Abundance, distribution and behaviour of humpback whales (Megaptera novaeangliae) along the Pacific coast of Nicaragua, Central America

Context. Previous research has shown the presence of an endangered humpback whale population breeding off the Pacific coast of Central America. However, little is known about the density, size, social-group structure and spatial habitat use of this subpopulation. Aim. The study goal was to characterise a potential breeding subpopulation of humpback whales in the waters off Nicaragua. Five objectives were used to achieve this goal: (1) estimate abundance, (2) determine encounter rates, (3) define group composition, (4) assess distribution, and (5) document habitat-use patterns. Method. Boat-based surveys were conducted between November and April at two study sites along the Pacific coast of Nicaragua in the winters of 2004–2008 and 2016–2020. Key result. Inter-annual mark–recapture estimates did not yield a reliable estimate of abundance. Encounter rates were lower for the northern study site than for the southern site. Group composition consisted of groups with calves, singers and competitive males. Conclusion. These results confirmed that Nicaragua is a breeding area based on known breeding-ground behaviours observed in other areas, and similar environmental characteristics. Implication. Distinct habitats were found at the two study sites, suggesting that Central American humpback whales might use different areas within the broader Central American breeding range according to their needs and activity.

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