Humpback whale sightings on the decline |22 November 2016

The Humpback Whale (Megaptera novaeangliae) is one of the most commonly observed whale species seen in shallower, warmer waters during the southern hemisphere winter and is the only whale species for which there is a clear seasonal pattern in sightings around Aldabra. Humpback Whales undertake an annual migration between high latitude summer feeding areas and low latitude winter breeding areas. Sightings of the whales at Aldabra are usually made from June/July - Sept/Oct, which is consistent with the general migration pattern of the species.

Anticipation for the arrival of the whales was high this year, with all staff at the research station hoping they would be the first to spot a whale.

The first sighting from the research station was made later than usual – on August 13 – and a further eight sightings were made throughout August.

This represents fewer sightings and a shorter season than in previous years.

The team is still on the lookout for any latecomers but it seems that the season is already over.

There are many factors that may influence Humpback Whale migration and the low number of whales seen this year.

Studies elsewhere have shown that decreasing food availability in the Antarctic feeding grounds due to global climate change and warmer ocean temperatures is directly linked to birth rates.

A recent long-term study showed that global climatic processes are also affecting Southern Right Whales, with a strong relationship between breeding success and the occurrence of an El Niño event.

It is therefore likely that the decline in Humpback Whale sightings in the South-western Indian Ocean this year is a consequence of the 2014-16 El Niño event, which further exacerbated the warmer ocean temperatures.

It is thought that global climate change will not only impact future breeding success of whales but also the seasonality of their migrations.

Although the whales are affected by these changes globally, we can all play a small part in reducing these effects by lowering our carbon footprint in our day-to-day lives.

Collectively this can make a difference in global atmospheric and climatic processes, therefore reducing their impact on whale populations.