HABITATWal - Habitat selection and population dynamics of harbour porpoises in the ecosystem of the German North Sea and Baltic Sea

Project description

As top predators, marine mammals such as the harbour porpoise are an important component of marine ecosystems. They are under increasing pressure from anthropogenic activities such as fisheries, offshore wind energy development, shipping or pollution. The survey and assessment of their populations and precise knowledge of their distribution patterns, habitat requirements and population trends are prerequisites for their effective protection and reasonable management of marine protected areas. In addition, the monitoring and assessments serve the accompanying reporting obligations of the Federal Republic of Germany towards the European Commission in the course of the implementation of the Habitats Directive (92/43/EEC) and the Marine Strategy Framework Directive (2008/56/EC).

Within the framework of this project, distribution patterns, population sizes and trends of marine mammals as well as their habitat selection will be studied in more detail. Also, their behaviour, the occurrence of mother-calf pairs (reproduction areas) and the influence of anthropogenic activities on occurrence and population dynamics are in focus, based on dedicated surveys of marine mammals in the German North Sea and Baltic Sea in their focal seasons and areas. These surveys using standardized methods provide data and information on space-time patterns and space use of marine mammals in the North Sea and Baltic Sea ecosystem.

Analyses will include both data newly collected by the project and existing data that have been collected with standardized survey by ITAW since 2002. This time series provides the necessary robust data basis required for the consideration of fundamental ecological across time and space. Habitat-based models are used to investigate which abiotic, biotic and anthropogenic factors fundamentally influence the occurrence and distribution of marine mammals. This is particularly relevant in the wake of the observed declining population trends of harbour porpoises in the German North Sea. Population dynamics models will provide information on the influence of various stressors on the development of harbour porpoise populations. These models will provide simulations of future population trends assuming different pressures from anthropogenic stressors and can, thus, inform the development of adequate management measures.

HABITATWal will also integrate the German contribution to the international SCANS-IV survey [AG1] , which conducts coordinated visual surveys in the shelf and offshore waters of the European Atlantic to generate robust abundance estimates for regularly occurring cetacean species. Detailed information on the occurrence of minke whales and possibly other cetacean species will be collected through a yearly shipboard survey on Dogger Bank and monitoring will be developed. In addition, the expansion of the recording methods in large-scale monitoring is to be accompanied scientifically. This also includes a feasibility study on the possible addition of a PAM (passive-acoustic monitoring) network in the German North Sea.