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A programme of observers on board Spanish shrimp trawlers in Angola was initiated by IEO in 2018 in order to improve the scientific information required by Sustainable Management of External Fishing Fleets (SMEFF Regulation of the EU). In this context, discard studies are considered very relevant, both for assessment purposes and for obtaining information on adverse ecological impacts in marine ecosystems. Most fishing hauls performed during the observed period November 2018 to December 2019 were carried out at depths between 384 and 649 m, with classic bottom otter trawl targeting the striped red shrimp Aristeus varidens. Discards accounted for 60% of the total catch during the analysed period. The estimated global discard rate for 2019 (2.2 discard/retained catch) indicates that 1915 tonnes of retained catch produced 4213 tonnes of discards, of which a small amount is of commercial species, as A. varidens (3.8 tonnes) and Merluccius polli (153 tonnes). A total of 131 discarded species were identified, with the highest group contribution being fish (70%), followed by crustaceans (20%). The most abundant species in discard weight were Ariomma melanum, Lamprogrammus exutus, Chaunax pictus, Centroscymnus owstonii, Hoplostethus cadenati, Lophius vaillanti, Yarrella blackfordi and Ariomma bondi (all together accounting for 55% of discards). The most frequent species were H. cadenati and L. exutus, discarded in 95% of the analysed fishing hauls. Discards estimations of commercial species obtained through a long-term observers program might result in improving the assessments of main commercial species from Angolan deep sea waters.

The recent establishment of the “landing obligation” under the reformed EU Common Fishery Policy has the twofold objective of reducing the excessive practice of discarding unwanted catch at sea and encouraging more selective and sustainable fisheries. Within this context, the awareness of the spatial distribution of potential unwanted catches is important for devising management measures aimed to decrease discards. This study analyzed the distribution of Hot Spot density areas of demersal fish and crustaceans below the Minimum Conservation Reference Size (MCRS) in four different southern European seas: continental Portuguese coast, Catalan Sea, South of Sicily, Liguria and northern Tyrrhenian Seas using both bottom trawl survey data and information on the spatial distribution of commercial fisheries. Critical areas for discarding were identified as zones where the highest densities of individuals below MCRS were consistently recorded throughout a series of years. Results clearly showed a patchy distribution of undersized individuals in each investigated area, highlighting the overlap between high density patches of both discards and fishing effort. The present findings provide a relevant knowledge for supporting the application of spatial-based management actions, such as the designation of Fisheries Restricted Areas (FRAs), in order to minimize the by-catch of undersized specimens and improve the sustainability of demersal fisheries

The landing obligation introduced in the reform of the European Union Common Fisheries Policy requires landing all catches of species under quota. However, exemptions may be granted for species for which “scientific evidence demonstrates high survival rates”. Captivity experiments are often used to determine fish survival rates, but they are difficult to perform for large species such as rays due to the limited storage capacity of tanks. Thus, little information is available on ray survival after release despite an identified potential for high survival. We used acoustic telemetry to study rays discarded from a coastal bottom trawl fishery in their natural environment and present a new ad hoc approach to derive a minimum survival rate. After capture under commercial conditions in a semi-enclosed bay, 144 rays were tagged with a miniature acoustic transmitter. Survival was assessed based on detections from 15 acoustic receivers deployed in the area and a mobile reception antenna. Then, combining detection data with information on currents provides useful results from a management perspective, as at least 49% of the rays were found to have survived the first 14 days after released, and because the only factor identified that likely decrease survival (i.e. smaller individuals) cannot be improved easily by changing fishing practices.

The landing obligation introduced in the reform of the European Union Common Fisheries Policy requires landing all catches of species under quota. However, exemptions may be granted for species for which “scientific evidence demonstrates high survival rates”. Captivity experiments are often used to determine fish survival rates, but they are difficult to perform for large species such as rays due to the limited storage capacity of tanks. Thus, little information is available on ray survival after release despite an identified potential for high survival. We used acoustic telemetry to study rays discarded from a coastal bottom trawl fishery in their natural environment and present a new ad hoc approach to derive a minimum survival rate. After capture under commercial conditions in a semi-enclosed bay, 144 rays were tagged with a miniature acoustic transmitter. Survival was assessed based on detections from 15 acoustic receivers deployed in the area and a mobile reception antenna. Then, combining detection data with information on currents provides useful results from a management perspective, as at least 49% of the rays were found to have survived the first 14 days after released, and because the only factor identified that likely decrease survival (i.e. smaller individuals) cannot be improved easily by changing fishing practices.

The landing obligation introduced in the reform of the European Union Common Fisheries Policy requires landing all catches of species under quota. However, exemptions may be granted for species for which “scientific evidence demonstrates high survival rates”. Captivity experiments are often used to determine fish survival rates, but they are difficult to perform for large species such as rays due to the limited storage capacity of tanks. Thus, little information is available on ray survival after release despite an identified potential for high survival. We used acoustic telemetry to study rays discarded from a coastal bottom trawl fishery in their natural environment and present a new ad hoc approach to derive a minimum survival rate. After capture under commercial conditions in a semi-enclosed bay, 144 rays were tagged with a miniature acoustic transmitter. Survival was assessed based on detections from 15 acoustic receivers deployed in the area and a mobile reception antenna. Then, combining detection data with information on currents provides useful results from a management perspective, as at least 49% of the rays were found to have survived the first 14 days after released, and because the only factor identified that likely decrease survival (i.e. smaller individuals) cannot be improved easily by changing fishing practices.

[EN] There is currently very little information on the survival to discarding of unwanted and non-regulated catches of invertebrates, after the stresses due to capture. A great number of the non-regulated invertebrate species are the basis of Essential Fish Habitats for important fisheries resources such as hake, red mullet or cuttlefish. Thus, data on their survival to discarding may help to interpret the role of these species within the benthic ecosystems. Furthermore, descriptor 6 of Marine Strategy Framework Directive (MSFD, EU Directive 2008/56/E) foresees maintaining sea floor integrity at a level that ensures that the structure and functions of the ecosystems are safeguarded and article 7(d) of the Common Fishery Policy (CFP, EU Reg. 1380/2013) foresees the implementation of management measures for fishing with low impact on the marine ecosystem and fishery resources. Survival measurements by direct recovering tagged discarded species are not effective in bottom trawl fisheries for which alternative studies, such as semi-quantitative measures obtained on board prior to discarding, can be considered as appropriate for mortality estimation. The present work assessed the survival of unwanted species using a Semi-Quantitative Assessment (SQA) on deck of trawlers and at the laboratory for a period of 96 hours in two Mediterranean areas (Catalan Coasts and Ligurian and Northern Tyrrhenian Sea). The results showed that a high number of discarded invertebrates had a high percentage of survival (>70%) in both assessments. The purpose of these results is to provide information that can help to achieve higher survival levels of the discarded specimens. At the same time, it is expected that this improvement can enhance the productivity of the fishing grounds by increasing the health of the benthic ecosystems, [ES] Actualmente, hay muy poca información sobre la supervivencia del descarte de los invertebrados no-deseados y no-regulados después del stress de la captura. Un gran número de especies de estos invertebrados son básicas para los hábitats esenciales de importantes recursos pesqueros como la merluza, el salmonete o la sepia. Por lo tanto, información sobre su supervivencia al ser descartados pueden ayudar a interpretar el papel de estas especies dentro de los ecosistemas bentónicos. Además, el punto 6 de la Directiva Marco de Estrategia Marina (MSFD, EU Directive 2008/56/E) prevé mantener la inte-gridad del fondo marino a un nivel que garantice la protección de la estructura y de las funciones de los ecosistemas, y el artículo 7 (d) de la Política Pesquera Común (PPC EU Reg. 1380/2013) prevé la implementación de medidas de gestión para la pesca, que tengan bajo impacto tanto en el ecosistema marino como en los recursos pesqueros. En el caso de las pescas de arrastre de fondo, no es efectiva la estimación de la supervivencia a partir del método directo de captura-recapture de las especies del descarte marcadas, por lo que los estudios alternativos, como las medidas semicuantitativas obtenidas a bordo antes del descarte, pueden considerarse una estimación de la mortalidad apropiada. El presente trabajo evaluó la supervivencia del descarte de especies no-deseadas utilizando una Evaluación Semicuantitativa (SQA) mediante dos estudios: uno sobre la cubierta de los arrastreros y el otro en laboratorio durante un período de 96 horas, en dos áreas del Mediterráneo, las costas Catalanas y en los mares de Liguria y del Tirreno Norte. Los resultados mostraron en ambos estudios, que un alto número de invertebrados descartados tenía un alto porcentaje de supervivencia (>70%). El propósito de estos resultados es proporcionar información que puede ayudar a alcanzar niveles de supervivencia más altos de los individuos descartados. Al mismo tiempo, se espera que con esta mejora se

[EN] With the full implementation of the landing obligation on 1 January 2019, In European waters it will become mandatory for the trawling fleet to land at port all catches of certain species because, according to Article 15 of the new European Common Fisheries Policy, the species subject to the minimum conservation reference size (MCRS) cannot be discarded. Additionally, since 2005, trawlers over 15 m in length are required to carry an onboard vessel monitoring system (VMS), which generates information on fleet dynamics. The objective of this work was to provide a tool for avoiding unwanted catches by integrating the catch study of trawlers operating in the port of Blanes together with VMS data. To achieve this objective, the catches of 40 hauls were monitored, sampled and analysed together with VMS data for the years 2012-2014 integrated in a geographical information system. The results show that specimens below the MCRS were often captured in crinoid aggregation habitats, bottoms with maërl and muddy bottoms that were identified as nursery habitats of commercial species, e.g. Merluccius merluccius, Pagellus spp. and Mullus spp. VMS data showed considerable fishing pressure on areas with maërl and muddy habitats during the recruitment periods of these and other commercially relevant species. Implementing spatial or seasonal closures in habitats where species regulated by the MCRS are subject to catches could be a useful tool for preventing unwanted catches, [ES] Con la plena aplicación de la Obligación de desembarque a partir del 1 de enero de 2019, pasará a ser obligatorio para la flota de arrastre desembarcar en puerto todas las capturas de ciertas especies, que según el Artículo 15 de la nueva política pesquera común no pueden ser descartadas, ya que están sujetas a MCRS. Por otro lado, desde 2005, se requiere a los arrastreros de más de 15 m de longitud, llevar a bordo un VMS, que proporciona información acerca de la dinámica de la flota. El objetivo de este trabajo fue proporcionar una herramienta para evitar capturas no deseadas integrando el estudio de la captura de arrastreros que operan en el puerto de Blanes junto con datos VMS de la flota de arrastre. Para lograr dicho objetivo, las capturas de 40 lances fueron monitoreadas, muestreadas y analizadas junto con los datos VMS de los años 2012-2014 integrados en un Sistema de Información Geográfica. Los resultados muestran que se capturaron de forma notable especímenes por debajo de la MCRS en hábitats de agregación de crinoideos, fondos con presencia de maërl y fondos fangosos que fueron identificaron como hábitats de cría para especies como Merluccius merluccius, Pagellus spp. y Mullus spp. Los datos VMS mostraron una notable presión pesquera en hábitats fangosos y fondos con presencia de maërl durante los períodos de reclutamiento de estas y otras especies comerciales relevantes. El uso de cierres espaciales o temporales en hábitats sujetos a descarte de especies reguladas por MCRS podría ser una herramienta útil para evitar capturas no deseadas

[EN] In this work we analysed the spatio-temporal variability of discards in the fishery of the deep-sea red shrimp Aristeus antennatus in the northwestern Mediterranean Sea. We sampled fishery discards in the fishing grounds of Palamós (the main harbour for this fishery on the Catalan margin), which are located in several areas of a submarine canyon. We found that the discard ratio in this fishery showed a marked seasonal variability, with a maximum in spring and a minimum in summer. Most of the discarded biomass (almost 96%) were of species with no commercial interest. Within these, the most represented group was elasmobranchs, making up to more than 50% of total discarded biomass. Our findings show that the landing obligation established by the EU will have a low impact in mitigating discards in this fishery, as the vast majority of discards are non-commercial species that are not specified in the regulation. Alternative management strategies, such as a temporary fishery closure in spring (when the discard ratio reaches its maximum), should be considered in order to preserve the vulnerable ecosystem hosted by the submarine canyon, [ES] En este estudio se analizó la variabilidad espacio-temporal de los descartes en la pesquería de la gamba roja de profundidad Aristeus antennatus en el mar Mediterráneo Noroccidental. Para ello se muestrearon las capturas obtenidas en los caladeros de Palamós (el mayor puerto para esta pesquería en Cataluña), que están localizados en diferentes áreas adyacentes a un cañón submarino. Nuestros resultados demuestran que la proporción de descartes en las capturas de esta pesquería presenta una marcada variabilidad estacional, con un máximo en primavera y un mínimo en verano. La mayoría de la biomasa de los descartes (casi el 96%) está constituida por especies sin ningún interés comercial. Entre éstas, el grupo más representado es el de los elasmobranquios, que constituye más del 50% de la biomasa total de los descartes. Nuestros resultados indican que la obligación de desembarcar las capturas establecida por la UE tendrá un impacto bajo en disminuir los descartes en esta pesquería, ya que la gran mayoría de los descartes está constituida por especies no comerciales que no están especificadas en la regulación. Medidas de gestión alternativas, como el establecimiento de una veda en primavera (cuando la proporción de descartes llega a su máximo) deberían considerarse para preservar el ecosistema vulnerable de este cañón submarino

In input-controlled multi-specific fisheries, seasonal closure has little biological rationale as a management measure, because it is difficult to adjust such closure for many target species and, in most cases, they are adopted for economic purposes. We aimed to determine effects of closure in biologic and economic terms, using 10-year landing data from two representative trawling ports of the Western Mediterranean: Dénia and La Vila Joiosa. Analysis of Variance (ANOVA) was used to detect significant differences, before and after the closure, in standardized catch per unit effort (CPUE) at different seasons and sale prices at home/closed and neighbour/open ports. ANOVAs showed significantly higher CPUE after the closure for total landings and Mullus spp. of the Red mullet métier, Merluccius merluccius CPUE (in two years) and the total landings of the Norway lobster métier. On the contrary, significant lower values were observed after the closure for total CPUE (in early summer) and Aristeus antennatus of Red shrimp métier. Similar CPUE was observed at all levels when the closure took place in late summer. In economic terms, market prices of target species have decreased or shown no changes after the closure at home/closed and neighbouring/open ports. The only exception was the significant increase of the price for A. antennatus in Dénia during the closure in La Vila Joiosa. Depending on its timing, the closure would highlight some positive biological effects on some target species. However, closure leads to an unavoidable reduction in most of target species prices. An alternative management measure that is based on effort reduction in input-controlled multi-specific fisheries could ban one day per week when market prices of target species are lower.

The daily variation of fishing effort and ex-vessel price was analysed to determine which day of the week is suitable to ban the fishery, as an alternative management measure to the one month seasonal closure. Thus, 10-years landings data were used from two representative trawling ports of the western Mediterranean: Dénia and La Vila Joiosa. Analysis of variance (ANOVA) was used to detect significant differences in fishing effort (total and by métier) and daily ex-vessel price of the main target species. Also, the economic loss produced by banning one day (the proposed measure) was compared to economic loss produced by the seasonal closure (the actual measure). Daily variation in the fishing effort was observed in La Vila Joiosa mainly due to higher effort at the end of the week devoted on crustacean métiers, while effort was similar among days in Dénia. The lowest mean prices for most target species were on Tuesday and Wednesday, and were higher on Monday and Friday. Banning one day per week (Tuesday or Wednesday), when market prices of target species are lower would reduce the double of effort than one month of seasonal closure, and likely without subsidies. However, the loss by banning all Wednesdays (approx. 50 days) was higher in both ports than one month, but lower than an equivalent two months closure.

In input-controlled multi-specific fisheries, seasonal closure has little biological rationale as a management measure, because it is difficult to adjust such closure for many target species and, in most cases, they are adopted for economic purposes. We aimed to determine effects of closure in biologic and economic terms, using 10-year landing data from two representative trawling ports of the Western Mediterranean: Dénia and La Vila Joiosa. Analysis of Variance (ANOVA) was used to detect significant differences, before and after the closure, in standardized catch per unit effort (CPUE) at different seasons and sale prices at home/closed and neighbour/open ports. ANOVAs showed significantly higher CPUE after the closure for total landings and Mullus spp. of the Red mullet métier, Merluccius merluccius CPUE (in two years) and the total landings of the Norway lobster métier. On the contrary, significant lower values were observed after the closure for total CPUE (in early summer) and Aristeus antennatus of Red shrimp métier. Similar CPUE was observed at all levels when the closure took place in late summer. In economic terms, market prices of target species have decreased or shown no changes after the closure at home/closed and neighbouring/open ports. The only exception was the significant increase of the price for A. antennatus in Dénia during the closure in La Vila Joiosa. Depending on its timing, the closure would highlight some positive biological effects on some target species. However, closure leads to an unavoidable reduction in most of target species prices. An alternative management measure that is based on effort reduction in input-controlled multi-specific fisheries could ban one day per week when market prices of target species are lower.

The daily variation of fishing effort and ex-vessel price was analysed to determine which day of the week is suitable to ban the fishery, as an alternative management measure to the one month seasonal closure. Thus, 10-years landings data were used from two representative trawling ports of the western Mediterranean: Dénia and La Vila Joiosa. Analysis of variance (ANOVA) was used to detect significant differences in fishing effort (total and by métier) and daily ex-vessel price of the main target species. Also, the economic loss produced by banning one day (the proposed measure) was compared to economic loss produced by the seasonal closure (the actual measure). Daily variation in the fishing effort was observed in La Vila Joiosa mainly due to higher effort at the end of the week devoted on crustacean métiers, while effort was similar among days in Dénia. The lowest mean prices for most target species were on Tuesday and Wednesday, and were higher on Monday and Friday. Banning one day per week (Tuesday or Wednesday), when market prices of target species are lower would reduce the double of effort than one month of seasonal closure, and likely without subsidies. However, the loss by banning all Wednesdays (approx. 50 days) was higher in both ports than one month, but lower than an equivalent two months closure.

There is increasing fishing pressure on the continental margins of the oceans, and this raises concerns about the vulnerability of the ecosystems thriving there. The current knowledge of the biology of deep-water fish species identifies potential reduced resilience to anthropogenic disturbance. However, there are extreme difficulties in sampling the deep sea, resulting in poorly resolved and indirectly obtained food-web relationships. Here, we modelled the flows and biomasses of a Mediterranean deep-sea ecosystem, the Catalan Sea continental slope at depths of 1000–1400 m. This is the first model of a deep-water ecosystem in the Mediterranean Sea. The objectives were to (a) quantitatively describe the food web structure of the ecosystem, (b) examine the role of key species in the ecosystem, and (c) explore the vulnerability of this deep-sea ecosystem to potential future fishing exploitation. We used the Ecopath with Ecosim (EwE) modelling approach and software to model the ecosystem. The trophic model included 18 consumers, a marine snow group, and a sediment detritus group. Trophic network analysis identified low levels of consumer biomass cycling and low system omnivory index when compared with expected values of marine ecosystems, and higher cycling and omnivory when compared with available EwE models of shallower areas of the Mediterranean Sea. The majority of flows in the ecosystem were concentrated at the trophic level of first-order consumers (TL 2). Benthic invertebrates and demersal sharks were identified to have key ecological roles in the ecosystem. We used the dynamic temporal model Ecosim to simulate expansion of the red-shrimp benthic trawl fishery that currently operates at shallower depths, down to 800 m depth. The simulations showed reductions in fish biomass and that the state of the deep continental slope ecosystem in the western Mediterranean seems to be the result of a long-term succession process, which has reached ecological stability, and is

The aim of the present paper is to study the relationships between some climatic indices and parental stock, recruitment and accessibility to trawl fishery of hake (Merluccius merluccius) and red shrimp (Aristeus antennatus) off Balearic Islands (western Mediterranean). Available annual catch per unit effort, recruitment and spawning stock biomass have been used as biological data. As environmental data, the meso- scale IDEA index and the large-scale North Atlantic Oscillation (NAO) and Mediterranean Oscillation (MO) indices have been used. To analyze possible links between these indices with the population dynamics of demersal resources, two non-linear approaches have been applied: (i) stock–recruitment relationships from Ricker and Beverton–Holt models, by sequentially incorporating environment factors; (ii) generalized additive modelling, both classical general and threshold non-additive models were considered. The latter simulate an abrupt change in explicative variables across different phases (time periods or climatic index values). The results have shown that two oceanographic scenarios around the Balearic Islands, associated with macro and meso-scale climate regimes, can influence the population dynamics of hake and red shrimp. This is especially true for recruitment, which seems to be enhanced during low NAO and IDEA indices periods. During these periods, colder-than-normal winters generate high amounts of cold Western Mediterranean Intermediate Waters (WIW) in the Gulf of Lions, which flow southwards and reach the Balearic Islands channels in spring, increasing the productivity in the area. This oceanographic scenario could also be favourable to the distribution of hake on the fishing grounds where the trawl fleet targets this species, increasing its accessibility to the fishery. Both spawning stock and abundance of red shrimp seems to be also enhanced by high MO index periods, which could reflect the increased presence of the saline and warm Levantine Int

The aim of the present paper is to study the relationships between some climatic indices and parental stock, recruitment and accessibility to trawl fishery of hake (Merluccius merluccius) and red shrimp (Aristeus antennatus) off Balearic Islands (western Mediterranean). Available annual catch per unit effort, recruitment and spawning stock biomass have been used as biological data. As environmental data, the meso-scale IDEA index and the large-scale North Atlantic Oscillation (NAO) and Mediterranean Oscillation (MO) indices have been used. To analyze possible links between these indices with the population dynamics of demersal resources, two non-linear approaches have been applied: (i) stock-recruitment relationships from Ricker and Beverton-Holt models, by sequentially incorporating environment factors; (ii) generalized additive modelling, both classical general and threshold non-additive models were considered. The latter simulate an abrupt change in explicative variables across different phases (time periods or climatic index values). The results have shown that two oceanographic scenarios around the Balearic Islands, associated with macro and meso-scale climate regimes, can influence the population dynamics of hake and red shrimp. This is especially true for recruitment, which seems to be enhanced during low NAO and IDEA indices periods. During these periods, colder-than-normal winters generate high amounts of cold Western Mediterranean Intermediate Waters (WIW) in the Gulf of Lions, which flow southwards and reach the Balearic Islands channels in spring, increasing the productivity in the area. This oceanographic scenario could also be favourable to the distribution of hake on the fishing grounds where the trawl fleet targets this species, increasing its accessibility to the fishery. Both spawning stock and abundance of red shrimp seems to be also enhanced by high MO index periods, which could reflect the increased presence of the saline and warm Levantine Inte

It is 20 years since Munro and Scott identified the causes and possible remedies for the dissipation of rents in fisheries. We analyse one of the solutions proposed by Munro and Scott by using insights from the British Columbia multi-species groundfish trawl fishery that has used ITQs since 1997. The history of this fishery shows that even the most difficult management problems including by-catch, equity concerns, concentration of quota holdings and vessel overages can be mitigated with the appropriate mix of incentives, monitoring and enforcement.

The shark species, blackmouth catshark (Galeus melastomus), velvet belly (Etmopterus spinax) and coastal spotted dogfish (Scyliorhinus canicula) are an important by-catch of the Balearic Islands (Western Mediterranean) trawl fishery. The catch compositions of the fishery taking these species is described and analysed in terms of landings and discards. Only two of these species are sufficiently abundant to be recorded in the landings (blackmouth catshark and spotted dogfish). The length compositions in terms of both landings and discards were analysed for these two species. Spotted dogfish catches reached similar proportions to those of the target species in the coastal fishery (red and striped red mullet) and in the shelf trawl fishery (European hake); whereas the catches of blackmouth catshark and velvet belly were a small proportion of the total catch in the slope fishery for red shrimp. The size range of the spotted dogfish was between 7 and 53 cm TL. Juveniles and adults were distributed throughout the whole area, although adults appeared to be more abundant in the coastal zone. The length distribution of blackmouth catshark showed a trend of increasing size with depth; the size range was between 9 and 63 cm TL. For both species, individuals smaller than 35 cm TL were usually discarded. Only 25% by number and 60% by weight of the total spotted dogfish catch was landed. For the total blackmouth catshark catch, the corresponding percentages were 10% by number and 35% by weight. The role of these species as indicators of fishing pressure was investigated, taking into account the differences between the two fishing zones sampled, one with a fleet of 24 trawlers and the other with only 4

A key assumption of many fish stock assessment models is that catchability is constant over time. We assume here that trends in catchability may occur through fishing power creeping. The tuning fleets, which are prone to fishing power development, may be identified using the "Hybrid" method. A range of catchability trends, including values derived from the "Hybrid" method, is then implemented to standardise the fishing effort of some tuning fleets used in the stock assessments performed by XSA (eXtended Survivors Analysis). Stocks being assessed are the North Sea cod, saithe, plaice and sole. The performances of the new and traditional XSA assessments are compared using criteria based on the precision of catchability estimates, stationarity of Log-catchability residuals and retrospective patterns relative to fishing mortality, spawning stock biomass and recruitment estimates. The performances of the North Sea cod, plaice and sole assessments could be enhanced by accounting for an overall annual increase in the catchability of some of the tuning fleets. No significant trends could be detected in the catchability of the tuning fleets relative to the assessment of the North Sea saithe. By contrast with the traditional assessment, the spawning biomass of cod is expected not to have increased between 1997 and 1998, while the fishing mortality of sole is expected to have increased over the same period.

[EN] The cepholopod founo collecled in 24 houls corried out in the upper continentol slope off Aliconte (Western Mediterroneon) by commerciol irowlers is onolysed. Somples were ioken ot depths between 237 ond ól I m from April 1998 to December I999. Eighteen species in 8 fomilies were coptured . Todarodes sogittotus, Todoropsis eblonoe, Rossio mocrosomo, Sepielta oweniono, Eledone cirrhoso ond Oclopus so/ufii were lhe mosl obundont species. Cepholopods represented 3.9 % oÍ the totol cotch (94 kg). Averoge cepholopod biomoss estimoted wos 89.2 g,/hectore. The known depth ronge lor Octopus defilippi in the Mediterroneon is exponded up to 320 m. Observed seosonol chonges in biomoss of moin species ore discussed., [ES] En el presente trobojo se onolizon los cefolópodos copfurodos por orrosfreros comercioles en 24 lonces reolizodos en el tolud superior de lo provincio de Aliconie {Mediterróneo occidentol). Los muesiros fueron tomodos enfre los 237 y 61,l m de profundidod, entre obril de 1998 y diciembre de 1999. Se copturoron I8 especies pertenecientes o 8 fomilios. Todorodes sagitfotus, Todoropsis eblonoe, Rossio mocrosomo, Sepietlo oweniona, Eledone cirrhoso y Octopus so/utii fueron los mós obundonles. Los cefolópodos representoron un 3,9 % de lo copturo rotol (94 kg.). Lo biomoso de cefolópodos medio esiimodo fue de 89,2 gr./hecl6reo. El rongo.de profundidod conocido poro Octopus defilippi en el Mediterróneo fue ompliodo hosto los 320 mehos. Se discuten los combios eslocionoles de biomoso de los especies mós importontes.