Cruise ship passengers witnessed the first Hector's dolphin calf of the season this morning, which are among the most endangered dolphins in the world. Black Cat Cruises Sales and Marketing Manager Natasha Lombart said the dolphins were spotted in the upper harbour near Wainui. "Seeing dolphin calves is brilliant, as Hector's dolphins are endangered, so it is a real thrill for both our crew and passengers to spot the first baby this season. "Because of their coastal habitat and slow reproductive rate they are particularly vulnerable to entanglement in fishing gear, especially gill nets, so spotting the first calf today is a real milestone." Black Cat Cruises skipper Julian Yates said four adult Hector's dolphins were spotted at Wainui, along with a baby calf. "The calf looked around just four weeks old, you can tell their age by the folds in their skin which help indicate how young the calf is," Mr Yates said. Females usually have one calf every two to three years.