[MARMAM] New paper on population dynamics of Guiana dolphins

Mauricio Cantor mauricio.cantor at ymail.com
Thu Dec 29 11:43:12 PST 2011

Dear colleagues,

We are pleased to announce a recent publication on the population dynamics
of Guiana dolphins:

Cantor M, Wedekin LL, Daura-Jorge FG, Rossi-Santos MR, Simões-Lopes PC.
2012. Assessing population parameters and trends of Guiana dolphins
(Sotalia guianensis): An eight-year mark-recapture study. Marine Mammal
Science 28(1): 63–83. DOI: 10.1111/j.1748-7692.2010.00456.x

This study represents the first attempt to study the population dynamics of
Guiana dolphins (Sotalia guianensis), by evaluating a set of demographic
parameters. The population of the Caravelas River Estuary, eastern Brazil,
was systematically monitored through a long-term mark-recapture experiment
(2002-2009). Abundance estimates revealed a small population (57 to 124
dolphins), comprised of resident dolphins and individuals that temporarily
leave or pass through the study area. Temporary emigration from the Estuary
to adjacencies (γ”=0.33±0.07 SE) and return rate (1-γ’=0.67) were moderate
and constant, indicating that some dolphins use larger areas. Survival rate
(φ=0.88±0.07 SE) and abundance were constant throughout the study period.
Power analysis showed that the current monitoring effort have high
probability of detecting abrupt population declines (1-β=0.9). Although the
monitoring is not yet sensitive to subtle population trends, sufficient
time to identify them is feasible (additional three years). Despite such
apparent stability, this population, as many others, inhabits waters
exposed to multiple human-related threats. Open and closed population
modeling applied to photo identification data provides a robust baseline
for estimating several demographic parameters and can be applied to other
populations to allow further comparisons. Such synergistic efforts will
allow a reliable definition of conservation status of this species.
Key words: population dynamics, mark-recapture models, temporary
emigration, survival, abundance, population trends, robust design, Sotalia
guianensis, Abrolhos Bank.

Pdf copies are available upon request to m.cantor at ymail.com

Best regards,

Mauricio Cantor

Laboratorio de Mamiferos Aquáticos (LAMAq)
Universidade Federal de Santa Catarina
Instituto Baleia Jubarte
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