First confirmed sightings of Blue Whales Balaenoptera musculus Linnaeus, 1758 (Mammalia: Cetartiodactyla: Balaenopteridae) in the Philippines since the 19th century

For over two centuries there were no records of Blue Whales Balaenoptera musculus in the Philippines. Whalers recorded Blue Whales in the Philippines in the 19th century, and the next confirmed sighting in the country was of a mother and calf in 2004. Since then 33 subsequent Blue Whale sightings of potentially one individual were recorded between 2004 and 2019, all within the central region of the Philippines around the Bohol Sea. This individual, recognized through photo-identification, was sighted on at least 13 occasions during eight different years: 2010, 2011, 2012, 2015, 2016, 2017, 2018, and 2019. The geographic location and timing of the sightings (January to July) suggest that Blue Whales in the Philippines may extend the outer range edge of the Indo-Australian population that migrate between western Australia, Indonesia, and East Timor. Blue Whale sightings in the Bohol Sea coincide with times of high ocean productivity, although further investigation is needed to determine if they are actually feeding in this region. Acoustic studies and photo-identification matching with other Blue Whale catalogues will clarify the stock identity of Blue Whales in the Philippines and their relation to the rest of the Blue Whale population, with implications for the conservation of this endangered species across multiple jurisdictions.