Subject: North Atlantic Right whale survival paper (fwd)

Mike Williamson (
Thu, 18 Mar 1999 07:32:45 -0500 (EST)

---------- Forwarded message ----------
Date: Tue, 16 Mar 1999 17:37:58 -0500
From: Solange Brault <>
Subject: North Atlantic Right whale survival paper

>From Solange Brault, Biology Department,
University of Massachusetts Boston

The following paper has just appeared.

Caswell, H., M. Fujiwara, and S. Brault.  1999.  Declining
survival probability threatens the North Atlantic right whale.
Proceedings of the National Academy of Sciences 96:3308-3313.


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

The paper is available at:

or write for reprints to:

Hal Caswell
Biology Department MS 34
Woods Hole Oceanographic Institution
Woods Hole MA 02543