Working Group on Marine Mammal Ecology (WGMME)

The Working Group on Marine Mammal Ecology (WGMME) met in February 2019. Two terms of reference (ToR) were standing ToR; under the first of these, ToR A, new and updated information on seal and cetacean population abundance, population/stock structure, management frameworks, and anthropogenic threats to individual health and population status were reviewed. Usually data on marine mammal surveys are only conducted during one season, but new data from Ireland revealed profound differences between summer and winter abundance and distribution of cetaceans, with implications for the spatial management of these species. New habitat modelling for cetacean species in the Northwest European Seas and North Atlantic Ocean and Mediterranean based on collated survey data as well as findings on threats to marine mammals such as bycatch, pollution, marine debris and noise were summarised under this ToR. Under ToR B, WGMME reviewed information on the ecological roles of marine mammals, expanding on efforts to review impacts on fisheries, interspecific competition, diet and impact on fish stocks from previous reports. The complexity and multitude of ecological interactions is underlined. A special emphasis under this ToR was put on the role of marine mammals as hosts and vectors of parasites. ToR C was implemented to review aspects of marine mammal fishery interactions not covered by ICES WGBYC. In 2019, WGMME focused its efforts on i) reviewing seal interactions with fisheries, including the numbers of bycaught seals, ii) investigating additional data sources for cetacean bycatch such as strandings, voluntary recording schemes and interview surveys, iii) identifying of potential bycatch risk areas, and iv) a review of recent work on setting safe limit thresholds for bycatch of marine mammals. To implement bycatch data in the management of marine mammals it is stressed that they should be aggregated on a management unit basis and corresponding data on abundance should be available. Under ToR D, WGMME followed up and updated on the 2015 threat matrix for the main marine mammal species in each of the regional sea areas. In addition to this update, a review of cumulative impacts from multiple environmental pressures and recent efforts to meaningfully analyse such cumulative impacts was produced. The approaches used to assess cumulative impacts are usually limited to a particular pressure. Efforts to expand the scopes of these tools are impeded by the complexity of the relevant interactions and knowledge gaps. ToR E, updating the database for seals, is the second standing term of reference. This year, WGMME adapted the ICES WGMME seal database to a proper database format and updated the data. WGMME also repeated its support for a data call from OSPAR to provide data for assessments under OSPAR indicators M3 and M5 on seal abundance and distribution.