Biological observations and new maximum reported sizes for two threatened rays: ornate eagle ray Aetomylaeus vespertilio and mangrove whipray Urogymnus granulatus from the Gulf of Mannar, India

Abstract

Record-sized specimens of the ornate eagle ray Aetomylaeus vespertilio and mangrove whipray Urogymnus granulatus were caught by single-day trawlers off Pamban Island in the Gulf of Mannar, Tamil Nadu, India during 2021 and 2022. All were landed at the Pamban Therkuvadi Fish Landing Centre (FLC). The largest ornate eagle ray was 384 cm disc width (DW) and weighed 530 kg, setting a new global record for the species, as the previous maximum size was reported to be 300 cm DW. This specimen was landed on 19 July 2021. Another large specimen of this species (360 cm DW and total weight of 453 kg) was caught and landed on 12 August 2022. The landed mangrove whipray was 153 cm DW and 150 kg total weight, larger than the previously reported maximum size of 141 cm DW. The morphometrics, stomach contents and reproductive state were studied. One of the eagle rays was a pregnant female with three full-term embryos in the uterus, while the whipray was a spent female. The main prey species in the stomach of eagle ray was big-eye scad Selar crumenophthalmus. The mangrove whipray had fed on a range of fish (pigface bream, goatfish, silverbellies, silverbiddies and lesser sardine) and octopus.