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Monitoring the abundance of harbour porpoises and other small cetaceans in German waters

Project data

Projectleader: Prof. Dr. Ursula Siebert
Scientist: Dr. Anita Gilles, Dr. Meike Scheidat, Denise Risch
Sponsoring: Bundesministerium für Verbraucherschutz, Ernährung und Landwirtschaft BMVEL

Several anthropogenic factors influence harbour porpoises (Phocoena phocoena) in German waters. To evaluate the effect of these factors it is important to know the local abundance of this species in German waters.In this project aerial and ship surveys are conducted to estimate the German harbour porpoise population size and to investigate the relationship between occurrence of pelagic fish and porpoises. Visual surveying of harbour porpoises is only possible during low sea states (less than 3 Bft). To increase the chance of detecting animals during ship surveys, acoustic methods are used in addition to the visual methods

During July and August 2004 as well as May and July 2005 visual and acoustic surveys were conducted on board of two research vessels from the Bundesforschungsanstalt für Fischerei (BfA). The vessels were investigating pelagic fish in the Baltic and North Sea.

The hydrophone array was towed at about 100m behind the vessels. The clicks produced by harbour porpoises are at a frequency around 125KHz and thus not audible to humans. A „click-detector“ allows us to visualize the clicks and to detect harbour porpoises even if weather conditions are not good enough for visual survey work.

The first results showed that the hydrophone performance depends very much on the vessel type, the speed of the vessel and the length of the towed cable.

In July 2004 and May 2005 aerial surveys were conducted in German waters and allowed us to look at the distribution of harbour porpoises. The data is analyzed at the moment to estimate the abundance of harbour porpoises in the study areas.

The results of this project will be used as a baseline to decide on how the porpoise can be protected in German waters and how conflicts with human use can be avoided. It will also provide new information on the relationship between fish distribution and porpoise distribution. This knowledge is needed to protect the porpoise as an integral part of the German waters. 

Contact person

Stiftung Tierärztliche Hochschule Hannover
Institute for Terrestrial and Aquatic Wildlife Research
Werftstr. 6
25761 Büsum

Dr. Anita Gilles

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Stiftung Tierärztliche Hochschule Hannover
Institute for Terrestrial and Aquatic Wildlife Research
Werftstr. 6
25761 Büsum
Tel.:+49 511 856-8177
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