Researchers from the Mammal Research Institute (MRI) Whale Unit have deployed satellite transmitters on four adult female southern right whales to monitor their migration and feeding pattern effectively. This research is of paramount importance considering the drastic changes that have been observed in southern right whale migration, reproduction, and body condition in the last ten years. These changes most likely result from reduced prey availability in the Southern Ocean due to climate change.
Furthermore, the Whale Unit has closely monitored the southern right whale population that breeds off the South African coast for the past 42 years. The in-depth research has underlined the significant population change related directly to reducing the right whale’s reproductive success and body condition (or “fatness”). In addition, there has been a considerable change in foraging and migration behaviour, all of which have resulted in reduced numbers of southern right whales being seen off the South African shores.
The primary food source for hungry southern right whales is found thousands of kilometres away from where they nurse their young, meaning that their successful migration and calving is dependent on them finding enough food during the summer months in the Southern Ocean to build up adequate fat reserves so that they can migrate and calve successfully.
The Whale unit’s 42nd annual aerial survey in October counted and photographed 382 females and calves (191 pairs) and 32 adult whales without a calf (“unaccompanied adults”), bringing the total to 414 southern right whales from Nature’s Valley to Muizenberg. However, the changes observed by the unit resolutely suggest reduced food availability for these whales in their Southern Ocean feeding grounds. As a result, it is essential to identify these feeding grounds so that the Whale Unit can assess what climatological and/or oceanographic changes lie at the root of this conservation problem.
Four satellite tags were deployed on adult female southern right whales as a pilot study to combat this challenge. These tags will provide adequate information on the location of each individual for up to a year, allowing the Whale Unit to closely monitor each animal’s migration and foraging behaviour. The Whale Unit will deploy 30 more satellite transmitters within the next two years if all goes well.
This research project is in collaboration with Dr Alex Zerbini and Dr Amy Kennedy from the National Oceanic and Atmospheric Administration (NOAA), University of Washington’s Cooperative Institute for Climate, Ocean and Ecosystem Studies (CICOES/UW), and the Marine Ecology and Telemetry Research (MarEcoTel). Furthermore, the Instituto Aqualie (Brazil) and the MRI Whale Unit provide this project’s necessary funding.