An Unexpected Journey: Tracking Southern Right Whales from the New Zealand Subantarctic Wintering Grounds
Leena Riekkola, Simon J. Childerhouse, Alexandre Zerbini, Virginia Andrews-Goff, Rochelle Constantine, Rosalind Cole, Esther Stuck And Emma L. Carroll
Satellite transmitters were deployed on six adult southern right whales - tohorā (SRW, Eubalaena australis) at the Auckland Islands Maungahuka (sub-Antarctic New Zealand) during August 2020 to investigate the migratory routes and offshore feeding grounds of the whales that winter in New Zealand. At the time of writing (1st March 2021), the tags had transmitted for an average of 125 days (range: 40-209 days), although two of the tags were still transmitting. The tags provided data on long-distance migration for five of the tagged individuals, while one tag did not transmit long enough to capture migratory movements. Tracking data showed south and westward migration pattern, not obviously towards the historical feeding grounds for New Zealand’s SRWs located east and northeast of mainland New Zealand, but instead towards likely feeding areas south of Australia. The movement patterns of the tagged whales revealed both individual variation and similarities between whales. While four individuals moved south and southwest after tagging, one whale initially travelled southeast to Campbell Island prior to migrating west, ending up traveling within a day and within few kilometres of another tagged whale. All five whales with migratory data moved towards similar areas south of Australia, however one individual (with a long tag duration) continued migrating to Antarctica. These findings improve our understanding of the contemporary migratory routes and destinations of SRWs wintering in New Zealand waters. The data reveal that this population inhabits vast extensions of the South Pacific, South Indian and Southern Oceans and likely feeds in the offshore waters south of Australia. These findings also have implications for allocation scenarios for historic catches of SRW, as the east-west movement (up to 5,800km) suggests that catches in the Indian Ocean may have been linked to New Zealand breeding stocks.