Search

Statocyst anatomy and fine morphology in Norwegian lobster (Nephrops norvegicus) are studied for the first time using scanning and transmission electron microscopy. N. norvegicus exhibits sensory setae projecting from the statocyst inner cavity floor into a mass of sand granules (statoconia) embedded in a gelatinous substance. The setae are distributed in four areas: a curved field made up of an inner single row and an outer double row that run on a circle around the medial and lateral rim of the central depression, a small setal field in the posterior part, a large setal field, opposite to the small field, and a short row, running internally and lying parallel to the inner single row, next to the small setal field. A study of the fine morphology of the statocyst sensory setae shows that the structure of the setae in the different areas is similar, with a bulb (the proximal portion of the sensillum), a setal shaft, a tooth (the smooth portion of the bulb), a fulcrum (a transverse fold), and filamentous hairs. The hair cells are firmly implanted within the cuticular layer. Although the type of innervation of the statocyst was not determined in the present study, the close taxonomic position of the lobster to that of the crayfish and crab would suggest that the setae in N. norvegicus are pure mechanoreceptors rather than sensory cells., This work was funded as part of the SATURN project, which received funding from the European Union’s Horizon2020 research and innovation program under grant agreement no. 101006443., Peer Reviewed, Postprint (published version)

We present a spatial analysis of Norway lobster Nephrops norvegicus through mosaics generated in the 2018 UnderWater Tele- Vision survey in Functional Units 3, 4, and 33. The aim is to assess the small-scale spatial relationships between N. norvegicus burrows and individuals with its conspecifics and other fauna present in the area., Peer Reviewed

In the context of marine conservation, trawl fishing activity is the most important ecosystem stressor in demersal Mediterranean waters. Limited management measures in bottom trawling have caused deep-sea stocks of the iconic Norway lobster Nephrops norvegicus to decrease over the last decade. This crustacean acts as an umbrella species for co-existing megafauna. Here, we used non-invasive Remote Operated Vehicle (ROV) video-surveys to investigate the status of a pilot deep-sea no-take reserve implemented in the northwestern Mediterranean by quantifying demographic indicators of Norway lobsters and the co-existing benthic community, seafloor restoration, and the presence of marine litter. The results revealed that in the no-take reserve the Norway lobster stock showed higher abundance and biomass, and slightly larger body sizes than in the control area without fishing prohibition. Some taxa, such as the fishes Helicolenus dactylopterus and Trigla lyra and anemones of the family Cerianthidae, increased in abundance. We also observed that all trawling marks were smoothed and most of the seafloor was intact, clear indicators of the recovery of the muddy seafloor. The accumulation of marine debris and terrestrial vegetation was similar in the no-take reserve and the fished area. On the basis of the results of this study, we suggest that the use of no-take reserves might be an effective measure for recovering the Norway lobster stock, its co-existing megafauna community, and the surrounding demersal habitat. We also suggest that ROV video-survey might be a useful, and non-invasive method to monitor megafauna and seafloor status in protected deep-sea environments

S’ha observat que la vida marina es veu afectada de manera directa o indirecta pel so antropogènic, el qual ha augmentat dràsticament en els últims anys arran del desenvolupament industrial. Aquest estudi es centra en un dels sorolls més comuns de l’oceà, el so del transport marítim, concretament el de portacontenidors. En el mar Mediterrani trobem una gran biodiversitat d’espècies marines, però ens centrarem en tres en concret, les quals presenten un alt valor comercial, el Mytilus edulis, el Nephrops norvegicus i la Sepia officinalis. A través d’un dispositiu creat per investigadors del LAB, l’AquaVib, capaç de separar les dues components del so, ona de pressió i moviment de les partícules, s’estudia i s’analitza si l’exposició d’aquests organismes a un so continu de vaixell portacontenidors durant 20 minuts (temps mitjà que pot trigar a passar pel damunt de les espècies) afecta el comportament d’aquestes. A més, s’exposa i s’estudia les dues components per separat, atès que es poden descompondre gràcies a l’AquaVib. Així com en diferents nivells d’exposició, des de 150 dB fins a 170 dB., La vida marina se ve directa o indirectamente afectada por el ruido antropogénico. Este efecto ha aumentado dramáticamente en los últimos años como resultado del desarrollo industrial. Este estudio se centra en uno de los ruidos más comunes en el océano, el transporte marítimo, específicamente producido por los buques portacontenedores. En el Mar Mediterráneo, encontramos una rica biodiversidad de especies marinas, pero nos centraremos en tres especies específicas que tienen un alto valor comercial: Mytilus edulis, Nephrops norvegicus y Sepia officinalis. A través de un dispositivo creado por investigadores del LAB, el AquaVib, capaz de separar las dos componentes del sonido, la presión acústica (PA) y el movimiento de partículas (MP), se estudia y se analiza si la exposición de estos organismos al ruido continuo de los buques portacontenedores durante 20 minutos (el tiempo promedio que tarda el buque en pasar sobre las especies) afecta su comportamiento. Además, se expone y se estudia a los animales en las dos componentes por separado, ya que pueden descomponerse gracias al AquaVib. Los experimentos se realizan a diferentes niveles de exposición, desde 150 dB hasta 170 dB., Marine life is directly or indirectly affected by anthropogenic noise. This effect, has increased dramatically in recent years as a result of industrial development. This study focuses on one of the most common ocean noise, maritime transport, specifically produced by container ships. In the Mediterranean Sea, we find a rich biodiversity of marine species, but we will focus on three specific ones, which hold high commercial value, Mytilus edulis, Nephrops norvegicus and Sepia officinalis. Through a device created by researchers at the LAB, the AquaVib, capable of separating the two components of sound, acoustic pressure (AP) and particle motion (PM), we study and analyze whether the exposure of these organisms to continuous container ship noise for 20 minutes (the average time it takes for the ship to pass over the species) affects their behaviour. Furthermore, we expose and study the animals to the two components separately, as they can be decomposed thanks to the AquaVib. The experiments were done at different exposure levels, from 150 dB to 170 dB.

Marine renewable technologies have rapidly been developing over the past decade. Wave power is one of the renewable sources and has the potential securing the renewable electricity production. However, all renewable energy extraction affects the environment in some way and for a true sustainable energy generation, environmental effects need to be investigated. Beside uncertain effects from the technologies to habitats or organisms e.g., collision risks, electromagnetic fields, noise, past studies have also shown benefits on diversity, size and abundance of species around marine renewable technologies as a result of habitat creation by the devices and fishery exclusion in designated offshore park areas. This thesis deals with environmental effects from heaving point-absorber wave energy converters developed at Uppsala University and deployed on the Swedish west coast at the Lysekil research site and the Sotenäs Project wave power park over a period of four years. The scope was the investigation of artificial reef effects from wave power foundations on local mobile, mega and macrofauna during visual inspections using scuba diving on the first hand. On the second hand, the effects from the incidental no-take zone on decapods and two sea pen species were investigated applying cage fishing and ROV seabed surveys. A third focus was on environmental monitoring around MRE sites and monitoring of MRE installations, both in an experimental and theoretical approach. In the Lysekil research site, the results highlight that abundance and diversity can be enhanced locally around wave power foundations compared to control areas. The abundance and size of decapods were not significantly different within the wave power park and up to a distance of 360 m outside of it. In the Sotenäs Project wave power park a positive effect on Nephrops norvegicus size and burrow density but not on abundance was found on a scale of up to 1230 m. Sea pen abundance was enhanced inside the wave power pa

The Norway lobster, Nephrops norvegicus, supports a key European fishery. Stock assessments for this species are mostly based on trawling and UnderWater TeleVision (UWTV) surveys. However, N. norvegicus are burrowing organisms and these survey methods are unable to sample or observe individuals in their burrows. To account for this, UWTV surveys generally assume that “1 burrow system = 1 animal”, due to the territorial behavior of N. norvegicus. Nevertheless, this assumption still requires in-situ validation. Here, we outline how to improve the accuracy of current stock assessments for N. norvegicus with novel ecological monitoring technologies, including: robotic fixed and mobile camera-platforms, telemetry, environmental DNA (eDNA), and Artificial Intelligence (AI). First, we outline the present status and threat for overexploitation in N. norvegicus stocks. Then, we discuss how the burrowing behavior of N. norvegicus biases current stock assessment methods. We propose that state-of-the-art stationary and mobile robotic platforms endowed with innovative sensors and complemented with AI tools could be used to count both animals and burrows systems in-situ, as well as to provide key insights into burrowing behavior. Next, we illustrate how multiparametric monitoring can be incorporated into assessments of physiology and burrowing behavior. Finally, we develop a flowchart for the appropriate treatment of multiparametric biological and environmental data required to improve current stock assessment methods.

The Norway lobster, Nephrops norvegicus, is one of the main commercial crustacean fisheries in Europe. The abundance of Nephrops norvegicus stocks is assessed based on identifying and counting the burrows where they live from underwater videos collected by camera systems mounted on sledges. The Spanish Oceanographic Institute (IEO) and Marine Institute Ireland (MI-Ireland) conducts annual underwater television surveys (UWTV) to estimate the total abundance of Nephrops within the specified area, with a coefficient of variation (CV) or relative standard error of less than 20%. Currently, the identification and counting of the Nephrops burrows are carried out manually by the marine experts. This is quite a time-consuming job. As a solution, we propose an automated system based on deep neural networks that automatically detects and counts the Nephrops burrows in video footage with high precision. The proposed system introduces a deep-learning-based automated way to identify and classify the Nephrops burrows. This research work uses the current state-of-the-art Faster RCNN models Inceptionv2 and MobileNetv2 for object detection and classification. We conduct experiments on two data sets, namely, the Smalls Nephrops survey (FU 22) and Cadiz Nephrops survey (FU 30), collected by Marine Institute Ireland and Spanish Oceanographic Institute, respectively. From the results, we observe that the Inception model achieved a higher precision and recall rate than the MobileNet model. The best mean Average Precision (mAP) recorded by the Inception model is 81.61% compared to MobileNet, which achieves the best mAP of 75.12%.

Current European Union fisheries policy encourages member states to improve fishing selectivity in order to minimize fisheries discards. Trawling on the Mediterranean upper slope often generates over 30% of discards of the total catch, including, among other, Nephrops norvegicus juveniles. Improvements in trawl selectivity, using T90 net panels, have successfully been trialled for other Mediterranean target species such as hake or horse mackerel, but the selectivity of T90 was not previously been tested for the Mediterranean Nephrops trawl fishery. Experimental and control paired trawl hauls (N=7 pairs) on board a commercial trawler based on the port of Blanes (N.E. Catalonia) were carried out in Summer 2019. For the control hauls we used a standard net currently used by the Mediterranean trawling fleet, where the extension piece was built entirely with diamond mesh 50 mm (nominal) and 206 meshes around the extension circumference. For the T90 experimental hauls the standard net was modified with a T90 panel in the extension piece made with 90ºturned mesh before the codend. The T90 net had a mesh of 50 mm (nominal), 140 meshes around the extension circumference and 100 meshes length. The results of the field tests were analysed statistically with catch analysis methods, considering that the individuals in the population have equal probability (0.5) of being captured by the test trawl net or the standard trawl net, but retention in each net codend may differ due to the different properties of the modified and standard extension pieces. The results showed a significant decrease in the capture of juvenile Nephrops (below 27 mm of carapace length) by using T90. The study showed that relatively simple modifications in the current trawl gear design used can significantly reduce the catches of juvenile Nephrops in the Mediterranean otter bottom trawl fishery

[EN] The current European Union fisheries policy encourages improving handling practices to increase the survival of discards. Trawling on the Mediterranean upper slope often generates over 30% of discards of the total catch. Among other species, Nephrops norvegicus juveniles are abundantly returned to the sea, sometimes exceeding 40% of discarded biomass. N. norvegicus discard survival probability has been recently shown to be related to vitality on board and to vary seasonally, being especially low during the summer (0.06). Environmental characteristics (especially, high on-deck temperature in summer) make it necessary to improve vitality on board in order to increase discard survival. We therefore tested new discard handling methodologies for a Mediterranean mixed trawl fishery, with N. norvegicus as the target species. The results showed a survival rate on board higher than 0.8 resulting from vitality status improvements achieved by immersing N. norvegicus in cooled seawater on board during the catch selection and discard time. The implementation of this method would make an important contribution to more sustainable Mediterranean trawl fisheries, [ES] La política pesquera actual de la Unión Europea fomenta la mejora de las prácticas de manipulación de los descartes para aumentar su supervivencia. La pesca de arrastre en el talud superior del Mediterráneo, suele generar más del 30 % de los descartes de la captura total. Entre otras especies, los juveniles de Nephrops norvegicus son devueltos en gran abundancia al mar, a veces llegando a superar el 40% de la biomasa descartada. Recientemente se ha demostrado que la probabilidad de supervivencia al descarte de N. norvegicus está relacionada con la vitalidad a bordo y varía estacionalmente, siendo especialmente baja durante el verano (0,06). En este contexto, probamos y proponemos nuevas metodologías de manipulación de los descartes para una pesquería de arrastre mixta en el Mediterráneo, con N. norvegicus como especie objetivo, ya que las características ambientales (especialmente, la alta temperatura en cubierta en verano) hacen necesario mejorar la vitalidad a bordo de los descartes, para aumentar su supervivencia. Los resultados mostraron una tasa de supervivencia a bordo superior a 0,8 debido a las mejoras en el estado de vitalidad al sumergir N. norvegicus en agua de mar enfriada, durante la selección de capturas y el tiempo de descarte. La implementación de esta metodología, que mejora la vitalidad a bordo, es relevante para conseguir pesquerías de arrastre más sostenibles en el Mediterráneo

The Norway lobster, Nephrops norvegicus, supports a key European fishery. Stock assessments for this species are mostly based on trawling and UnderWater TeleVision (UWTV) surveys. However, N. norvegicus are burrowing organisms and these survey methods are unable to sample or observe individuals in their burrows. To account for this, UWTV surveys generally assume that “1 burrow system = 1 animal”, due to the territorial behavior of N. norvegicus. Nevertheless, this assumption still requires in-situ validation. Here, we outline how to improve the accuracy of current stock assessments for N. norvegicus with novel ecological monitoring technologies, including: robotic fixed and mobile camera-platforms, telemetry, environmental DNA (eDNA), and Artificial Intelligence (AI). First, we outline the present status and threat for overexploitation in N. norvegicus stocks. Then, we discuss how the burrowing behavior of N. norvegicus biases current stock assessment methods. We propose that state-of-the-art stationary and mobile robotic platforms endowed with innovative sensors and complemented with AI tools could be used to count both animals and burrows systems in-situ, as well as to provide key insights into burrowing behavior. Next, we illustrate how multiparametric monitoring can be incorporated into assessments of physiology and burrowing behavior. Finally, we develop a flowchart for the appropriate treatment of multiparametric biological and environmental data required to improve current stock assessment methods

Although the ingestion of plastics has been reported in a wide variety of organisms, there remains a lack of knowledge regarding the extent of spatial and temporal gradients and no consensus concerning the definition of monitor species for benthic marine environments. The present study aims at demonstrating the correlation between the presence of tangled balls of fibres and high levels of total plastic fibre ingestion in Nephrops norvegicus to assess the potential use of the prevalence of tangled balls as indicators of fibre pollution. To do so, the presence of plastics in stomach contents from several European populations of N. norvegicus is characterized in detail, including size distribution and polymer composition, and then its correlation with the prevalence of balls tested. Our results demonstrate that the prevalence of balls (>20%) is significantly correlated to higher levels of plastic ingestion, regardless of polymer composition and size distribution of ingested fibres. Plastic fibre ingestion levels across wide temporal and geographical scales are assessed using only the prevalence of balls, highlighting areas of increased fibre ingestion (e.g., the Gulf of Cadiz, N Barcelona) and areas of potentially lower fibre pollution (e.g., the Ebro Delta, the NW Iberian margin). Moreover, the relationship between the prevalence of balls and diet composition is analysed to discard a potential relationship with geographical differences in diet habits. Finally, we discuss the benefits and drawbacks of the use of the prevalence of tangled balls of fibres as an affordable, cost-effective and easy to implement indicator of fibre pollution for monitoring purposes in this species

Anthropogenic pollution is considered one of the main threats to the marine environment, and there is an imperious need to assess its potential impact on ecologically and economically relevant species. This study characterises plastic ingestion and tissue levels of potentially toxic metallic elements in Nephrops norvegicus and their simultaneous levels in abiotic compartments from three locations of the Catalan coast (NW Mediterranean Sea). A multidisciplinary assessment of the health condition of N. norvegicus through condition indices, enzymatic biomarkers and histological techniques is provided, and its relationship with anthropogenic pollutant levels explored. Plastic fibres were commonly found in stomachs of N. norvegicus (85% of the individuals), with higher abundances (13 ± 21 fibres · ind−1) in specimens captured close to Barcelona. The presence of long synthetic fibres in near-bottom waters, as well as the mirroring trends in abundance among locations for water and ingested plastics, suggest that uptake from water may be occurring potentially through suspension feeding. The spatial variability in the levels of metallic elements in N. norvegicus was poorly correlated to the variability in sediments. In any case, present levels in abdominal muscle are considered safe for human consumption. Levels of ingested plastics only showed significant, yet weak, correlations with glutathione S-transferase and catalase activities. However, no other health parameter analysed showed any trend potentially associated to anthropogenic pollutant levels. Neither the condition indices nor the histopathological assessment evidenced any signs of pathologic conditions affecting N. norvegicus. Thus, it was concluded that presently there is no evidence of a negative impact of the studied pollutants on the health condition of N. norvegicus in the studied grounds

Nowadays, there is increasing concern about animal welfare and more discussion between scientists about whether decapod crustaceans have the ability to suffer. In 2005, the European Food Safety Authority (EFSA) stated that decapod crustaceans should receive protection but, actually, there is no regulation and the implementation of a legal framework to assess their protection is needed. To evaluate pain, we can study the structure of the nervous system (NS), search for physiological and neurological biomarkers or look for behavioural changes. Therefore, it is essential to study the nervous system (NS) of the species that are under investigation. The Norway lobster, Nephrops norvegicus, belonging to the infraorder Astacidea, is the one of the most important fishing species in the EU. However, there is little knowledge about its NS). The main objective of this study is to make an atlas of N. norvegicus NS, with the aim to set up welfare protocols during their production and sacrifice. Lobster were caught by trawling on fishing vessels. At the laboratory the different parts of the NS were dissected from 39 lobsters, fixed with paraffin or resin, and sections from 1300 slides were stained with haematoxylin and eosin or methylene blue. The results show that N. norvegicus shares proportions and nerve structures (brain, subesophageal, thoracic, and abdominal ganglia) with other decapod species, especially of the infraorder Astacidea. In general, they share neuropils, tracts, commissures, and clusters of cell bodies in most ganglions. Furthermore, the NS has integrated parts and ganglion fusions, such as subesophageal ganglion and glia cell envelopes. In the brain, some neuropils are highly developed indicating a strong mecano- and chimioreceptor sensorial capacities. Hence, this study evidences that the NS internal morphology of N. norvegicus is highly developed and organized suggesting the ability to experience pain

The Norway lobster Nephrops norvegicus is one of the most important marine resources for European fisheries. However, overfishing has caused the stocks to decline over the last decades, particularly in the Mediterranean Sea. The implementation of no-take marine reserves could change these current trends, thus achieving a more sustainable fishery. The effectiveness of no-take reserves depends on optimal size design, and because of this, new behavioural data on the spatial ecology of the species are of pivotal importance. Here, for the first time, we investigated the spatial movements and daily activity patterns of Norway lobster in a deep-water (315-475 m depth) no-take marine reserve of 10 km2 in the continental slope of the northwestern Mediterranean Sea, by combining acoustic tracking and tagging-recapture procedures. The results revealed the territorial behaviour of Norway lobster, centred in small exclusive individual areas where most displacements took place at midday. We found that once settled in a place, their home ranges reached approximate sizes of 17.75 to 736.25 m2, suggesting that no-take marine areas focussed on recovering Norway lobster populations do not require large extents to be effective. Tag-recapture data indicated minimal spillover of biomass, implying that Norway lobsters are site settled and do not perform large movements. Future studies on larval spread and recruitment would be necessary to focus on the possible spillover benefit for fisheries. The acoustic telemetry system used in the present experiment effectively revealed the range of movement of individuals, and thus represents a promising monitoring tool to assess no-take marine reserve sizes and reciprocal spacing for deep-water demersal resources

Autonomous Underwater Vehicles and Remotely Operated Vehicles equipped with HD cameras are used by the scientist to capture the underwater footages efficiently and accurately. The abundance of the Norway Lobster Nephrops norvegicus stock in the Gulf of Cadiz is assessed based on the identification and counting of the burrows where they live, using underwater videos. The Instituto Espa˜ nol de Oceanograf´ıa (IEO) conducts an annual standard underwater television survey (UWTV) to generate burrow density estimates of Nephrops within a defined area, with a coefficient of variation (CV) or relative standard error of less than 20%. Currently, the identification and counting of the Nephrops burrows are carried out manually by the experts. This is quite hectic and time consuming job. Computer Vision and Deep learning plays a vital role now a days in detection and classification of objects. The proposed system introduces a deep learning based automated way to identify and classify the Nephrops burrows. The proposed work is using current state of the art Faster RCNN models Inception v2 and MobileNet v2 for objects detection and classification. Tensorflow is used to evaluate the Inception and MobileNet performance with different numbers of training images. The average mean precision of Inception is more than 75% as compared to MobileNet which is 64%. The results show the comparison of Inception and MobileNet detections, as well as the calculation of True Positive and False Positive detections along with undetected burrows.

Microplastic (MP) ingestion has been previously highlighted in some crustacean species (Carreras-Colom et al., 2018; Devriese et al., 2015; Murray and Cowie, 2011). Their close relationship with the sediment (burrowing behaviour, variedbentophagousdiet) is thought to lead to an increased ingestion of MPs which may be retained due to the complexity of the digestive system (gastric mill). Particular occurrence of plastics in Nephrops norvegicushas been reported in the North and Irish Sea (Hara et al., 2020; Murray & Cowie, 2011; Welden & Cowie, 2016a) and hasalsobeen studied under controlled conditions (Welden and Cowie, 2016b) with a significant negative impact on body condition after prolonged exposure to Mps. The present study evaluates the occurrence of MPs in wild-caught individuals of N. norvegicusfrom the NW Mediterranean Sea and its potential negative impact on individual’s health. Three localities along the Catalan Coast were sampled in summer 2019. Biological parameters (size, total weight and weight of hepatopancreas and gonad, body condition indices) and enzymatic activities in tail muscle and hepatopancreas (acetylcholinesterase and lactate dehydrogenase, among others) were recorded. MPs were identified through visual inspection of digestive contents, with strict measures to prevent airborne contamination, and characterised withoptical microscopy. Overall, 85% of the individuals analysed contained fibre-shaped MPs which were sometimes tangled up in balls (20%). Differences in fibre load per individual between localities were not found (mean values of 22.3mm/individual), yet occurrence of balls was lower in the southernmost sampling locality. No clear negative correlations were found between MPs and body condition indices nor enzymatic activities. Only a possible inhibition of catalase and an enhancement of glutathione-S-transferase were observed. Our results suggest that these individuals might be able to cope with the MP loads observed, which are lower t

The landing obligation in the revised European Union Common Fisheries Policy allows for exemptions to obligatory landing of the entire catch for species for which “high survival” of discards can be demonstrated. Nephrops norvegicus is an important target species in many fisheries across Europe in the Mediterranean Sea, NE Atlantic Ocean and North Sea. Historically, Mediterranean fisheries have had a high discard rate of small-sized Nephrops, and it is suspected that this unwanted component of the catch may have a high survival potential that is comparable to those of other EU fisheries, where survival rates of up to 0.56 have been demonstrated. However, to date, no investigations have confirmed a high discard survival rate for Nephrops in the Mediterranean Sea. Furthermore, the environmental, technical and biological characteristics that could affect Nephrops survival have been shown to be substantially different from those in the survival assessments conducted in the NE Atlantic and the North Sea. To address this knowledge gap, this study was conducted to determine the survival of Nephrops discarded from trawls in the Mediterranean Sea. The survival and vitality status of the discarded Nephrops removed from trawl catches were monitored onboard and for 14 days in the laboratory. The results showed seasonality in survival, with the highest survival rate in winter (0.74; CI: 0.7−0.78), lower survival in spring (0.36; CI: 0.31−0.41) and the lowest survival in summer (0.06; CI: 0.04−0.09). Survival was monitored to the asymptote in all cases, and season and vitality status were shown to have statistically significant relationships with survival

The main characteristics concerning the distribution of two of the most important decapod crustaceans of commercial interest in the Mediterranean Sea, the deep-water rose shrimp, Parapenaeus longirostris, and the Norway lobster, Nephrops norvegicus, are studied in the European Mediterranean waters. The study is based on data collected under the MEDITS trawl surveys from 1994 to 2015 from the Gibraltar Straits to the northeastern Levantine Basin (Cyprus waters). The observed differences can be interpreted as different responses to environmental drivers related to the differing life history traits of the two species. In fact, N. norvegicus is a long-living, benthic burrowing species with low growth and mortality rates, while P. longirostris is an epibenthic, short-living species characterized by higher rates of growth and mortality, Se investigaron las características de la distribución de dos de los crustáceos decápodos más importantes a nivel comercial del mar Mediterráneo, la gamba de altura, Parapenaeus longirostris y la cigala, Nephrops norvegicus, en aguas mediterráneas europeas. El presente estudio se basa en datos recopilados en las campañas de pesca experimental de arrastre MEDITS, relizadas de 1994 a 2015 desde el estrecho de Gibraltar hasta la cuenca levantina nororiental (aguas de Chipre). Las diferencias observadas en el patrón de distribución se pueden interpretar como distintas respuestas a factores ambientales relacionados con los diferentes rasgos del ciclo vital de las dos especies. De hecho, N. norvegicus es una especie bentónica de vida larga, con bajas tasas de crecimiento y mortalidad, mientras que P. longirostris es una especie epibentónica de vida corta, caracterizada por tasas más altas de crecimiento y de mortalidad

In the context of the landing obligation set by the new Common Fisheries Policy (CFP), Norway lobster Nephrops norvegicus was identified as a species likely to have high survival rate when discarded in the bottom trawl fishery of the Bay of Biscay. Previous studies in this area reported a survival rate between 30% and 51%, but the experiments were done on a limited monitoring period and the seasonal variations were not investigated. This study was designed to obtain a reliable value for survival rate after a 14-day monitoring period in onshore tanks allowing considering delayed mortality. The study also tested the effect on the survival rate of using a discarding chute system, a sorting device that was made mandatory on the 1st of January 2017 for Nephrops trawlers in the Bay of Biscay. This device, which enables fishermen to discard undersized Nephrops back to the sea while sorting, led to an increased average survival rate (51.2%) compared with the standard sorting practice (36.9%). The impact of biological, environmental and fishing operation related variables on survival from the first day of captivity to the end of the monitoring period was examined using a generalized linear model. The results of the GLM indicate that injuries, season and duration of the air exposure, significantly influence the survival from the 1st day of captivity to the end of the monitoring period. The survival rate was higher for non-injured Nephrops as well as for Nephrops that have undergone short air exposure, in summer and autumn.

Impact studies of chronic bottom trawling aiming to reveal long-term effects on benthic organisms are often hampered by the lack of comparable untrawled conditions and the difficulty in assessing the spatial distribution of trawling intensity. We sampled soft-seafloor macrofauna over a precise trawling gradient in the Kattegat using hourly vessel monitoring systems and logbooks. The gradient included the establishment of a marine protected area (MPA), where trawling intensity declined sharply to zero. Our results show shifts in the macrofauna assemblage and non-linear responses, with decreases in the number and diversity of species at low to medium trawling intensities. The benthic community was dominated by burrowing brittle stars, of which one species, Amphiura chiajei, increased in abundance from low to medium trawling intensities. We interpret this positive response to increasing trawling intensities as a consequence of reduction in predation by benthivorous flatfish and Norway lobster Nephrops norvegicus, which are significant catches of the fishery. The response was supported by a corresponding trend towards lower abundance of the dominating brittle stars following enforcement of the MPA and presumably an increase in benthivore density and predation pressure within the MPA. We conclude that chronic bottom trawling reduces diversity and may boost the abundances of species resistant to bottom trawling. The results emphasize the need to consider food web effects when assessing the impact of bottom trawling.

Background The Norway lobster, Nephrops norvegicus, is economically important in European fisheries and is a key organism in local marine ecosystems. Despite multi-faceted scientific interest in this species, our current knowledge of genetic resources in this species remains very limited. Here, we generated a reference de novo transcriptome for N. norvegicus from multiple tissues in both sexes. Bioinformatic analyses were conducted to detect transcripts that were expressed exclusively in either males or females. Patterns were validated via RT-PCR. Results Sixteen N. norvegicus libraries were sequenced from immature and mature ovary, testis and vas deferens (including the masculinizing androgenic gland). In addition, eyestalk, brain, thoracic ganglia and hepatopancreas tissues were screened in males and both immature and mature females. RNA-Sequencing resulted in >600 million reads. De novo assembly that combined the current dataset with two previously published libraries from eyestalk tissue, yielded a reference transcriptome of 333,225 transcripts with an average size of 708 base pairs (bp), with an N50 of 1272 bp. Sex-specific transcripts were detected primarily in gonads followed by hepatopancreas, brain, thoracic ganglia, and eyestalk, respectively. Candidate transcripts that were expressed exclusively either in males or females were highlighted and the 10 most abundant ones were validated via RT-PCR. Among the most highly expressed genes were Serine threonine protein kinase in testis and Vitellogenin in female hepatopancreas. These results align closely with gene annotation results. Moreover, a differential expression heatmap showed that the majority of differentially expressed transcripts were identified in gonad and eyestalk tissues. Results indicate that sex-specific gene expression patterns in Norway lobster are controlled by differences in gene regulation pattern between males and females in somatic t

[Background] The Norway lobster, Nephrops norvegicus, is economically important in European fisheries and is a key organism in local marine ecosystems. Despite multi-faceted scientific interest in this species, our current knowledge of genetic resources in this species remains very limited. Here, we generated a reference de novo transcriptome for N. norvegicus from multiple tissues in both sexes. Bioinformatic analyses were conducted to detect transcripts that were expressed exclusively in either males or females. Patterns were validated via RT-PCR., [Results] Sixteen N. norvegicus libraries were sequenced from immature and mature ovary, testis and vas deferens (including the masculinizing androgenic gland). In addition, eyestalk, brain, thoracic ganglia and hepatopancreas tissues were screened in males and both immature and mature females. RNA-Sequencing resulted in >600 million reads. De novo assembly that combined the current dataset with two previously published libraries from eyestalk tissue, yielded a reference transcriptome of 333,225 transcripts with an average size of 708 base pairs (bp), with an N50 of 1272 bp. Sex-specific transcripts were detected primarily in gonads followed by hepatopancreas, brain, thoracic ganglia, and eyestalk, respectively. Candidate transcripts that were expressed exclusively either in males or females were highlighted and the 10 most abundant ones were validated via RT-PCR. Among the most highly expressed genes were Serine threonine protein kinase in testis and Vitellogenin in female hepatopancreas. These results align closely with gene annotation results. Moreover, a differential expression heatmap showed that the majority of differentially expressed transcripts were identified in gonad and eyestalk tissues. Results indicate that sex-specific gene expression patterns in Norway lobster are controlled by differences in gene regulation pattern between males and females in somatic tissues., [Conclusions] The current study presents the first multi-tissue reference transcriptome for the Norway lobster that can be applied to future biological, wild restocking and fisheries studies. Sex-specific markers were mainly expressed in males implying that males may experience stronger selection than females. It is apparent that differential expression is due to sex-specific gene regulatory pathways that are present in somatic tissues and not from effects of genes located on heterogametic sex chromosomes. The N. norvegicus data provide a foundation for future gene-based reproductive studies.

Dit rapport beschrijft de testen die zijn uitgevoerd binnen het project ‘Sectorale en Ketenintegrale aanpak Langoustines’ in de periode april 2014 – december 2015 dat was gericht op het verminderen van discards binnen de visserij op Noorse kreeft (Nephrops norvegicus). Het project is een initiatief van de Coöperatieve Visserij Organisatie (CVO) en maakte onderdeel uit van breder programma waarin de sector zich voorbereid op de aanlandplicht. De aanlandplicht, als onderdeel van het nieuwe gemeenschappelijke visserijbeleid, is sinds 2015 van kracht en houdt in dat maatse en ondermaatse vissen en schaaldieren van soorten waarvoor vangstbeperkingen gelden niet meer in zee terug mogen worden gezet. Discards in de visserij op Noorse kreeft bestaan o.a. uit kleine Noorse kreeft, schar (Limanda limanda) en ondermaatse schol (Pleuronectes platessa).

Automated video and image analysis can be a very efficient tool to behavior study, especially in hard access environments for researchers. The understanding of this social behavior can play a key role in the sustainable design of control policies of many species. This paper proposes the use of computer vision algorithms to identify and track, the Norway lobster, Nephrops norvegicus, a burrowing decapod with relevant commercial value which is captured by trawling. These animals can only be captured when are engaged in seabed excursions, which are strongly related with their social behavior. This emergent behavior is modulated by the day-night cycle, but social interactions remain unknown to the scientific community. The paper introduces an identification scheme made of four distinguishable black and white tags (geometric shapes). The project has recorded 15-day experiments in laboratory, under monochromatic blue light (472 nm.) and darkness conditions (recorded using Infra Red light). Using this massive image set, we propose a comparative of state-of-the-art computer vision algorithms to distinguish and track the different animals' movements. We evaluate the robustness to the high noise presence in the infrared video signals and free out-of-plane rotations due to animal movement. The experiments show promising accuracies under a cross-validation protocol, being adaptable to the automation and analysis of large scale data. In a second contribution, we created an extensive dataset of shapes (46027 different shapes) from four daily experimental video recordings, which will be available to the community

Sustainable capture policies of many species strongly depend on the understanding of their social behaviour. Nevertheless, the analysis of emergent behaviour in marine species poses several challenges. Usually animals are captured and observed in tanks, and their behaviour is inferred from their dynamics and interactions. Therefore, researchers must deal with thousands of hours of video data. Without loss of generality, this paper proposes a computer vision approach to identify and track specific species, the Norway lobster, Nephrops norvegicus. We propose an identification scheme were animals are marked using black and white tags with a geometric shape in the center (holed triangle, filled triangle, holed circle and filled circle). Using a massive labelled dataset; we extract local features based on the ORB descriptor. These features are a posteriori clustered, and we construct a Bag of Visual Words feature vector per animal. This approximation yields us invariance to rotation and translation. A SVM classifier achieves generalization results above 99%. In a second contribution, we will make the code and training data publically available

Sustainable capture policies of many species strongly depend on the understanding of their social behaviour. Nevertheless, the analysis of emergent behaviour in marine species poses several challenges. Usually animals are captured and observed in tanks, and their behaviour is inferred from their dynamics and interactions. Therefore, researchers must deal with thousands of hours of video data. Without loss of generality, this paper proposes a computer vision approach to identify and track specific species, the Norway lobster, Nephrops norvegicus. We propose an identification scheme were animals are marked using black and white tags with a geometric shape in the center (holed triangle, filled triangle, holed circle and filled circle). Using a massive labelled dataset; we extract local features based on the ORB descriptor. These features are a posteriori clustered, and we construct a Bag of Visual Words feature vector per animal. This approximation yields us invariance to rotation and translation. A SVM classifier achieves generalization results above 99%. In a second contribution, we will make the code and training data publically available., Peer Reviewed

Future ocean acidification (OA) and warming following climate change elicit pervasive stressors to the inhabitants of the sea. Previous experimental exposure to OA for 16 weeks at pH levels predicted for 2100, has shown to result in serious immune suppression of the Norway lobster, Nephrops norvegicus. The lobsters are currently affected by stressors such as periodical hypoxia inducing high levels of bioavailable manganese (Mn). Here, we aimed to investigate possible effects of interactions between OA and these stressors on total hemocyte counts (THC) and on recovery of inoculated bacteria in the lobsters, measured as a proxy for bacteriostatic response. The effects were judged by following numbers of culturable Vibrio parahaemolyticus in hepatopancreas, 4 and 24 h post inoculation in lobsters kept in replicate tanks with six different treatments; either ambient (pCO2∼ 500 μatm/pH∼8.1 units) or CO2 manipulated seawater (OA; pCO2 1550 μatm/pH∼7.6 units) for 8 weeks. During the last two weeks additional stress of either hypoxia (∼23% oxygen saturation) or Mn (∼9 mgL−1) was added except in control treatments. Our results showed clear effect on bacteriostatic response in Norway lobsters exposed to these stressors. In lobster kept in ambient seawater without additional stressors the number of culturable bacteria in hepatopancreas was reduced by ∼ 34%. In combined treatment of ambient seawater and hypoxia the reduction was ∼23%, while in the Mn-exposed animals, there was no reduction at all. This was also the case in all OA-treatments where mean numbers of culturable V. parahaemolyticus tended to increase. In lobsters from ambient seawater with or without hypoxia, the total hemocyte count (THC) was not significantly different as was also the case in OA without additional stressors. However, in OA-treatments combined with either hypoxia or Mn, THC was reduced by ∼ 35%.While the reduction of culturable V. parahaemolyticus in lobsters was clearly affected by these stressors

Landings of Nephrops norvegicus from North Galicia (Northwest Spain) have decreased by 80% from 1975 to 2001. Variability in the landings per unit effort (LPUE) of this stock was investigated by using time series approach. The LPUE time series (1975–2001) exhibited a seasonal pattern. The seasonal decomposition of the LPUE showed a declining in the trend-cycle component from 1987 onwards. Univariate and dynamic regression ARMA models were fitted to the LPUE time series. Population (proportion of males, proportion of ovigerous females and recruits) and environmental variables (temperature, salinity, nitrates and chlorophyll at 70 m depth, upwelling and sea surface temperature) were tested at different lags as explanatory variables. The proportion of males 4 years ago was the key factor explaining LPUE fluctuations.

[EN] Nephrops norvegicus is an important fishery resource for Europe. Its rhythmic burrowing behavior is strictly related to catchability. Here I studied such behavior under laboratory conditions. I investigated the combined effect of light and current cycles demonstrating that tidal current is an important parameter to take in account in fishery management plan not only for Nephrops. Then I used a transcriptomics and RT-qPCR approach on cDNA extracted from the eyestalk to elucidate the putative molecular genetics mechanisms underlying circadian gene regulation. My data are in accordance with the current knowledge of the crustacean circadian clock, reinforcing the idea that the molecular clockwork of this group shows some differences with the established model in Drosophila melanogaster. Finally, I studied the burrow emergence behavior in group of 4 lobsters organized in dominance hierarchy demonstrating that lower ranks are more vulnerable to trawling. I hypothesized common neural mechanisms for agonistic and non-agonistic behaviors, [ES] Nephrops norvegicus es un importante recurso pesquero. La emergencia rítmica de la madriguera afecta las capturas. He estudiado dicho comportamiento en laboratorio investigando el efecto de ciclos lumínicos y de corrientes demostrando que las mareas es un factor importante para gestionar el estado del recurso. Mediante técnica de secuenciación masiva y PCR en tiempo real sobre cDNA procedente del pedúnculo ocular he elucidado el presunto mecanismo molecular detrás de la regulación circadiana. Los resultados están de acuerdo con el conocimiento actual de relojes biológicos en crustáceos, reforzando la idea que la maquinaria molecular de este grupo muestra algunas diferencias respecto el modelo consolidado de Drosophila melanogaster. Finalmente, he estudiado el comportamiento de emergencia en grupos de 4 cigalas organizadas en una jerarquía de dominancia demostrando que los rangos más bajos son más vulnerables a ser capturados. Además he supuesto la existencia de mecanismos neuronales comunes entre comportamiento agonístico y non agonístico

Premi Extraordinari de Doctorat, promoció 2014-2015. Àmbit d'Enginyeria Civil, Nephrops norvegicus is an important fishery resource for Europe. Its rhythmic burrowing behavior is strictly related to catchability. Here I studied such behavior under laboratory conditions. I investigated the combined effect of light and current cycles demonstrating that tidal current is an important parameter to take in account in fishery management plan not only for Nephrops. Then I used a transcriptomics and RT-qPCR approach on cDNA extracted from the eyestalk to elucidate the putative molecular genetics mechanisms underlying circadian gene regulation. My data are in accordance with the current knowledge of the crustacean circadian clock, reinforcing the idea that the molecular clockwork of this group shows some differences with the established model in Drosophila melanogaster. Finally, I studied the burrow emergence behavior in group of 4 lobsters organized in dominance hierarchy demonstrating that lower ranks are more vulnerable to trawling. I hypothesized common neural mechanisms for agonistic and non-agonistic behaviors., Nephrops norvegicus es un importante recurso pesquero. La emergencia rítmica de la madriguera afecta las capturas. He estudiado dicho comportamiento en laboratorio investigando el efecto de ciclos lumínicos y de corrientes, demostrando que las mareas son un factor importante para gestionar el recurso. Mediante la técnica de secuenciación masiva y PCR en tiempo real sobre cDNA procedente del pedúnculo ocular, he elucidado el presunto mecanismo molecular que hay detrás de la regulación circadiana. Los resultados están de acuerdo con el conocimiento actual de los relojes biológicos en crustáceos, reforzando la idea que el proceso molecular de este grupo muestra algunas diferencias respecto el modelo consolidado de Drosophila melanogaster. Finalmente, he estudiado el comportamiento de emergencia en grupos de 4 cigalas organizadas en una jerarquía de dominancia, demostrando que los rangos más bajos son más vulnerables a la captura. Además he supuesto la existencia de mecanismos neuronales comunes entre comportamiento agonístico y non agonístico., Award-winning, Postprint (published version)

The wish was expressed in the Netherlands to set up a Nephrops survey. Such surveys are carried out in other ICES member countries, e.g. the UK, Ireland, Denmark. Contacts were made with experts from these countries and IMARES participated in ICES WGNEPS in 2013 to retrieve information on the procedures and instrumentation used. A standard technique is to use a UWTV-sledge with cameras to count Nephrops burrows and estimate abundance. A UWTV-survey is preferred over a survey using a headline unit on commercial fishing gears. It will supply a fisheries independent abundance estimate, and has developed into a standard method within ICES. Aspects of methodology and technology are reviewed in the report.

Rearing Norway lobsters for restocking is a management option to compensate fishing overexploitation, but this requires, among other topics, developing specific pellet diets. The activity of digestive enzymes and the histological organization of the hepatopancreas were analyzed to assess the effectiveness of a pellet diet on digestive performance. Thirty animals were reared individually for 6 mo, fed with mussels and pellets or starved. Comparisons with wild lobsters were also conducted. Survival rate of lobsters fed with frozen mussels was the greatest. Trypsin and amylase activity in the hepatopancreas of the lobsters fed pellets was greater than that of other treatments. In contrast, pepsin activity in the gastric juice of starved animals was the greatest. Levels of alkaline proteases in the gastric fluid were greater in lobsters fed with mussels and the pellet diet in contrast to fasted animals. Amylase was greater in specimens fed frozen mussels. The greatest level of lipid accumulation observed in lobsters fed with the pellet diet indicated a physiological imbalance between the absorptive and transport capacity of the hepatopancreatic cells resulting from an excess of dietary lipids. These results might serve as a reference for future studies for formulating feeds specifically designed for Nephrops norvegicus

[EN] The Norway lobster, Nephrops norvegicus, can be captured by haul nets only during the emergence from its burrow. In the last few decades, an extensive field research revealed distinct diel (24-h-based) catchability patterns at different depths. Laboratory experiments suggested that burrow emergence (used as a proxy of catchability) is endogenously controlled via a circadian system. Results were usually presented in terms of mean effects without a quantification of inter-individual variability and arrhythmia. Here, we studied the burrow emergence of 52 adult Nephrops by an infrared actograph endowed with an artificial burrow. Animals were exposed to 12-12 h light-darkness cycle, simulating photic condition of the lower shelf. Forty-five animals showed rhythmic emergence (87%), while seven were arrhythmic (13%). Rhythmic animals were clustered according to their timing of emergence: 54% at dusk and 4% at dawn. Moreover, other animals showed fully diurnal or nocturnal emergence (10% and 19%, respectively). The comparison of our results with those derived from temporally scheduled trawling indicates that bimodal catch patterns observed in shelf populations are poorly observed during individual experiments in the laboratory, where the same light conditions are simulated. Nephrops burrow emergence seems to be the result of a mixed endogenous-exogenous control, while arrhythmia could also be present in the wild, [ES] La cigala, Nephrops norvegicus, es capturada con arte de arrastre cuando emerge de su madriguera. En las últimas décadas, una extensa investigación de campo ha revelado distintos patrones diarios (24-h) de capturas en diferentes profundidades. Se ha observado en experimentos de laboratorio que la emergencia desde la madriguera (interpretable como capturabilidad), está bajo el control endógeno de un sistema circadiano. En estos estudios los resultados se han presentado como efecto promedio en la población experimental, sin una cuantificación de la variabilidad inter individual o del porcentaje de arritmicidad. En este trabajo se estudió la actividad de emergencia desde la madriguera de Nephrops en 52 animales mediante un actógrafo de infrarrojos en un tanque dotado de una madriguera artificial, con un fotoperiodo de 12-12 luz-oscuridad, a fin de simular las condiciones fóticas de la plataforma marina. Cuarenta y cinco animales mostraron una emergencia rítmica (87%), mientras que siete fueron arrítmicos (13%). Los animales rítmicos fueron agrupados de acuerdo al momento de emergencia: 54% al “atardecer” y 4% al “amanecer”, mientras que otros mostraron una emergencia totalmente diurna o nocturna (10% y 19%, respectivamente). La comparación de nuestros resultados con los datos procedentes de pescas experimentales de arrastre, indica que los patrones bimodales de captura observados en poblaciones de la plataforma, son pobremente reproducidos en laboratorio, donde se simulan las mismas condiciones fóticas del fondo marino. La emergencia de Nephrops desde la madriguera parece estar controlada por un proceso tanto endógeno como exógeno, mientras que la arritmicidad podría ser observada también en el campo

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.

Summary: In the western Mediterranean, deep water decapod crustaceans form a considerable fraction of the megafaunal biomass in the upper (US, 200-500 m) and middle slope (MS, 500-800 m), being also a very important component of the catches of the commercial fishery. In the Balearic Islands, they represent around 17% in weight and 50% in revenues of the bottom trawl fishery, which operates between 50 and 800 m depth. The most important species in terms of biomass is Aristeus antennatus, followed by a mixed category of shrimps (including Pandalidae and Pasiphaeidae), Parapenaeus longirostris, Geryon longipes and Nephrops norvegicus. Economically, A. antennatus is also the most important species, followed by N. norvegicus, the mixed category and P. longirostris. The main objective of this thesis is to analyse the community and population dynamics of the deep water decapod crustaceans off the Balearic Islands. The partial objectives are: (i) to study the short spatial and temporal patterns of the main populations of two nearby locations with different environmental regimes; (ii) to explore relationships between the main species abundances and the environmental conditions; (iii) to characterise the species assemblages in the slope trawl fishing grounds; (iv) to estimate ecological indicators, both at species and at community level, to assess the impact of fishing in these communities, and (v) to analyse the effect of new management measures to improve the selectivity and to reduce the fishing impact. Data have been obtained from different sampling strategies: (i) seasonal and annual scientific surveys (fishery-independent data), and (ii) directly from the fishing sector (fishery-dependent data). A third type of data was obtained from scientific selectivity pilot studies. During the scientific surveys and the pilot studies, abundance, biomass and length frequency distributions of all the species were collected. Biological information of A. antennatus, P. longirostris and, Resum: Al Mediterrani occidental, els crustacis decàpodes de profunditat formen una considerable fracció en la biomassa de la megafauna del talús superior (US, 200-500 m) i el talús mitjà (MS, 500-800 m), essent a més una part important de les captures de la pesca comercial. A les Illes Balears, representen aproximadament un 17% en pes i un 50% dels guanys de la pesqueria d’arrossegament de profunditat, que opera entre 50 i 800 m de fondària. L’espècie més important en biomassa és Aristeus antennatus, seguida d’una categoria de gambes mesclades (que inclou Pandalidae i Pasiphaeidae), Parapenaeus longirostris, Geryon longipes y Nephrops norvegicus. Des d’un punt de vista econòmic, A. antennatus és també l’espècie més important, seguida de N. norvegicus, la categoria de mescla i P. longirostris. L’objectiu principal d’aquesta tesi és analitzar la comunitat i la dinàmica poblacional dels crustacis decàpodes de profunditat de les Illes Balears. Els objectius parcials són: (i) estudiar els patrons espacials i temporals a petita escala de les principals poblacions de dues zones properes, amb diferents règims ambientals; (ii) explorar les relacions entre l’abundància de les principals espècies i les condicions ambientals; (iii) caracteritzar les associacions d’espècies en els caladors d’arrossegament del talús; (iv) estimar indicadors ecològics, tant a nivell d’espècies com a nivell de comunitat, per avaluar l’impacte de la pesca en aquestes comunitats i (v) analitzar l’efecte de noves mesures de gestió per millorar la selectivitat i reduir l’impacte de la pesca. Les dades s’han obtingut a partir de diferents estratègies de mostreig: (i) campanyes científiques estacionals i anuals (dades independents de la pesqueria) i (ii) directament del sector pesquer (dades dependents de la pesqueria). Un tercer tipus de dades s’han obtingut mitjançant estudis pilot de selectivitat. Durant les campanyes científiques i els estudis pilot, es va recollir informació de l’abundància, biomas, Resumen: En el Mediterráneo occidental, los crustáceos decápodos de profundidad forman una considerable fracción en la biomasa de la megafauna en el talud superior (US, 200-500 m) y el talud medio (MS, 500-800 m), siendo además una parte importante de las capturas de la pesca comercial. En las Islas Baleares, representan aproximadamente un 17% en peso y un 50% de las ganancias de la pesquería de arrastre de profundidad, que opera entre 50 y 800 m de profundidad. La especie más importante en términos de biomasa es Aristeus antennatus, seguida de una categoría de gambas mezcladas (que incluye Pandalidae y Pasiphaeida), Parapenaeus longirostris, Geryon longipes y Nephrops norvegicus. Económicamente, A. antennatus es también la especie más importante, seguida de N. norvegicus, la categoría de mezcla y P. longirostris. El objetivo principal de esta tesis es analizar la comunidad y la dinámica poblacional de los crustáceos decápodos de profundidad de las Islas Baleares. Los objetivos parciales son: (i) estudiar los patrones espaciales y temporales a pequeña escala de las principales poblaciones de dos zonas cercanas, con diferentes regímenes ambientales; (ii) explorar las relaciones entre la abundancia de las principales especies y las condiciones ambientales; (iii) caracterizar las asociaciones de especies en los caladeros de arrastre del talud; (iv) estimar indicadores ecológicos, tanto a nivel de especies como a nivel de comunidad, para evaluar el impacto de la pesca en estas comunidades y (v) analizar el efecto de nuevas medidas de gestión para mejorar la selectividad y reducir el impacto de la pesca. Los datos se han obtenido a partir de diferentes estrategias de muestreo: (i) campañas científicas estacionales y anuales (datos independientes de la pesquería) y (ii) directamente del sector pesquero (datos dependientes de la pesquería). Un tercer tipo de datos se han obtenido a partir de estudios pilotos de selectividad. Durante las campañas científicas y los estudios

Er is een omvangrijke afzetmarkt in Italië, Spanje en Frankrijk met potentie voor Nederlandse langoustines, vooral voor dagverse producten in het hogere horecasegment. De Nederlandse aanvoer van langoustines is beperkt in vergelijking met de aanvoer in het Verenigd Koninkrijk, Ierland en Frankrijk. Toch zijn er mogelijkheden voor de Nederlandse langoustinesector. De meest kansrijke promotiemiddelen zijn: een kwaliteitslabel en het Nederlandse verhaal verspreiden via handelaren.

Dit rapport beschrijft de tests van een nieuw ontwikkeld quadrig-tuig voor het vissen op Noorse kreeft (Nephrops norvegicus). Het doel van dit tuig was om het gasolieverbruik terug te brengen en om de discards te verminderen: Less Fuel and Discards (LFD). Het LFD-tuig is lichter dan het conventionele tuig, door gebruik van dunner materiaal en kleinere, lichtere borden. Daarnaast zijn de vlerken wijder, wat zou moeten zorgen voor minder weerstand. Voor het verminderen van de discards is onder andere een T90 tunnel voor de zak geplaatst. Deze aanpassing is aanvullend op het in de Noorse kreeftvisserij reeds verplichte paneel met vierkante mazen. Onderliggende rapportage beschrijft het onderzoek dat is begeleid door IMARES. Hierbij is nauw samengewerkt met de opdrachtgever en Viking visserijproducten. De laatste was verantwoordelijk voor de ontwikkeling van de netten en het brandstofgedeelte. In een tijdsperiode van 3 jaar zijn verschillende metingen uitgevoerd, waarbij we keken naar vangstsamenstelling en discardpercentages bij zowel het conventionele als het nieuwe tuig. Ook zijn brandstofgegevens bijgehouden. In 2010 zijn aanvullende proeven gedaan om het discardspercentage te verminderen. Uiteindelijk werden de volgende conclusies getrokken: · Het lijkt erop dat minder brandstof werd verbruikt door gebruik van het LFD-tuig, maar omdat de metingen niet heel nauwkeuring waren kunnen hier geen harde uitspraken over worden gedaan. · Er zijn duidelijke aanwijzingen gevonden dat het LFD-tuig leidt tot een vermindering van discards ten opzichte van conventionele tuigen. · Bij gebruik van het LFD-tuig is het niet waarschijnlijk dat er grote verliezen in vangst van Noorse kreeft zijn. · Het vissen met grotere maaswijdtes leek het meest veelbelovend als het gaat om het verder vergroten van selectiviteit van de netten. Het LFD project heeft een waardevolle bijdrage geleverd aan het vergroten van de selectiviteit van de visserij op Noorse kreeft met een quadrig-tuig. Desondank

Zijn er mogelijkheden om de verloren markt van langoustines weer opnieuw op te bouwen? Ja, zeggen onder andere de Vlaamse vismijndirecteur Johan Vandesteene, reder Pieter Kramer (Z 525) en diverse restauranthouders in Oostende. De langoustines werden na afloop van de workshop in diverse amuses geserveerd. De Werkgroep Vlaamse Langoustinevisserij van het ILVO wil de visserij van deze delicatesse uit de Noordzee nieuw leven inblazen. Om die reden werd vorige week vrijdag in Oostende een workshop gehouden. Daarin werden met name de afzetmogelijkheden en omzetkansen met de Noorse kreeftjes tegen het licht gehouden.

The Norway lobster (Nephrops norvegicus) is economically important in Europe. However, apart from the female reproductive system, very little is known about its internal anatomy. This article focuses on studying the internal anatomy and ultrastructure of the male reproductive system. This system follows the general pattern found among decapod crustaceans, with several peculiarities. Testes are composed of lobular sperm ducts in which the spermatozoa are fully constituted. The spermatozoa present three lateral arms and a long acrosome, which gives a false appearance of flagellated spermatozoa. The two testes form a double H under the heart, and the vas deferens (VD) arise from each side at the posterior edge of the double H. The main characteristic of the VD is the presence of a sphincter in the enlarged area of the distal end of the middle VD. The MVD here shows an increase in musculature of the wall as compared to the VD, which regulates the passage of the sperm cord to the distal VD (DVD) and thence to the thelycum of the female. The wall of the spermatophore is formed in the distal part of the proximal VD, which surrounds the unique sperm cord present in the VD. Isolated spermatophores are not observed in the VD. The sperm cord is pinched off during copulation by the musculature of the DVD. Then, a portion of the sperm cord is transferred from each VD to form the isolated spermatophores. The wall of the spematophores and the spermatozoa that are observed inside the thelycum have the same morphology as those observed in the VD. © 2012 Wiley Periodicals, Inc.

The diurnal and seasonal regulation of the complex burrowing behavior of Nephrops norvegicus complicates population assessment for this species. Population assessment is traditionally carried out by Virtual Population Analysis (Length Cohort Analysis; LCA) and swept area density estimations from catch data. However, burrow counting from visual surveys has also acquired increasing importance in recent years as an alternative and apparently efficient method. All these approaches produced non-equivalent assessment results in the literature, and therefore, a comparison and critical discussion of these methods is warranted. In this review, we pursued this goal by using already published and unpublished fishery data for a commercially exploited western Mediterranean shelf (60–100 m) population as an example. The cross-assessment was carried out by LCA, the swept area method and burrow counting in different seasons (spring-summer and autumn–winter) to highlight biases in abundance estimations in relation to Nephrops behavior. We also used novel trawl density data for other fish and decapod species in the area because the burrowing behavior of these species may deeply bias Nephrops abundance in visual surveys. LCA provided intermediate assessment values when compared to the swept area and photographic estimates, which over- and underestimated the abundance, respectively. We reviewed the problems related to the peculiar burrowing behavior of the species that generate assessment estimations of such different magnitude

The bottom trawl fishery developed on the slope off Balearic Islands (western Mediterranean) has been analysed from different sources of information: (i) data obtained during experimental bottom trawl surveys developed annually since 2001; (ii) daily sale bills from the bottom trawl fleet, available since 2000. Considering both hydrographical and geomorphologic conditions, the study area was divided in four geographical sectors. Multivariate techniques were applied to identify assemblages and their main species, and to investigate the influence of environmental variables in the slope communities. Fishery-independent and fishery-dependent indicators were calculated, both at specific and community level, for the assemblages identified. In all cases, they were summarised using the Traffic Light approach. Three assemblages have been identified in the slope trawl fishing grounds off the Balearic Islands: (1) the almost unexploited shelf break, where teleosts predominate; (2) the upper slope, where teleosts still predominate but crustaceans are also very important (with Nephrops norvegicus as target species); (3) and the middle slope, where crustaceans predominate (with Aristeus antennatus as target species). Depth was the main factor affecting the species composition of the assemblages, although other factors such as area, year and effort level also affect. Indicators estimated from both sets of data suggested an improvement in the state of N. norvegicus, although the results suggest the influence of other factors than fishing impact in the state of this resource. For A. antennatus, marked differences have been found depending on the data source. In the upper slope, indicators suggested an improvement in the state of this assemblage, which can be related to a decreasing trend found in the fishing effort exerted in this depth range. Indicators from the middle slope showed differences for both sets of data. The characteristics of both data sources and of the species analys

In dit document wordt de kennis samengevat over de Noorse kreeft (Nephrops norvegicus), in de volksmond ook wel Langoestines genoemd. Dit ‘kennisdocument’ is geschreven op verzoek van de Kenniskring Langoestine en wordt gefinancierd door het ministerie van Economische Zaken, Landbouw en Innovatie (EL&I). De kennis voor dit document is verkregen door middel van literatuuronderzoek en analyse van gegevens uit logboeken van vissers en bemonsteringsprogramma’s van IMARES.

RFID is an innovative information technology that allows the ability to attain massive amounts of data. It can be used for traceability of good trough the different production stages as well as in behavioural sciences to identify different animals within a group. In this work we summarized two different sectors where this system could be developed. The first concerning the application of such technology to fresh fish supply chain, the second concern a laboratory application for the study of behaviour in laboratory held crustaceans of commercial importance (i.e. the Norway lobster, Nephrops norvegicus). The presented application of RFID to fresh fish supply chain consisted in the application of RFID tags along the fresh fish supply-chain of high commercial value. In the laboratory, a system of distributed architecture made by a microcosm tank with set of RFID controllers below it, each handling a group of seven readers in order to contemporarily portrait the behaviour of up to four individuals

Radio frequency identification (RFID) devices are currently used to quantify several traits of animal behaviour with potential applications for the study of marine organisms. To date, behavioural studies with marine organisms are rare because of the technical difficulty of propagating radio waves within the saltwater medium. We present a novel RFID tracking system to study the burrowing behaviour of a valuable fishery resource, the Norway lobster (Nephrops norvegicus L.). The system consists of a network of six controllers, each handling a group of seven antennas. That network was placed below a microcosm tank that recreated important features typical of Nephrops’ grounds, such as the presence of multiple burrows. The animals carried a passive transponder attached to their telson, operating at 13.56 MHz. The tracking system was implemented to concurrently report the behaviour of up to three individuals, in terms of their travelled distances in a specified unit of time and their preferential positioning within the antenna network. To do so, the controllers worked in parallel to send the antenna data to a computer via a USB connection. The tracking accuracy of the system was evaluated by concurrently recording the animals’ behaviour with automated video imaging. During the two experiments, each lasting approximately one week, two different groups of three animals each showed a variable burrow occupancy and a nocturnal displacement under a standard photoperiod regime (12 h light:12 h dark), measured using the RFID method. Similar results were obtained with the video imaging. Our implemented RFID system was therefore capable of efficiently tracking the tested organisms and has a good potential for use on a wide variety of other marine organisms of commercial, aquaculture, and ecological interest