Migratory connections among breeding grounds off the Eastern Pacific and feeding areas in the Antarctic Peninsula based on genotype matching

Abstract

Humpback whales (Megaptera novaeangliae) have a cosmopolitan distribution with populations in all three major ocean basins.  Six breeding stocks have been recognised by the IWC that feed around Antarctica and breed in the tropics.  The identity of each of these stocks has been defined based on their distribution in high latitude feeding grounds and breeding grounds in tropical sites.  Migratory connections between summer and winter grounds have been suggested for these stocks based on photo ID comparisons and genetic analyses.  We analysed 114 samples collected in different locations within the stock G breeding grounds, including Ecuador and the northern and southern Pacific of Colombia.  We genotyped 15 microsatellite loci, sexed all samples, and performed genotype comparisons. Genotype comparisons were done using a DNA register of previously genotyped individuals from the Colombian breeding ground and the Antarctic Peninsula feeding Area.  We found recaptures within each sampling location in the same year, but we also found a few recaptures in the same locations between years both in breeding and feeding grounds.  Interestingly, we found recaptures between breeding and feeding grounds using samples collected 20 years apart, providing some information about longevity in this stock.  Further comparisons with other data sets (Brazil, North Pacific) are needed to understand the migratory connectivity of this stock.