[MARMAM] new paper on demographic assessment of California sea lions

Manuela Gonzalez Suarez manuela.gonzalez at asu.edu
Wed Jul 2 10:52:45 PDT 2008

Dear colleagues,

A new paper on demographic assessment of California sea lions was recently
published in *Ecological Applications*. [The paper was also featured in the
ESA *Bulletin *art gallery (year 2008, vol 89, pp 221-222)]

You can send PDF requests to: manuela.gonzalez at asu.edu

Jeffrey Wielgus, Manuela Gonzalez-Suarez, David Aurioles-Gamboa, and Leah R,
STAGE-SPECIFIC ABUNDANCES. *Ecological Applications* 18 (5): 1287–1296.

*Abstract. *A pressing need exists to develop new approaches for obtaining
information on demographic rates without causing further threats to
imperiled animal populations. In this paper, we illustrate and apply a
data-fitting technique based on quadratic programming that
uses stage-specific abundance data to estimate demographic rates and
asymptotic population growth rates (k). We used data from seven breeding
colonies of California sea lions (*Zalophus californianus*) in the Gulf of
California, Mexico. Estimates of k were similar to those from previous
studies relying on a diffusion approximation using trends in total
abundance. On average, predicted abundances were within 24% of the observed
value for the inverse estimation method and within 29% of the observed value
for the diffusion approximation.
Our results suggest that three of the seven populations are declining (k ,
1), but as many as six may be at risk. Elasticity and sensitivity analyses
suggest that population management in most sites should focus on the
protection of adults, whose survival generally contributes the most to k.
The quadratic programming approach is a promising noninvasive technique for
estimating demographic rates and assessing the viability of populations of
imperiled species.


"I have never let my schooling interfere with my education"
Mark Twain
Manuela Gonzalez
SOLS Biology Graduate Program
P.O Box 874601 ASU Tempe, AZ 85287-4601
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