years), based on abundance data and levels of exploitation, and the species is assessed as Endangered A2bd.

The Little Gulper Shark has a widespread, yet patchy, global distribution in the Mediterranean Sea, Atlantic and Indo-Pacific Oceans (White et al. 2022). This species was previously referred to as C. granulosus in the Mediterranean Sea and elsewhere in its range, and C. zeehaani in Australia (White et al. 2022).

Taxonomic uncertainty and identification issues have led to some confusion over the occurrence of gulper sharks, often leading to this group reported under a generic category (e.g., Centrophorus spp). Species-specific population trend data are available from two sources: (1) nomimal catch-per-unit-effort (CPUE) in the Gulf of Mexico (C. Cotton unpub. data 2019), and (2) standardized catch-per-unit-effort (CPUE) in the Southwest Pacific (Walker and Gason 2007). The trend data from each source were analysed over three generation lengths (186 years) using a Bayesian state-space framework (Winker et al. 2020). This analysis yields an annual rate of change, a median change over three generation lengths, and the probability of the most likely IUCN Red List category percent change over three generations (see the Supplementary Information).

First, in the Gulf of Mexico, nominal CPUE between 2011–2018 (C. Cotton unpub. data 2019) showed an annual rate of increase of 10.7%, consistent with an estimated increase of 120.4% over three generation lengths (186 years), with the highest probability (99%) of no major reductions in population over three generation lengths.

Second, the trend analysis using standardized CPUE between 1996–2006 off southeast Australia showed an annual rate of decline of 11%, consistent with an estimated decrease of 100% over three generation lengths (186 years), with the highest probability (88%) of >80% reductions in population over three generation lengths. In addition, significant reductions (>95%) in the catch of gulper sharks (mainly C. harrissoni, C. uyato and C. moluccensis) from 1976–77 to 1996–97 on the upper slope trawl fishery off New South Wales (NSW), Australia, have been documented by fishery-independent surveys (Graham et al. 2001). This accounts for only a small proportion (<10%) of the species known range. A recent vulnerability assessment of the combined effects of fishing and climate change on the chondrichthyan fauna of southern Australia indicates that resilience risk of Little Gulper Shark is high, and the vulnerability was high during 2000‒2006 and medium during 2018 ((Walker et al. 2021). For fishing, resilience risk is high, and during 2000‒2006, when exposure was high, the vulnerability was high. However, by 2018, when exposure was medium (following a large reduction in the number of vessels engaged in the trawl fishery on the upper slope), the vulnerability was medium. For climate change, resilience risk is low (i.e., intrinsic resilience is high), and because exposure is low, the vulnerability is low.

Nearly all landings of gulper sharks other than the Leafscale Gulper Shark (Centrophorus squamosus) from the Northeast Atlantic have been reported from the Portuguese longline fishery (ICES-WGEF 2018). Annual landings were ~100 t until 2008, and rapidly declined to 2 t in 2009, likely in response to reduced abundance and restrictive management measures (ICES-WGEF 2018). In the Mediterranean, there are uncertainties with species identification in this region, but the species is considered generally rare (Bradai et al. 2012). It may be locally abundant in the western Mediterranean Sea (Guallart 1998). The species was rarely observed in commercial bottom trawl surveys operating to depths of 800 m in the eastern Iberian Peninsula (Ruiz-García et al. 2023).In the east Atlantic, reported landings from distant water fleets increased from 600,000 t to 4.5 million t between 1950 and 2000 (Alder and Sumaila 2004). Between 1984–2001, landings of the most reported squaloid sharks in the Mauritania hake fishery, including gulper sharks, declined steadily from 158 t to 37 t, with a minimum catch of 3.5 t reported in 1999 (Fernández et al. 2005), amounting to a reduction in squaloid landings of >99% over three generations. Causes of these declines have been attributed to changes in the fishing fleet, economics, and likely over-exploitation of both the target species and bycatch (Fernández et al. 2005). Many regional fisheries are now characterised by severe over-exploitation and declines in abundance of marine resources (e.g., Gascuel et al. 2007). The total demersal biomass of inshore stocks is estimated to have declined by 75% since 1982 (Meissa and Gascuel 2015). Despite documented declines in marine resources, fishing effort is on the rise. In Ghana and Senegal, for example, artisanal total fishing effort increased by 10-fold between 1950 and 2010; industrial effort decreased since the 1990s, with total fishing CPUE declining by a third since 1950 (Belhabib et al. 2018).

The gulper shark stock off India is suspected to have similarly collapsed as a result of the rapid development of deep-water fishing off western India. Gulper shark landings declined from 114 t in 2008 to 39 t in 2011 (K.K. Bineesh unpub. data 2019), equating to a population reduction of >99% over three generations (186 years). Off the southwest coast of the South Andaman Islands, the hooking rate of gulper sharks declined from 18% to 1–14% between 1984–2004 (Soundararajan and Roy 2004). In Sri Lanka, the targeted gulper shark fishery at Valaichchenai, which dates back to the 1980s, has seen a large reduction in effort, from 30 to 2 vessels, in recent years (A. Tanna pers. comm. 21/11/2019). The rationale for this reduction in fleet is claimed to be self-regulation of the fishery, although lack of long-term economic and biological viability of the fishery is also suspected.

The Little Gulper Shark is both estimated and suspected to be declining across much of its range and estimated to be increasing in the Gulf of Mexico. Overall, a population reduction of 50–79% was estimated over the last three generations, based on abundance data and levels of exploitation. Therefore, the species is assessed as Endangered A2bd.

The Little Gulper Shark is demersal on continental and insular shelves and slopes at depths of 210–1,400 m, and mostly between 400–800 m (Weigmann 2016, White et al. 2022). Tracking data shows that in Australia at least this species has a restricted and narrow distribution and is mainly restricted to the upper continental slope between the 300–700 m bathymetric contours near the seafloor (Daley et al. 2015). It reaches a maximum size of 113 cm total length (TL); males mature at 75–85 cm TL and females mature at 85–99 cm TL (White et al. 2022). Reproduction is aplacental viviparous, fecundity is very low, with a single pup per litter, and size-at-birth estimated at 35–45 cm TL (Ebert et al. 2013). Generation length of this species is estimated at 62 years (B. Moe, pers. comm. 30 March 2024), but should be used with caution as further validation is required.

The Little Gulper Shark is taken as both targeted and incidental catch across its range in mid-water and demersal trawl, surface and demersal longline, and setnet fisheries.

Where targeted fishing occurs, fishing activity has been intensive. In India, fisheries employing a number of gear types (trawl, longline, gill net, hook and line) have expanded further offshore into deeper waters as inshore stocks become heavily exploited. A targeted gulper shark liver oil fishery (operating at depths of >300–1,000 m) commenced in 2002, and between 2002–2008, there was a major increase in landings of deep-water sharks (see Akhilesh et al. 2011, 2013; Akhilesh and Ganga 2013). Targeting fishing has also occurred off the Andaman Islands and Sri Lanka since the 1980s (Soundararajan and Roy 2004, A. Tanna pers. comm. 21/11/2019). Reports of large quantities of shark liver oil recently transported out of Somalia may be indicative of developing fisheries in this region (K.K. Bineesh unpub. data 2019).

In the Northeast Atlantic, this species was previously reported in small quantities in Portuguese longline fisheries (ICES-WGEF 2018). It is reported in bottom longlines and trammel nets throughout the Mediterranean (Guallart 1998, Massutí and Moranta 2003, Lteif et al. 2017). Despite a number of management measures to reduce deep-water shark fishing mortality, deep-water sharks are still captured in demersal fisheries (e.g., Fauconnet et al. 2019). Discard mortality is unknown, but presumed to be high (Rodríguez-Cabello and Sánchez 2017) and the extent of illegal, unreported, and unregulated (IUU) fishing is unknown (ICES-WGEF 2018).

Between 1950–1998, there was an apparent increase in reported landings of deep-water sharks and dogfishes across the east central Atlantic region (e.g., Vasconcellos and Watson 2004). Deep-water sharks were first exploited in Senegal during World War II, and have been reported in landings from Cape Verde since the 1950s (Diop and Dossa 2011). More recent targeted longline fisheries for deep-water sharks have been identified in countries such as Mauritania and Ghana (FAO 2016). In Mauritania and Namibia, deep-water sharks have been reported as bycatch from black hake (Merluccius senegalensis and M. polli) fisheries (Fernández et al. 2005, Kainge et al. 2010) and unidentified deep-water sharks are also reported from regional and distant water shrimp trawlers (FarFish 2017). Accurate species-specific catches are difficult to determine and likely underestimated due to on-board processing as deep-water sharks are rarely landed whole (Fernández et al. 2005). Gulper sharks are occasionally reported (<1 t annually between 2010–2012) in demersal trawl and hake longline fisheries off South Africa (da Silva et al. 2015).

The species likely has some refuge from fishing in the US Gulf of Mexico, where Royal Red Shrimp (Pleoticus robustus) trawl fisheries operate on relatively restricted fishing grounds adjacent to home ports at depths of 250–550 m (Stiles et al. 2007, Reed and Farrington 2010). The species, however, is still susceptible to longline fisheries (Driggers et al. 2017). Elsewhere in the Gulf, there are a number of deep-water fisheries where Centrophorus spp. have been reported (Benavides et al. 2014). There are a number of deep-water fisheries from Venezuela, fishing at depths of 200–800 m; demersal chondrichthyans are not targeted but are encountered as bycatch (O. Lasso-Alcalá pers. comm. 11/10/2019). There is increasing interest in developing deep-water fisheries in the Caribbean (e.g., Paramo et al. 2017) and the development of any fishery should be monitored as this species may be susceptible to being caught as bycatch.

Deep-water sharks have been targeted in demersal longline and gillnet fisheries operating in areas managed under the Southern Indian Ocean Fisheries Agreement (SIOFA); the latter of these fisheries ceased in 2015 (Georgeson et al. 2019).

Gulper shark liver oil, rich in squalene, is considered among the most valuable of shark liver oil and is an important marine resource for local communities (K.K. Bineesh unpub. data 2019). Oil may be processed locally or shipped overseas (e.g., Dubai) for processing before sold on the international market. High grade oil is exported to Japan and the European Union (Dharmadi unpub. data 2019, K.K. Bineesh unpub. data 2019, A. Tanna pers. comm. 21/11/19). Flesh is sold to local markets (K.K. Bineesh unpub. data 2019), while waste products from liver oil production is utilized as aquaculture and poultry feed (A. Tanna pers. comm. 21/11/19). Gulper shark fins are of low value (Jaiteh et al. 2017), but have been reported in the international fin trade in low quantities (Fields et al. 2018).

Further information is required on population size and trends of the Little Gulper Shark, as well as interactions with fisheries across its range, particularly around Africa. There are some species-specific and general management arrangements of relevance in place in the Northeast Atlantic and the Southwest Pacific. Elsewhere, targeted deep-water shark fishing is not permitted in the South East Atlantic Fisheries Organization (SEAFO) Convention Area or under the Southern Indian Ocean Fisheries Agreement (SIOFA) (SIOFA 2019, SEAFO 2016). Conservation measures are generally lacking elsewhere in the species' patchy range.

Management action implemented for the conservation and long-term sustainability of deep-water sharks in the Northeast Atlantic may indirectly offer the species some refuge. These actions include banned use of trawls and gillnets in waters >200 m in Azores, Madeira and Canary Islands and international waters regulated by ICES (NEAFC regulatory Area); banned use of gillnets by European Union vessels at depths >600 m; maximum bycatch limits of deep-water shark in Hake (Merluccius merluccius) and Monkfish (Lophius spp) gillnet catches; area restrictions by vessel size and gear, gear restrictions (hook size, maximum number of hooks on longline gear); a network of closed areas in Azorean waters; and closure of the Condor seamount to deep-water fishing in 2010 (ICES-WGEF 2018). In addition, the General Fisheries Commission for the Mediterranean (GFCM) banned bottom trawling below depths of >1,000 m in the Mediterranean Sea in 2005.

In Australia, this species has the most detailed recovery plan for any deep-water shark in the world. Gulper sharks are assessed and managed as a multi-species stock (Centrophorus spp.). Both the Little Gulper Shark and Harrisson’s Dogfish (C. harrissoni) are listed as Conservation-Dependent under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). Species are subject to recovery plans that specify management actions to halt fishing mortality, including combined trigger limits of these two species, a zero retention limit, and guidelines for handling practices (Patterson et al. 2018). Gulper shark protection areas (closed to all methods of fishing) were carefully implemented based on species' demographic data (Daley et al. 2015). Individual based simulation modelling of tracking data and life history predicted stock off southern Australia can recover from a precautionary estimate of 8% of initial numbers to 20%; however, this was estimated to take 64 years due to the low reproductive capacity of this species (Daley et al. 2019). In some areas, the species is still caught incidentally, and without fisheries closures, the stock is estimated to collapse in <30 years (Daley et al. 2019). A combination of trawling closures in most of the Southern and Eastern Scalefish and Shark Fishery (SESSF) waters deeper than 700 m since 2005, as well as the closure of the South Tasman Rise Fishery in 2007 (Patterson et al. 2018), may offer refuge in this region.