EU additional request on mitigation measures to reduce bycatches of common dolphin (Delphinus delphis) in the Bay of Biscay and Iberian Coast
ICES concludes that taking into account the data from 2019–2021, most of the proposed scenarios to reduce bycatch of the common dolphin (Delphinus delphis) in the Bay of Biscay and Iberian Coast as described in the ICES advice in 2020 are likely to still reduce bycatch below the potential biological removal (PBR) limit. ICES notes that uncertainty in knowledge of the extent and the dynamics of the species’ distribution area and abundance, as well as the availability of reliable bycatch estimates for the entire range of the species distribution area, are of concern.
None of the scenarios, when evaluated with the data from 2019–2021, met the candidate management objective of reducing estimated bycatch to less than 10% of the PBR. This is in contrast to the previous results using 2016–2018 data and is due to greater bycatch arising from a combination of improvements to the knowledge base (including bycatch rates, métiers covered, and effort reporting) and changes in the distribution of common dolphin within the Bay of Biscay.
ICES advises for the common dolphin in the Bay of Biscay and Iberian Coast a combination of temporal closures of all métiers of concern and the application of pingers on pair trawlers to mitigate bycatch outside of the periods of closure.
Given the low observation rates in several métiers of concern, ICES reiterates the issues of data quality, representivity and coverage. ICES recommends enhanced monitoring to assess the effectiveness of management measures (including pinger use) and to augment precision in bycatch mortality estimates of common dolphin.
Published under the auspices of the following ICES Steering Group or Committee