2021 Volume 3 Pages 139-151
This study describes a paternity method based on microsatellite DNA genotypes to estimate the abundance of mature male Antarctic minke whales (Balaenoptera bonaerensis) in the Indo-Pacific region of the Antarctic using a maximum likelihood approach. The analyses were based on biological and genetic (microsatellite DNA at 12 loci) data from Antarctic minke whales collected by surveys of the Japanese Whale Research Program under Special Permit in the Antarctic-Phase II (JARPAII) in the Indo-Pacific region of the Antarctic. A total of 2,126 Antarctic minke whales taken in the austral summer seasons 2006/07, 2008/09, 2009/10, 2010/11 and 2011/12 from locations 35°E to 145°W were used in the analyses. The abundance of mature males estimated by this method was then extrapolated to estimate total abundance for comparison with results for abundance obtained using conventional line transect methods in the research area. The total abundance derived from the paternity method (ca. 210,000–220,000) was generally lower than that obtained by the line-transect method (ca. 260,000–410,000), although the figure from the line-transect method was within the 90% confidence interval of the estimates by the paternity method, and the area covered by both methods was slightly different. Additionally, the geographical locations of mother/fetus–father pairs provided the opportunity to evaluate the current hypothesis on population structure of this species in the Indo-Pacific region. Results for the geographical distribution of mother/fetus–father pairs were generally consistent with the hypothesis of separate Eastern Indian Ocean and Western South Pacific Ocean populations, because 8 of 10 pairs were found in the expected areas of distribution of either populations. However, two pairs were found in distant areas. As a whole, the results from the present study demonstrated the utility of the paternity method for estimating the abundance of Antarctic minke whales and for assisting the interpretation of population structure hypotheses.
