Mozambique · Acoustic Telemetry Network
Mozambique Smalleye Stingray Research Project
MMF's research on the smalleye stingray in southern Mozambique, from the species' first record in the western Indian Ocean in 2008 to long-term photo-identification and acoustic tracking of this rare giant.
In Mozambique we have an extraordinary opportunity to study the rare and enigmatic smalleye stingray. Despite being the largest of the marine stingrays, the species has eluded research efforts to date, leaving it data deficient and vulnerable to exploitation.
This project aims to understand the distribution, movement, and habitat use of smalleye stingrays in the Inhambane Province to determine their population status and conservation needs.
In 2008 MMF researchers made a landmark discovery: a large population of the gigantic and elusive smalleye stingray, Megatrygon microps, living off the coast of Mozambique. The discovery represented a range extension for the species of over 5000 km, and some of the first live sightings of the species. Elsewhere, sightings of this enormous stingray are infrequent, suggesting it remains rare and patchily distributed.
Objectives
Now that we have determined that the natural spot patterning on these stingrays is stable enough to use in long-term individual identification studies we are beginning to estimate the abundance and movements of these rays along the southern Mozambican coast.
Acoustic telemetry is now allowing us to study the movements of this large and unusually mobile ray for the first time. Rays fitted with acoustic tags are detected automatically whenever they pass one of our receivers, building a picture of their home ranges, habitat use, daily movement patterns, depth preferences, and general behavior that no amount of diving could assemble on its own. The collection of small tissue samples from individual rays allows us to examine their ecological role in the area.
We will also be monitoring artisanal fisheries to quantify catches of this species along the coast and to identify ‘hotspot’ areas for further investigation.
What we've done
- MMF scientists reported the first record of the smalleye stingray in Africa (opens in a new tab) - a range extension of 5000 km from its closest known location, in the Maldives.
- Through sustained monitoring efforts our team has now identified almost 100 individual rays in southern Mozambique - the largest and most comprehensive database of its kind in the world.
- MMF co-authored the current IUCN Red List Assessment (opens in a new tab) for this species.
- We have identified over a dozen sites – including throughout the Bazaruto Seascape – with regular sightings of smalleyes in southern Mozambique over the last decade, with our preliminary data showing that these semi-pelagic rays show fidelity to certain reefs.
- MMF scientists published the first study examining the longevity of dorsal spot patterning (opens in a new tab) and the feasibility of using photo-identification techniques (opens in a new tab) for long-term monitoring of smalleye stingrays.
- We are now tracking smalleye stingrays with acoustic tags: three rays were tagged in 2023, and two more off Tofo in August 2026, from a Peri-Peri Divers boat on a dive where four were seen together. Two tagged rays have shown year-round residency inside the Bazaruto Archipelago National Park.
Support this project
Donations to our Mozambique program fund the fieldwork, photo-identification, and acoustic tracking described on this page.
You can also donate stock or cryptocurrency, recommend a grant from your donor-advised fund, or leave a gift in your will.
Our work on smalleye stingrays in Mozambique
A Mysterious Giant
Despite being the largest known marine stingray, little is known about the biology or ecology of smalleye stingrays. The species is currently listed as ‘Data Deficient” on the IUCN’s Red List of Threatened Species. Regular sightings on inshore reefs in southern Mozambique confirm that this area is not only a critical habitat for the species but is also the best area to study them.
Conservation Needs for Smalleye Stingrays
A marked increase in the use of indiscriminate fishing practices such as gill-netting, long-lining, and seine netting along the Mozambican coast represents a clear threat to smalleye stingrays. The large size of this species, and their curiosity toward people, make them easy targets. To exacerbate the problem, large stingrays typically take years to reach adulthood and have small litters, making them particularly susceptible to overexploitation. Considerable research on this species is needed to address the lack of biological data and these conservation concerns.
First tracking results
The first years of acoustic tracking have produced two findings that were impossible to establish from sightings alone. Two tagged smalleye stingrays have shown year-round residency inside the Bazaruto Archipelago National Park, appearing consistently across the receiver network rather than passing through — evidence that the park’s reefs are sustained habitat for the species, not an occasional stop. And their movement is strongly crepuscular, peaking at dawn and dusk, which is consistent with a foraging strategy tied to low light.
That matters for conservation. A species that is resident inside a protected area benefits directly from that protection, and a species that concentrates its activity into predictable windows can be monitored, and protected, far more efficiently. Further rays were tagged at Tofo in August 2026, and analysis of the growing acoustic dataset is underway.
Research team
Dr. Stephanie Venables
Research Associate
Stephanie has been working with MMF since 2014. Her research involves applying different research techniques as conservation tools, using methods such as telemetry (tagging), population genetics, and demographic modeling to better understand species and the way they interact with their environment.
Rare footage of smalleye stingrays in Africa
Atlantine Boggio-Pasqua on smalleye stingray photo-identification
Adopt a smalleye stingray
The largest marine stingray on record, a rare giant MMF scientists first reported from Africa in 2008.
MMF Project Team
Dr. Nakia Cullain
Dr. Stephanie Venables
Dr. Clare Prebble
Nilza de Catarina
Dr. Andrea MarshallSupporters & Partners
Research papers
- 2023Smalleye stingray Megatrygon microps
- 2019Spotting the “small eyes”: using photo-ID methodology to study a wild population of smalleye stingrays ( Megatrygon microps) in southern Mozambique
- 2015Megatrygon microps
- 2008New record of the smalleye stingray, Dasyatis microps (Myliobatiformes: Dasyatidae), from the western Indian Ocean
In the news
Coverage of this work.
Travel with our scientists
Every MMF expedition is hosted by a working marine scientist, who shares the latest research and conservation discoveries about the animals you'll see.
Mozambique Acoustic Telemetry Network
Bazaruto Seascape Marine Research
Mozambique Elasmobranch Diversity Research Project
Závora Marine Conservation