|Scientific Name:||Mobula rochebrunei|
|Species Authority:||(Vaillant, 1879)|
Cephaloptera rochebrunei Vaillant, 1879
|Taxonomic Notes:||Similarity of morphology among mobulids may account for common misidentifications of this ray.|
|Red List Category & Criteria:||Vulnerable A4d ver 3.1|
|Assessor/s:||Valenti, S.V. & Kyne, P.M.|
|Reviewer/s:||Notarbartolo di Sciara, G., Fowler, S.L. & IUCN SSG Pelagic Shark Red List Workshop participants (Shark Red List Authority)|
This Lesser Guinean Devil Ray (Mobula rochebrunei) is found in the eastern Atlantic from Mauritania to Angola and from only two records off Brazil in the Southwest Atlantic. It reaches a maximum size of 133 cm disc width (DW) and is known to produce only one pup per litter. M. rochebrunei is both a target species and a utilized bycatch of fisheries operating throughout much of its range in the eastern Atlantic. Its schooling habit makes them highly vulnerable to capture in large numbers. This species is probably rare in the Southwest Atlantic and the large majority of the global population exists off the western coast of Africa, where fishing pressure is high from both artisanal and foreign fleets. Although no specific data are available on population trends, given their susceptibility to capture, known heavy and unregulated fishing pressure throughout large areas of their range, and their very low reproductive potential, it is highly likely that numbers have been significantly reduced. This species is assessed as Vulnerable on the basis of suspected population declines, as a result of continuing, unregulated, high levels of exploitation throughout much of its range.
|Range Description:||Eastern central and southeast Atlantic: from Mauritania (Maigret and Ly 1986), Senegal (McEachran and Séret 1990), Guinea (Domain 1989), Guinea-Bissau (Sanches 1991), and Angola (Bianchi 1986).
Southwest Atlantic: known only from two records from Brazil in the southwest Atlantic, both from Paraná State (Barletta et al. 1989, Charvet 1995, Gomes and Gadig 2003, P. Charvet-Almeida pers. comm.). The first specimen was caught in coastal waters of Baía de Paranaguá (Barletta et al. 1989) and the second from off Superagui, close to the border with São Paulo (Charvet 1995, P. Charvet-Almeida pers. comm.).
Native:Angola (Angola); Brazil (Paraná); Guinea; Guinea-Bissau; Mauritania; Senegal
|FAO Marine Fishing Areas:||
Atlantic – eastern central; Atlantic – southeast; Atlantic – southwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||No specific data are available on population or catch trends for this species. This is probably a rare species in the southwest Atlantic.|
|Habitat and Ecology:||A pelagic species that is usually found at the surface or close to the bottom (McEachran and Seret 1990). Like all Mobula, this species is viviparous, giving birth to one young per litter (McEachran and Séret 1990). Both Brazilian records were gravid females bearing a single near-term embryo (Barletta et al. 1989, Charvet 1995, Gomes and Gadig 2003, P. Charvet-Almeida pers. comm.). Mobula rochebrunei attains a maximum size of 133 cm disc width (DW), with near-term embryos 34?35 cm DW (Notarbartolo-di-Sciara 1987) and feeds on small fish and plankton (Maigret and Ly 1986). No other information is available on its biology.|
Mobulid rays are taken by surface gillnet, longline, purse seine and directed harpoons throughout much of their range, but detailed information on these fisheries is poorly documented (White et al. 2006). Mobula rochebrunei is of commercial importance to fisheries throughout its range (McEachran and Séret 1990) and is taken either as a target species or a utilised bycatch of gillnet fisheries. Their aggregating habit makes them easy to target in large numbers as they travel in schools. There are no specific data, however, on landings in local fisheries where the species is taken in West Africa.
The northwestern African shelf is considered fully exploited (Zeeberg et al. 2006) and ranks amongst the most intensively fished areas in the world. Foreign industrial freezer trawlers targeting small pelagic fish (Sardinella, sardine, and horsemackerel) operate nearly year-round on the shelf off western Africa, with some of these vessels amongst the largest fishing boats in the world (Zeeberg et al. 2006).
Zeeberg et al. (2006) examined the bycatch of megafauna in European trawlers operating off Mauritania between 2001 and 2005. They demonstrated considerable bycatch of ?manta rays? which most probably includes Mobula rochebrunei (note that while the authors refer constantly to ?manta rays?, figure 3 in their manuscript clearly shows an entangled Mobula, and subsequent communications with the primary author indicated that they observed both Manta birostris and Mobula species). Zeeberg et al. (2006) extrapolated from their results that some 120?620 ?manta rays? are captured annually by the Irish and Dutch trawl freezer-trawl fleet. Actual bycatch levels off Mauritania will be considerably higher are there are also Russian, Icelandic and Lithuanian trawlers operating in the same areas.
The subregional workshop for sustainable management of sharks and rays in West Africa, 26?28 April 2000 in St Louis, Senegal (Anon. 2000) noted the high threat to sharks in the west African region and a noticeable decline in the CPUE of total sharks and rays. Increased targeting of sharks and rays began in the 1970s, when a Ghanaian fishing community settled in the Gambia and established a commercial network throughout the region, encouraging local fishermen to target sharks for exportation to Ghana. By the 1980s many fishermen were specialising in catching sharks, resulting in a decline in overall shark populations (Walker et al. 2005).
Mobulid species appear to be particularly susceptible to overfishing as their fecundity is among the lowest of all elasmobranchs (with litter sizes of typically only one pup and an assumed gestation period of 1?3 years (White et al. 2006).
Additional research is needed to quantify the extent of target and non-target fisheries take for this species throughout its range. Further research is also required on its life history.
Elasmobranch fisheries are generally unmanaged throughout the range of this species, and attempts to regulate fisheries in these regions would greatly improve conservation of M. rochebrunei and other chondrichthyans.
The development and implementation of management plans (national and/or regional e.g., under the FAO International Plan of Action for the Conservation and Management of Sharks: IPOA?Sharks) are required to facilitate the conservation and sustainable management of all chondrichthyan species across the regions where this ray occurs.
The vulnerability of mobulids and increasing catches requires urgent international conservation measures. These will need to focus on harvest and trade management.
|Citation:||Valenti, S.V. & Kyne, P.M. 2009. Mobula rochebrunei. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. <www.iucnredlist.org>. Downloaded on 25 May 2013.|
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