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Approximately one third of the North Atlantic right whale populationhas white ventral skin patches. Most white-marked animals have both a belly and a chin patch, and the distribution of white pigment suggests that the patches represent a single ventral marking that varies in size and location. Population frequencies and cow-calf inheritance patterns indicate that the white mark is an autosomal recessive trait. There is no evidence to suggest that ventral coloration patterns are currently under selection. White-marked and black cows appear to experience similar levels of reproductive success based on calving intervals and length of sighting histories. Also, white-marked animals were equally common among cows and nulliparous adult females and among live vs. dead animals. Male reproductive success could not be tested because calf paternity is not known; white-marked and black males exhibit similar survival rates. White-marked cows were more common amongfemales that took some or all of their calves to the Bay of Fundy summer nursery area compared to females that did not visit Fundy. This suggests that female habitat-use patterns may influence nuclear gene flow. Increased sample sizes and additional markers are needed to further investigate gene flow. [ABSTRACT FROM AUTHOR]

Strandings of previously identified individuals, while rare, providean opportunity to examine age-length relationships in humpback whales (Megaptera novaeangliae) from the North Atlantic. Ages and lengths of 23 individuals are presented: 11 females and 12 males, 9 of known age and 14 with estimated minimum ages. Lengths ranged from 853 to 1,430 cm, ages 0.5-17 yr. These individuals were generally smaller and more variable in size at age than reported from commercial catches. Fifteen of the stranded individuals were four years of age or younger,while few of the animals taken by whalers were this young, and theseprobably represented the larger individuals in these age categories.Thus the data presented herein help to give more definition to the early growth curve for the humpback whale than has previously been available. Growth equations illustrate a difference of about one meter in asymptotic length through age five between stranding and catch data. The close fit of growth models to data from younger and older animals separately and the difficulty of fitting a single growth model to animals of all ages, could indicate that a dynamic or staged growth pattern exists in this species. [ABSTRACT FROM AUTHOR]

Although much is known about the humpback whale, Megaptera novaeangliae, regional studies have been unable to answer several questions that are central to the conservation and management of this endangered species. To resolve uncertainties about population size, as well as the spatial and genetic structure of the humpback whale population in the North Atlantic, we conducted a two-year ocean-basin-wide photographic and biopsy study in 1992-1993. Photographic and skin-biopsy sampling was conducted of animals in feeding and breeding areas throughout most of the range of this species in the North Atlantic, from the West Indies breeding grounds through all known feeding areas as far north as arctic Norway. A standardized sampling protocol was designed to maximize sample sizes while attempting to ensure equal probability of sampling, so that estimates of abundance would be as accurate and as precise as possible. During 666 d at sea aboard 28 vessels, 4,207 tail fluke photographs and 2,326 skin biopsies were collected. Molecular analyses of all biopsies included determination of sex, genotype using six microsatellite loci, and mitochondrial control region sequence. The photographs and microsatellite loci were used to identify 2,998 and 2,015 individual whales, respectively. [ABSTRACT FROM AUTHOR]

Correlation-matrix principal components of North Atlantic sea-surface temperature anomalies for the interval 1950--1970 account for the anomalous variability observed during the interval 1972--1992 better than do similar numbers of covariance-matrix principal components, regional averages, or carefully selected local anomalies. When drift in the seasonal cycle is taken into account, local anomalies for 127 6 deg. x 4 deg. longitude-by-latitude North Atlantic cells could be recovered with an average skill as high as 0.79. Surprisingly, skill increased monotonically with increasing numbers of principal components, and the maximum value was not obtained until 62 were used to characterize the field. Clearly, far more principal components carry useful information about local details than has been previously suspected. [ABSTRACT FROM AUTHOR]

Mean sea-surface temperatures were computed within 127 6 deg. x 4 deg. longitude-by-latitude cells comprising most of the North Atlantic for 171 three-month seasons from 1950 to 1992, the mean seasonal cycle was removed, and cells with correlated seasonal anomalies were clustered into regions of coherent thermal behaviour. Clustering algorithms consistently produced smaller thermal regions in the vicinity of the Gulf Stream, and while the regions were generally contiguous, a disjoint region was consistently found near the Grand Banks. Examining within-region variability as a function of the number of regions revealed no obvious 'best' number of regions. For 26 regions, correlations between pairs of cells within a common region were typically 0.7; for 13 regions, a sizeable fraction were less than 0.5; and for only seven regions, within-region correlations were distributed fairly uniformly between 0.2 and 0.8. [ABSTRACT FROM AUTHOR]