North Atlantic humpback whales (Megaptera novaeangliae (Borowski, 1781)) are increasing in number, necessitating current data from winter areas for assessing potential interactions with humans. Occurrence patterns of humpback whales wintering off Puerto Rico were investigated to predict where whales aggregate in nearshore areas. Here we describe the relationship between group associations of humpback whales and bathymetric features off western Puerto Rico. Data were collected from 2011 to 2014. Effort consisted of 240.9 vessel h, 13.0 aerial h, and 303.6 h of land observations conducted over 165 days. A total of 197 humpback whale groups were observed with n = 331 individuals: 91 (46.2%) singletons, 67 (34%) dyads, 17 (8.6%) mother–calf pairs, 8 (4.1%) competitive groups, 8 (4.1%) mother–calf–escort groups, and 6 (3.1%) mixed-species associations. A linear regression model supported that group composition correlated with hotspots associated with four bathymetric features. Dyads and competitive groups were dispersed among features in deeper water. Singletons were observed farther from a shelf edge, whereas singing males were closely associated with a shelf edge. Mother–calf pairs occurred nearshore in shallow water; however, when mother–calf pairs were sighted with an escort, they were offshore. This study is especially important ahead of possible removal from the Endangered Species list.

The authors describe antagonistic interactions between short-finned pilot whales (Globicephara machrorhyncus) and humpback whales (Megaptera novaeangliae) in Puerto Rican waters.

A study of humpback whales (Megaptera novaeangliae, Borowski, 1781) was conducted off Puerto Rico, from 2012 through 2016, in an attempt to understand the spatial and temporal connection among current low density areas throughout the southeastern Caribbean. Six hundred and sixteen animals were sighted, of which 87 (14%) were individually identified. Seventeen individuals (20%) were re-sighted in one or more of the North Atlantic Caribbean breeding areas. Two newly reported inter-seasonal re-sightings (between Puerto Rico and Guadeloupe), and one intra-seasonal exchange (including the only reported match between Puerto Rico and Anguilla) between Puerto Rico and the southeastern Caribbean are reported here. A paucity of data failed to confirm that humpback whales are repopulating their full extent of the historical range, including Puerto Rico; however, these observations may provide a glimpse of the future importance of the southeastern Caribbean. It is especially important to understand the occupancy, movements, and habitat use throughout the entire winter range as sources of anthropogenic impacts (including vessel traffic from the growing cruise ship industry) increase throughout the Caribbean.