Evidence of a small, island-associated population of common bottlenose dolphins in the Mariana Islands

• DOI: 10.3389/fmars.2023.1254959
• Publication Date: 2024-01-18T13:39:00Z
• Authors: Karen K. Martien; Marie C. Hill; Frederick I. Archer; Robin W. Baird; Andrea R. Bendlin; Louella Dolar; Allan D. Ligon; Erin M. Oleson; Kelly M. Robertson; Samuel M. Woodman; Adam C. Ü; Kymberly M. Yano; Amanda L. Bradford
• Keywords: Bottlenose dolphin; Archipelago

Small, island-associated populations of cetaceans have evolved around numerous oceanic islands, likely due to habitat discontinuities between nearshore and offshore waters. However, little is known about the ecology structure cetacean Mariana Islands, a remote archipelago in western Pacific Ocean. We present sighting, photo-identification, genetic data collected during twelve years surveys these islands that reveal existence small, population bottlenose dolphins. Nearly half photo-identified individuals were encountered more than one year. Both haplotypic nuclear diversity among sampled was low (haplotypic = 0.701, heterozygosity 0.658), suggesting abundance. used mark-recapture analysis photo-identification estimate yearly abundance southern portion population’s range from 2011 2018. Each less 54 individuals, with each upper 95% confidence interval below 100. Additional survey effort necessary generate full estimate. found extensive introgression Fraser’s dolphin DNA into both mitochondrial genomes population, at least two hybridization events generations past. The Islands are extensively by U.S. military for land sea training operations. Thus, this unique faces high exposure multiple threats.