[MARMAM] New publication on cookie-cutter sharks and whales

Theoni Photopoulou theoni.photopoulou at gmail.com
Sun Apr 10 23:52:01 PDT 2016


Dear all,

I am pleased to announce the publication of our paper in PLoS ONE.

Best PB, Photopoulou T (2016). Identifying the “demon whale-biter”:
Patterns of scarring on large whales attributed to a cookie-cutter shark
Isistius sp. PLoS ONE 11(4): e0152643. doi:10.1371/journal. pone.0152643

Abstract
The presence of crater-like wounds on cetaceans and other large marine
vertebrates and invertebrates has been attributed to various organisms. We
review the evidence for the identity of the biting agent responsible for
crater wounds on large whales, using data collected from sei (*Balaenoptera
borealis*), fin (*B. physalus*), inshore and offshore Bryde’s (*B. brydeii*
sp) and sperm whales (*Physeter macrocephalus*) examined at the Donkergat
whaling station, Saldanha Bay, South Africa between March and October 1963.
We then analyse the intensity and trends in its predation on large whales.
Despite the scarcity of local records, we conclude that a cookie-cutter
shark Isistius sp is the most likely candidate. We make inferences about
the trends in (1) total counts of unhealed bitemarks, and (2) the
proportion of unhealed bitemarks that were recent. We use day of the year;
reproductive class, social grouping or sex; depth interval and body length
as candidate covariates. The models with highest support for total counts
of unhealed bitemarks involve the day of the year in all species. Depth was
an important predictor in all species except offshore Bryde’s whales.
Models for the proportion of recent bites were only informative for sei and
fin whales. We conclude that temporal scarring patterns support what is
currently hypothesized about the distribution and movements of these whale
species, given that Isistius does not occur in the Antarctic and has an
oceanic habitat. The incidence of fresh bites confirms the presence of
*Isistius* in the region. The lower numbers of unhealed bites on
medium-sized sperm whales suggests that this group spends more time outside
the area in which bites are incurred, providing a clue to one of the
biggest gaps in our understanding of the movements of mature and maturing
sperm males.

The article is freely available online
<http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0152643>
​ or from me (theoni.photopoulou at gmail.com).


Kind regards,
Theoni

-- 
Theoni Photopoulou, Postdoctoral Fellow
Centre for Statistics in Ecology, Environment and Conservation
Department of Statistical Sciences, University of Cape Town, South Africa
" Be silly. Be honest. Be kind " Ralph Waldo Emerson
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