Distribution and migratory destinations of humpback whales off the Pacific coast of Central America during the boreal winters of 19962003

Here, we examine the distribution, habitat use, and migratory destinations of North Pacific humpback whales wintering off Central America. Coastal boat surveys were conducted off Costa Rica and Panama between 1996 and 2003. In 1999, a broader survey was conducted along most of Central America. Over 23,000 km were surveyed, with the greatest effort off southern Costa Rica. We made 191 sightings of 320 individual humpback whales. Whales were seen between 14◦N and 8◦N,making this the most southerly of the North Pacific wintering areas. Encounters included singles, adult pairs, singers, and mother/calf pairs. Mother/calf pairs accounted for 27% of all groups sighted, which is one of the highest sighting rates reported among North Pacific wintering areas. Sixty percent of sightings occurred in depths<50 m. Average sea surface temperature was 28.6◦C (±1.0 SD). Ninety percent of the 77 unique whales photo-identified were also seen in the California–Oregon–Washington feeding aggregation. The 1999 survey showed that humpback whales were widely distributed along the Central American coast at relatively low densities. The extensive distribution of animals, the higher proportion of calves, and the almost exclusive migration to a single feeding area contrast with observations in other regions.