The humpback whales which breed in the Mexican Pacific represent an important fraction (~38%) of the estimated population of the North Pacific. Despite the importance of Mexican waters for the reproductive habits of this species, little is known about the ecology of these whales, along the continental coast of Mexico. We analysed the temporal variation of abundance, group types, and inter- and intra-annual recapture rates in the waters adjacent to Isabel Island National Park as well as intra- and inter-seasonal movements with Banderas Bay breeding areas. Inter- and intra-annual recapture rates in Isabel Island National Park were low (1.8%); while 34% of 222 individuals photo-identified in Isabel Island National Park were also recaptured in Banderas Bay. Groups with calves were uncommon (9.5%), while pairs (33.5%) and competitive groups (29.5%) were more common. Intense singing activity was detected in the waters adjacent to Isabel Island. These waters seem to function as a reproductive corridor for the so-called ‘coastal stock’ of humpback whales in the waters adjacent to the continental coast of the Mexican Pacific. Therefore, mid- and long-term studies are needed to understand the dynamics of these displacements. Our findings suggest that Isabel Island National Park is an important area for the mating ecology of the humpback whales of the continental waters of the Mexican coast, and support the initiative to incorporate a Marine Protected Area within the Isabel Island National Park.

The behavioural patterns of humpback whales are known to vary according to the social function of individuals in a group. To identify behavioural patterns related to specific group compositions, we observed events and behavioural states of humpback whales during research cruises in the Abrolhos Bank, Brazil, in the reproductive seasons from 1992 to 2003. We monitored 3022 groups and found a predominance of competitive groups without calves, when compared to competitive groups with calves. A Bayesian network analysis supplied occurrence probabilities for the behaviours analysed, indicating higher probabilities of occurrence for the behavioural patterns designated travelling and socializing. The model, generated from a binomial logistic regression, was able to predict competitive groups in association with the occurrence of the following aggressive behaviours: head-lunging, trumpet and bubblestreams. This study suggests the existence of behavioural patterns associated with specific group compositions and reinforces the concept that there is a clear-cut relation between competitive groups and the occurrence of aggressive behaviours. The preferential association of males to females with high reproductive potential for the following year (i.e. females without a calf) was also identified.

Humpback whales (Megaptera novaeangliae) have a worldwide distribution in the oceans and are known for their very long migratory potential. Their migration routes consist of productive feeding areas located in high-latitudes and to low-latitude areas used as breeding and calving grounds. Genetic studies in humpback whale populations consist mainly of nuclear and mitochondrial DNA. In general, these studies provide similar results to estimates of gene flow, but some discrepancies may be caused by gender-biased migration to breeding grounds and further dispersion by males. There is little evidence of trans-equatorial and inter-oceanic migrations, but those movements have been confirmed by both analysis of photo-ID of naturally marked individuals and also genetic analysis. The combination of migratory and genetic analyses suggest an overlapping of breeding grounds in low-latitude areas, where the gene flow among those oceanic populations is more likely to happen, despite the opposite seasons in the northern and southern hemispheres. These results have important implications in the conservation perspective, especially for the determination of protected areas and for development of international agreements.

Megaptera novaeangliae sightings were gathered in the 2002 winter season, between February and April throughout several seismic survey cruises in a study area located north of Margarita Island. The data were processed by GIS (MapInfo 4.5) considering environmental features such as underwater topography and bathymetry. The spatial and temporal distribution of M. novaeangliae in the study area suggested a significant concentration of whales within the Margarita–Los Testigos submarine platform region in a transition zone along the shelf edge between the north coast of Margarita Island and La Blanquilla Island. This apparent wintering habitat includes protected calving areas such as the Los Frailes Archipelago and Margarita Island itself. The seasonal presence of this species in the territorial waters of the north-east coast of Venezuela indicates the biological value of these animals, as well as the vulnerability of the whales that dwell in this area to oil and gas exploration and development activities.

Photo-identification surveys of humpback whales Megaptera novaeangliae were conducted at West Greenland during 1988–93, the last 2 years of which were part of the internationally coordinated humpback whale research programme YoNAH, with the primary aim of estimating abundance for the West Greenland feeding aggregation. The area studied stretched from the coast out to the offshore margin of the banks, determined approximately by the 200 m depth contours, between c. 61°70′N and c. 66°N. The surveys were conducted between early July and mid-August and 993 h were expended on searching effort. A total of 670 groups of humpback whales was encountered leading to the identification of 348 individual animals. Three areas of concentration were identified: an area off Nuuk; an area at c. 63°30′N; and an area off Frederikshåb. Sequential Petersen capture–recapture estimates of abundance were calculated for five pairs of years at 357 (1988–89), 355 (1989–90), 566 (1990–91), 376 (1991–92), and 348 (1992–93). Excluding the anomalously high estimate in 1990–91, the simple mean is 359 (SE = 27.3, CV = 0.076) and the inverse CV-squared weighted mean is 356 animals (SE = 24.9, CV = 0.070). These calculations lead us to conclude that between 1988 and 1993 there were 360 humpbacks (CV = 0.07) in the West Greenland feeding aggregation. Using the Cormack–Jolly–Seber model framework non-calf survival rate was estimated at 0.957 (SE = 0.028). Our data have low power (P < 0.3) to detect a trend of 3.1%, assuming the probability of a type I error was 0.05.