A young dolphin swum into the harbour 10 days ago.
The common dolphin was monitored by Jersey vets and volunteers from the British Divers Marine Life Rescue, who said she was healthy and feeding well.
However, it is thought the animal was so young, it should probably have been with its mother.
Volunteers in Jersey are looking for a dolphin, which had been swimming in the harbour for more than a week.
The Common dolphin has not been seen since yesterday morning and it is thought she might have found her way out, having gone in search of deeper waters.
The public are being asked to keep an eye out for the animal, in case it gets into any difficulty and ends up stranded on one of the Island's beaches.
Donna de Gruchy, Jersey Co-ordinator of the British Divers Marine Life Rescue, has thanked Islanders for their care, and for efforts to keep the harbour calm and peaceful while the dolphin was there.
The weekend event coincides with International Pride Month and the 51st anniversary of the Stonewall riots.
The scheme has been backed by the island's Lieutenant-Governor, and is the first of its kind in the Channel Islands.
Sunny spells and isolated light showers. After dusk fair spells with isolated showers.