This document summarizes a study that tracked giant freshwater stingrays in the Maeklong River in Thailand using acoustic telemetry to understand their life history, life cycle, and habitats. Ten male and ten female stingrays were fitted with acoustic transmitters and monitored using receivers. The tracking revealed information about their movement patterns, seasonal migrations, and habitat use to help inform management plans and protected area design for this endangered species that faces threats from fishing and degradation of riverine environments.

1. Tracking of Giant Freshwater Stingray
(Himantura chaophraya/ Urogymnus
polylepsis) by Using Acoustic
Telemetry in Maeklong River, Thailand
Nitiwadee Keschumras , DVM
Veterinary Medical Aquatic animal Research Center,
Chulalongkorn university

2. The Giant Freshwater Stingray
“RAHU” Stingray

3. ü A size can be up to 240 cm disc width (DW) and 600 kg
in weight.
ü Males mature by 110 cm DW.
ü Young (a single pup) are born at about 30 cm DW.

4. Geographic range
ü Found in Chaophraya,
Nan, Maeklong, Bang
pakong, Tachin, Mekong
rivers.
ü The species does appear
to occur in both brackish
and freshwater
of Himantura chaopraya

5. Endangered status in 2000

6. Endangered status in 2018

7. Threats
ü Bycatch or invasive techniques fishing
ü Capture for aquariums and sport fishing
ü For food (urban area)

8. Mass deaths
ü Degradation of
riverine environments
and pollutions

9. Life history by tagging ……
ü V9-180 KHZ transmitter
ü VR2W-180 KHZ receivers
Study life history, life
cycle and habitats

12. Identification
ü RFID TAG Pocket Reader
ü Passive Integrated
Transponder tags (PIT tags)
/ microchip

14. 1
2
3
4
5
6
7
8

16. ü 10 Males
ü 10 Females

17. Monitoring Techniques and Technology
ü Acoustic telemetry
- Movement pattern
- Seasonal migration
- Habitat use
ü Reduce the frequency of capturing
ü Management plans and design
protected areas