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Reports submitted to the IWC SC in 2020 and 2022 highlighted the apparently precarious state of the Iberian porpoise due to high bycatch mortality. In the present report we provide an update with (mainly) recent information on the biology, ecology, threats and conservation status. The Committee noted that the level of bycatch of Iberian harbour porpoise (Phocoena phocoena) is considered unsustainable and will consequently cause a population-level decline. In 2022 the Committee recommended immediate actions to effectively reduce and, where possible, eliminate bycatch of harbour porpoise throughout Iberian Peninsula waters. Information published since spring 2022 includes papers on aerial surveys in Portugal, bycatch mortality estimated from strandings in Galicia (NW Spain) and Portugal, and diet. We also present some unpublished and in press material from project reports, conference presentations, the forthcoming report of the ICES Working Group on Marine Mammal Ecology (WGMME), and a review of biology, ecology, threats to, and status of, Iberian porpoise due to be published later this year. Estimates of total mortality derived from on-board observation and from strandings both suffer from limited and incomplete data, e.g. due to low onboard observer coverage, and an absence of bycatch information from strandings data for most of the northern coast of Spain, but generally suggest that annual bycatch mortality could be around 200-300 animals. Spain is developing a Recovery Plan for Iberian porpoise, which Spain considers to be “in danger of extinction”. Portugal has established a Working Group to develop the necessary Action Plan to minimize the serious threat of cetacean bycatch in fishing. The range of the population was recently designated as an Important Marine Mammal Area. It is suggested that a Working Group concerned with the ecology and conservation of this population could be formed, for example involving ASCOBANS, ACCOBAMS, ICES and the IWC

Information on cetacean distribution is needed at a range of scales, such as European, national, subregional or regional level. Providing detailed information at larger scales, with the highest possible spatial resolution, is essential to adequately assess and evaluate the impacts of human activities at the population or subpopulation level, as required by several legal instruments and international agreements (e.g., OSPAR or ASCOBANS). In this study, we modelled the distribution and relative abundance of common dolphin (Delphinus delphis), bottlenose dolphin (Tursiops truncatus), and pilot whale (Globicephala melas) in continental shelf waters of the Spanish North Atlantic waters, using a time series of 13 years of sightings collected on the PELACUS multipurpose survey in spring months by means of Distance Sampling methodology. Species distribution models were fitted using geographical and biological explanatory variables. The more than 20,000 km of effort, regularly distributed over the study area throughout the time series, provided more than 400 sightings of the species of interest. The three species showed interannual variability in distribution and relative abundance. These annual differences might reflect changes in their movement patterns due to the different timing of oceanographic and biological processes between years, as shown by the models and the variables analysed. The results prove the relevance of the continental shelf in southern Galicia (the Rias Baixas) as an area of importance for these species. The maps produced have several applications, including the identification of relevant areas for these species and, when combined with other data (e.g., fishing effort, underwater noise), quantitative risk analysis to different anthropogenic activities

Five terms of reference (ToRs) were addressed at the working group. The first three terms of reference were standing ones. Under ToR A, new information on cetacean and seal population abundance, distribution, and population/stock structure, was reviewed, including information on vagrancy in cetacean and pinniped species. For cetaceans, coverage from the latest SCANS-IV survey (summer 2022) was presented as well as the results of recent regional/national surveys, particularly those in the Bay of Biscay and around the Iberian Peninsula. Updates on population estimates and distribution were provided for particular species studies, such as some coastal bottlenose dolphin populations. For seals, latest monitoring results were given for harbour, grey, and Baltic and Saimaa ringed seals. In addition, where possible, local long-term trends were illustrated for those species, based on earlier efforts by WGMME to assemble these data into a seal database. For both species’ groups, recent records of vagrant species were summarised. Under ToR B, cetacean and seal management frameworks in the North Atlantic were discussed, with an overview of the EU Maritime Spatial Planning Directive, and examples from the United Kingdom, Spain and the Faroe Islands of national management frameworks regarding marine mammals., ToR C provided an overview of new published information with regards to anthropogenic threats to marine mammal populations following on from the review by WGMME in 2015 (ICES, 2015) and subsequent updates. These were considered under the following headings: cumulative effects, fishery interactions, chemical pollution including marine debris, underwater noise, ship strikes and other physical trauma, tourism disturbance, climate change, and new pathogens (including avian influenza). ToR D focused upon bycatch. In support of WGBYC, this ToR aimed to contribute to the Roadmap for ICES PETS bycatch advice. ToR E involved liaison with other WGs. The Chairs of the newly-formed WGJCDP introduced to WGMME members, the Joint Cetacean Database Programme, which is to be hosted by the ICES Data Centre. The scope to collect information on other marine species besides cetaceans was discussed. A meeting with another newly formed ICES working group, on Marine Protected Areas, was planned but was deferred at the request of that group. On behalf of the working group, the Chairs would like to thank The Swedish Museum of Natural History for hosting the meeting

The Working Group on Marine Mammal Ecology met in 2022 to address five terms of reference. Under the first of these, ToR A, new information on cetacean and seal population abundance, distribution, population/stock structure, was reviewed, including information on vagrant ma-rine mammal species. This was done to ensure the recording of possible range changes in marine mammal species in the future. For cetaceans, an update is given for the different species, providing for a latest estimate for all species studies. In this report, particular attention is given to the updating of information from Canadian and US waters, and together with those countries, latest estimates for cetacean species are provided. For seals, latest monitoring results are given for harbour, grey and Baltic ringed seals. In addition, where possible, local long-term trends are illustrated for those species, based on earlier WGMME efforts to assemble these data into the WGMME seal database. For both spe-cies’ groups, a first account of vagrant species is provided

Several recent studies have suggested that the Iberian harbour porpoise is genetically and morphologically distinct and may represent a separate subspecies. The main threat facing this population is fishery bycatch. Recent data on porpoise bycatch are available from strandings and on-board observations. Generally, more bycaught porpoises are recorded from strandings than from on-board observations. Portugal has previously reported porpoise bycatches based on on-board observation in Iberian waters, although Spain has consistently reported zero porpoise bycatch Data from on-board observations of porpoise bycatch in Iberian waters (2005-2021) submitted to ICES WKMOMA appear to be anomalous in that they apparently do not include the majority of bycatch records previously submitted to ICES WGBYC. The minimum annual estimate of bycatch mortality, consisting of documented bycatch mortalities from strandings and observers in both Spain and Portugal, is around 0.5% (14 animals per year). Both types of data can be used to estimate both total bycatch and bycatch rate, given a population size estimate and (in the case of strandings) an overall mortality rate derived from a life table. In both cases, it is necessary to assume that samples are representative in order to scale up to the population level, and in both cases this is rather unlikely. Nevertheless, the results from all data sources are remarkably consistent, suggesting an annual bycatch mortality rate of no less than 8% (around 230 individuals) per year

Over the last decade, national authorities and European administrations have made great efforts to establish methodological standards for the assessment of underwater continuous noise, especially under the requirements set by the Marine Strategy Framework Directive (MSFD). Through the MSFD implementation across EU Member States Marine Reporting Units (MRUs), it is intended to establish the Good Environmental Status (GES) whether it is achieved or not. The evaluation of the Sound Pressure Level (SPL) at the local or regional scale for 1/3 octave band of 63 Hz and 125 Hz and the identification of long temporary trends were considered to be a priority due to the valuable information they can offer in relation to continuous low-frequency noise. Nevertheless, the methodology to determine threshold values from which to evaluate the GES has become difficult to define, and new approaches and considerations are currently being discussed by groups of experts, such as the technical subgroup on underwater acoustics (TGnoise) and regional commissions (e.g., OSPAR). This work presents a methodology to perform the assessment of a given area, providing a risk index that is related to potential appearance of masking effect due to the underwater noise produced by marine traffic. The risk index is hinged on the calculation of area under curves defined by the density of animals and a variable related to underwater noise SPL, defined as percentage of communication distance reduction. At this stage, the methodology presented does not consider physiological or behavioral mechanisms to overcome the masking by animals. The methodology presented has been applied to the bottlenose dolphin (Tursiops truncatus) inhabiting the ABIES—NOR marine demarcation to illustrate the possible use of risk-based models to manage marine areas related to human pressures, such as marine traffic, with the potential adverse impact on a given species (e.g., masking effect)

Shorewatch is a citizen science project, managed by Whale and Dolphin Conservation (WDC), that records the occurrence of cetaceans during regular, standardized watches from a series of locations along the coast of Scotland (United Kingdom). Observer training and a clearly defined protocol help deliver a valuable source of information about cetacean occurrence and activity along the coast. Between 2005–2018, over 52000 watches generated over 11000 sightings of at least 18 cetacean species. Generalized Additive Models based on sightings for the five most commonly sighted species (bottlenose dolphin, harbor porpoise, minke whale, Risso’s dolphin, and common dolphin), at those sites with the longest time series, demonstrated seasonal, geographical and year-to-year differences in their local occurrence and relative abundance. Bottlenose dolphins are mainly present at observation sites located on the east coast of Scotland, being uncommon on the west coast, while harbor porpoise and minke whale are principally present at sites located on the west coast. The seasonality observed in cetacean occurrence is consistent with peak abundance in summer months described by previous studies in the area. Mean depth around the observation sites is the static variable that apparently has the greatest influence on species presence and number of sightings, except for Risso’s dolphin. All the species except bottlenose dolphin showed upward trends in occurrence and number of sightings over the period 2012–2018. Evidence of temporal autocorrelation was found between results from consecutive watches at the same site on the same day as well as between results from consecutive days at the same site. The power to detect declines in local abundance over a 6-year period depends on the underlying sighting rate of each cetacean species, the number of watches performed and the rate of decline. Simulations performed to determine the power to detect a decline suggest that the current intensity of obse

Shorewatch is a citizen science project, managed by Whale and Dolphin Conservation (WDC), that records the occurrence of cetaceans during regular, standardized watches from a series of locations along the coast of Scotland (United Kingdom). Observer training and a clearly defined protocol help deliver a valuable source of information about cetacean occurrence and activity along the coast. Between 2005–2018, over 52000 watches generated over 11000 sightings of at least 18 cetacean species. Generalized Additive Models based on sightings for the five most commonly sighted species (bottlenose dolphin, harbor porpoise, minke whale, Risso’s dolphin, and common dolphin), at those sites with the longest time series, demonstrated seasonal, geographical and year-to-year differences in their local occurrence and relative abundance. Bottlenose dolphins are mainly present at observation sites located on the east coast of Scotland, being uncommon on the west coast, while harbor porpoise and minke whale are principally present at sites located on the west coast. The seasonality observed in cetacean occurrence is consistent with peak abundance in summer months described by previous studies in the area. Mean depth around the observation sites is the static variable that apparently has the greatest influence on species presence and number of sightings, except for Risso’s dolphin. All the species except bottlenose dolphin showed upward trends in occurrence and number of sightings over the period 2012–2018. Evidence of temporal autocorrelation was found between results from consecutive watches at the same site on the same day as well as between results from consecutive days at the same site. The power to detect declines in local abundance over a 6-year period depends on the underlying sighting rate of each cetacean species, the number of watches performed and the rate of decline. Simulations performed to determine the power to detect a decline suggest that the current intensity of obse