[MARMAM] New publication: Fin whale abundance and survival estimation in the Gulf of St. Lawrence

Anna Schleimer achs at st-andrews.ac.uk
Mon Mar 18 02:10:29 PDT 2019


Dear Colleagues,

On behalf of my co-authors, I am pleased to announce the publication of the
following article in Ecology and Evolution:

Schleimer A, Ramp C, Delarue J, Carpentier A, Bérubé M, Palsbøll PJ, Sears
R, Hammond PS (2019) Decline in abundance and apparent survival rates of
fin whales (Balaenoptera physalus) in the northern Gulf of St. Lawrence.
Ecol Evol:ece3.5055

This mark-recapture study includes a critical assessment of the assumption
of capture homogeneity in relation to divergent site fidelity patterns and
the effects of terminal bias on long time-series of survival estimates.

Abstract:
Estimates of abundance and survivorship provide quantifiable measures to
monitor populations and to define and understand their conservation status.
This study investigated changes in abundance and survival rates of fin
whales (Balaenoptera physalus) in the northern Gulf of St. Lawrence in the
context of anthropogenic pressures and changing environmental conditions. A
long‐term data set, consisting of 35 years of photo‐identification surveys
and comprising more than 5,000 identifications of 507 individuals, formed
the basis of this mark–recapture study. Based on model selection using
corrected Akaike Information Criterion, the most parsimonious
Cormack–Jolly–Seber model included a linear temporal trend in noncalf
apparent survival rates with a sharp decline in the last 5 years of the
study and a median survival rate of 0.946 (95% confidence interval (CI)
0.910–0.967). To account for capture heterogeneity due to divergent
patterns of site fidelity, agglomerative hierarchical cluster analysis was
employed to categorize individuals based on their annual and survey site
fidelity indices. However, the negative trend in survivorship remained and
was corroborated by a significant decline in the estimated super‐population
size from 335 (95% CI 321–348) individuals in 2004–2010 to 291 (95% CI
270–312) individuals in 2010–2016. Concurrently, a negative trend was
estimated in recruitment to the population, supported by a sharp decrease
in the number of observed calves. Ship strikes and changes in prey
availability are potential drivers of the observed decline in fin whale
abundance. The combination of clustering methods with mark–recapture
represents a flexible way to investigate the effects of site fidelity on
demographic variables and is broadly applicable to other individual‐based
studies.

The open-access paper is available online at:
https://onlinelibrary.wiley.com/doi/10.1002/ece3.5055

Alternatively, you can contact me (achs at st-andrews.ac.uk) for PDF requests
or comments.

best wishes,

Anna Schleimer
PhD student
University of St Andrews | University of Groningen
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