[MARMAM] new paper - modelling harbour porpoise seasonal density

Anita Gilles Anita.Gilles at tiho-hannover.de
Fri Aug 12 00:53:54 PDT 2011

Dear list members,

The paper below has just been published in Endangered Species Research - special theme section 'Beyond Marine Mammal Habitat Modeling: Applications For Ecology And Conservation'.

Gilles A, Adler S, Kaschner K, Scheidat M, Siebert U (2011) Modelling harbour porpoise seasonal density as a function of the German Bight environment: implications for management. Endang Species Res 14:157-169

ABSTRACT: A classical user–environment conflict could arise between the recent expansion plans of offshore wind power in European waters and the protection of the harbour porpoise Phocoena phocoena, an important top predator and indicator species in the North Sea. There is a growing demand for predictive models of porpoise distribution to assess the extent of potential conflicts and to support conservation and management plans. Here, we used a range of oceanographic parameters and generalised additive models to predict harbour porpoise density and to investigate seasonal shifts in porpoise distribution in relation to several static and dynamic predictors. Sightings were collected during dedicated line-transect aerial surveys conducted year-round between 2002 and 2005. Over the 4 yr, survey effort amounted to 38720 km, during which 3887 harbour porpoises were sighted. Porpoises aggregated in distinct hot spots within their seasonal range, but the importance of key habitat descriptors varied between seasons. Predictors explaining most of the variance were the hydrographical parameter ‘residual current’ and proxies for primary production and fronts (chlorophyll and nutrients) as well as the interaction ‘distance to coast/water depth’. Porpoises preferred areas with stronger currents and concentrated in areas where fronts are likely. Internal cross-validation indicated that all models were highly robust. In addition, we successfully externally validated our summer model using an independent data set, which allowed us to extrapolate our predictions to a more regional scale. Our models improve the understanding of determinants of harbour porpoise habitat in the North Sea as a whole and inform management frameworks to determine safe limits of anthropogenic impacts. 

The paper can be downloaded from the journal website:

best regards,

Note: Change of affiliation!
Dr. Anita Gilles
Institute of Terrestrial and Aquatic Wildlife Research (ITAW)
University of Veterinary Medicine Hannover, Foundation
Werftstr. 6
25761 Büsum
Tel: +49 (0)4834-604105
Fax: +49 (0)4834-604199
email: Anita.Gilles at tiho-hannover.de

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