|Scientific Name:||Dasyatis colarensis|
|Species Authority:||Santos, Gomes & Charvet-Almeida, 2004|
|Taxonomic Notes:||This species is often mistaken with Dasyatis guttata but snout length and pelvic fin shape differ.|
|Red List Category & Criteria:||Vulnerable A3d ver 3.1|
|Assessor(s):||Charvet-Almeida, P. & de Almeida, M.P.|
|Reviewer(s):||Kyne, P.M. & Fowler, S.L. (Shark Red List Authority)|
A large (to at least 165 cm disc width), common endemic estuarine dasyatid species with a limited distribution mainly in the region of influence of the Amazon River discharge in northern Brazil. The species may occur into Venezuela, but this is uncertain at present. Very limited information is available concerning the habitat and ecology of this species that seems to inhabit shallow costal waters. However, its large size suggests limited biological characteristics, which place the species at risk of overexploitation. Indeed, examined females have had only 1 to 4 pups per litter and the species is thought to produce only a single litter per year. This species is caught as bycatch by both artisanal and industrial fisheries throughout its known range, including fisheries aimed at large catfish in the Amazon estuary. Furthermore, directed industrial fishing for this species has recently commenced and catches are being exported to European countries. This raises considerable concern for this species, a large inshore dasyatid with low fecundity, which is susceptible to capture in a variety of fishing gear and which has a restricted distribution (even if the species is shown to occur further west into Venezuela, its range is still limited). With directed industrial fishing pressure and bycatch impacts it is projected that this species will undergo declines in abundance over the next three generation period, thus meeting the criteria for Vulnerable A3d.
|Range Description:||This species has a relatively restricted geographical range and is found mainly in the region of influence of the Amazon River discharge. During the dry season it is commonly found in the Marajó Bay region. It is probably present in a few other neighboring areas but further observations and documentation are required.|
Native:Brazil; Venezuela, Bolivarian Republic of
|FAO Marine Fishing Areas:||
Atlantic – southwest; Atlantic – western central
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||This species in common in the Marajó Bay region during the dry season of the year (Charvet-Almeida and Almeida pers. obs.). Other population trends and dynamics are completely unknown for this species.|
|Habitat and Ecology:||
Very limited information is available concerning the habitat and ecology of this estuarine species that seems to inhabit shallow costal waters.
Little known of the species' biology. Reaches at least 165 cm DW. Examined females have had only 1 to 4 pups per litter and the species is thought to produce only a single litter per year.
This species presents annual movements (migration?) that are influenced by seasonal salinity variations. It moves closer to the coast and enters bays during the dry season and during the rainy season it is not present in bays and moves farther from the coast. These movements seem to be somehow related to the reproductive cycle since most females caught closer to the coast and in bays had embryos in early stages of development. This movement pattern is similar to what has been observed for the freshwater stingray Plesiotrygon iwamae (Charvet-Almeida 2001), however, pregnancy development stages differ between those two species when they are caught closer to the coast and inside bays (Charvet-Almeida and Almeida unpublished data).
Life history parameters
Age at maturity (years): Unknown.
Size at maturity (total length cm): Unknown.
Longevity (years): Unknown.
Maximum size (disc width): At least 165 cm DW.
Size at birth (cm): Unknown.
Average reproductive age (years): Unknown.
Gestation time (months): Unknown.
Reproductive periodicity: Unknown but preliminary information indicates once a year.
Average annual fecundity or litter size: Observed litters of 1 to 4 pups.
Annual rate of population increase: Unknown.
Natural mortality: Unknown
This stingray is susceptible to capture in a variety of fishing gear and is caught mainly as bycatch (hooking, netting and entanglement) in both artisanal and industrial fisheries aimed at large catfish that are present in the Amazon estuary. However, recently a directed fishery has commenced and the local industrial fleet started capturing this species to be exported. It is now being currently exported to European countries by a few fishing industries located in the State of Pará (Brazil).
Intrinsic factors probably also represent a threat for this species as to most other elasmobranchs (Camhi et al. 1998).
Research actions are urgently needed for this species. Preliminary baseline studies have just started and are in progress to obtain further data on the biology, ecology, habitat status, uses and fishery data of this species. Studies are also needed to better define the distribution of D. colarensis.
Captures should also be quantified and closely monitored. An effective management plan would also help manage the industrial fishery/exportation of this species. In the future a catch or export quota system may be required.
Habitat conservation, including the future creation of protected areas, is recommended since within its area of occurrence the industrial fishery is increasing.
Education and public awareness could also contribute to the understanding that fisheries must be carried out within sustainable yield levels.
The development and implementation of a national management plan (e.g., under the FAO International Plan of Action for the Conservation and Management of Sharks: IPOA-Sharks) is required to facilitate the conservation and sustainable management of all chondrichthyan species in Brazil. At the time of writing, Brazil was in the progress of preparing a National Plan of Action (Anonymous 2004), which is in urgent need of implementation.
Anonymous. 2004. Report on the implementation of the UN FAO International Plan of Action for Sharks (IPOA–Sharks). AC20 Inf. 5. Twentieth meeting of the CITES Animals Committee, Johannesburg (South Africa), 29 March–2 April 2004.
Camhi, M., Fowler, S., Musick, J. Bräutigam, A. and Fordham, S. 1998. Sharks and their relatives: ecology and conservation. Occasional Paper of the IUCN Species Survival Commission 20.
Charvet-Almeida, P. 2001. Ocorrência, Biologia e Uso das Raias de Água Doce na Baía de Marajó (Pará, Brasil), com Ênfase na Biologia de Plesiotrygon iwamae (Chondrichthyes: Potamotrygonidae). Masters Dissertation. Belém, Museu Paraense Emílio Goeldi & Universidade Federal do Pará.
IUCN. 2006. 2006 IUCN Red List of Threatened Species. www.iucnredlist.org. Downloaded on 04 May 2006.
IUCN SSC Shark Specialist Group. Specialist Group website. Available at: http://www.iucnssg.org/.
Santos, H.R.S., Gomes, U.L. and Charvet-Almeida, P. 2004. A new species of whiptail stingray of the genus Dasyatis Rafinesque, 1810 from the Southwestern Atlantic Ocean (Chondrichthyes: Myliobatiformes: Dasyatidae). Zootaxa 492:1–12.
|Citation:||Charvet-Almeida, P. & de Almeida, M.P. 2006. Dasyatis colarensis. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 29 March 2015.|