Declining survival probability threatens the North Atlantic right whale

Abstract

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).

Particulate hexavalent chromium is cytotoxic and genotoxic to the North Atlantic right whale (Eubalaena glacialis) lung and skin fibroblasts

“…The North Atlantic right whale migrates along the Environmental and Molecular Mutagenesis. DOI 10.1002/em [Caswell et al, 1999]. In our previous study [Wise et al, 2008], we calculated (based on whale lung volume and respiration rate and atmospheric Cr levels) that right whales near the Baltimore harbor were potentially exposed to 260 lg Cr in a 24-hr period.…”

Characterization of Ship Traffic in Right Whale Critical Habitat

“…Modeling studies suggest that the North Atlantic population is declining and some models predict that extinction could occur within 191-245 years (Caswell et al, 1999;Fujiwara & Caswell, 2001). Declining survival of females is of particular concern for the species.…”

Statistical Tools for Fitting Models of the Population Consequences of Acoustic Disturbance to Data from Marine Mammal Populations (PCAD Tools II)

“…the early and late 1990's (Caswell et al 1999, Fujiwara and Caswell 2001, Kraus et al 2005), but we have shown that population health has declined over the period of the analysis. Specifically, we have documented stable health of the population in the 1980's, decline in the 1990's, to a stable, but lower, health in the 2000's ( Figure 7).…”