ESR 42:67-82 (2020)  -  DOI: https://doi.org/10.3354/esr01038

ABSTRACT: Humpback whales Megaptera novaeangliae were severely depleted by commercial whaling. Understanding key factors in their recovery is a crucial step for their conservation worldwide. In Oceania, the Chesterfield-Bellona archipelago was a primary whaling site in the 19^th century, yet has been left almost unaffected by anthropogenic activities since. We present the results of the first multidisciplinary dedicated surveys in the archipelago assessing humpback whale populations 2 centuries post-whaling. We encountered 57 groups during 24 survey days (2016-2017), among which 35 whales were identified using photographs of natural markings (photo-ID), 38 using genotyping and 22 using both. Humpback whales were sparsely distributed (0.041 whales km^-1): most sightings concentrated in shallow inner-reef waters and neighbouring offshore shallow banks. The recently created marine protected area covers most of the areas of high predicted habitat suitability and high residence time from satellite-tracked whales. Surprisingly for a breeding area, sex ratios skewed towards females (1:2.4), and 45% of females were with calf. Connectivity was established with the New Caledonia breeding area to the east (mtDNA F_ST = 0.001, p > 0.05, 12 photo-ID and 10 genotype matches) and with the Australian Great Barrier Reef breeding area to the west (mtDNA F_ST = 0.006, p > 0.05). Movement of satellite-tracked whales and photo-ID matches also suggest connections with the east Australian migratory corridor. This study confirms that humpback whales still inhabit the Chesterfield-Bellona archipelago 2 centuries post whaling, and that this pristine area potentially plays a role in facilitating migratory interchange among breeding grounds of the western South Pacific.

KEY WORDS: Chesterfield-Bellona archipelago · Connectivity · Coral Sea · Habitat use · Humpback whale · Satellite tracking · Sex ratio · Whaling

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Cite this article as: Garrigue C, Derville S, Bonneville C, Baker CS and others (2020) Searching for humpback whales in a historical whaling hotspot of the Coral Sea, South Pacific. Endang Species Res 42:67-82. https://doi.org/10.3354/esr01038 Export citation Share:    Facebook - - linkedIn