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Confirmed Occurrence of the Australian snubfin dolphin, Orcaella heinsohni in Papua New Guinea: Conservation Considerations for Small Isolated Populations

Isabel Beasley , Maria Jedensjo, Jim Anamiato, Michael McGowen

Abstract

Context. The taxonomic status of Orcaella sp. in Papua New Guinea waters is unknown. The Australian snubfin dolphin (Orcaella heinsohni) has been identified from northern Australian waters south of Papua New Guinea, and the Irrawaddy dolphin (O. brevirostris) from Borneo northwest of Papua New Guinea. Methods. Genetic analyses were conducted on eleven Orcaella sp. samples from Papua New Guinea and eight new Australian snubfin dolphin samples from northern Australia, including the type specimen. A 489-base sequence of the mitochondrial control region (HVR-1) was analyzed using Maximum Likelihood and Bayesian Inference to infer phylogenetic relationships. Key results. Phylogenetic reconstruction showed that the Papua New Guinea samples are nested within Australian snubfin dolphin samples and did not form a monophyletic group. Conclusions. These results confirm that the Australian snubfin dolphin occurs in southern Papua New Guinea. Implications. There are no confirmed records of Orcaella sp. from other regions of the Pacific Islands or New Guinea. The geographic demarcation between Australian snubfin and Irrawaddy dolphin populations remains unknown, although it is located within the Wallacea region. The viability of this apparently small, isolated population of Australian snubfin dolphins in southern Papua New Guinea is uncertain. The main threat to this population is accidental by-catch in gillnet fisheries targeting fish for swim-bladders. Urgent conservation and management strategies that focus on mitigating by-catch are essential.

PC23059  Accepted 03 April 2025

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