Earthquake disrupts sperm whales’ feeding for a year

A new study has revealed how an earthquake affected the ability of a group of ‘dazed and confused’ whales to find food for over a year.

Kaikoura is a coastal town on the South Island of New Zealand known for its abundant marine wildlife including a population of sperm whales.

On November 14^th, 2016 a 7.8-magnitude earthquake shook the region triggering widespread mudslides in the underwater canyon off the coastline, altering the undersea landscape.

Scientists had been monitoring over 50 sperm whales in local waters for many years before the tremors hit. After the earthquake it was noticed that the whales spent about 25 per cent more time at the surface than before.

Researchers from the University of Otago had the advantage of all the previous data, so when the earthquake struck they knew where the sperm whales were and also their usual behaviour patterns.

‘With sperm whales, because they feed at deep depth and spend so much time underwater, it's hard to know exactly what is going on but you can use these times at the surface to determine what they are doing,’  says lead researcher, Dr Marta Guerra.

More time on the surface means the whales were probably spending time and effort diving and searching for food because of less prey to feed on or having to "re-familiarise" themselves with underwater areas that may have changed.

The study also found large underwater sounds produced by earthquakes and aftershocks caused hearing damage and behavioural changes.

The whales' behavioural changes lasted for around a year before returning to normal levels.

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