Killer whales live in stable social groups, called "pods." It has been suggested that the structure of such groups may influence the vital rates, and hence the fitness, of their members. To test this suggestion we used data from a long-term study of killer whales in the Pacific Northwest ). We constructed stage-classified matrix population models for the entire population, two sub-populations, and individuals pods. The population growth rate for the entire population is A = 1.0254, with 90% bootstrap confidence interval from 1.0178 to 1.0322. The mean female population stage distribution is not significantly different from the predicted stable stage distribution. Population growth rate is most sensitive to changes in adult and juvenile survival, followed by fertility. Factors that cause even small changes in survival will thus have a large impact on population growth. Pod-specific growth rates range from A= 0.9949 to A= 1.0498. Most of the interpod variance in growth rate is due to variance in adult reproductive output. Randomization tests show that this variance is not significantly greater than expected on the basis of variation in individual life histories within the population. We conclude that there is no evidence for an effect of social structure on pod-specific population growth rate. The restriction of population growth rates to such a narrow range suggests, but does not prove, a possible role for density-dependent processes.

Although trends in reproduction, mortality, and entanglement events have been analyzed for the endangered North Atlantic right whale (Eubalaena glacialis) population, no method has been available to assess individual right whale health. Here, we describe a technique for assessing health based on evaluation of selected physical parameters from archived photographs of right whales. A scoring system was developed to assess body and skin condition, blowhole cyamids, and rake marks in over 200 000 photographs. Comparison of body condition scores of females during calving and noncalving years found that females were significantly thinner in calving years and in the year after calving compared with the year before calving, showing that changes in body condition known to occur during the reproductive cycle can be successfully evaluated from photographs. Comparison of scores for all parameters between living whales and whales with more than a 5-year gap in sighting history ("presumed dead") found that presumed dead whales received health assessment scores indicating compromised health with body condition emerging as a key visual indicator. This health assessment method provides a new tool to monitor health trends in right whales at individual and population levels and may provide a model for assessments of other well-photographed cetaceans.

The North Atlantic northern right whale (Eubalaena glacialis) is considered the most endangered large whale species. Its population has recovered only slowly since the cessation of commercial whaling and numbers about 300 individuals. We applied mark-recapture statistics to a catalog of photographically identified individuals to obtain the first statistically rigorous estimates of survival probability for this population. Crude survival decreased from about 0.99 per year in 1980 to about 0.94 in 1994. We combined this survival trend with a reported decrease in reproductive rate into a branching process model to compute population growth rate and extinction probability. Population growth rate declined from about 1.053 in 1980 to about 0.976 in 1994. Under current conditions the population is doomed to extinction; an upper bound on the expected time to extinction is 191 years. The most effective way to improve the prospects of the population is to reduce mortality. The right whale is at risk from entanglement in fishing gear and from collisions with ships. Reducing this human-caused mortality is essential to the viability of this population. The North Atlantic northern right whale (Eubalaena glacialis)is considered the most endangered of any population of large whales. The preferred target of commercial whalers during the 18th and 19th century, it was reduced to near extinction by 1900 (1, 2). It has recovered only slowly since the elimination of commercial whaling. There are now about 300 individuals in the western Atlantic; the eastern Atlantic population is considered extinct (2, 3). Right whales are found along the eastern coast of North America from Florida to the Bay of Fundy and are at risk of mortality from entanglement with fishing gear, collisions with ships, and pollution (2, 4-6).We report here the first statistically rigorous estimates of survival for E. glacialis. We also develop a stochastic model from which we estimate population growth rates and extinction probabilities. Our results are a first step toward models that can be used to choose targets for management interventions (for example, see refs. 7-10).

Given new distribution patterns of the endangered North Atlantic right whale (NARW; Eubalaena glacialis) population in recent years, an improved understanding of spatio-temporal movements are imperative for the conservation of this species. While so far visual data have provided most information on NARW movements, passive acoustic monitoring (PAM) was used in this study in order to better capture year-round NARW presence. This project used PAM data from 2004 to 2014 collected by 19 organizations throughout the western North Atlantic Ocean. Overall, data from 324 recorders (35,600 days) were processed and analyzed using a classification and detection system. Results highlight almost year-round habitat use of the western North Atlantic Ocean, with a decrease in detections in waters off Cape Hatteras, North Carolina in summer and fall. Data collected post 2010 showed an increased NARW presence in the mid-Atlantic region and a simultaneous decrease in the northern Gulf of Maine. In addition, NARWs were widely distributed across most regions throughout winter months. This study demonstrates that a large-scale analysis of PAM data provides significant value to understanding and tracking shifts in large whale movements over long time scales.