|Scientific Name:||Diplobatis ommata (Jordan & Gilbert, 1890)|
Diplobatus ommata (Jordan & Gilbert, 1890)
|Red List Category & Criteria:||Vulnerable A2bd+3bd+4bd ver 3.1|
|Assessor(s):||de Carvalho, M.R., McCord, M.E. & Bizzarro, J.J.|
|Reviewer(s):||Fowler, S.L. & Kyne, P.M. (Shark Red List Authority)|
This electric ray has a restricted distribution in shallow water within a heavily trawled area. It is taken as bycatch in shrimp fisheries and although it is not utilized it may appear incidentally in markets. The genus Diplobatis has been shown to have a 27.5% occurrence in the captures of the offshore trawl fishery operating off the Caribbean coast of northern Colombia. There is little information available on this species, however its restricted regional distribution indicates that it is threatened by high levels of incidental fishing mortality, furthermore due to identification difficulties the catch rate is likely to be under-recorded, and therefore it may be more heavily fished than currently thought. As a result this species is assessed as Vulnerable, given its relatively restricted distribution in the areas where there is intensive trawling pressure.
|Range Description:||Eastern Central Pacific, from Baja California to the mid-Colombian coast. Countries of occurrence include: Mexico, Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica, Panama, Colombia, Ecuador, USA (Baja, California) (Love et al. 2005). |
From Bahia San Juanico (26°13'N, 112°28'W), southern Baja California (de La Cruz Agüero et al. 1994), to Ecuador (Bearez 1996), including the Gulf of California (McEachran 1995).
Native:Colombia; Costa Rica; Ecuador; El Salvador; Guatemala; Honduras; Mexico; Nicaragua; Panama; United States
|FAO Marine Fishing Areas:|
Atlantic – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||This species is common over sandy substrates, but also over rocky bottoms, in bays and on rock reefs (De la Cruz Agüero et al. 1997, Allen and Robertson 1994 and Michael 1993). It reportedly lies partially buried in the sand, near rock reefs (Thomson et al. 2000). |
Love et al. (2005) lists 3 m as the shallowest occurrence from an LA County Museum specimen (LACM 49744.002), while Beebe and Tee-Van (1941) report it from 1 fathom (ca. 2 m). The deepest occurrence was 94 m, as reported by A. Linares (1996 cited in Love et al. 2005).
This guitarfish is typically a solitary species, which is inactive during the day and commonly occurs in shallower water at night, utilizing its pelvic fins for benthic locomotion (Beebe and Tee-Van 1941, Michael 1993).
The maximum reported size for this species, is 25 TL (McEachran 1995), with the first size at maturity for females <18.5 cm (Beebe and Tee-Van 1941). The size at first maturity for males is unknown.
Based on a small sample size, it is known to prey on crustaceans [Amphipoda, Decapoda (small shrimp)] and polychaetes (Beebe and Tee-Van 1941).
|Major Threat(s):||Within Mexican waters, this species is not commonly taken by artisanal fisheries, however it is taken as bycatch by shrimp trawlers (Bizzarro pers. comm. Feb 2006). This species itself is not of commercial interest; however its restricted range coincides with that of intense trawling pressure for shrimp. This considerable pressure from large commercial fishing fleets is likely to go unrecorded as this species caught as unused bycatch.|
Improved monitoring of bycatch and other fishery impacts required in order to develop appropriate conservation and management strategies for this and other affected bycatch species.
Further research is one of the most pressing issues, in order to learn more about this species' biology and quantify its contribution to shrimp bycatch. This will require species-specific identification or independent sampling. At present there is not enough known to substantiate an estimate on this species population status and quantify the actual impact of perceived threats (Bizzarro pers. comm. Feb 2006).
|Citation:||de Carvalho, M.R., McCord, M.E. & Bizzarro, J.J. 2006. Diplobatis ommata. The IUCN Red List of Threatened Species 2006: e.T61403A12471646.Downloaded on 12 December 2017.|