Taxon name
Rhizoprionodon acutus
(Rüppell, 1837)
Uploaded by
National Red List Database
Taxonomic information
Scientific name
Rhizoprionodon acutus
(Rüppell, 1837)
Assessed taxon level
Species
Higher level taxonomic groupings
Vertebrates
Fishes
Species authority
(Rüppell, 1837)
Taxonomic notes and synonyms listed
Molecular evidence supports the idea that Rhizoprionodon acutus is a complex of (at least) four species that needs further taxonomic investigation (Naylor et al. 2012).
Location and scope
Specific locality or subnational name or regional name
United Arab Emirates (the)
Scope (of the Assessment)
National
Countries included within the scope of the assessment
United Arab Emirates (the)
Does the assessment cover a marine EEZ area(s)?
Not_assigned
Conservation Status
Assessed as
Near Threatened
Qualifying criteria (if given)
A2cd
Criteria system used
IUCN
(see Assessment details)
Assessment rationale/justification
The Milk Shark occurs throughout UAE waters. It is very commonly taken in a wide range of artisanal, subsistence and commercial fisheries, and is often the dominant shark species in landings in the UAE. Inshore fishing pressure is intense and intensifying in parts of the Arabian Sea, and its abundance is suspected to have declined due to fishing. Though data specifically from the UAE are not available, individuals in the UAE are a component of a larger, interconnected and migratory population that occurs broadly in the north-western Indian Ocean. Given the intense fishing pressures faced by this species throughout the Arabian Seas (and until recently, in the UAE), and ongoing threats from bycatch and habitat loss, it is inferred that declines reported in the Arabian Seas are representative of the status in the UAE. Based on recorded levels of exploitation and decline in habitat quality, it is suspected to have declined by 20-30% over the past three generation lengths, or about 15 years. It is listed as Near Threatened, nearly meeting the thresholds for Vulnerable A2cd.
Assessment details
Assessors/contributors/reviewers listed
UAE National Red List Workshop
Criteria system used
IUCN
Reference for methods given
IUCN. 2012. IUCN Red List Categories and Criteria: Version 3.1, Second edition. IUCN, Gland, Switzerland and Cambridge, UK. iv + 32pp pp. And IUCN. 2012. Guidelines for Application of IUCN Red List Criteria at Regional and National Levels: Version 4.0. Gland, Switzerland and Cambridge, UK: IUCN. iii + 41pp.
Further information
Endemism (according to assessment)
Endemic to region
Not assigned
Taxon distribution as listed in assessment
The Milk Shark occurs throughout UAE waters. Globally, it is widespread in the Indo-West Pacific and Eastern Atlantic Oceans (Last and Stevens 2009).
Is there a map available in assessment?
Yes
Habitat and systems
Ecological system type
Habitat
Habitat details as listed in assessment
The Milk Shark is a common continental shelf species that mostly inhabits muddy waters in coastal areas to about 50 m depth (Weigmann 2016). Across its range, it is reported to reach a maximum size of 178 cm, however, in the Arabian Seas region, the largest specimen recorded is 98 cm TL (Jabado et al. 2015). Females reach maturity between 59.7-74 cm TL and males between 60-76.5 cm TL (Henderson et al. 2006, Moore et al. 2012, Jabado et al. 2015, Shaaban et al. 2018, Sen et al. 2018). Off northwest India, it reaches maturity at the end of its second year and is a moderately fast-growing species of shark (Sen et al. 2018). Its natural mortality rate off northwest India was estimated as 0.61 year<sup>-1</sup> (Sen et al. 2017). It has a very productive life history being born at around 35-37 cm TL, maturing at young ages (2-3 years), producing 2-8 young every year and living up to 10 years (Henderson et al. 2006, Kizhakudan et al. 2015). Generation length is estimated at 5.25 years (Compagno 1984, Last and Stevens 1994).
Threats and conservation measures listed
Threats listed in assessment
In the UAE, sharks have been impacted by targeted commercial fisheries until 2014 when a ban on export of sharks was imposed (Ministry of Climate Change and Environment). Sharks continue to be impacted by artisanal and bycatch fisheries (Annual Fisheries Statistical Report for Abu Dhabi Emirate 2001-2018), though catch data are not species-specific. Marine habitats in the region have experienced high levels of disturbance and are quickly deteriorating due to major impacts from development activities (Sheppard <em style=""font-variant-ligatures: normal;font-variant-caps: normal;orphans: 2; text-align:start;widows: 2;-webkit-text-stroke-width: 0px;text-decoration-style: initial; text-decoration-color: initial;word-spacing:0px"">et al. 2010).
Publication
Ralph, G.M., Stump, E., Linardich, C., Bullock, R.W., Carpenter, K.E., Allen D.J., Hilton-Taylor, C., Al Mheiri, R., and Alshamsi, O. 2021. UAE National Red List of Marine Species: Reef-building corals, cartilaginous fishes and select bony fishes. 2021. Ministry of Climate Change and Environment, Dubai, United Arab Emirates.
