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This document is the product of an expert group under the auspices of the International Council for the Exploration of the Sea and does not necessarily represent the view of the Council. The Working Group on Nephrops Surveys (WGNEPS) is the international coordination group for Nephrops underwater television and trawl surveys within ICES. This report summarizes the national contributions on the results of the surveys conducted in 2019 together with time series covering all survey years, problems encountered, data quality checks and technological improve-ments as well as the planned for survey activities for 2020. In total, 19 surveys covering 25 func-tional units (FU's) in the ICES area and 1 geographical subarea (GSA) in the Adriatic Sea were discussed and further improvements in respect to survey design and data analysis, standardiza-tion and the use of most recent technology were reviewed. A new survey summary template by FU/GSA has been developed and adopted for future re-ports, which shall allow the data end users to extract the most relevant information on the survey results in a more easy way.Necessary actions and reviewer comments were addressed on the draft version of the Series of ICES Survey Protocols (SISP). Similarly, the working group reviewed the specifications for a Nephrops underwater TV database to be established at the ICES data centre and agreed on fur-ther action on this issue.First results from field studies on behaviour aspects of burrow emergence using bottom cages monitored by an automated camera system and on short-range migration using acoustic tracking are now available.Comparison of standard definition (SD) and high definition (HD) indicates the change to HD system mounted with a different camera angle may affect the detection rate and may thus require a revision of bias correction factors. New image reviewing software allows an easier way of an-notation of burrows than previous mosaicking methods, which has further advantages for inter-preting the results from different counters and for providing quality assured material for deep learning methods. The WG members agreed to collect information on burrow diameter size us-ing HD images and burrow annotation or mosaicking software because a change in the burrow size distribution may indicate recruitment events and the size of the burrow has an effect on bias correction factors in general. Automatic burrow detection based on deep learning methods applied to a test data set with an-notated burrow counts from a HD camera system showed promising results. The WG members were encouraged to provide more material with annotated burrow counts for further develop-ment of machine learning tools.

International audience; In this paper we used a modelling approach integrating both physical and biological constraints to understand the biogeographical distribution of the great scallop Pecten maximus in the English Channel during its whole life cycle. A 3D bio-hydrodynamical model (ECO-MARS3D) providing environmental conditions was coupled to (i) a population dynamics model and (ii) an individual ecophysiological model (Dynamic Energy Budget model). We performed the coupling sequentially, which underlined the respective role of biological and physical factors in defining P. maximus distribution in the English Channel. Results show that larval dispersion by hydrodynamics explains most of the scallop distribution and enlighten the main known hotspots for the population, basically corresponding to the main fishing areas. The mechanistic description of individual bioenergetics shows that food availability and temperature control growth and reproduction and explain how populations may maintain themselves in particular locations. This last coupling leads to more realistic densities and distributions of adults in the English Channel. The results of this study improves our knowledge on the stock and distribution dynamics of P. maximus, and provides grounds for useful tools to support management strategies.

Most worldwide fish stocks are overexploited, and so exploited beyond the Maximum Sustainable Yield (MSY) and the Maximum Economic Yield (MEY). Not exploiting fisheries resources at MSY or MEY leads to the loss of production and rents from the fisheries. A large part of the EU fisheries are managed based on single species stock assessments; however, in reality, most species are caught together with other species and by different fleets. In multi-species and multi-fleet fisheries, single species assessments, and consequently MSY and MEY reference points, are often not valid, and so the catch recommendations. In this paper it is investigated the MSY and MEY estimation in multi-species and multi-fleet fisheries in comparison to single species assessments. Analyses are applied to the Bay of Biscay demersal fishery using the IAM bio-economic model. The impact of exploiting at MSY and MEY on the optimal effort allocation between fleets with different exploitation patterns and economic structures is analyzed. When accounting for the multi-species nature of the fishery, MSY landings are 0.4% to 2.7% lower than the single species simulations estimates. When accounting for the multi-fleet nature of the fishery, MSY landings are 27.2% to 30.2% higher than the single-fleet estimates. When considering the multi-fleet characteristics, MEY landings are 6.6% higher and profits are 66.5% higher than in the single-fleet simulation. Optimal effort at MEY is lower than at MSY, but when accounting for multi-fleet the optimal effort decreases for some fleets while increases for gillnetters. The results also provide an estimation of the profits at MEY (or costs of not being at MEY). Profits can be then up to 10.7 times larger than the current profits (256 million Euros compared to the current 24 million Euros).

Laurans, M., Fifas, S., Demaneche, S., Brérette, S., and Debec, O. 2009. Modelling seasonal and annual variation in size at functional maturity in the European lobster (Homarus gammarus) from self-sampling data. – ICES Journal of Marine Science, 66: 1892–1898. Fishers from Le Croisic (France) measure all the lobsters (Homarus gammarus) they capture, indicating their sex and whether the females are ovigerous or non-ovigerous. Between 2003 and 2006 and mainly between April and September, 16 884 lobsters were measured in this manner. These self-sampled data were used to study catchability and functional maturity of lobsters. The sex ratio was 50%, and catchability did not change if a female was ovigerous or non-ovigerous. With the help of a logistic function, a relationship was established between body size and the proportion of ovigerous females. For the study area, 100% of the females were mature upon reaching a carapace length (CL) of 115 mm, and the proportion of ovigerous females reached 70% each year. The L50 value evolved over a CL of 103–106 mm. From the size when 100% of the females matured (115 mm), there was a larger proportion of ovigerous females than in other studies carried out in more northern European areas.

The Nephrops fishery in the Bay of Biscay is an important commercial fishery which generates large amounts of discards owing to the use of small mesh trawls. To reduce discards, French trawlers were equipped with a variety of selective devices, from 2005 onwards. This study examines their efficacy using data from the French on-board observer programme, 2003–2010. Generalized linear models were built for catches, discards, and landings of Nephrops and hake, controlling for the other factors which drive the variability in these variables. A dorsal square-mesh panel meant to let small hake escape did not affect hake catch, but was found to decrease Nephrops catches and discards. Among the devices intended to reduce Nephrops discards, the flexible grid was the most efficient, as it decreased catches and discards in large proportions while increasing landings but this result was supported by a small number of observations; a larger mesh size in the codend (80 mm instead of 70) slightly decreased Nephrops discards; and a ventral square-mesh panel was not found to affect catch or discards of either species. The design of the on-board observer programme was meant to estimate discard amounts, which limited their utilization to investigate factors for discarding.

8 pages, 4 figures, 4 tables, MSY objectives are being adopted as major fisheries management targets worldwide. However, in fisheries where discards account for an important share of the catches, the yield, effort, and biomass at MSY can be significantly different when accounting or not for discards and thus when, basing the yield estimations on landings or catches. Also whether accounting for a certain survival rate, of discards can lead to different MSY targets estimates. Hence, both decisions have important, implications on catch and effort reduction recommendations, and consequently on the quota, calculations for fisheries managed by quotas. Results from the Bay of Biscay nephrops fishery confirm, that the optimal exploitation level can vary significantly when optimising for catches or landings, and, by assuming a certain survival rate of the discards. By doing this, the present study also allows to, explore the basis to clarify the definition of MSY in fisheries where discarding takes place. © 2014 Elsevier Ltd., This work has been carried out with the support of the French Research Agency, ANR (Agence National pour la Recherche) through the research programme entitled Adhoc (ANR-09-PEXT-000) and with the support of the European FP 7 project Benthic Ecosystem Fisheries Impact Study (BENTHIS) (KBBE 2012.1.2-09)

In order to estimate the abundance of scallops it is necessary to estimate the efficiency of the experimental fishing gear (scallop dredge with rings of 50 mm diameter, 2 m wide and a toothed bar with 30 teeth). The age-size structure of catches does not usually correspond to that of the actual population because of selectivity of the gear. Several previous studies on the Saint-Brieuc scallop stock (English Channel, France) have used a ratio estimator per age group: an assumption of increase in efficiency vs. scallop size is taken into account. The evaluation of the gear efficiency used for this stock since 1986 has been carried out by diving according to a random sampling plan. Factors such as sedimentary heterogeneity, tide, current, and depth are neglected. There are drawbacks as regards to the definition of dredge efficiency by this method: (1) a ratio estimator is biased when the number of samples is small such as the number of diving units in this study; and (2) the definition of the estimator using age rather than scallop size limits the period of assessment validity: intra-annual extrapolations are not valid. These two difficulties are resolved when dredge efficiency is defined against scallop size. A logistical curve is used and requires three parameters: (1) maximum asymptotical efficiency (e max ); (2) parameter describing the selection deviation (α) and; (3) size corresponding to 50% of e max (L 50 ). The matrix of variances-covariances of three parameters is also obtained.

The rapid development of the albacore tuna (Thunnus alalunga) driftnet fishery in the Bay of Biscay (Atlantic ocean, France) has incited European management authorities to ask for a study of its ecological impact on populations of common dolphins and striped dolphins. A programme with onboard observers has been led during 1992 and 1993, and a sighting survey has allowed the evaluation of the abundances of fractions of populations in the studied area. For the population of common dolphins, the biological parameter estimation has allowed the building of a discrete age-structured model based on a Leslie matrix. Sensitivity studies have been conducted using four model parameters (age of first reproduction, interval between births, juvenile and adult survival rates). Results show that the increase rate of the population presents the highest sensitivity versus adult survival rate and, in second place versus the interval between births.

Full text: http://archimer.ifremer.fr/doc/00110/22135/19774.pdf (Version officielle éditeur, 0.51 Mo); International audience; Several fleets with various fishing strategies operate as a mixed fishery in the Bay of Biscay. Among the main fleets, bottom trawlers target Norway lobster (Nephrops norvegicus) and, together with gillnetters, they also catch hake (Merluccius merluccius). Trawling leads to average-size catches that are below the minimum landing size (MLS); such catches are discarded since they cannot be sold. These discards result in negative impacts on stock renewal, as most of them do not survive. This also results in an economic loss for both bottom trawlers and gillnetters since these discards represent a future loss of rent. This study, based on the 2009 and 2010 selectivity experiments at sea, assesses the short-and long-term bio-economic impacts of four experimental selective devices aimed at reducing N. norvegicus and M. merluccius discards over a 20-year simulation period. Tests were conducted at sea on a research trawler. Using the impact assessment model for fisheries management (IAM model), selectivity scenarios for trawlers in the Bay of Biscay were compared to a theoretical selective scenario of adopting an optimal device that catches only N. norvegicus and M. merluccius above MLS (9 cm and 27 cm total length, respectively). Costs and benefits were analyzed with the objective of finding the best compromise between a reduction in discards of undersized fish and a loss of valuable catches among the experimental devices. Selectivity scenarios show positive impacts on stocks but different economic impacts between fleets. The combination of a square mesh cylinder with a grid and square mesh panels gives the closest results to the theoretical scenario tested in terms of stock recovery and economic benefits. This experimental device leads to low economic losses in the short term and eventually to higher N. norvegicus yields, which would be favourable for fleets that greatly contribute to N. norvegicus fishing efforts.

International audience; Academia and management agencies show a growing interest for ecosystem-based fishery management (EBFM). However, the way to operationalize this approach remains challenging. The present paper illustrates how the concepts of stochastic co-viability, which accounts for dynamic complexities, uncertainties, risk and sustainability constraints, can be useful for the implementation of EBFM. In the present case, this concept is used to identify fishing strategies that satisfy both ecological conservation and economic sustainability in a multi-species, multi-fleet context. Economic Viability Analysis (EVA) and the broader Co-Viability Analysis (CVA), are proposed to expand the usual Population Viability Analysis (PVA) and precautionary approach. An illustration is proposed, using data on the fisheries of Bay of Biscay (France) exploiting the stocks of nephrops and hake. Stochastic simulations show how CVA can guarantee both ecological (stock) and economic (profit) sustainability. Using 2008 as a baseline, the model is used to identify fishing efforts that ensure such co-viability. (C) 2012 Elsevier B.V. All rights reserved.

En ligne : http://www.nss-journal.org/articles/nss/pdf/2010/04/nss10402.pdf; International audience; Since a report by the European Court of Auditor in December 2007, EU officials have been suggesting that the failure of the Common Fisheries Policy (CFP) results from too much non compliance and a weak and inefficient enforcement system. As a result, a stakeholder consultation was organised EU-wide, and a new control regulation has been presented by the European Commission in autumn 2008. The objective of the paper is to discuss the reality and the scope of this assertion in the situation of a French coastal fishery managed through effort control (the Saint-Brieuc scallop fishery). Key outlines of the French control strategy are presented for the first time, based on an extensive work with the key stakeholders (national and regional administrations and fishermen representatives). It shows that the system is rather complex, involving several administrations and various types of rules to be enforced. A preliminary assessment of the control strategy in place in Saint-Brieuc shows that despite rather high control costs, the level of non-compliance remains elevated. Such an unsatisfactory outcome, which can be explained by the low deterrence level observed, questions the efficacy of this kind of control strategies.; Depuis un rapport de la Cour des comptes européenne en décembre 2007, les instances communautaires ont porté une attention particulière à l'une des causes possibles de l'échec de la politique commune de la pêche : trop de contrevenants à la réglementation et un système de contrôle globalement inefficace. L'article discute la nature et les fondements de cette explication dans le cas d'une pêcherie côtière française gérée par l'effort de pêche. Il présente pour la première fois le cadre général du contrôle des pêches en France et analyse sa mise en œuvre dans la pêcherie de Saint-Brieuc. Il montre que, malgré des coûts de contrôle importants, le niveau de fraude y reste relativement élevé. Ce bilan mitigé, qui peut s'expliquer par le faible niveau de dissuasion observé, conduit à s'interroger sur l'efficacité des différentes stratégies de contrôle dans cette pêcherie.

This paper proposes an empirical model for the recruitment of the scallop stock, Pecten maximus (L.), in Saint-Brieuc Bay (English Channel, France). This stock shows important fluctuations in recruitment. The use of traditional models for fish population dynamics based upon an equilibrium state were inadéquate. This model includes three independent variables: spawning biomass, effects of fishing effort on the unexploited year classes, and temperature. Correlations between these expressions of independent parameters and recruitment are systematically analysed. The choice of the final model relies on minimization of the total variance unexplained portion. Introduction of fishing pattern into the model is realized by testing fishing effort effects upon two seasons of the unexploited cohort life (0 and 1-age groups). This procedure shows a more significant effect of fishing effort upon the 0-age group. The expressions of temperature are first tested on the seasonal anomalies defined by différences between monthly or bi-weekly temperature periods and the mean value for the same period. Seasonal anomalies do not give a significant explanation of recruitment, and other temperature expressions are defined. They are called thermal residues and are defïned as seasonal anomalies weighted by anomalies of the corresponding year. Thermal residues are used as algebraie or absolute values for monthly and bi-weekly periods. Absolute values of residues for bi-weekly periods give results that fit best. Only bi-weekly periods with a significant contribution to the recruitment explanation are retained. Détection of these critical values is carried out using Fisher-Snedecor test. This procédure leads to a multiplicative combination of the spawning biomass, the 0-age group mortality due to fishing effort and exponential functions of absolute values for the thermal residues. Two critical periods are detected by the statistical operation: the first fortnight of March and the second of July. Correspondence between the two critical periods and stages of the reproduction cycle (start of sexual maturation, first spawning and larval development) is discussed. Analysis of absolute values shows scallops are adapted to mean thermal conditions. Temperature appears to be a regulating factor of sexual maturation and spawning. The exponential multiplicative functions for the spawning biomass translates the interannual fluctuations of the population fecundity., Cet article propose un modèle empirique du recrutement du stock de coquilles Saint-Jacques, Pecten maximus (L.) en baie de Saint-Brieuc (Manche, France). Ce stock présente de fortes fluctuations du recrutement qui rendent inadéquate l'utilisation des modèles traditionnels de la dynamique des populations exploitées faisant appel à un état d'équilibre. Le modèle intègre trois variables: la biomasse féconde, les effets de l'effort de pêche sur les classes d'âge non exploitées et la variable « température ». Les corrélations entre les différentes expressions des paramètres et le recrutement sont systématiquement analysées. Le choix du modèle final repose sur la minimisation de la part inexpliquée de la variance totale. L'impact de l'effort de pèche sur les fluctuations du recrutement est testé sur deux saisons de pêche avant la mise en exploitation d'une cohorte (groupes d'âge 0 et 1), afin d'intégrer le régime d'exploitation dans le modèle final. Cette procédure révèle un effet plus significatif de l'effort de pêche exercé sur le groupe d'âge 0 de la cohorte. Pour la température, les expressions initialement retenues sont les anomalies saisonnières, définies comme les écarts de température, par période mensuelle ou bimensuelle, par rapport à la température moyenne de la même période. Les anomalies saisonnières n'ont pas conduit à une explication significative du recrutement; d'autres expressions de la température ont été recherchées. Elles sont définies comme des anomalies saisonnières pondérées par l'anomalie de l'année correspondante et sont appelées résidus thermiques. Les résidus thermiques sont utilisés sur des périodes mensuelles et bimensuelles en valeur algébrique et en valeur absolue. Les valeurs absolues des résidus thermiques par période bimensuelle fournissent les meilleurs résultats lors des ajustements. Seules les périodes contribuant significativement à l'explication du recrutement sont retenues. La détection de ces périodes critiques est faite par un test de FisherSnedecor. Cette procédure conduit à une combinaison multiplicative de la biomasse féconde, de la mortalité provoquée sur le groupe d'âge 0 par l'effort de pêche et des fonctions exponentielles de résidus thermiques en valeur absolue. Deux périodes critiques sont identifiées, la première quinzaine de mars et la seconde de juillet. La correspondance entre les deux périodes critiques d'anomalie thermique et des étapes du cycle de reproduction de l'animal (le début de la maturation sexuelle, la première ponte et le développement larvaire) est discutée. Le fait que les valeurs absolues semblent plus adéquates indique une adaptation de l'animal aux conditions thermiques moyennes du milieu. La température intervient donc comme un facteur régulant la dynamique de maturation sexuelle et de ponte. Sa rétention sous forme exponentielle multipliant la biomasse féconde traduit les fluctuations inter-annuelles de la fécondité réelle de la population.

The objective of this paper is to assess the benefits and costs of decommissioning policies aimed at reducing fleet capacity through premiums offered by the public authority to fishermen to scrap their vessels. A case study, the limited entry scallop fishery of the Saint Brieuc Bay, France, is used to con- sider the problem of excess capacity and to model the bioeconomic consequences of disinvestment behavior. Special attention is paid to the assessment of fishermen's willingness to leave the fishery and to the implementation of public policy in terms of budget level and premiums offered to the fishermen. Spreadsheet simulations show that the impact of decommissioning programs is positive in terms of net surplus, even in the case of increasing technical efficiency of the vessels.