[MARMAM] New publication: The abundance of common bottlenose dolphins (Tursiops truncatus) in the former special marine reserve of the Cres-Lošinj archipelago, Croatia

Grgur Pleslić grgur.pleslic at plavi-svijet.org
Wed Nov 27 07:21:22 PST 2013

Dear MARMAM subscribers,


My co-authors and me are pleased to anounce recent publication:


Journal: Aquatic Conservation: Marine and Freshwater Ecosystems


Title: The abundance of common bottlenose dolphins (Tursiops truncatus) in
the former special marine reserve of the Cres-Lošinj archipelago, Croatia


Authors: Pleslić G., Rako Gospić N., Mackelworth P., Wiemann A., Holcer D.
and Fortuna C.



1.       There is a resident common bottlenose dolphin population inhabiting
the Kvarnerić area of the northern Adriatic Sea, Croatia. The observed
decline in population size between 1995 and 2003 led to the declaration of a
part of the Kvarnerić as the Cres-Lošinj Special Marine Reserve (CLSMR) in
2006. Protection lasted three years, before lapsing. 

2.       A boat based photo-identification study was conducted between 2004
and 2011 with the aim to estimate the number of bottlenose dolphins
inhabiting the CLSMR area, investigate the factors influencing their habitat
use and explore the possibility that this area is representative of the
population for the whole Kvarnerić.

3.       Standard mark-recapture methods and Mth estimator of Chao for
closed populations were applied. The lowest value was estimated in 2008
(N=112; 95% CI=94-150) and the highest in 2006 (N=310; 95% CI=265-392). The
statistically significant inter-annual variability is likely to reflect
natural and anthropogenic driven shifts in habitat use rather than actual
changes in population size.

4.       The average monthly sighting rate was lower in the tourist season
(Jun-Aug) compared to pre- and post-season indicating that developed
nautical tourism may influence shifts in habitat use. Other potential causes
are distribution of prey and fishing effort.

5.       Inclusion of data from the rest of the Kvarnerić of the years of
2005 and 2011 did not reveal a significant increase of estimated abundance
(2005: z=-0.413, p=0.3398; 2011: z=-1.749, p=0.0401). This indicates that
the CLSMR area is representative for the whole Kvarnerić.

6.       The number of bottlenose dolphins using the CLSMR area seems to
have increased compared to the previous study (1995-2003). This could be due
to a shift in habitat use or an increase in population size. However, yearly
variations indicate processes causing displacements within the dolphin
population home range. Conservation measures aiming at reducing the
displacements are proposed.


The paper can be accessed via:


Or contact me directly: grgur.pleslic at blue-world.org
<mailto:grgur.pleslic at blue-world.org> 


Kind regards,

Grgur Pleslić

Senior Researcher

Blue World Institute, Veli Lošinj, Croatia

blue-world.org <http://www.blue-world.org/> 



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