[MARMAM] Three new publications about southern-Iberian cetaceans

Joan Giménez Verdugo joan.gimenez at csic.es
Mon Sep 25 23:05:30 PDT 2017

Dear colleagues,

We are pleased to announce our last three articles published by our
research team.

*1:* Giménez, J., Louis, M., Barón, E., Ramírez, F., Verborgh, P.,
Gauffier, P., Esteban, R., Eljarrat, E., Barceló, D., Forero, M.G., and de
Stephanis, R. (2017) Towards the identification of ecological management
units: A multidisciplinary approach for the effective management of
bottlenose dolphins in the southern Iberian Peninsula. Aquatic
Conservation: Marine and Freshwater Ecosystems.

*2:* Giménez, J., Marçalo, A., García‐Polo, M., García‐Barón, I., Castillo,
J. J., Fernández‐Maldonado, C., Saavedra, C., Santos, M.B., and de
Stephanis, R. (2017). Feeding ecology of Mediterranean common dolphins: The
importance of mesopelagic fish in the diet of an endangered subpopulation.
Marine Mammal Science.

*3:* Giménez, J., Marçalo, A., Ramírez, F., Verborgh, P., Gauffier, P.,
Esteban, R., Nicolau, L., González-Ortegón,  E., Baldó, F., Vilas, C.,
Vingada, J., Forero, M.G., and de Stephanis, R. (2017). Diet of bottlenose
dolphins (*Tursiops truncatus*) from the Gulf of Cadiz: Insights from
stomach content and stable isotope analyses. PloS one, 12(9), e0184673.

You can find the abstracts below.


1: Determining discrete and demographically independent management units
within wildlife populations is critical for their effective management and
conservation. However, there is a lack of consensus on the most appropriate
criteria to delimit such management units. A multi‐ disciplinary,
multi‐scale approach that combines tools informing in the short‐term (i.e.
photo-identification), with mid‐term ecological tracers (stable
isotopes–δ13C, δ15N and δ34S– and persistent organic pollutants –POPs–),
and mid‐ to long‐term genetic markers (microsatellites and mitochondrial
DNA), was used to define management units within bottlenose dolphins (*Tursiops
truncatus*) inhabiting the southern Iberian Peninsula. Although genetically
indistinguishable, individuals inhabiting the Strait of Gibraltar and the
Gulf of Cadiz showed differences in their isotopic composition and the
concentrations of certain POPs. Accordingly, the lack of photographic
recaptures between the two sites pointed to the existence of at least two
different ecological management units that segregate spatially and may
require different conservation strategies. Different time‐scale approaches
can reveal different management units. The results highlighted the use of
medium‐ and short‐term approaches for properly identifying ecologically
different units for effective management and conservation. Furthermore,
these results have important management implications as European
legislation promotes specific management plans for this species.

 2: The Mediterranean subpopulation of common dolphin (*Delphinus delphis*)
is classified as endangered by the IUCN. Still, information about their
diet in the Mediterranean is scarce. Stomach contents of 37 common dolphins
stranded in the Alboran Sea and Strait of Gibraltar were analyzed. A total
of 13,634 individual prey of 28 different taxa were identified. For fish,
Myctophidae was the most important family as indicated by the highest index
of relative importance (IRI =8,470), followed by the family Sparidae (IRI
=609). The most important Myctophidae species was Madeira lantern fish
maderensis*) and for Sparids, the bogue (*Boops boops*). Cephalopods,
instead, were found in low quantities only with 31 prey from the
Loliginidae, Ommastrephidae, and Sepiolidae families. Overall, our results
indicate that common dolphins are mainly piscivorous (99.77%N, 94.59%O,
99.73%W), feeding mostly on mesopelagic prey. Although common dolphins
inhabit mainly coastal waters in the study area, the narrow continental
shelf seems to facilitate the availability of Myctophids and other members
of the mesopelagic assemblage to dolphins when the assemblage migrates to
the surface at night. Our results represent the first attempt at
quantifying the diet of this predator in the Alboran Sea and Strait of

3: The ecological role of species can vary among populations depending on
local and regional differences in diet. This is particularly true for top
predators such as the bottlenose dolphin (*Tursiops truncatus*), which
exhibits a highly varied diet throughout its distribution range. Local
dietary assessments are therefore critical to fully understand the role of
this species within marine ecosystems, as well as its interaction with
important ecosystem services such as fisheries. Here, we combined stomach
content analyses (SCA) and stable isotope analyses (SIA) to describe
bottlenose dolphins diet in the Gulf of Cadiz (North Atlantic Ocean). Prey
items identified using SCA included European conger (*Conger conger*) and
European hake (*Merluccius merluccius*) as the most important ingested
prey. However, mass-balance isotopic mixing model (MixSIAR), using *δ*13C
and *δ*15N, indicated that the assimilated diet consisted mainly on
Sparidae species (*e*.*g*. seabream, *Diplodus annularis* and *D*.
*bellottii*, rubberlip grunt, *Plectorhinchus mediterraneus*, and common
pandora, *Pagellus erythrinus*) and a mixture of other species including
European hake, mackerels (*Scomber colias*, *S*. *japonicus* and *S*.
*scombrus*), European conger, red bandfish (*Cepola macrophthalma*) and
European pilchard (*Sardina pilchardus*). These contrasting results
highlight differences in the temporal and taxonomic resolution of each
approach, but also point to potential differences between ingested (SCA)
and assimilated (SIA) diets. Both approaches provide different insights, *e*
.*g*. determination of consumed fish biomass for the management of fish
stocks (SCA) or identification of important assimilated prey species to the
consumer (SIA).

Article available at:


Best Regards,


*Joan Giménez Verdugo*
*PhD Student* *Severo Ochoa*
Estación Biológica de Doñana (EBD-CSIC)
Department of Conservation Biology
Americo Vespucio Ave, s/n
41092 Sevilla (Spain)
Research Gate: Joan Giménez
Phone: +34 619 176 849
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