The placement of Megatrygon microps in the family Dasyatidae is provisional; it may be more closely related to the freshwater Neotropical stingrays (Potamotrygonidae) of South America. Further investigations are needed to determine the position of this species in the order Myliobatiformes, but it may belong in its own family (Last et al. 2016).

The Smalleye Stingray (Megatrygon microps) is a large (to at least 250 cm DW) poorly-known stingray that occurs on the continental shelf in coastal waters, including estuaries and river mouths, but may also occur in the open ocean. It occurs to a depth of 222 m, but is mostly found in waters less than 30 m. It has a low fecundity of a single pup which reduces its resilience to fishing pressure. The species is is semi-pelagic but may also be demersal and its records of occurrence are patchy and discrete across its range. Mozambique is the only location with relatively regular in-water sightings, but even with increased dive effort and focused research effort, sightings are still low. There is no information available to determine population trends, and juvenile individuals are seldom reported. There is intensive and mostly unregulated fishing pressure throughout much of the Smalleye Stingray’s range, and it is occasionally landed by artisanal fisheries and in trawl fisheries. It has been assessed as high risk from tuna fishing gear (i.e., purse seine, longline, and drift gillnets) in the Indian Ocean likely due to its large size and semi-pelagic habitat, with this pelagic habitat use possibly accounting for its rare landings in demersal fisheries. It is unknown if this species is naturally rare or if its populations have declined due to fishing pressure. Given that the full depth range and its relative use of pelagic and demersal habitats is unknown, it is not possible to ascertain the level of overall interactions with fisheries. Since it is unknown if fishing is causing a population reduction, there is currently inadequate information available to assess the Smalleye Stingray beyond Data Deficient.

The Smalleye Stingray has a patchy distribution in the Indo-West Pacific. The known record of its occurrences to date are: Mozambique (Pierce et al. 2008, Boggio-Pasqua et al. 2019, Keeping et al. 2021, O’Connor and Cullain 2021), Kenya (iNaturalist 2023), the Persian Gulf (Moore 2010), Pakistan (Osmany et al. 2015, Moazzam and Osmany 2021), India (including the Ganges River) (Nair and Soundararajan 1976, Ishihara et al. 1998, Kapoor et al. 2002, Purushottama et al. 2018), Bangladesh (Annandale 1908), Maldives (Adam et al. 1998), Gulf of Thailand (Last et al. 2016b), Malaysia (Sabah and Sarawak) (Mohsin and Ambak 1996), Philippines (iNaturalist 2023), Indonesia (White et al. 2006, White and Dharmadi 2007), Papua New Guinea (Last et al. 2016b), and northern and eastern Australia (Meekan et al. 2016, Kyne et al. 2021, A.O. Armstrong unpub. data 2023). Based on its current distribution, it also likely occurs in other areas in the Indo-West Pacific.

There is no available information on population size, structure, and trend. There are a low number of recorded observations of this species throughout its known range. Despite significant diver tourism operations in some areas, the Smalleye Stingray is only occasionally sighted by scuba divers off eastern Australia (Meekan et al. 2016, A.O. Armstrong unpub. data 2023) and the Maldives (Adam et al. 1998, G.M.W. Stevens pers. comm. 3 April 2023). It has been sighted around reefs in southern Mozambique (Boggio-Pasqua et al. 2019, Keeping et al. 2021), but sightings are not common despite significant diving effort and focused research. Most encounters are with larger mature individuals (both female and male animals) with only a couple of smaller, presumably juvenile individuals recorded (A.D. Marshall unpub. data 2023). In India, few individuals (less than 20) have been recorded during the last 10 years of fishery observation records, despite long-term fisheries monitoring surveys (K.K. Bineesh unpub. data 2023). Across its remaining range, most published and reported records are limited to one observation (e.g., Mohsin and Ambak 1996, White et al. 2006, Moore 2010, Osmany et al. 2015, Last et al. 2016b, iNaturalist 2023). The scarcity of records of the Smalleye Stingray and its apparent patchy distribution may indicate this species is naturally rare. Due to the lack of population estimates or time series, the population trend due to interactions with fisheries is unknown.

The Smalleye Stingray is a demersal and semi-pelagic species found in coastal waters and river mouths at depths of 0–222 m; however, most sightings of the Smalleye Stingray are in waters less than 30 m depth (Kapoor et al. 2002, Boggio-Pasqua et al. 2019, Meekan et al. 2016, A.O. Armstrong unpub. data 2023, A.D. Marshall unpub. data 2023). This species has mostly been observed swimming in mid-water indicating that it is possibly semi-pelagic, which may account for its rarity in catches throughout its range compared to other dasyatid species (Pierce et al. 2008). However, it has been visually confirmed that individuals can and do rest on the sea floor (A.D. Marshall unpub. data 2023). Individuals in southern Mozambique have shown a high degree of residency to certain deepwater reefs, but they have also been recorded making straight-line movements up to 200 km (A.D. Marshall unpub. data 2023). The species is occasionally seen in groups of up to four individuals (Keeping et al. 2021). It reaches a maximum size of 250 cm disc width (DW) (A.D. Marshall unpub. data 2023). Reproduction is viviparous with litter sizes of a single pup with a size-at-birth of approximately 33 cm DW (Last et al. 2016b). Low fecundity makes this species more biologically sensitive to population depletion than many other stingray species.

There is limited information on the bycatch of the Smalleye Stingray reported throughout its range. It is known to be caught in trawl and Danish Seine fisheries. There is a high level of fisheries resource use and increasing fishing pressure across the range of the Smalleye Stingray, and demersal coastal fisheries resources have been severely depleted in significant areas of the Indo-West Pacific, including India and Southeast Asia (Stobutzki et al. 2006). An increase in fishing pressure along the Mozambique coast over the last decade has coincided with dramatic declines in other large ray species, like manta rays and devil rays (Rohner et al. 2013), which suggests that the Smalleye Stingray may have also declined in that region although it is the only location worldwide where this species is observed with any regularity. Despite regular in-water observations, researchers have only verified three individuals landed by artisanal fishers in the Inhambane Province since 2003 (Boggio-Pasqua et al. 2019, A.D. Marshall unpub. data 2023). A single individual was targeted by spearfishers and two were caught in nets. While such a large stingray can be difficult and dangerous for artisanal fishers to land, interviews with fishers have also indicated that this species is rare and opportunities to target the species do not occur frequently (A.D. Marshall unpub. data 2023). The Smalleye Stingray has been assessed as having a high susceptibility to capture in the three main tuna fishing gears, that is, purse seine, longlines and drift gillnets within the Indian Ocean Tuna Fisheries Commission area of competence, with the highest susceptibility to purse seine and longline gear (Roberson et al. 2022).

In Pakistan, low numbers of this species are reported in fisheries, including a specimen from Karachi Fish Harbour (122 cm DW) and a specimen from 77 m in offshore Sindh waters (142 cm) (Moazzam and Osmany 2021). The size of these specimens suggest they could be juveniles or sub-adults. In 2022, there was one confirmed record of the Smalleye Stingray as bycatch of a trawl net, possibly caught at Khori Great Bank, near the Indian border (Muhammad Moazzam Khan pers. comms. 4 May 2023). In India, there is one unpublished record of Smalleye Stingray from south Andaman Islands, where it is caught as bycatch in demersal trawls at a depth range 20–40 m (K.K. Binesh unpub. data 2023). During the last 10 years of fishery observation data, few individuals (<20) have been observed (K.K. Bineesh unpub. data 2023). Analysis of catch data from eastern Indonesia indicates the Smalleye Stingray makes up less than 0.1% of the biomass of batoids caught in the fishery (White and Dharmadi 2007). The species is caught occasionally as by-product in trawl and Danish seine fisheries operating in west (between Natuna and Karimata Islands) and south Kalimantan waters of Indonesia (Fahmi et al. 2016). The Smalleye Stingray was recorded only twice in the Danish seine fishery during studies of catches in August 2005 and May 2007 (two individuals were captured measuring 222 cm DW and 245 cm total length (TL)). Only one Smalleye Stingray was reported in the Indonesian tangle net fishery of north-western Java between 2001–2005 where almost 1,600 elasmobranchs were reported in catches (D’Alberto et al. 2022).

In Papua New Guinea, it has been caught in low numbers in the Gulf of Papua trawl fishery (Baje et al. 2021), and an ecological risk assessment of the Smalleye Stingray in this fishery, suggests the species is at medium risk based on susceptibility to capture and a limited ability to recover (Baje et al. 2021). In Australia, it has been recorded in low numbers in the Developmental Fin Fish Trawl Fishery in the Gulf of Carpentaria (Knuckey et al. 2022) and in the Northern Prawn Fishery where it has been assessed as at low risk from the fishery as the mandatory use of bycatch reduction devices since 2001 are likely to have reduced the catch of this species significantly due to its large size (Brewer et al. 2004, Sporcic et al. 2021). The rarity in capture of the Smalleye Stingray across its range, despite high fisheries pressure throughout its large geographic range, may be due to its semi-pelagic nature offering some refuge from demersal trawling. However, it is also possible the species is under-reported in catch data.

The Smalleye Stingray is occasionally utilised for its meat and cartilage in Indonesia (White et al. 2006, White and Dharmadi 2007), Mozambique (Boggio-Pasqua et al. 2019) and possibly elsewhere. In India, there are reports of large sized rays transported to Chennai or Kolkata and utilised fresh or salted for local consumption (K.K. Bineesh unpub. data 2023).

There are no species-specific measures currently in place for the Smalleye Stingray. Given this species has been assessed as highly susceptible to tuna fishing gear in the Indian Ocean, and is likely misidentified or only recorded in aggregated groups (e.g., ‘rays’) (Roberson et al. 2022), it is recommended that improved monitoring and species-specific catch data are urgently needed to estimate the population trend for the Smalleye Stingray. Further research is also needed to better define the species' distribution, depth-use, habitat, and life history.