A group of bottlenose dolphins that swam up a New Zealand river four days ago, apparently to escape killer whales, have returned to the sea, a conservation official said on Saturday.
Four dolphins swam back down the Oruaiti River to Mangonui Harbor on the east coast of North Island either late Friday or early Saturday, Department of Conservation area manager Jonathan Maxwell said.
“We were very hopeful the dolphins would make their own way to sea without the need for interference from us, so this is a great result,” Maxwell said.
Killer whales have been spotted recently in Mangonui Harbor and conservation department staff suspect the dolphins headed up river for safety on Wednesday. Killer whales, also known as orca, hunt and eat dolphins.
A fifth dolphin died on Thursday after it got stranded. Conservation staff had been monitoring the remaining dolphins to ensure no more became trapped.
Conservation staff unsuccessfully attempted on Thursday to herd the dolphins out of the Oruaiti river and into Mangonui Harbour.
Department spokeswoman Carolyn Smith said the dolphins had appeared to be acting normally so on advice from national marine mammal experts staff decided not to interfere, in the hope they would head back out to sea of their own accord.
She said it was not uncommon for bottlenose dolphins to swim up rivers, but that if they spent extended periods in a freshwater environment there was an increased risk of disease and parasites, and only a limited food source.
Source: Hindu Times