[MARMAM] New paper on social structure of killer whales in the Strait of Gibraltar

Ruth Esteban ruthesteban at gmail.com
Wed Nov 4 02:56:18 PST 2015

Dear MARMAM subscribers,

We are pleased to announce the publication of the following paper in
"Behavioral Ecology and Sociobiology":

Esteban, R., Verborgh, P., Gauffier, P., Giménez, J., Foote, A.D., de
Stephanis, R.

The primary prey of killer whales (*Orcinus orca*) in the Strait of
Gibraltar is the bluefin tuna (*Thunnus thynnus*). All killer whales
observed in this area hunt tuna by chasing individual fish until they
become exhausted and can be overcome. However, a subset of pods also
interact with a dropline tuna fishery which has developed since 1995. Here,
we investigated the social structure within and among social units (pods).
Our data suggested that social structure was shaped by maternal kinship,
which appears to be a species-specific trait, but also by foraging
behavior, which is less common at the intra-population level. At the start
of the study, only one cohesive pod interacted with the fishery, which
during the course of the study underwent fission into two socially
differentiated pods. Social structure within these two fishery-interacting
pods was more compact and homogenous with stronger associations between
individuals than in the rest of the population. Three other pods were never
seen interacting with the fishery, despite one of these pods being
regularly sighted in the area of the fishery during the summer. Sociality
can influence the spread of the novel foraging behaviors and may drive
population fragmentation, which, in this example, is already a critically
small community. Observations of social changes in relation to changes in
foraging at the earliest stages of diversification in foraging behavior and
social segregation may provide insights into the processes that ultimately
result in the formation of socially isolated discrete ecotypes in killer

You can downloaded in this link:

Kind Regards,

Ruth Esteban

Ruth Esteban
CIRCE (Conservation Information and Research on Cetaceans)
C/Cabeza de Manzaneda 3
C.P. Pelayo-Algeciras (Cádiz) Spain
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