Sessile animals that live on the foreshore undergo tidal cycles, and have to facevariations in physical and chemical parameters such as oxygen concentration. Duringemersion, availability of dissolved oxygen can be lowered for bivalves, which have only asmall reserve of seawater inside their closed shell. Differences in oxygen concentrationare thus expected to lead to modifications of the metabolism, including changes inmitochondrial activity. Previous studies investigated air exposure under extremeconditions, which do not always reflect environmental conditions these invertebrates haveto cope with. In this study, oxidative capacities of gill mitochondria of the oysterCrassostrea gigas were studied during a tidal cycle period, bycomparing oysters collected after emersion and immersion. Only minor differences werefound in state 3 (oxidative phosphorylation) or state 4 (non-phosphorylating oxygenconsumption) rates between the two conditions. Similarly, no difference was observed incytochrome c oxidase activity or in oxygen consumption related to maximalelectron flux through complexes I-IV, II-IV and IV. While capacities of substrateoxidation were maintained in both emersion and immersion conditions, capacity ofmitochondria to produce adenosine triphosphate (ATP) was significantly lower in oysterssampled during emersion. These results suggest that although C. gigascould maintain aerobic metabolism during emersion period within a tidal cycle inits environment, energy producing mechanisms are affected.

The status of an exploited population is ideally determined by monitoring changes inabundance and distributional range and pattern over time. Area of occupancy is a measureof the current distribution. Unfortunately, for many populations, scientific abundance anddistribution information is not readily available. To evaluate the reliability ofcommercial fishing data for deriving occupancy indicators that could serve as proxies forstock abundance, we investigated four questions: 1) Occupancy changes with stock biomass,but is this change strong enough to make occupancy a sensitive indicator of populationbiomass? 2) Fishing boats follow fish, but when does such activity alter the positivemacroecological relationship between occupancy and abundance? 3) When does the activity ofpursuing fish adversely affect occupancy estimates derived from catch and effort data? 4)How does uncertainty in fishing effort data affect occupancy estimates? Spatialsimulations mimicking the dynamics of four deep-water fish species showed thatbiomass-occupancy relationships can be weak. Fishers following fish can modify the spatialdistribution of target species, even reversing the sign of the biomass-occupancyrelationship in certain cases, and can affect the reliability of occupancy indicators,which can also be impaired by error in effort data. Using commercial catch and effort dataand abundance indices for deep-sea fish populations to the west of the British Isles itwas found that only for roundnose grenadier might occupancy provide insights into biomasschanges. In conclusion, care should be taken when using occupancy for evaluating rangechanges in cases where fishing might have modified spatial distributions, uncertaincommercial data are used or when the abundance-occupancy relationship is too flat.

In the Western and Central Pacific Ocean (WCPO), which accounts for over half of world tuna production, purse seine effort and catch on floating objects have increased significantly due to a rapid increase in the use of fixed and free-floating fish aggregation devices (FADs). FAD fishing has had an impact on the current status of the stocks of the three main target tunas in the equatorial WCPO, skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares) and bigeye (T. obesus). FADs have been shown to influence the behaviour and movement patterns of the three tuna species with the juveniles of each species occupying shallower habitats when associated with FADs. Aggregation of tunas around drifting objects increases their vulnerability to purse seine gear, particularly for juvenile and small size classes. Further to the impacts on the target stocks, the use of FADs has increased the vulnerability of other fishes to the purse seine method, including some shark and billfish species. Given the concern over FAD-related fishing effort on target and bycatch species, there is a need to understand how FAD use affects target and bycatch stocks. Science needs to better support management decisions are highlighted including the need to identify the magnitude of broader community-level affects.

The benefits of implementing no-take Marine Protected Areas (MPAs) for the conservationof highly migratory species are not easy to assess. They depend on several factors, suchas the fish mobility, fisher behaviour and the area covered by the MPA with respect to thedistribution area of the species to protect. In this study, we explore the simultaneouseffects of MPAs and fishing scenarios on skipjack tuna population dynamics, using thespatially-explicit APECOSM-E model. The model represents the size-structured populationdynamics of skipjack tuna in the Indian Ocean and their dependence on climatic variabilityand exploitation by fisheries. Numerical experiments were run from the beginning ofindustrial fisheries in the early 1980s to the year 2030, considering different scenariosfor the future development of fisheries. These scenarios combined different trends infishing effort and technological development, either assuming a continuous increasefollowing historical trends or a stabilization of these factors at present values. Thesimulations were designed to explore the effects of two MPAs of different size andlocation: the recently established Chagos MPA, and a hypothetical MPA covering a largepart of the Western Indian Ocean, where most of the skipjack catches are presently made.We modelled the redistribution of fishing effort around the MPAs assuming that the fishershad partial knowledge of the spatial distribution of the skipjack population. The effectsof the two MPAs on the population dynamics, catch and fishing mortality are shown. Ourresults revealed a very minor effect of the Chagos MPA on the skipjack tuna population,while the Western Indian Ocean MPA had an important impact on the fishing mortality andsucceeded in stabilizing the spawning population. The simulations also showed that theeffect of an MPA depends on the evolution of fisheries and it is therefore important toexplore different fishery scenarios to assess the future benefits of an MPA.

The biology, ecology, and dynamics of the deep-sea teleost black scabbardfish in thenortheast Atlantic are reviewed. The black scabbardfish is a commercial bathypelagicspecies found in the NE Atlantic mostly from Iceland to the Canary Islands and WesternSahara, at depths from 800 to 1300 m. The spatial structure of its population is stilluncertain, although the existence of one single stock that migrates around the NE Atlanticdriven by feeding and reproduction is the most likely hypothesis consistent with availabledata. This review is based on data from commercial fisheries off the Faroe Islands, HattonBank, the west of the British Isles, and Portugal (mainland, Azores, and Madeira) and fromIcelandic and Scottish scientific surveys collected between 1988 and 2012. Spawning ofblack scabbardfish occurs around Madeira and the Canary Archipelagos during the lastquarter of the year. According to the migratory hypothesis, eggs, larvae, and possiblyjuveniles move north to areas from south of Icelandic and Faroe Islands to the west of theBritish Isles where they remain for some years to feed and grow. Then, they move south tothe area off mainland Portugal, where they reach the size of first maturity but do notreproduce, and later move further south to the spawning grounds. Further studies areneeded to understand which of the environmental conditions prevailing around Madeira andthe Canaries, but not elsewhere, allow this species to mature and subsequently reproduce.This review suggests that a multidisciplinary approach is required to confirm thespatiotemporal migration and habitats used by black scabbardfish populations in the NEAtlantic at different life stages. Otolith contour shape and microchemistry, fatty acids,carbon and nitrogen stable isotopes, as well as steroid hormones are proposed as promisingalternative tools for responding to this challenge.

Several pelagic fish species are known to associate with floating objects. However, quantitative information on the main factors that drive this associative behaviour is still lacking. Small pelagic fish offer a particularly interesting case study for this phenomenon, since the small spatial scales involved in their association with floating objects allow experimental data to be collected at a fine scale. Here, we monitored twelve acoustically-tagged bigeye scads, Selar crumenophthalmus (Carangidae), (mean fork length 16.4 cm, SD 2.1 cm) around a floating object moored in shallow water (15 m depth) playing the role of a coastal fish aggregating device (FAD). To quantify the role played by variations in current and daylight, we calculated the speed distribution, pair correlation function and group polarization for the tagged fish hourly, from midday to dusk (13:00–18:00), for varying current strengths and daylight conditions. We found that the current induced a shift in the position of the aggregation upstream of the FAD, at distances that increased with the current strength. We found evidence of an expansion and a higher coordination in the aggregation at dusk, with increasing speed, distance among conspecifics and alignment. We discuss possible scenarios in which group polarization increases at dusk and suggest complementary measurements for future experiments that could confirm our findings.

Bivalve molluscs survive lack of oxygen and may present cellular characteristics allowingtolerance to oxygen deprivation. The objective of the present work was to determine invitro responses of circulating cells (i.e., hemocytes) of Pacific oyster,Crassostrea gigas, to oxygen deprivation by analysis of mitochondrialmembrane potential (ΔΨm) and reactive oxygen species (ROS) production.Hemocytes submitted to oxygen deprivation showed a reduced ROS production and an increasedΔΨm. Confrontation of present results with recently reported findingsallows us to hypothesize the existence of an alternative mitochondrial reductase, and theinvolvement of mitochondrial potassium channel in maintenance of ΔΨm.Tolerance of bivalve hemocytes to variable oxygen availability appears, at leastpartially, related to mitochondrial specificities.

An integrated research program was initiated to evaluate if the European shagPhalacrocorax aristotelis can be used as a robust indicator of themarine environment in Mor Braz, Brittany, France. This program focuses on aspects of theecology of the shag including its abundance, demography, diet and at-sea distributionmeasured at three breeding colonies. The annual population growth rate was estimated at1.01 for the period 1987–2009. The number of breeding pairs (mean: 565) was highlyvariable from year to year. Part of this interannual variation was explained by variationsin sea surface temperature and sea surface height in winter and spring: the number ofbreeding pairs was negatively related to sea surface temperature and sea surface height.First year, second year and adult survival probabilities were 0.44, 0.76 and 0.81,respectively. Juvenile survival rate varied between colonies, despite the short distancesseparating these islets. Average productivity was one young fledged per nest, but itvaried between years and islets. Density of individuals at sea varied between 1.40ind.km-2 during the breeding season and 3.08 ind.km-2 after thebreeding season had ended. Individuals foraged up to 7 km from the nest and performed onaverage 2.7 foraging trips per day. The average number of dives deeper than 5 m variedfrom 126 to 400 per day. Mean diving depth, dive duration and time spent at bottom were 13m, 28 s, and 19 s respectively. Regurgitated pellets were collected regularly. Four fishfamilies (Gadidae, Gobiidae, Atherinidae and Labridae) represented more than 65% of thepreys throughout the year, a percentage reaching more than 95% of the prey from May toOctober. The other fish in the diet were Cottidae, Ammodytidae, and Clupeidae. The diet ofthe European shag consisted of benthic fish throughout the year, and also included pelagicfish more frequently between June and October. The synchronous variations of productivitybetween colonies suggest that some common environmental factors affect this demographicparameter at the regional scale. Thus, the European shag has a good potential for being areliable ecological indicator of the state of this marine environment. Finally, improvedknowledge on the foraging ecology of shags will be useful in the process of designingMarine Protected Areas in the Mor Braz to help ensure sustainable management of marineresources and biodiversity conservation.

Information about the spatial distribution of bycatch species and their spatial overlap with the target species is essential for fisheries management. The present study used fishery-dependent data (vessel monitoring systems, logbooks and official daily landings) to study the spatial distribution and overlap between black scabbardfish Aphanopus carbo and leafscale gulper shark Centrophorus squamosus taken by the longline fishery operating off mainland Portugal. The geostatistical method kriging was applied to estimate the distribution of the leafscale gulper shark in relation to black scabbardfish and thus assess the impact of the fishery on the leafscale gulper shark. Results indicate that in fishing grounds where the black scabbardfish is more abundant, the relative occurrence of deepwater sharks is reduced. These findings have implications for alternative management measures to be adopted in this particular fishery, particularly where it concerns the minimization of deepwater shark bycatch.

Research on the biology and ecology of cold-water corals (CWCs) is still in its infancy.The growth patterns of CWCs in their natural environments are poorly known. Growth rateinvestigations on these deep-sea reef builder species are needed to predict recovery timesfollowing damage to their ecosystems. This study investigates a new approach for analysingCWC growth rate, suitable for in situ application. Lopheliapertusa and Madrepora oculata (Scleractinian) were collectedfrom the Lacaze-Duthiers canyon in the northwestern Mediterranean Sea (520 m depth),marked and then either redeployed in situ for 6 months, or maintained inaquaria for growth rate comparison at a constant temperature of 13 °C, corresponding totheir habitat conditions. Two different types of staining (calcein and manganese) andthree different exposure times (30, 60 and 240 min) were tested. The results show thatcalcein offers rapid incorporation and easy detection, making it particularly suitable forskeletal growth rate investigations compared with other chemical staining. In situlinear polyp growth rates of 7.5 ± 1.2 mm y-1 and 3.5 ± 2.1 mmy-1 were measured in new polyps of L. pertusa and M.oculata, respectively. Those values were significantly higher in young polypsthan in older ones, where they decreased to 1.3 ± 1.5 mm y-1 and 1.2 ± 1.2 mmy-1. Beyond the study of coral reef growth processes, this approach offers amethodological basis for habitat quality assessment which could be used in the managementof deep-sea marine protected areas (MPA).

This study was designed to measure responses of four-year-old black-lip pearl oysters(Pinctada margaritifera) to different temperatures and foodconcentrations and to identify the energy requirements of each sex. Oysters were fed amonospecific microalgal diet of Isochrysis affinis galbana(T-iso). Measurements of oxygen consumption and ingestion rates were carried outat 24 °C and 27 °C and at two algal (T-iso) concentrations: 5000 and 30 000 cellml-1. Glycogen content in adductor muscle, absorption efficiency and scopefor growth were also estimated. Females and males responded differently to environmentalfactors, with food level being the most influential parameter. Oxygen consumption andabsorption efficiency were significantly higher in females than in males, but males hadsignificantly higher glycogen content than females. At high food concentration, glycogencontent, ingestion rate, oxygen consumption, and scope for growth were significantlyhigher than at the low food concentration. Only absorption efficiency was significantlyhigher at the low food concentration. Oxygen consumption was significantly higher at 27 °Cthan at 24 °C. These results indicate that females and males have different bioenergeticfunctioning and that energy demands for reproduction are higher in females.

The pole and line tuna fishery in the Maldives relies heavily on an array of 45 anchored fish aggregating devices (FADs), making it one of the largest anchored FAD-based tuna fisheries in the world. We examined the behaviour of skipjack (Katsuwonus pelamis) and yellowfin (Thunnus albacares) tuna around anchored FADs (1 000 to 2 000 m deep) in the Maldives using passive acoustic telemetry. Eight neighbouring FADs (distance range: 30 to 95 km, average: 50 km) were equipped with automated acoustic receivers in January 2009, for a period of 13 months. A total of 40 skipjack (37−54 cm FL) and 21 yellowfin (35−53 cm FL) tuna were tagged with Vemco V13 transmitters in January (start of the northeast monsoon, dry season) and November (end of the southwest monsoon, wet season) 2009 and released at the two central FADs within this instrumented array. No movement between FADs was observed for any acoustically-tagged tuna in the instrumented FAD array. These results suggest that FADs in the Maldives may act independently. The maximum time a tagged skipjack remained associated with a FAD was 12.8 days in January but only one day in November. In addition, residence times at FADs were found to differ with time (month) and space (FAD location) for skipjack tuna, suggesting that external biotic factors (e.g., prey, conspecifics or predators) might influence the time this species spends at FADs. In November, the residence times of yellowfin tuna (maximum observed time: 2.8 days) were three times greater than those of skipjack tuna at the same FADs. This specific difference could be explained either by the two species responding to different factors or by the species’ responses being dependent on the same factor but with different thresholds. No particular preference for time of departure from the FADs was observed. Some monospecific and multispecific pairs of acoustically-tagged individuals were observed leaving the FADs simultaneously. Thus, this study indicates a high degree of complexity in the behavioural processes driving FAD associations.

A statistical approach to evaluate the temporal trends in the abundance of female Centroscymnus coelolepis in Portuguese waters of ICES division IXa is presented. A state space model is used, which integrates all the available information of the species’ life history as well as knowledge of its biological dynamics. The model involves two processes that run in parallel: a non-observed process (the state process) that describes the annual female population abundance and an observational process of annual fisheries catches in numbers, assumed to be measured with error. Estimation is done within the Bayesian paradigm using sequential importance sampling with resampling. To evaluate the sensitivity of the model to the prior distributions chosen for the parameters, three scenarios with different levels of prior information were considered. Trends in population abundance level and the abundance levels themselves are quite similar in the two scenarios using biological information, but the model that incorporated all the available biological information in the priors provided the best fit to the observed data. The results indicate that taking into account the main biological drivers and the fishing information in the same state space model provides a coherent picture of the population abundance trends, further suggesting that the fishing impact on the population inhabiting Portuguese mainland waters was low.

Marine protected areas (MPAs) have been depicted as a useful tool for improving fisherymanagement and protecting biodiversity. For example, by acting as source populations, MPAsmay provide a spillover of adults/propagules, enhancing recruitment to surrounding,non-protected waters. However, such positive effect will depend on how a MPAs designmatches population biology and dispersal abilities of the target species. High levels ofintraspecific genetic diversity without pronounced structure have been found in manymarine organisms over large spatial scales (from hundreds to thousands kilometres) but donot hold for other ecologically and economically important species such as coral reeffishes, seagrasses and kelps. In particular, the limited potential for dispersal of manymacroalgae suggests the occurrence of self-sustaining, “closed” populations that contrastwith the “open” populations of many fishes and invertebrates. Consequently, the highresilience of fish/invertebrate populations cannot be generalized to the whole marinerealm. In the present work, we use genetic tools to explore the role of the MPAParc naturel marin d’Iroise in the management of the emblematic kelpLaminaria digitata. While kelps have received much more scientificattention than any other seaweed group, there is still critical baseline knowledge whichneeds to be addressed for their effective management. Our genetic survey of 12 L.digitata populations along the Brittany coast, four of them located within theboundaries of the Parc naturel marin d’Iroise, allowed us to assess theconservation value of these kelp populations. In particular, classical genetic metrics aswell as more recent clustering approaches were used to identify and characterizeManagement Units. Moreover, assignment tests were employed to determine contemporarymigration events and source/sink populations. Our results show that populations withinthis MPA have high conservation value. However, we also identify other populations ofconservation interest.

A fish aggregating device (FAD) called a payao is conventionally installed to catch pelagic species in the Philippines. The waters around the Philippines are important regions for yellowfin tuna stocks because they include spawning grounds and nurseries. To understand the schooling behavior of juvenile yellowfin tuna Thunnus albacares around a payao, 13 juveniles (20.5−24.0 cm fork length) double tagged with ultrasonic transmitters (V7-2L-R256; Vemco Ltd.) and data loggers (DST-micro; Star-Oddi Ltd.) were released around a payao. A self-recording receiver (VR2-DEL; Vemco Ltd.) was attached on the mooring rope of the payao to follow the horizontal movements and data loggers recorded the vertical movements of tagged juveniles. Nine juveniles were recaptured simultaneously by ring net at the same payao after 4-7 days. One juvenile was recaptured by hand line at another payao 12 km away from the tagging site after 6 days. Recaptured juveniles showed a diurnal schooling pattern suggesting different school shape and foraging strategy between daytime and nighttime. Juveniles showed a diurnal horizontal moving pattern, concentrated near the payao during daytime, while they were distributed around the payao at nighttime. The fluctuations of swimming depth were synchronized among fish. Juveniles also showed a diurnal vertical movement pattern in surface mixed layer. They concentrated in a shallow and narrow range (11.2±8.2 m, mean ± SD) at nighttime, while they were distributed to a deep and wide range (20.0 ± 11.8 m) during daytime. The maximum vertical neighbor distance indicated the vertical thickness of the school and showed a peak around noon. Higher vertical movement speed during daytime indicated vertical foraging in a water column, while at nighttime the juveniles might forage horizontally following the diurnal migration patterns of prey in the surface layer.

Deepwater fish are characterized by long lifespans, late maturity and low productivity. This implies slow recovery from low biomass levels and it is, therefore, important to manage these stocks correctly to avoid overfishing. However, these stocks are generally data poor, which it makes difficult to apply quantitative assessment models on which to base their management. The management strategy evaluation (MSE) approach consists in evaluating the performance of management strategies by simulation before their implementation. In the evaluation, the main sources of uncertainty in a fishery system and its management process should be taken into account in order to find robust management strategies. Thus, the MSE approach is relevant to the management of data-poor stocks. We used the FLBEIA software, an FLR library coded in the R statistical language, to conduct a bio-economic impact assessment of fisheries management strategies. We evaluated the performance of several management strategies in three different deepwater case studies using the MSE approach: beaked redfish (Sebastes mentella) in the Norwegian Sea, blackspot seabream (Pagellus bogaraveo) in the Strait of Gibraltar, and French mixed deepwater fisheries in the North East Atlantic. In conclusion, we found that the S. mentella stock is very sensitive to the stock recruitment relationship chosen. For P. bogaraveo, simulations showed that the present constant catch management is as good as more sophisticated strategies. Finally, in mixed fisheries, case study fleet dynamics were key for the success of management strategies

Fish aggregating devices (FADs) used in the Gulf of Thailand are made of bamboo poles, twisted wire and coconut leaves, fastened to a concrete block. Purse seines with 2.5 cm mesh size are used to surround the fish, using fishing boats ranging from 18 to 26 m in overall length. Fishing grounds are located in the central Gulf of Thailand at a depth of 25–60 m. Catch per unit effort (CPUE), species composition and size of economically important species were analyzed by collecting data from fishing boats using FADs at nine main fishing ports along the Gulf of Thailand between January and December 2007. The results show that the average CPUE was 3351 kg day-1, which was composed of 88% pelagic fishes, 5% demersal fishes, 4% trash fishes and 2% squids and cuttlefishes. The major pelagic species were Indian mackerel (Rastrelliger kanagurta), Indian scad (Decapterus russelli) and bigeye scad (Selar crumenophthalmus), which made up 25%, 24% and 8% of the total catch, respectively, while neritic tunas (kawakawa; Euthynnus affinis, frigate tuna; Auxis thazard thazard and longtail tuna; Thunnus tonggol) made up 8% of the total catch. The mean length of ten economically important species was smaller than their size at first maturity, while two species were above their size at first maturity. The results indicated that juvenile fish were mostly being caught by FAD fishery, and this may lead to depletion in fisheries resources and economic loss. Although there is a set of measures to control the use of purse seines, effective management of the FAD capacity is also urgently needed.

Data from the MEDITS bottom trawl surveys in the Eastern Ionian Sea, covering a depth range of 28 to 845 m were analysed for the period 1998–2008. For each trawling location, environmental and geographical parameters were recorded, while biomass, abundance, biodiversity and size-based metrics were estimated for the total megafaunal community, as well as for four taxonomic sub-communities (Osteichthyes, Chondrichthyes, Crustacea and Cephalopoda) which were expected to respond differently to environmental changes and fishing. In addition, biomass and abundance of ten species selected based on commercial interest, depth range and life history traits were explored, with particular emphasis on deep-sea species. Fishing effort data collected during the study period were analysed and showed a decreasing trend, mainly due to a decrease in the activity of static nets. The relation between the estimated parameters and environmental and spatial factors, as well as temporal (interannual) effects and the effect of fishing effort were explored using generalized additive models (GAMs). Results of GAMs showed that depth and location explained much of the variation in community metrics, probably reflecting mesoscale spatial features and species/communities requirements. Even though the different communities and species exhibited variant patterns in bathymetric and spatial distribution, some common aggregation patterns in productive areas were identified. Despite the relatively short time series, GAMs were effective in detecting increasing trends for several metrics; taking into account spatial factors further contributed to attributing the remaining deviance to temporal effects. These trends were partly explained by the observed decline of fishing effort, which is further supported by the fact that negative relations between several metrics and fishing effort were identified, for some of the selected communities and populations. Abundance, species richness and maximum length proved the most informative metrics concerning the effect of fishing. The current decline in fishing effort in the area seems to be a move in the right direction and should be complemented by additional measures aiming to prevent allocation of effort towards the deep sea.

Moored FADs (MFADs) have been a key area for development in Guadeloupe (Lesser Antilles) since the late 1980’s. The main objectives underpinning the development of MFADs were to (i) reduce fishing pressure on coastal fishing resources; (ii) boost fishermen’s incomes; and (iii) increase local consumption of locally generated fishery products as a proportion of overall consumption. This paper gives an overview of the current structure of Guadeloupe’s fishing fleet and fisheries, with a specific focus on MFAD fleets in a relatively unstructured environment with regard to regulation, and so how these fleets operate in a context of unrestricted development of private MFADs. In addressing the following key issues, this paper aims to: assess the economic performance of fleets operating on MFADs, understand why the MFAD fishing activity has not developed more than it has, and suggest how better MFAD management could improve the situation. Socio-economic information on a trip and fleet level basis were collected and stored on a fisheries information system to analyse the relative attractiveness of MFAD fishing and assess the overall economic performance of MFAD fleets as compared to other non-MFAD fleets. Non-monetary variables were also tested to explain the degree of dependence on MFADs. In 2008, economic returns from FADs were relatively low, both in terms of wages for the crews and in terms of profit for vessel owners. Earnings were higher than coastal fishing activities, but seem to have been very sensitive to the indicators used in our analysis. MFADs are expected to become much more attractive as a result of MFAD regulation, especially through the establishment of collective MFADs.

This paper aims to investigate the potential interest of using a Vessel Monitoring System (VMS) based on GPRS/GSM (Global System for Mobile Communications) technology to obtain a better estimation of fishing activity and distribution of a small-scale artisanal fleet, for which the European satellite-based system is not available. Since the early 1980s, the artisanal fishery targeting blackspot seabream (Pagellus bogaraveo), commonly known as “voraz”, has been developing along the Strait of Gibraltar area. Up to now the fishing effort was estimated using the number of sales, a proxy for the number of fishing days. This measure does not, however, capture the “missing effort”, i.e., fishing days resulting in no catch or not enough catch to be sold at public auction. The European satellite-based VMS provides information about the dynamics of different fishing fleets, but is not installed on small vessels (<15 m), such as those used by the artisanal “voracera” fleet targeting blackspot seabream in the Strait of Gibraltar. The Andalucía Regional Government installed its own vessel monitoring system on several artisanal fleets using GPRS/GSM cellular network technology that sends data on vessel positions and speed every three minutes. Data collected from 2009 to 2011 using this system were filtered and analysed to estimate fishing effort, catch rates and the spatial distribution of the blackspot seabream fishery. The estimates obtained seem to provide a good representation of fishery reality. As expected, the missing effort increases as the resource levels decrease. Additionally, expert knowledge of the fishery allowed application of an algorithm for splitting these daily trips into estimated fishing hauls. Afterwards the spatial distribution of catches and Catch per Unit Effort (CPUE) could be obtained linking VMS locations with landings information. This study provides a considerably finer spatial scale view of the fishery than data available in the past.