[MARMAM] New article on the demographic consequences of fisheries interaction on killer whales

Paul Tixier paul.tixier at gmail.com
Mon Jul 31 19:32:34 PDT 2017

Dear colleagues,

we are happy to announce the publication of the following article in Marine

"Demographic consequences of fisheries interaction within a killer
whale (*Orcinus
orca*) population"

Tixier, P., Barbraud, C., Pardo, D., Gasco, N., Duhamel, G., and Guinet, C.

You can access the paper online at
https://link.springer.com/article/10.1007/s00227-017-3195-9. You can also
email me at paul.tixier at gmail.com to request a copy or if you have
questions about the study.

This work was conducted at the Centre d'Etudes Biologiques de Chize (CEBC -
CNRS) - Marine Predators unit, as part of Dr Christophe Guinet's research
team on marine mammals interactions with demersal longline fisheries in the
Southern Ocean. http://www.cebc.cnrs.fr/GB_index.htm


Individual heterogeneity in foraging behavior has been widely documented
within predator populations. In highly social apex predators such as killer
whales (*Orcinus orca*), specialization may occur at the matriline level. A
small population of killer whales has been documented to occur around the
Crozet Islands. These whales feed on a wide range of prey items including
seals, penguins and large whales, as well as depredate the local Patagonian
toothfish (*Dissostichus eleginoides*) longline fishery. The level of
interactions with fisheries varies greatly between matrilines. Here, we
present the results on the effects of such behavioral heterogeneity on the
demographic trends of this killer whale population. We used
photo-identification data from 1977 to 2011 in a mark–recapture framework
to test the effect of varying levels of fisheries interactions on adult
survival. We documented significant differences in survival between
depredating and non-depredating whales, resulting in divergent
intra-population demographic trends. These differences showed low survival,
and thus a negative effect, for depredating whales when illegal fishing
occurred (poachers used lethal methods to deter killer whales from
depredating longlines). After illegal fishing stopped (2003–2011), the
survival rates of depredating individuals exceeded the survival rates of
non-depredating individuals, suggesting a positive influence of “artificial
food provisioning”. This effect was further supported by a higher
population growth rate for depredating whales. This study highlights the
potential demographic costs and benefits that cetaceans face from
depredating fisheries and addresses the demographic consequences of both
intra-population feeding specialization and the influence of anthropogenic
changes in resource availability.

Kind regards


*Paul Tixier, PhD *

Postdoctoral fellow

ARC Linkage Project 2016 – 2020 “Developing global solutions to marine
mammals – fisheries interactions”

School of Life and Environmental Sciences, Faculty of Science Engineering &
Built Environment

*Deakin University*

Melbourne Burwood Campus, 221 Burwood Highway, Burwood, VIC 3125

Tel: +61 (0)4 84 122 796

Email: p.tixier at deakin.edu.au

<p.tixier at deakin.edu.au>

Research Gate: https://www.researchgate.net/profile/Paul_Tixier
Google Scholar Citations:
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