A taxonomic review of this group is required to properly identify the species of this genus.

The Arrowhead Dogfish (Deania profundorum) is a small (to 97 cm total length) deep-water shark known from a patchy distribution in the East Atlantic (Western Sahara to South Africa), West Atlantic (United States and Gulf of Mexico), and the Indo-west Pacific. It occurs on continental and insular slopes at depths of 205–1,800 m. The species is caught as both targeted and incidental catch in midwater and demersal trawl, demersal longline, and gillnet fisheries operating across most its known range, but the species is likely to find refuge at depth. A number of management measures were implemented for deep-water sharks in recent years, both species-specific and more generally. There is high distribution overlap with intensive fishing pressure, reported declines in part of its range but stable trends in others, and a lack of species-specific management across its entire range. The Arrowhead Dogfish is inferred to have undergone a population reduction of 20–29% over the past three generations (90 years) based on abundance data and actual levels of exploitation, and it is assessed as Near Threatened (close to meeting Vulnerable A2bd).

The Arrowhead Dogfish has a patchy distribution in the East Atlantic (Western Sahara to South Africa), Northwest and Western Central Atlantic (United States and Gulf of Mexico), and the Indo-west Pacific (South Africa, Madagascar, Gulf of Aden, Philippines) Oceans (Ebert et al. 2021).

Taxonomic uncertainty and identification issues have led to some confusion over the occurrence of dogfishes, often leading to this group reported under a generic category (e.g., Deania spp).

In the Gulf of Mexico (Western Central Atlantic), population trends are likely to be stable based on the lack of deep-water fishing in the region. Off the west coast of Scotland and Ireland (Northeast Atlantic) the species is very rare as indicated by the Scottish deep-water surveys (F. Neat unpub. data 2024). In the Eastern Central Atlantic, reported fish landings from distant water fleets have increased from 600,000 t to 4.5 million tonnes (t) between 1950 and 2000 (Alder and Sumaila 2004). Between 1984–2001, landings of the most reported squalid sharks in the Mauritania hake fishery, including the Arrowhead Dogfish, 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 squalid landings of  >99% over three generations (90 years). Importantly, causes of these declines have been attributed to changes in the fishing fleet, economics, and the likely over-exploitation of both target and bycatch species (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 catch-per-unit-effort (CPUE) declining by a third since 1950 (Belhabib et al. 2018).

Estimating mortality and changes in catch rates of this species is difficult in the Northwest Pacific. The liver of this species may be utilised and/or exported, and annual export data can be used to ascertain changes to the interactions. Annual exports of shark liver oil from the Philippines peaked at 336 t in 1980 to 45 t in 1993 (BFAR 2017), although there are no data available on species composition. Across Taiwan, both industrial and artisanal fishing effort has increased substantially since the 1950s (Kuo and Booth 2011, Liao et al. 2019), with industrial effort declining after 1990. Landings data showed a 52% decline of all combined shark species over 63 years from 1953 to 2015. The annual landings rose from ~8,300 t annually in the 1950s to a peak of 32,400 t in 1975, then declined steadily to 4,023 t in 2015 (Liao et al. 2019, H. Hsu, Taiwan National Fisheries Statistics pers. comm. 2019). These long-term declines in abundance of sharks can be inferred to represent reductions in their populations, as the declines have occurred since the peak catches of the mid–1970s, prior to any noticeable reduction in the 1990s of industrial fisheries effort. This represents a 65% decline when scaled to the past three generation lengths (90 years) for the Arrowhead Dogfish, and although not species-specific, is informative for inferring the possible levels of reduction of this species in Taiwan.

Across the regions, the Arrowhead Dogfish was inferred to be stable in the Western Central Atlantic and have declined in West Africa and the Northwest Pacific. Due to estimated declines in parts of its range, caused by high levels of exploitation, a global population reduction of 20–29% was inferred over three generation lengths (90 years). Therefore, the Arrowhead Dogfish is assessed as Near Threatened (close to meeting Vulnerable A2bd).

The Arrowhead Dogfish has been recorded from continental and insular slopes at depths of 205–1,800 m (Weigmann 2016). It reaches a maximum size of 97 cm total length (TL); males mature at 43–67 cm TL; females mature at 62–80 cm TL (Ebert et al. 2021). Reproduction is aplacental viviparous with litter sizes of 5–7 pups and size-at-birth is >31 cm TL (Ebert et al. 2021). Nothing else is known of its biology. Age parameters are unknown but can be inferred from a closely related species, the Birdbeak Dogfish (Deania calcea), which has a female age-at-maturity of 21.5 years and a maximum age of 37 years, resulting in a generation length of 30 years (Irvine et al. 2012). However, the Birdbeak Dogfish is larger than the Arrowhead Dogfish (120 cm vs 97 cm TL) and therefore this generation length is likely overestimated.

The Arrowhead Dogfish is taken as both targeted and incidental catch across its range in midwater and demersal trawl, demersal longline, and gillnet fisheries.

In the Northwest Atlantic, there is limited deep-water fishing effort. In the US Gulf of Mexico, 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).

Across the Eastern Central Atlantic region, an apparent increase in reported landings of deep-water sharks and dogfishes has been reported from 1950–1998, (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 recently, longline fisheries targeting deep-water sharks have been identified in Mauritania and Ghana (FAO 2016). In Mauritania and Namibia, deep-water sharks have been reported as bycatch in Black Hake (Merluccius senegalensis and M. polli) fisheries (Fernández et al. 2005, Kainge et al. 2010), while unidentified deep-water sharks have also been 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; deep-water sharks are rarely landed whole (Fernández et al. 2005). Demersal inshore and offshore hake trawl fisheries off South Africa occasionally report Deania spp in logbooks with an annual catch of <1 t between 2010 and 2012 (da Silva et al. 2015). However, the amount of Deania spp captured may be higher; from 2010–2018, 139 t of Deania spp was reported to be landed in those same fisheries (MSC, 2020). Despite a number of management measures to reduce deep-water shark fishing mortality around the Azores, the species is still captured in considerable quantities in demersal fisheries (Fauconnet et al. 2019). At-vessel-mortality is high, and post-release mortality is also likely to be high (Rodríguez-Cabello and Sanchez 2017). 

In the Indian Ocean, 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). There is currently no known deep-water fishing where the species occurs off Oman and the Gulf of Aden. 

In the Pacific Ocean, deep-water dogfish fisheries date back to the 1960s (Flores 2004). These fisheries use demersal longline gear to primarily target Centrophorus spp, although they are likely to catch Deania spp occasionally (LAMAVE 2017). These fisheries are known for their boom-and-bust nature, given the lack of management, collapsing over short periods of time (~10 years) before moving onto new areas (Flores 2004). Taiwanese fleets have increased their effort in deeper areas over the past 30 years, following the worldwide trend for fisheries to explode deeper waters. As a consequence, current fishing operations at 300–700 m deep occur during most of the year and overlapping with the distribution of this species. However, there is some refuge at depth beyond 700 m and during the monsoon season when the fishery operates at shallow depths. Additionally, there has been a marked increase in landing rates in Taiwan since 2013. This increase in landings could partly be accounted for by the increased fishing depth, although that has been occurring for the past 30 years with the increase in landings only noted in the past six years, and improvements in reporting can not be ruled out. Any Deania spp caught in Taiwanese fisheries is likely retained and sold locally (Liu et al. 2013). 

Historically, this species has been utilised for its flesh and liver oil. Fins from Deania spp 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 Arrowhead Dogfish, as well as interactions with fisheries across its range, particularly around Africa. 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.

Since 2010, the European Union Fisheries Council prohibited direct fishing for deep-water sharks, including the Arrowhead Dogfish, in European Community and international waters, and in 2012, no allowances for bycatch were implemented (ICES-WGEF 2018). Management actions for the northern Eastern Central Atlantic region 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), and a network of closed areas in Azorean waters; closure of the Condor seamount to deep-water fishing in 2010 (ICES-WGEF 2018).