Demography and ecology of southern right whales Eubalaena australis wintering at sub-Antarctic Campbell Island, New Zealand

Abstract

Since the decimation of the southern right whale Eubalaena australis population in New Zealand by whaling, research on its recovery has focused on the wintering ground at the Auckland Islands, neglecting potentially important wintering habitat at Campbell Island. For the first time in 20 years we conducted an expedition to sub-Antarctic Campbell Island to document and describe E. australis occupying this wintering habitat. We used a variety of methods including photo-identification, genetic and stable isotope analyses of tissue samples, and visual surveys of abundance and distribution, to provide details on the demography, population connectivity and ecology of E. australis wintering at Campbell Island. Our primary findings include (1) a lack of calves observed at Campbell Island, (2) an age-class bias toward sub-adults encountered at Campbell Island, (3) nine photo-identification matches between individuals observed at Campbell Island and previously documented elsewhere in New Zealand, (4) no genetic differentiation between E. australis at Campbell Island and the broader New Zealand population, (5) increased abundance estimates of E. australis at Campbell Island over the last 20 years, and (6) indications that E. australis forage within the sub-Antarctic region based on stable isotope analyses. Our results confirm that the Auckland Islands are currently the only significant calving area for E. australis in New Zealand, and therefore previous abundance estimates based on demographic data from the Auckland Islands are applicable to the entire New Zealand population of E. australis. However, future periodic surveys to Campbell Island are recommended to monitor population recovery and expansion.