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The European sardine (Sardina pilchardus, Walbaum 1792) is indisputably a commercially important species. Previous studies using uneven sampling or a limited number of makers have presented sometimes conflicting evidence of the genetic structure of S. pilchardus populations. Here, we show that whole genome data from 108 individuals from 16 sampling areas across 5000 km of the species’ distribution range (from the Eastern Mediterranean to the archipelago of Azores) support at least three genetic clusters. One includes individuals from Azores and Madeira, with evidence of substructure separating these two archipelagos in the Atlantic. Another cluster broadly corresponds to the center of the distribution, including the sampling sites around Iberia, separated by the Almeria–Oran front from the third cluster that includes all of the Mediterranean samples, except those from the Alboran Sea. Individuals from the Canary Islands appear to belong to the Mediterranean cluster. This suggests at least two important geographical barriers to gene flow, even though these do not seem complete, with many individuals from around Iberia and the Mediterranean showing some patterns compatible with admixture with other genetic clusters. Genomic regions corresponding to the top outliers of genetic differentiation are located in areas of low recombination indicative that genetic architecture also has a role in shaping population structure. These regions include genes related to otolith formation, a calcium carbonate structure in the inner ear previously used to distinguish S. pilchardus populations. Our results provide a baseline for further characterization of physical and genetic barriers that divide European sardine populations, and information for transnational stock management of this highly exploited species towards sustainable fisheries.

Samples of Anemonia sulcata were collected in 2022 from different areas of the Canary Islands affected by different natural contamination sources, such sandstorms, submarine volcanic activity, continuous rainfall, upwelling and dinoflagellate blooms. Significant differences were observed between the zones for the metals and trace elements analyzed (Al, Zn, Cd, Pb, Ni, Co, Fe, B, Cu, Mg and Li). Anemones from volcanic areas showed higher levels of Cd, Pb and Ni. Individuals from sandstorm areas showed elevated levels of Al, Zn and Fe. Samples collected from areas affected by upwelling processes had higher concentrations of Cu, Mg and Li. Finally, the areas affected by dinoflagellates showed lower levels of Zn, Pb, Fe, Mg and Li. The study reveals how natural phenomena dramatically influence metal accumulation in A. sulcata, which is of great value for anticipating and managing potential problems associated with public health.

The European sardine (Sardina pilchardus, Walbaum 1792) is indisputably a commercially important species. Previous studies using uneven sampling or a limited number of makers have presented sometimes conflicting evidence of the genetic structure of S. pilchardus populations. Here, we show that whole genome data from 108 individuals from 16 sampling areas across 5000 km of the species' distribution range (from the Eastern Mediterranean to the archipelago of Azores) support at least three genetic clusters. One includes individuals from Azores and Madeira, with evidence of substructure separating these two archipelagos in the Atlantic. Another cluster broadly corresponds to the center of the distribution, including the sampling sites around Iberia, separated by the Almeria-Oran front from the third cluster that includes all of the Mediterranean samples, except those from the Alboran Sea. Individuals from the Canary Islands appear to belong to the Mediterranean cluster. This suggests at least two important geographical barriers to gene flow, even though these do not seem complete, with many individuals from around Iberia and the Mediterranean showing some patterns compatible with admixture with other genetic clusters. Genomic regions corresponding to the top outliers of genetic differentiation are located in areas of low recombination indicative that genetic architecture also has a role in shaping population structure. These regions include genes related to otolith formation, a calcium carbonate structure in the inner ear previously used to distinguish S. pilchardus populations. Our results provide a baseline for further characterization of physical and genetic barriers that divide European sardine populations, and information for transnational stock management of this highly exploited species towards sustainable fisheries.

Small-scale fisheries in Canary Islands is made by small boats with passive fishing gears performing polyvalenceand with multiple aim species, with local landing and selling of the catches, with great socio-economic and cultura limportance at the local scale and with a fishers behavior highly influenced by the search of the economic viability of their multiple aim species exploitation. TROPICALIZATION OF COASTAL ICHTHYOFAUNA: 1. Natural expansion of distribution range (1980-2010). 2. In addition, Introduction of tropical species (2010-TODAY) 3. Population decrease of temperate/cold species. MERIDIONALIZATION: Population increase of NATIVE thermophilic species, some towards the colder Eastern islands. Here we present some preliminary results of the tropicalization of landings performed by commercial fisheries, based on the official sale notes information.

The bluespotted seabream P. caeruleostictus is assessed by CECAF as one single stock of “seabreams” (Sparidae) for Guinea-Bissau, Guinea, Sierra Leone and Liberia. Taking into account the mix of species, the consideration of one single stock for these four countries follows practical reasons and has no any biological basis.

DEMERSTEM- Objectives of WP 1: -Improve the knowledge on the selected demersal stocks with a particular effort to solve the problems of stock identification and improvement of the quality of the data used for the assessment. -This follows the recommendations regularly made by CECAF.

The Cassava croaker P. senegalensis is assessed by CECAF within one single stock of croakers (Pseudotolithus spp.), for Côte d´Ivoire, Ghana, Togo and Benin. Taking into account the mix of three species, the consideration of one single stock for these four countries follows practical reasons and has no any biological basis.

Length-weight relationships (LWR) were determined for Brotula barbata, Dentex angolensis, Dentex macrophthalmus, Neomerinthe folgori and Scorpaena stephanica using individual fish records collected between July 2002 and January 2003, during a pilot project of experimental fishing over the shelf off Guinea Bissau. Fishes were caught by commercial vessels using bottom longline, measured defrost for the total length (to the lower 0.1 cm) and weighted for the total weight (TW, to the 0.1 g), and sexed. Two new maximum total lengths were registered for Scorpaena stephanica and Neomerinthe folgori, whose LWR b-values corresponded to the limits of the range obtained, between 2.833 and 3.318, respectively. All LWRs were obtained from well-adjusted linear regressions with r2 ≥ 0.90. Data presented herein expand the knowledge base for these species in West Africa, as they have limited or no LWR data available.

Mercury is a very dangerous toxic metal that bioaccumulates very easily in organisms, and it migrates through the food web. The specimens studied in this study were Scomber colias. In the results obtained for the years 1973, 1992, and 2021, the concentration of mercury has been decreasing considerably over the decades, starting with 0.23 ± 0.04 mg/kg in 1973, and having less than half in 2021 with 0.11 ± 0.01 mg/kg. This may be due to the laws imposed by the countries against pollution and to a greater extent in the elimination of mercury; thanks to these measures it has been possible to reduce the concentration of mercury by half in S. colias. Otherwise, the conservation and availability of historical collections of living beings should be considered an unvalued source of information which could help to monitor legislation measures launched to ameliorate the human impact on the natural environment.

Based on the previous work from WKARHOM3 (ICES, 2018), the Working Group on Biological Parameters (ICES, 2020) identified the need for a new otolith exchange followed by an age read-ing Workshop. The Workshop on Age reading of Horse Mackerel, Mediterranean Horse Macke-rel and Blue Jack Mackerel (Trachurus trachurus, T. mediterraneus and T. picturatus) (WKAR-HOM4) had several main objectives; to review the current protocols of ageing Trachurus species, to update the advances in the validation of the ageing criteria (i.e. the annual deposition of one annulus, coherency of the interpretation), to evaluate the new precision of ageing data of Tra-churus species and to update guidelines, common ageing criteria and reference collections of otoliths. An online otolith exchange was performed using SmartDots during 2021 and 2022, and results including the three Trachurus species were published in advance of the meeting, showing a low Percentage of Agreement (PA) both when considering all the readers (44-55%) and the advanced readers only (52-54%) (Massaro and Jurado-Ruzafa, 2022). For T. trachurus the Coef-ficient of Variation (CV) was lower for the sliced samples (22-18%) than for whole otoliths sam-ples (44-38%). Readers participating in the exchange, following discussion during the WKAR-HOM4 meeting, agreed that the main cause of age determination error for T. trachurus was due to the different otolith preparation techniques (whole/sliced). These differences reflect the stunted growth and compactness of the annuli in older specimens (from the 4th-5th annuli on-wards). Anyway, for the three Trachurus species, there are several difficulties in age determina-tion: identification of the first growth annulus, presence of many false rings (mainly in the first and second annuli) and the interpretation and identification of the edge characteristics (opaque/translucent). The second reading exercise was performed during the workshop orga-nized in four different events (i.e. Trachuru

The Atlantic chub mackerel (Scomber colias) is one of the main fishing resources for the fisheries targeting small pelagics in NW African waters. This species is expanding its geographical distribution through higher latitudes in southern European Atlantic waters, and it has become an important fishing resource in Iberian Atlantic waters during the last decades. The present study addresses the growth variability of S. colias in the Iberian waters, from southern Bay of Biscay up to Gulf of Cadiz. Age estimates based on otoliths and growth parameters were obtained from specimens collected within the study area during one decade (from both commercial landings and scientific-acoustic surveys), and sexual growth variation was analysed. A common pattern of abundant cohorts was observed in various areas. However, differences in the demographic structure of the catches were observed among the different areas, with the southernmost area studied (Portuguese and Spanish waters off Gulf of Cadiz) standing out with younger individuals. These new findings are of interest for the stock assessment of S. colias, which has not been addressed in ICES waters so far.

Length-weight relationships (LWR) of twelve fish species collected by fish pots (half an inch mesh size), bottom horizontal longlines (hook size 3/0) and set gillnets (80 mm mesh size) from two Marine Protected Areas in the Canary Islands were determined using individual fish records collected at least once a year during ten scientific surveys between 2003 and 2010, excluding 2007. Fish was measured fresh for the total length (to the lower 0.1 or 0.5 cm, depending on the scientific surveys design) and weighted for the total weight (TW, to the 0.1 g). With the exception of Bathytoshia centroura with a b-value of 1.77, the LWR parameter b ranged between 2.71 (Heteropriacanthus cruentatus (Lacepède, 1801)) and 3.86 (Gymnothorax maderensis (Johnson, 1862)). All LWRs were obtained from well-adjusted linear regressions with R2 ≥0.74. In addition, six new maximum lengths were recorded for six of the sampled species. Data presented herein expand the knowledge base for these species in the Archipelago, as they have limited or no LWR data available

In waters off The Canary Islands, small pelagic fish are targeted by an artisanal purse seine fleet. This fishery has been monitored within the EU Data Collection Framework since 2013. The status assessment of the most important commercial species (i.e. Scomber colias, Trachurus spp, Sardinella spp and Sardina pilchardus) are included in the Fishery Committee for the Eastern Central Atlantic (CECAF). However, the short time series and the limited knowledge of the life history traits of these species in the Archipelago had been considered too limited to perform any assessment exercise. In this context, a multi-model approach was attempted to assess the status of these species for the first time in the area, using the methods recommended by CECAF and the International Council for the Exploration of the Sea (ICES). Time series of landings and fishing effort includes data since 2009 to 2020, being less reliable at the beginning of the series. In addition, the biological and population information needed as input data in those models, are available depending on the species, this increasing the uncertainty of these analyses. A total of six data-limited (length- and catch-based) methods was applied. Results show that a quantitative assessment of the Canaries small pelagic stocks, with the final aim of providing scientific advice for management purposes, is not yet feasible. Therefore, it is necessary and urgent to address the current uncertainties around these species and fisheries, both by improving the knowledge of their life histories and by solving the shortfalls related to the data of this artisanal and multispecific fishery.

In the last decade there has been a growing interest in the Atlantic chub mackerel, Scomber colias, due to a noticeable expansion of this species in the East Atlantic Ocean from areas of greater abundance off northwest Africa to Atlantic Iberian waters and the Mediterranean Sea (ICES, 2021). To implement sustainable management measures in the current global warming situation it is crucial not only to identify biologically-meaningful management units, but also to understand otolith morphological variability along its geographic distribution areas. We analysed the otolith shape variability in S. colias considering four origins in as one metapopulation.

Small pelagic fish (SPF) present relatively short life cycles, with fast growth, high mobility and plankton-base feeding. Therefore, they are highly sensitive to fluctuations in environmental conditions, including those related to Climate Change, and fishing. On the one hand, reproductive traits have been recently described for all these species in the Canary archipelago, which show a clear decreasing pattern of their sizes at first maturity during the last years (Jurado-Ruzafa et al., 2021). On the other hand, a regional increase in the sea water temperature has been observed in NW African waters during last decades (Vélez-Belchí et al., 2015). Foreseeing potential variations in the life history traits of SPF is critical for effective management measures in the current Global Warming scenario.

The present study aims to investigate the reproductive biology of the small pelagic Sardinella aurita Valenciennes, 1847 in the Canary Islands, to enable its reliable assessment and advise on appropriate management measures for a fishing resource showing a declining trend in landings. Reproductive biology and sexual patterns of round sardinella were examined from monthly random samples of commercial catches landed by the artisanal purse-seine fleet. The landings' length frequencies, ranging between 9–32 cm (based on the total lengths, TL), were recorded from 2013–2019. The overall mean value of TL was 20.9 cm, with annual mean values between 20–22 cm, except in 2016 (TL = 19 cm). The overall sex ratio M:F was 1:0.92, with males significantly predominant. Sex ratios fluctuated as a function of size and month: females were more abundant in the larger length classes, as well as before and after spawning, whereas males were more abundant in the smaller length classes and during spawning. Based on gonad maturity stages and gonadosomatic index, round sardinella spawns during almost all the year, with a peak in January–February and a resting period during October–November. The length at first maturity was estimated at TL of 18.2 cm, notably smaller than the value obtained for the NW African coastal waters where the demographic structure in round sardinellas' landings is totally different.

Regarding the research activities carried out by Oceanographic Centre of the Canary Islands (IEO-CSIC) during intersession, several studies on different topics were presented. Firstly, reproductive traits for the four main species have been analysed including all the data obtained since the monitoring system was launched in 2013. Although with some variations, the spawning season matched with winter and beginning spring for S. colias, T. picturatus and S. pilchardus. However, spawning individuals of S. aurita are present all year round. Sizes at first maturity (SFM) were also estimated, with slightly smaller sizes obtained for S. colias and T. picturatus (around 19 cm of total length) compared with the reference values (20 cm and 23 cm, respectively) (Jurado-Ruzafa and Santamaría, 2013; Lorenzo and Pajuelo, 1996). It seems that SFM remains stable for S. pilchardus (15 cm) (Méndez-Villamil et al., 1997). In the case of S. aurita, size at first maturity has been estimated for the first time in the Canary Islands, and has been recently published (Jurado-Ruzafa et al., 2022). Secondly, a first attempt to describe total catches of the Canary artisanal purse-seine fleet based on scientific observation shows that discards are more relevant than what was supposed, reaching the 25 percent of the total catches. The situation is even more concerning if only S. colias is considered, with discards around 40 percent of the total catches, mainly impacting on juveniles’ fraction, which is usually used as bait by commercial vessels but that are not officially reported. Finally, very preliminary results were shown to the working group about the potential adaptive plasticity in Scomber colias from the Canary Islands, based on otolith shape analyses. These results were obtained from analysing 748 otoliths extracted from August 2016 to December 2017. A DIvisive ANAlysis (DIANA) Clustering method using the fourth wavelet obtained from otolith contours resulted in the detection of five di

Small pelagic fish in the Canary Islands (CE Atlantic, from 29°27'N to 27°37'N and from 18°12'W to 13°17’W) are mainly targeted by artisanal purse-seiners, whose activity is monitored by the Canary Oceanographic Centre (IEO-CSIC) in the Data Collection Framework since 2013. The Atlantic chub mackerel (Scomber colias) is the main of the four species targeted by this fleet (45% of the total landings), with landings quite stable around a mean value of 850 tons/year. From August 2016 to December 2017, 792 otoliths of S. colias corresponding to monthly analyses of the mentioned fleet’s landings have been launched used to identify the potential presence of different morphotypes inhabiting Canary waters, based on otolith shape analysis. A DIvisive ANAlysis (DIANA) Clustering method using the 4th wavelet obtained from otolith contours resulted in the detection of five different morphotypes or otolith phenotypes. Differences where found mainly in the collicum-antirostrum and the dorsal margin areas of the otoliths’ contours. Two of the morphotypes represented 85% of the samples analyzed, whose individuals were slightly larger than the other morphotypes, considering mean lengths (≥25cm vs. ≤24.5cm). These very preliminary results open many future questions to be explored: 1) Do these results suggest intra-specific variation in the growth rate among phenotypes?; 2) Do phenotypes proportions change in relation to seasonal variations?; 3) May exist different ecological strategies related to each phenotypes?; and 4) Are these otolith phenotypes present in other geographical areas?

Atlantic chub mackerel is a pelagic species present in the Atlantic Ocean that in recent decades has expanded northwards in the eastern Atlantic. Fish samples were collected in scientific surveys and commercial catches between 2011 and 2019. We analysed the geographical variation of the biological parameters (age, length, weight and condition), as well as the length-weight relationship, maturity-at-length and spawning season onset and duration in five geographical areas (from south to north): the Canary Islands, Gulf of Cadiz, western Portuguese coast, northwestern Spanish coast and Canta-brian Sea. The influence of sea surface temperature (SST) on fish length was modelled as a potential driver of geographical variability. All biological parameters increased progressively northwards, while the spawning season was delayed and prolonged with increasing latitude, from January in the Canary Islands to May-August in the Cantabrian Sea, when SST was between 15°C and 19°C. SST had a positive effect on length in three study areas and a negative one in two of them, suggesting that each group is at a different position within their thermal tolerance range. Deviance from the geographical pattern of some biological parameters in the Gulf of Cadiz suggests that it could be a hinge or mixing zone between Atlantic African, Mediterranean and Atlantic Iberian population components.

The common octopus, Octopus vulgaris, is a very important demersal fishery resource targeted, among other fleets, by freezer bottom-trawlers in the Mauritanian Economic Exclusive Zone (MEEZ). From August 2010 to September 2011, a total of 1696 octopuses caught in the MEEZ where analysed. Many organisms trapped into the octopuses’ mantle were found and identified, which are jointly swept while the trawling catches the targeted species. A latitudinal (by ecoregion) and depth study was performed to determine differences in the taxonomic diversity of these hidden organisms. The findings showed that the diversity patterns were similar to already established in the area based on scientific surveys. Therefore, this ignored bycatch could provide complementary ecological information of the habitat of O. vulgaris