Occurrence of starry ray Amblyraja radiata in marine protected areas of the German Exclusive Economic Zone in the North Sea

Abstract

On a global scale, about one quarter of all chondrichthyan fishes, i.e. sharks, rays and chimaeras, are supposed to be threatened. This is mainly caused by fishing mortality to which these species are particularly vulnerable because of their k-selected life-history strategy including e.g. large body size, slow growth and late maturity. This is especially true for the intensively fished North Sea. Although nowadays the fishing effort has been reduced in this region, a high number of chondrichthyan species is still depleted and listed as threatened in regional and/or national red lists. The German MSFD Programme of Measures opens up prospects for including further species in the existing system of marine protected areas in the North Sea. As a precondition, species in question need to be identified as threatened and must occur in the marine protected areas. Unfortunately, records of chondrichthyans are generally infrequent as these species are still rare and the regular scientific surveys are primarily designed for catching highly commercial bony fishes. In order to identify a potential overlap between the distribution range of chondrichthyan fishes and the German marine protected areas, species distribution modelling is performed for the starry ray Amblyraja radiata. This species is used as a start since it is currently the most abundant skate species in the North Sea and thus a higher number of records is available. The results shall reveal whether this method is suitable to predict the potential occurrence of data-deficient chondrichthyans in particular areas such as the German sanctuaries. If this can be confirmed, the presented approach could provide justification for adequate protection of chondrichthyan species in the German marine protected areas.