New haplotypes found in stranded long-finned pilot whales (Globicephala melas) in the eastern North Atlantic and adjacent waters

Long-finned pilot whale (Globicephala melas) mitochondrial (mtDNA) genetic diversity is considered low, especially in the North Atlantic, where only seven haplotypes have been recorded in previous studies using a 345 bp control region fragment. Such studies have not included samples from Ireland or the Netherlands. In this study we analyzed a longer sequence of the mtDNA control region (631 bp) from individuals stranded around Ireland, Scotland, and the Netherlands between 1995 and 2019 (n = 180). Nine haplotypes were identified, of which five were newly described (haplotype diversity h = 0.511). Pairwise tests revealed significant differentiation between the Irish and Scottish samples. Potential confounding factors are discussed but given that failure to recognize population structure may compromise conservation efforts, the findings show the need for further investigation using nuclear markers. Six mass stranding events were included, of which one event reported two haplotypes among individuals confirming a mixing of matrilineal groups. Although the permanence of this combination cannot be determined, this is the first record of such an occurrence within the North Atlantic. This study shows that stranding sample databases are a useful resource for genetic studies and provides new insights into genetic diversity of long-finned pilot whales in the eastern North Atlantic and adjacent waters.