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MEPS prepress abstract   -  DOI:

A piece of the puzzle: analyses of recent strandings and historical records reveal new genetic and ecological insights on New Zealand sperm whales

Emily Palmer, Alana Alexander, Libby Liggins, Marta Guerra, Sarah J. Bury, Hannah Hendriks, Karen A. Stockin, Katharina J. Peters*

*Corresponding author:

ABSTRACT: Cetacean strandings provide important opportunities to extend current knowledge on species or populations, particularly for species that are notoriously difficult to study such as sperm whales (Physeter macrocephalus; parāoa). Between 25 May and 9 June 2018, 13 male sperm whales stranded in Taranaki, Aotearoa New Zealand, with an additional male stranding 1 month later in Clifford Bay, Marlborough. We profiled these 14 males for mitochondrial DNA (mtDNA) and carbon and nitrogen stable isotopes to examine their similarity to sperm whales from other geographic areas. Analyses of mtDNA revealed 7 haplotypes, including one not previously described (‘New’), and an additional haplotype (‘M’) new-to-New Zealand that had been previously reported in sperm whales of the Pacific region. Analysis of rare haplotypes found in New Zealand males suggested genetic links within New Zealand and the Southwest Pacific. Differences in stable isotope ratios indicated that, despite the close temporal proximity of these stranding events, individuals originated from at least 2 separate groups, with the whale stranded in Clifford Bay identified as being a regular visitor to Kaikōura. The analysis of stranding records in New Zealand dating back to 1873 indicated an increase in recorded single strandings since 1970, and a peak in single strandings in the austral summer months, but no seasonality for mass strandings. Sex predicted latitudinal location for single strandings, with 95.1% of female strandings occurring north of 42°S, fitting the general global distribution of female sperm whales limited to lower latitudes. This study provides the first temporal and spatial assessment of sperm whale strandings in New Zealand and highlights the need for future research on movements and genetic exchange between New Zealand sperm whales and sperm whales in the wider Pacific region.