First Sighting of a Humpback Whale (Megaptera novaeangliae) with Leucism in the Colombian South Pacific

The animal world manifests different types of dermal abnormalities (e.g., albinism, leucism, and xanthism), which are the result of deficiencies in the skin due to different genetic, trophic, environmental, and anthropogenic factors that may have consequences on the life cycle of the species. The aim was to document a case of leucism in a humpback whale (Megaptera novaeangliae) in the Colombian South Pacific. A M. novaeangliae was observed in the waters off the Pacific coast of Nariño, specifically in front of the Bocagrande neighborhood in the municipality of Tumaco, on August 4, 2024, during a whale-watching excursion. The individual exhibited an atypical white pigmentation along its peduncle and fluke. Based on these observations, this individual may be considered to have leucism, being the first recorded sighting of a humpback whale with leucism in the area. The presence of leucism in M. novaeangliae suggests that this whale has biological and ecological disadvantages caused by genetic abnormalities. This chance encounter of an unusually pigmented humpback whale highlights a geographical area and a species that would benefit from increased monitoring to assess the survival of this individual whale and address information gaps about this species in this region.