All European Union (EU) countries surrounding the Baltic Sea are involved in the international project Static Acoustic Monitoring of the Baltic Sea Harbour Porpoise (SAMBAH, www.sambah.org). The aim of SAMBAH is to secure the conservation of the Baltic Sea harbour porpoise (Phocoena phocoena). The harbour porpoise subpopulation in the Baltic Sea is classed as critically endangered (CR) on the International Union for Conservation of Nature (IUCN) Red List (Hammond et al. 2008). See www.porpoisedetectors.co.uk for some background information on harbour porpoises.

DATA COLLECTION

Data on harbour porpoise activity is collected by SAMBAH using static acoustic dataloggers, called C-PODs, deployed throughout the Baltic Sea. See www.c-podclickdetector.co.uk for details on how C-PODs work. For SAMBAH C-POD positions, see www.sambah.org; ca. 300 C-PODs were deployed between May 2011 and May 2013.

As outlined in www.cetaceanmonitoring.com, multiple methods are often employed to study marine mammals thoroughly. The SAMBAH project also plans to tag harbour porpoises, conduct acoustic/visual trials and calibration tests, and write a corresponding literature review.

DATA ANALYSIS

The SAMBAH project will perform density analysis and habitat modelling. In order to determine average density and abundance of harbour porpoises across the whole Baltic Sea, density analysis methodology involves taking animal counts from specific areas and looking at the spatial relationship between those areas (http://help.arcgis.com). The SAMBAH project uses two types of point transect methods (e.g. Whitehead 2009) for density analysis: cue counting (e.g. Marques et al. 2011), which uses the detection of individual clicks and snapshot methods, which use detection of individuals or groups within a certain time frame. See Buckland et al. (2005) for an introduction into these methods.

Habitat modelling techniques investigate how harbour porpoise presence relates to their environment (e.g. depth, Sea Surface Temperature (SST), salinity, food sources etc.). The SAMBAH project uses Generalised Additive Models (GAMs, https://en.wikipedia.org) and Generalised

Additive Mixed Models (GAMMs, e.g. Wood (2006); Block et al. (2011)) to produce distribution maps. These methods not only highlight distribution and potential habitat preferences, but can also show possible ‘hotspots’. Harbour porpoise distribution results are then combined with anthropogenic data (e.g. fishing, tourism etc.) to see if there is any overlap, and therefore potential for increased risk.