[MARMAM] New publication: bottlenose dolphins in Venezuela

Shannon Barber-Meyer shannonbarbermeyer at gmail.com
Thu Jan 14 17:52:31 PST 2021

Dear MARMAM community,

My colleagues and I are pleased to announce our new publication

Historic population estimates for bottlenose dolphins (Tursiops truncatus)
in Aragua, Venezuela, indicate monitoring need

Sergio Cobarrubia-Russo, Shannon Barber-Meyer, Guillermo R. Barreto, and
Alimar Molero-Lizarraga

This study reports historic, capture-mark-recapture survival and abundance
estimates of common bottlenose dolphins (Tursiops truncatus) based on
photo-identification surveys of coastal Venezuela (along the Aragua coast
between Turiamo Bay and Puerto Colombia). We used the most recent data
available: dolphins identified by unique dorsal fin marks during wet and
dry season surveys conducted from 2004-2008. Dolphin encounter histories
were analyzed in the Closed Capture Robust Design framework, with the top
model including random movement, constant survival, and capture-recapture
probabilities that varied by secondary periods. Survival of marked adults
was estimated at 0.99 (95% CI = 0.97-1.00). Population estimates for all
adults (marked and unmarked) averaged 31 animals (SD = 13.8), and for all
dolphins (all adults and calves), 41 animals (SD = 17.2). Coastal
bottlenose dolphins face numerous threats including ship strikes, oil
spills, conflict with recreational and industrial fisheries, other negative
human interactions, biotoxins, chemicals, noise, freshwater discharge, and
coastal development. Further, small populations are, in general, at
increased risk due to reduced resiliency and recovery potential when
exposed to such threats and to expected environmental and demographic
stochasticity. These historic estimates of abundance and survival are
critical for establishing a reference state and indicate a need for ongoing
monitoring of the small dolphin population while the Aragua coast is still,
as-of-yet relatively little-impacted by humans. Should coastal development
increase (as is the global trend) and / or environmental catastrophes occur
(e.g., harmful algal blooms, hurricanes, oil spills), these historic
estimates will be essential for assessing impacts and guiding management
and conservation interventions. Our results show year-round dolphin
presence and highlight the Venezuelan coastal-oceanic landscape as an area
of both future research and conservation importance.

Cobarrubia-Russo, S., S.M. Barber-Meyer, G. Barreto, and A.
Molero-Lizarraga. 2021. Historic population estimates for bottlenose
dolphins (Tursiops truncatus) in Aragua, Venezuela indicate monitoring
need. Aquatic Mammals, 47(1):10-20, DOI: 10.1578/AM.47.1.2021.10.

The article is available at:


Shannon Barber-Meyer
sbarber-meyer at usgs.gov
Research Wildlife Biologist
Ely, MN 55731
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