Mapping of Fish Spawning in the North Sea; Report of the “KINO-2” Project for 2019

Abstract

Increased and updated knowledge of reproductive strategies of fish is crucial to optimize the temporal and spatial planning for conducting seismic surveys; in order to reduce its potential negative ecosystems impacts. The overall goal of this study is to improve our general knowledge about spawning areas of major North Sea fish stocks, including their spawning behavior and spawning period. This report describes the methodology, preliminary results and experiences gained during the data sampling period August 2017 to December 2019. Molecular barcode and traditional visual taxonomic analyses were performed on eggs and larvae, systematically collected with plankton nets along a south to north axis in the North Sea. In total, 201 samples have been analysed from which 35 different fish taxa are identified. Based on historic data and previously published literature, our results agree with the expected number of the most prevalent fish species breeding in the North Sea. Both the taxonomic and molecular methods used, demonstrate robust and similar results in the identification of taxonomic groups. The results further demonstrate that the molecular taxonomic approach is more appropriate for identification to species levels for most taxonomic groups, whilst the identification of egg and larvae developmental stages can only be performed using the visual taxonomic method. The two techniques have the potential of complementing each other to provide a detailed description of the annual fish spawning cycle for the main North Sea species. Our results demonstrate that the fish species diversity increase northwards, but here the spawning season is more concentrated. We have also identified new species spawning in the area, traditionally found more to the south or west of our study area. To improve the spatial and temporal statistical data resolution required for achieving sufficient scientific evidence as basis for producing robust advice in timing of seismic surveys, modifications to the sampling protocol and equipment was made during 2019. Expectantly, this potential proves to work over the coming annual reproduction cycle. Our study also confirms that the study area represents a highly dynamic environment, thus we strongly recommend considering extending the time period for data collection, beyond what is planned so far (due out August 2020) and an expansion of the geographical coverage to include regions also further north and west.