Documentation of a New Zealand blue whale population based on multiple lines of evidence
Open Access
- 17 May 2018
- journal article
- research article
- Published by Inter-Research Science Center in Endangered Species Research
- Vol. 36, 27-40
- https://doi.org/10.3354/esr00891
Abstract
Species conservation depends on iobust population assessment. Data on population abundance, distribution, and connectivity are ciitical foi effective management, especially as baseline information for newly documented populations. We describe a pygmy blue whale Balaenoptera musculus brevicauda population in New Zealand waters with year-round presence that overlaps with industrial activities. This population was investigated using a multidisciplinary approach, including analysis of survey data, sighting records, acoustic data, identification photographs, and genetic samples. Blue whales were reported during every month of the yeai in the New Zealand Exclusive Economic Zone, with reports concentrated in the South Taranaki Bight (STB) region, where foraging behavior was frequently observed. Five hydrophones in the STB recorded the New Zealand blue whale call type on 99.7% of recording days (January to December 2016). A total of 151 individuals were photo-identified between 2004 and 2017. Nine individuals were resighted across multiple years. No matches were made to individuals identified in Australian or Antarctic waters. Mitochondrial DNA haplotype frequencies differed significantly between New Zealand (n = 53 individuals) and all other Southern Hemisphere blue whale populations, and haplotype diversity was significantly lower than all other populations. These results suggest a high degree of isolation of this New Zealand population. Using a closed capture recapture population model, our conservative abundance estimate of blue whales in New Zealand is 718 (SD = 433, 95 % CI = 279-1926). Our results fill critical knowledge gaps to improve management of blue whale populations in New Zealand and surrounding regions.Keywords
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