The ban on swimming with bottlenose dolphins applies to tour operators in the North Island’s Bay of Islands, a region consisting of 144 islands that are abundant in marine life and popular with tourists. According to the department of conservation (DOC) research has shown that visitors were "loving the dolphins too much" and human interaction was "having a significant impact on the population’s resting and feeding behaviour."
Currently bottlenose dolphins in the Bay spend about 86% of their daylight hours in the presence of at least one boat. So in order to give them large periods of human-free time, the DOC is also restricting dolphin-watching boat tours to mornings and afternoons only and cutting back interaction time from 30 minutes to 20, according to the New Zealand Herald.
In New Zealand, bottlenose dolphins are classified as endangered because the three main populations are small and more vulnerable than elsewhere in the world. The population in the Bay of Islands is particularly tiny, plummeting from 270 in 1999 to about 31 today. And latest reports show a 75% mortality rate among their calves. Much of that can be attributed to the high volume of boat trips in the area which are causing dolphins to spend less time "feeding, nursing their young and sleeping," as they interact with humans instead, according to the DOC.
"It's very difficult to manage a group of wild animals swimming freely. The dolphins often swim towards boats themselves and you simply can't put a barrier around them or monitor every interaction they have," Sue Reed-Thomas, DOC Northern North Island Director of Operations said in an earlier statement. "Everyone who puts a boat on the water in the Bay of Islands needs to be aware of the problem so they play their part in protecting the local dolphin population."
The ban only applies to tour operators in the Bay of Islands. Other boat tours that interact with different species of dolphin in New Zealand are still permitted.