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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 We also present some unpublished and in press material from project reports, conference presentations, the forthcoming report of the ICES Working Group on Marine Mammal Ecology (WGMME), and a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

Taxonomic identification of whale bones found during archaeological excavations is problematic due to their typically fragmented state. This difficulty limits understanding of both the past spatio-temporal distributions of whale populations and of possible early whaling activities. To overcome this challenge, we performed zooarchaeology by mass spectrometry on an unprecedented 719 archaeological and palaeontological specimens of probable whale bone from Atlantic European contexts, predominantly dating from ca 3500 BCE to the eighteenth century CE. The results show high numbers of Balaenidae (many probably North Atlantic right whale (Eubalaena glacialis)) and grey whale (Eschrichtius robustus) specimens, two taxa no longer present in the eastern North Atlantic. This discovery matches expectations regarding the past utilization of North Atlantic right whales, but was unanticipated for grey whales, which have hitherto rarely been identified in the European zooarchaeological record. Many of these specimens derive from contexts associated with mediaeval cultures frequently linked to whaling: the Basques, northern Spaniards, Normans, Flemish, Frisians, Anglo-Saxons and Scandinavians. This association raises the likelihood that early whaling impacted these taxa, contributing to their extirpation and extinction. Much lower numbers of other large cetacean taxa were identified, suggesting that what are now the most depleted whales were once those most frequently used.

Fishery bycatch mortality is generally considered to be the main threat to cetaceans in European Atlantic waters. The marine waters in the Northwest of the Iberian Peninsula are among the richest in fishery resources in Europe and, consequently, they are also very important for fisheries. Analysis of cause of death and life history data from strandings in Galicia suggested that the bycatch is a major threat in common dolphins (Delphinus delphis) and harbour porpoises (Phocoena phocoena). The mortality rate in the Iberian population of the harbour porpoise could be well above safe limits. MERMACIFRA (“Monitoring, Assessment and Reduction of Accidental Mortality of Cetaceans due to Interactions with the Spanish Fleet - Review and Action”) is a national Project funded by the Fishery Ministry of Spain, the main objective of which is to monitor, assess and reduce bycatch of cetacean species in Spanish Atlantic waters. This includes acquisition of information on bycaught animals from strandings and on-board monitoring, to quantify bycatch mortality and to build a “profile” of bycaught animals in terms of their sex, size, age, reproductive status and health status. The project collaborates with the Galician stranding network, which attends stranded cetaceans on the Galician coast. Between 1990 and 2020, 3,404 strandings of common dolphins (on average 114 per year) and 344 strandings of harbour porpoises (on average 11 per year) were reported. It was observed that, over the last decade, the number of strandings with bycatch evidence has tended to increase. For 2021, considering only those carcasses examined which preservation state were from fresh to slight (n = 52 for common dolphin, and n = 13 for harbour porpoise), it was obtained that 54% of common dolphins (n = 28) and 23% of harbour porpoises (n = 3) had evidence of fishery interaction. During 2022-2023, we received two notifications from fishers regarding bycaught dolphins. In the first, two common dolphins were coll

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

Cetaceans play an important role in maintaining the health and stability of marine ecosystems. To understand the trophic relationships of these top predators in waters off the Northwest Iberian Peninsula, and to determine their possible competition with fisheries, the stomach contents of 751 common dolphins (Delphinus delphis), 60 striped dolphins (Stenella coeruleoalba), 124 bottlenose dolphins (Tursiops truncatus), and 72 harbour porpoises (Phocoena phocoena) stranded on the Galician coast between 1990-2018 (almost 30 years) were analysed. Results indicated that their diets are mainly piscivorous (after identified 90 different taxa: 68 fish and 22 cephalopods), being the blue whiting (Micromesistius poutassou) and the European hake (Merluccius merluccius) the most important preys (in occurrence, number, and biomass) throughout all the years studied and for the four cetacean species. The long time series available allowed to detect interannual variation in the diet of both common dolphins and harbour porpoises by means of Generalised Additive Models (GAMs), observing an increase in the presence of European hake and a decrease of sardines (Sardina pilchardus) in the stomachs through time. Seasonal variation in the diets of the common and striped dolphins were also observed, with a higher consumption of blue whiting during the summer (May-September). Significant differences were found in the diet of the two bottlenose dolphin ecotypes present in Galicia, the coastal ecotype contains a higher percentage of demersal preys in the stomachs, while the oceanic ecotype contains more pelagic preys, confirming the habitat separation between the two. Results also confirmed an ontogenic variability in the diet of harbour porpoises, with juvenile animals showing a higher presence of coastal preys in the diet (e.g., pouting – Trisopterus luscus). There is an overlap between the diet of these four cetacean species and the fisheries‟ target species in the area, indicating competiti

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

In habitat modelling, environmental variables are assumed to be proxies of lower trophic levels distribution and by extension, of marine top predator distributions. More proximal variables, such as potential prey fields, could refine relationships between top predator distributions and their environment. In situ data on prey distributions are not available over large spatial scales but, a numerical model, the Spatial Ecosystem And POpulation DYnamics Model (SEAPODYM), provides simulations of the biomass and production of zooplankton and six functional groups of micronekton at the global scale. Here, we explored whether generalised additive models fitted to simulated prey distribution data better predicted deep-diver densities (here beaked whales Ziphiidae and sperm whales Physeter macrocephalus) than models fitted to environmental variables. We assessed whether the combination of environmental and prey distribution data would further improve model fit by comparing their explanatory power. For both taxa, results were suggestive of a preference for habitats associated with topographic features and thermal fronts but also for habitats with an extended euphotic zone and with large prey of the lower mesopelagic layer. For beaked whales, no SEAPODYM variable was selected in the best model that combined the two types of variables, possibly because SEAPODYM does not accurately simulate the organisms on which beaked whales feed on. For sperm whales, the increase model performance was only marginal. SEAPODYM outputs were at best weakly correlated with sightings of deep-diving cetaceans, suggesting SEAPODYM may not accurately predict the prey fields of these taxa. This study was a first investigation and mostly highlighted the importance of the physiographic variables to understand mechanisms that influence the distribution of deep-diving cetaceans. A more systematic use of SEAPODYM could allow to better define the limits of its use and a development of the model that would si

Distribution maps of cetaceans and seabirds at basin and monthly scales are needed for conservation and marine management. These are usually created from standardized and systematic aerial and vessel surveys, with recorded animal densities interpolated across study areas. However, distribution maps at basin and monthly scales have previously not been possible because individual surveys have restricted spatial and temporal coverage. This study develops an alternative approach consisting of: (a) collating diverse survey data to maximize spatial and temporal coverage, (b) using detection functions to estimate variation in the surface area covered (km2) among these surveys, standardizing measurements of effort and animal densities, and (c) developing species distribution models (SDM) that overcome issues with heterogeneous and uneven coverage. 2.68 million km of survey data in the North‐East Atlantic between 1980 and 2018 were collated and standardized. SDM using Generalized Linear Models and General Estimating Equations in a hurdle approach were developed. Distribution maps were then created for 12 cetacean and 12 seabird species at 10 km and monthly resolution. Qualitative and quantitative assessment indicated good model performance. Synthesis and applications. This study provides the largest ever collation and standardization of diverse survey data for cetaceans and seabirds, and the most comprehensive distribution maps of these taxa in the North‐East Atlantic. These distribution maps have numerous applications including the identification of important areas needing protection, and the quantification of overlap between vulnerable species and anthropogenic activities. This study demonstrates how the analysis of existing and diverse survey data can meet conservation and marine management needs

1. Distribution maps of cetaceans and seabirds at basin and monthly scales are needed for conservation and marine management. These are usually created from standardized and systematic aerial and vessel surveys, with recorded animal den- sities interpolated across study areas. However, distribution maps at basin and monthly scales have previously not been possible because individual surveys have restricted spatial and temporal coverage. 2. This study develops an alternative approach consisting of: (a) collating diverse survey data to maximize spatial and temporal coverage, (b) using detection func- tions to estimate variation in the surface area covered (km2) among these surveys, standardizing measurements of effort and animal densities, and (c) developing species distribution models (SDM) that overcome issues with heterogeneous and uneven coverage. 3. 2.68 million km of survey data in the North-East Atlantic between 1980 and 2018 were collated and standardized. SDM using Generalized Linear Models and General Estimating Equations in a hurdle approach were developed. Distribution maps were then created for 12 cetacean and 12 seabird species at 10 km and monthly resolution. Qualitative and quantitative assessment indicated good model performance. 4. Synthesis and applications. This study provides the largest ever collation and standardization of diverse survey data for cetaceans and seabirds, and the most comprehensive distribution maps of these taxa in the North-East Atlantic. These distribution maps have numerous applications including the identification of im- portant areas needing protection, and the quantification of overlap between vul- nerable species and anthropogenic activities. This study demonstrates how the analysis of existing and diverse survey data can meet conservation and marine management needs.

The incidence of cetacean strandings is expected to depend on a combination of factors, including the dis- tribution and abundance of the cetaceans, their prey, and causes of mortality (e.g. natural, fishery bycatch), as well as currents and winds which affect whether carcasses reach the shore. We investigated spatiotemporal patterns and trends in the numbers of strandings of three species of small cetacean in Galicia (NW Spain) and their relationships with meteoro- logical, oceanographic, prey abundance and fishing-related variables, aiming to disentangle the relationship that may exist between these factors, cetacean abundance and mor- tality off the coast. Strandings of 1166 common dolphins (Delphinus delphis), 118 bottlenose dolphins (Tursiops truncatus) and 90 harbour porpoises (Phocoena phocoena) during 2000–2013 were analysed. Generalised additive and generalised additive-mixed model results showed that the variables which best explained the pattern of strandings of the three cetacean species were those related with local ocean meteorology (strength and direction of the North– South component of the winds and the number of days with South-West winds) and the winter North Atlantic Oscil- lation Index. There were no significant relationships with indices of fishing effort or landings. Only bottlenose dolphin showed possible fluctuations in local abundance over the study period. There was no evidence of long-term trends in number of strandings in any of the species and their abun- dances were, therefore, considered to have been relatively stable during the study period.

A comprehensive review of the natural history of the Harbour Porpoise Phocoena phocoena in Spain.

Galicia, north-west Spain, is one of the world’s main fishing regions and fishing is an important component of the economy. Previous interview surveys with fishermen five and ten years ago highlighted a high (up to 1700 cetaceans per year) and potentially unsustainable cetacean by-catch rate