A dolphin was reportedly entangled in a fishing line at Bedok Jetty yesterday morning.
An eyewitness who gave his name only as Mr Chia told The Sunday Times that he was cycling and took a rest at the end of the jetty at about 7.30am.
"Looking out at the sea, I saw this thing that was floating," said the 55-year-old architect.
"I thought it was a stingray, but it was drifting towards the jetty and I realised that it was a dolphin. It was struggling. The tail looked like it was entangled in some string. There was a hook on the string, attached to a fisherman's line at the jetty."
Mr Chia said a crowd started to gather when they realised there was a dolphin near the jetty.
"Somebody behind me was talking to some authorities, asking them to come down but shortly after, the fisherman cut the line and the dolphin drifted away," he said.
"The dolphin looked very weak and drifted out to sea."
He said the entire episode lasted about 15 minutes and there was no blood or any sound from the dolphin. "I've never seen dolphins before at the jetty. I've seen wild dolphins only in Malaysia," he said.
Mr Kalai Vanan, deputy chief executive of Animal Concerns Research and Education Society, said it received a call about the incident and responded, but the animal had left when its staff arrived.
The animal was sighted again a while later and then disappeared, he said.
"We suspect it might (still) be entangled in something," he said.
Dolphins are not uncommon in Singapore's waters.
In 2016, a dolphin carcass washed ashore at East Coast Park. It was identified as an Indo-Pacific humpbacked dolphin, or pink dolphin, the most commonly sighted dolphin species in Singapore waters.
In sightings reported to the National University of Singapore's Tropical Marine Science Institute, at least 169 dolphins were spotted between 2008 and 2011 in the waters between Singapore and Batam, near St John's Island and Pulau Semakau, and as close to shore as Marina Barrage.