Declining survival probability threatens the North Atlantic right whale

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 ind ividuals. We applied mark-recapture statistics to a catalog of photographic ally identified individuals to obtain the first statistically. rigorous est imates of survival probability for this population. Crude survival decrease d from about 0.99 per year in 1980 to about 0.976 in 1994. We combined this survival trend with a reported decrease in reproductive rate into a branch ing process model to compute population growth rate and extinction probabil ity. population growth rate declined from about 1.053 in 1980 to about 0.97 6 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 e ffective way to improve the prospects of the population is to reduce mortal ity, 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.