At least 31 shortfin dolphins washed ashore and died on New Zealand’s South Island. Animal protection experts spotted dolphins swept away on Thursday.

On Friday, rescue teams managed to graze 5 dolphins that survived the night in deep water, but two of them washed ashore again later and had to be euthanized to lessen their suffering.

Animal rights activists told BBC News.

Similar mass extinctions of dolphins occur regularly in the Farewell Spit section of the sandy coast. According to the local authorities, it is a very sad but normal phenomenon. It’s not entirely clear why bottlenose dolphins beach themselves, but based on experience, they are more susceptible to this than other species.

Stretching for 26 kilometers, the Farewell Spit is a strip of sand that extends into the sea and is a frequent site of beaches, although scientists have not yet found a satisfactory explanation for this. One theory is that the shape of the sandbar may confuse the direction of the dolphins.

Last year, about 50 bottlenose dolphins washed ashore in this section, and 28 specimens were rescued. The most tragic delinquency occurred in 2017, when about 700 specimens washed ashore and 250 died. In the past 15 years, at least 11 mass delinquencies have occurred in the area.

Cover photo: AFP / Department of Conservation New Zealand / Handout