|Scientific Name:||Fontitrygon geijskesi|
Dasyatis geijskesi Boeseman,1948
|Taxonomic Source(s):||Last, P.R., Naylor, G.J.P. and Manjaji-Matsumoto, B.M. 2016. A revised classification of the family Dayatidae (Chondrichthyes: Myliobatiformes) based on new morphological and molecular insights. Zootaxa 4139(3): 345-368. http://doi.org/10.11646/zootaxa.4139.3.2.|
|Taxonomic Notes:||Last et al. (2016) placed Dasyatis colarensis, D. garouaensis, D. geijskesi, D. margarita, D. margaritella, and Urogymnus ukpan within their newly described genus Fontitrygon. The two western Atlantic species (F. colarensis and F. geijskesi) differ significantly from the other taxa in this genus and may prove to be non-congeneric with the four species from western African (Last et al. 2016).|
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Assessor(s):||Charvet-Almeida, P. & de Almeida, M.P.|
|Reviewer(s):||Fowler, S.L. & Kyne, P.M.|
This is an amended version of the 2006 assessment to accommodate the change in genus name.
A large, relatively uncommon, stingray that is found on the northern coast of South America in the Western Central and Southwest Atlantic, mainly in estuarine and coastal areas near the Amazon River mouth. Very limited data are available about the habitat and ecology of this species. Pregnant females are observed with only one to three pups per litter. Population trends and dynamics are completely unknown. The species is taken as bycatch by both artisanal and industrial fisheries, which continue to be unregulated. It is used regionally as a subsistence food source but as a secondary option due to its dark (reddish) coloured flesh. Fishery industries tend to show an interest in large dasyatids as a source of minced fish products, implying that exploitation pressure and population depletion may increase in the future. Base-line studies and fishery monitoring are required for this species, but given its inshore occurrence in fished regions, relatively restricted range and habitat, biology and apparent interest to industrial fisheries, the species is assessed as Near Threatened.
|Previously published Red List assessments:|
|Range Description:||This species has a relatively restricted geographic range (northern Atlantic coast of South America), ranging from northern Brazil to the Venezuelan coast, including French Guiana, Guyana, Suriname and Trinidad and Tobago (Cervigón et al. 1992, Uyeno et al. 1983). It is found mainly in the region of influence of the Amazon River discharge. During the dry season it is found closer to the shore and is present in the Marajó Bay region (authors' observations).|
Native:Brazil; French Guiana; Guyana; Senegal; Trinidad and Tobago; Venezuela, Bolivarian Republic of
|FAO Marine Fishing Areas:|
Atlantic – western central; Atlantic – southwest
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||This species is not very common as other dasyatid species throughout its distribution range. Population size, trends and dynamics remain unknown for this species.|
|Current Population Trend:||Unknown|
|Habitat and Ecology:||It is considered a shallow water species (Cervigón et al. 1992) but Uyeno et al. (1983) have reported that it was found at greater depths (810 m). The authors have observed it at depths of 8 to 20 m. |
Very little data is available about the habitat and ecology of this marine/estuarine species that seems to inhabit mainly shallow coastal waters.
As for other dasyatids found in the North region of South America, this species exhibits movements (migrations?) associated with seasonal salinity variations. It moves closer to the coast and enters bays during the dry season and during the rainy season it moves farther from the coast. These movements might be related to the reproductive cycle, since most females caught close to the coast and in bays had embryos in early stages of development as observed in Fontitrygon colarensis. This movement pattern is also similar to that observed for the freshwater stingray Plesiotrygon iwamae (Charvet-Almeida 2001), however, pregnancy development stages differ between F. geijskesi and P. iwamae when these two species are found close to the coast (authors' information).
Further information on the life history of this species is currently under study.
Life history parameters
Age at maturity (years): Unknown.
Size at maturity (total length cm): Unknown.
Longevity (years): Unknown.
Maximum size (disc width): At least 150 cm DW (Cervigón et al. 1994).
Size at birth (cm): Unknown.
Average reproductive age (years): Unknown.
Gestation time (months): Unknown.
Reproductive periodicity: Preliminary data indicates once a year (authors' observation).
Average annual fecundity or litter size: Observed litters of 1 to 3 pups (authors' observation).
Annual rate of population increase: Unknown.
Natural mortality: Unknown.
This stingray is caught as a bycatch (hooking, netting and entanglement) in artisanal and industrial fisheries aimed at large catfish that are present in the Amazon estuary. This species is also taken regionally as a secondary option subsistence food source. Fishery industries tend to show an interest in large dasyatids as a source of minced fish products, implying that exploitation pressure and population depletion may increase in the future.
Intrinsic factors probably also represent a threat for this species as to most other elasmobranchs species (Camhi et al. 1998), particularly given this species' large size and low fecundity.
Research actions are required for this species. Preliminary base-line studies are in progress to obtain further data on the biology, ecology, uses and fishery data of this species.
Captures should also be monitored to observe if they are within a sustainable range and to verify if there are tendencies of increase. Industries that recently began processing minced fish products are very likely to show an interest for this species as for other dasyatids.
Habitat maintenance and conservation are desired for most coastal species that are likely to be susceptible to environmental changes.
Education and public awareness could also contribute to the understanding that future increases in catches should be carefully studied and monitored.
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 in the region. See Anon. (2004) for an update of progress made by nations in the range of F. geijskesi.
|Citation:||Charvet-Almeida, P. & de Almeida, M.P. 2016. Fontitrygon geijskesi. The IUCN Red List of Threatened Species 2016: e.T60153A104171793.Downloaded on 24 April 2017.|
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