Hector's dolphins have one of the most restricted ranges of all dolphins; they live only in some coastal areas of New Zealand and nowhere else. They prefer shallow waters less than 100m (328ft) deep and 16km (just under 10 miles) from New Zealand’s shore. Preferring to stick to where they know, individual dolphins usually cover an area of about 50km of coastline, and scientists have recorded the same individuals in the same general area year-round for over 20 years. These days, their distribution is patchy around New Zealand’s coast – a stark reminder of the difficulties they face. Due to a major decline in numbers, only small, fractured populations remain.