Dear colleagues,
I am glad to inform you that a new article is now available online:
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0062180
*The Stranding Anomaly as Population Indicator: The Case of Harbour
Porpoise /Phocoena phocoena/ in North-Western Europe.*
Helene Peltier, Hans J. Baagøe,Kees C. J. Camphuysen,Richard Czeck,Willy
Dabin,Pierre Daniel,Rob Deaville,Jan Haelters,Thierry Jauniaux,Lasse F.
Jensen,Paul D. Jepson,Guido O. Keijl,Ursula Siebert,Olivier Van
Canneyt,Vincent Ridoux
*
*Abstract:
Ecological indicators for monitoring strategies are expected to combine
three major characteristics: ecological significance, statistical
credibility, and cost-effectiveness. Strategies based on stranding
networks rank highly in cost-effectiveness, but their ecological
significance and statistical credibility are disputed. Our present goal
is to improve the value of stranding data as population indicator as
part of monitoring strategies by constructing the spatial and temporal
null hypothesis for strandings. The null hypothesis is defined as: small
cetacean distribution and mortality are uniform in space and constant in
time. We used a drift model to map stranding probabilities and predict
stranding patterns of cetacean carcasses under H_0 across the North Sea,
the Channel and the Bay of Biscay, for the period 1990--2009. As the
most common cetacean occurring in this area, we chose the harbour
porpoise /Phocoena phocoena/ for our modelling. The difference between
these strandings expected under H_0 and observed strandings is defined
as the stranding anomaly. It constituted the stranding data series
corrected for drift conditions. Seasonal decomposition of stranding
anomaly suggested that drift conditions did not explain observed
seasonal variations of porpoise strandings. Long-term stranding
anomalies increased first in the southern North Sea, the Channel and Bay
of Biscay coasts, and finally the eastern North Sea. The hypothesis of
changes in porpoise distribution was consistent with local visual
surveys, mostly SCANS surveys (1994 and 2005). This new indicator could
be applied to cetacean populations across the world and more widely to
marine megafauna.
All the best
Helene Peltier
--
Hélène PELTIER -PhD
Observatoire PELAGIS UMS 3462
Université de La Rochelle-CNRS
5, allées de l'océan
17000 La Rochelle, France
hpelt...@univ-lr.fr
+33 (0) 16 49 67 82 /+33 (0) 6 82 74 08 41
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