Prey distribution (SP 2)

Data on prey distribution in the North Sea

Atlantic cod. Photo: Hans-Petter Fjeld, Wikimedia Commons.

Noise is likely to have a larger effect on the porpoise population if it keeps animals away from important foraging sites. The population is also likely to be more vulnerable if associated with a small number of sites with sufficient food. It is therefore important to obtain estimates of the spatial variation in prey availability over the population’s range.

The study of the porpoise population in the IDW assumed that the prey distribution was related to the local porpoise population densities. These were calculated from the distribution of satellite-tracked animals. This approach requires satellite-tracking data from a large number of animals tagged in different parts of the population’s range, and is therefore not an option for the North Sea population in the near future. Instead the resource distribution can be estimated based on direct observations of porpoises from the SCANS surveys (SCANS II 2008) and the Seabirds at Sea database (JNCC 2012), which includes year-round observations of porpoises. In addition, similar data sets which have been gathered from the other countries bordering the North Sea will be incorporated to produce modelled distribution.  Work is ongoing to identify all other data sources which can be utilised for this sub-project.