Population Studies of the North Atlantic Right Whale
Hal Caswell and Christine Hunter, Biology Department, WHOI
Awarded: May 2004
Population
models contribute to conservation in four ways: by assessment
of population status, diagnosis of the
causes of poor performance, prescription of
management interventions, and prognosis of
population viability. These tasks all require estimates of the vital rates and
the construction and analysis of population models, especially analysis of
population growth, sensitivity to perturbations, and environmental
fluctuations.
This
research program will produce a new generation of population analyses of the
right whale. It will
require advances in mark-recapture estimation of the vital rates and powerful
new analyses of population models. Our previous work applying mark-recapture analysis
to the right whale photo ID catalog provided striking insights into the right
whale population (Caswell et al. 1999, Fujiwara and Caswell 2001, 2002a,b,
Fujiwara 2002). It showed that survival, especially of females with calves, has
been declining since the 1980s, that inter-birth intervals have increased, and
that these trends (especially the first) have reduced population growth rate
from positive to negative values.
As is so often the case in science, each step in the analysis has opened up new questions. Fortunately, the development of new analytical and modeling methods has kept pace; they make it possible for us to answer these questions. Our overall goal is to increase - dramatically - our understanding of right whale population dynamics (is the population increasing or declining? how fast? in response to what kinds of environmental fluctuations? how much heterogeneity is there in the population?) and our ability to focus management activities (what is the relative importance of changes in survival and reproduction? of survival of different stages in the life cycle? how much must survival or reproduction improve to affect persistence?). Here we document the overall directions of the analysis and specify goals for Phase 1.