SEAwise Report on the key species and habitats impacted by fishing

The implementation of ecosystem-based fisheries management requires knowledge on the ecological impact of fishing activities on species and their habitats – those both targeted and not targeted by fisheries. To identify which ecological impacts are key and what is known about them, SEAwise consulted stakeholders through European Advisory Councils and conducted a systematic review of the scientific literature to map the available knowledge and evidence. Specific reference was given to the bycatch of Protected, Endangered and Threatened (PET) species, benthic habitats, food webs and biodiversity, and impact from fisheries-related litter and ghost nets. 

At the stakeholder consultations, sharks and/or elasmobranchs, turtles, species interactions, and seals or marine mammals were identified as top ranked in at least three out of the five regions. Other terms identified by at least two Case Study regions were: seabirds, sensitive species, benthic habitats, litter, PET species, invasive species and species interactions. 

Relevant data were extracted from 549 retained papers. The majority of studies were conducted in the Mediterranean Sea, whereas only few papers reported on fishing impacts in the Baltic Sea (see figure below). Bony fish (teleosts) and benthos were the most studied ecosystem components in all Case Study regions, whereas marine mammals and cartilaginous fish were often studied in relation to bycatch of PET species.  Out of the 549 papers, most of them were related to fishing impacts on food webs and biodiversity and benthic habitats, followed by bycatch of PET species and other fishing impact studies (not related to any task). Fewest studies were related to the impact of fisheries-related litter and ghost nets. Demersal trawls were by far the most studied gear in studies on commercial fishing impacts. For recreational fisheries, hooks and lines, in particular angling, was the most studied fishing activity. 

Among the items identified by the stakeholders, marine mammals, seabirds and reptiles were all covered in at least 25 papers each, indicating that there is a considerable body of knowledge even though not all areas may have information for all species. Litter was the key item that was least frequently reported on in the literature, especially outside the Mediterranean, where scientific papers were rare. As a consequence, areas outside the Mediterranean may lack information for further analysis unless a dedicated effort is made in SEAwise to remedy this. The regional differences in topics identified by stakeholder scoping did not reflect the regional amount of papers available. 

This report describes results of the SEAwise project. More information about the project can be found at https://seawiseproject.org/