Pérez-Jorge, S., Gomes, I., Hayes, K., Corti, G., Louzao, M., Genovart, M. and Oro, D. 2016 :
Effects of nature-based tourism and environmental drivers on the demography of a small dolphin population Biological Conservation:
doi:10.1016/j.biocon.2016.03.006
Abstract: Many marine top predators are experiencing significant declines due to
anthropogenic impacts, and therefore reliable monitoring is essential to
understand their population dynamics. We used Pollock's robust design
capture–recapture modelling to assess the influence of oceanographic
variables, artisanal fisheries and human disturbance on several
demographic parameters (abundance, temporary emigration and survival) of
the Indo-Pacific bottlenose dolphin (
Tursiops aduncus), using
long-term data on marked individuals from East Africa.
Photo-identification data was collected over 551 boat-based surveys
between 2006 and 2009, with 137 individuals identified. Our best fitting
model indicated that exposure to tourism (represented by the number of
tourist boats) increased the probability of dolphins seasonally
emigrating from the study area. The return rate of temporary emigrants
was negatively linked to the seasonal sea surface temperature, probably
associated with food availability. That model supported the existence of
heterogeneity in annual local survival estimates, with transient
dolphins showing a lower value than resident individuals (0.78 and 0.98,
respectively). Furthermore, abundance estimates showed a small
population size ranging from 19 individuals (95% CI: 11–33) to a maximum
of 104 dolphins (95% CI: 78–139). This small population, together with
their high site fidelity and coastal distribution, might be particularly
vulnerable to human disturbances. This study highlights the influence
of environmental and anthropogenic factors on dolphin demography and
population dynamics and the need to integrate these drivers to provide
robust evidences for conservation stakeholders in an adaptive management
framework.
