Genetic Analysis of the North Atlantic Right Whale: Implications for Species Recovery and Conservation Actions
Rosalind Rolland and Moira Brown, New England Aquarium
Awarded: May 2004
The North Atlantic right whale (Eubalaena glacialis) is one of the most endangered large whales, with approximately 300 individuals remaining. The critically endangered status and low genetic variability exhibited in this species is thought to be due to several centuries of intensive whaling. However, the species has shown no signs of recovery since whaling pressures were removed through international protection measures initiated in 1935. This lack of recovery suggests that factors other than whaling have seriously affected the recovery potential of this species. Although some detrimental factors are known, such as the high rate of mortality due to ship strikes and entanglement in fishing gear, it has also been identified that the reproductive rate is significantly lower than expected, and the factors resulting in this reduced reproductive performance remain unknown. Due to the small number of reproductively successful individuals in the entire species, identification of the factors affecting reproduction requires detailed information on the reproductive success of each individual. We propose to provide this necessary information by combining long-term photo-identification data with high-resolution genetic analyses to create a family tree for the species. This genealogy will contain all behaviorally- and genetically-identified relationships, and thus will provide details regarding the reproductive success of specific individuals as well as their lineages. This dataset will be used to test specific hypotheses regarding the role of genetic factors on reproduction and species recovery. Additionally, these data will be made available to other researchers and managers to facilitate the determination of the factors affecting reproduction, and therefore the recovery potential of the species. This project offers the rare opportunity to investigate a wild species with a level of genetic detail that is often only available in captive breeding programs.
Of the remaining right whale population, approximately 100 females produce an average of 11 calves per year, a rate of reproduction that is one third of that expected in comparison to the South Atlantic right whale (Eubalaena australis). Indicators of reproductive dysfunction in this species include a high incidence of neonatal mortality; an average inter-birth interval that is almost twice as long as expected; and a large percentage of adult females that have never been seen with a calf. Current initiatives to evaluate health and reproduction include the development of assays for reproductive and stress hormones in feces, analysis of feces for pathogenic parasites and marine biotoxins and development of a visual health assessment technique based on archived photographic images. Here we propose to use genetic analyses to augment these initiatives as well as to address the role of low levels of genetic variability on the reduced reproductive performance of this species.
Seasonal Basque whaling in Labrador, Canada during the 16th - 17th centuries is proposed to be responsible for the most extensive depletion of this species. A second way to investigate current recovery potential is by assessing ancient specimens exhibiting pre-exploitation genetic characteristics. We propose to use genetic analysis of ancient bones to investigate the impacts of whaling on the population size and genetic variability of this species. Combined with the data on reproduction, this research provides methods for scientifically testing hypotheses concerning both the factors that resulted in the endangered status of this species as well as the factors currently affecting its recovery.