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Different tracking devices are currently used to record the activity of fishing vessels in space and time and to analyse the pattern of fishing effort with respect to sea substrates, resources, or socio-economics factors. Among these devices, the Vessel Monitoring System (VMS) and the Automatic Identification System (AIS) represent the most interesting and fertile data sources for fisheries investigations but an integration of these two sources was never explored. Two large VMS and AIS datasets, covering the activity of the Italian fishing vessels with length-over-all ≥15 m for the whole year 2012, were used to perform the first assessment of the features characterizing each data source, and ultimately the properties of the estimators of ecological indicators of fishing pressure obtained using these data. In this way, a dataset related to five vessels equipped by a third high frequency device (the Fishing Observing System) was used as reference for a comparative analysis of fishing activity as reconstructed by VMS and/or AIS. Moreover, the ecological indicator 5 of fishing pressure as spatial extent of fishing activity (defined within the Data Collection Framework for Fisheries—DCF) was used as a reference to test the separate and integrated usage of VMS and AIS data. Results evidenced important differences in spatial, temporal and fleet coverage between VMS and AIS. Namely, VMS is affected by a lower frequency with respect to AIS but covers a larger portion of the fleet. Furthermore, AIS mainly operates near the harbours, so that offshore activity is underrepresented. The integration of VMS and AIS data, however, allows valorising the strengths and minimizing the limits of each source. In fact, the assessment of the total spatial extent of fishing activities (as captured by the DCF indicator 5) is significantly improved by the integrated usage of VMS and AIS data.

An effective management of trawl fishing should be based on the classification of strategies adopted by fishers in terms of fishing grounds selected and target species. In addition, the dynamics behind strategy selection should be investigated and understood, since they are likely to affect the status of the stocks. This study applies artificial neural networks to identify the main strategies characterizing the fishing activity of Italian trawlers operating in the Central Mediterranean during the period 2009–2016. Moreover, the rationale driving fishers' choice is modelled using General Additive Models (to investigate the role of external factors) and Conditional Logit (to investigate the interaction among fishers). Five strategies were identified together with the potential effects on some key stocks which, in turn, determine the fishers' preference towards alternative strategies. Results suggest that both external factors and interactions are relevant in driving fishers’ behavior, and provide some potentially useful insights for the set-up of management strategies in which the adaptation of fishers to biological and economic factors are explicitly considered.

The higher mortalities and lower morphological quality of juveniles with a non-inflated swim bladder still remain a major problem in intensive farming. The aim of this study was to investigate a possible relationship between the presence of an abortive swim bladder and skeleton anomalies in gilthead seabream juveniles. A batch of 109 DAH (LS range: 16–47 mm) gilthead seabream was split into two groups on the basis of the presence (SB group)/absence (WSB group) of a normally inflated swim bladder, and processed for skeletal anomaly and meristic count analysis. The presence of pectoral fin anomalies and the absence of any clear-cut and sound relationship between abortive swim bladder and axis deviations characterize the WSB group. Rarer anomalies, such as scoliosis and lordosis in the pre-haemal vertebrae, kyphosis in the haemal vertebrae, pre-haemal and haemal vertebrae body anomalies, exclusively affected the WSB seabream. This result contradicts what is observed in other species, where abortive swim bladder is shown to cause axis deviation. The authors hypothesize that when gilthead seabream larvae with uninflated swim bladder encounter difficulty in maintaining the level in the water column, they have to overuse flapping of the pectoral fins (which appear more deformed in the seabream without swim bladder of this study). This determines a hyper-activity of the pectoral muscles, which then exerts an intense mechanical load on pre-haemal muscles and ossifying vertebrae. Vertebrae and axis anomalies in the pre-haemal and in haemal (in this study still rare in the WSB lot) regions may be later effects, as postural consequences due to the uninflated swim bladder.

Marine litter has significant ecological, social and economic impacts, ultimately raising welfare and conservation concerns. Assessing marine litter hotspots or inferring potential areas of accumulation are challenging topics of marine research. Nevertheless, models able to predict the distribution of marine litter on the seabed are still limited. In this work, a set of Artificial Neural Networks were trained to both model the effect of environmental descriptors on litter distribution and estimate the amount of marine litter in the Central Mediterranean Sea. The first goal involved the use of self-organizing maps in order to highlight the importance of environmental descriptors in affecting marine litter density. The second goal was achieved by developing a multilayer perceptron model, which proved to be an efficient method to estimate the regional quantity of seabed marine litter. Results demonstrated that machine learning could be a suitable approach in the assessment of the marine litter issues.

The first attempts to reproduce dusky grouper (Epinephelus marginatus, Lowe 1834) under controlled conditions started in 1995, but the egg and larvae quality was very low. Mass production is still encountering many difficulties, mainly concentrated in the larval period when very high mortality rates are observed, confirming what has been observed in the rearing of other grouper species. The main bottlenecks have been identified as the difficulty to properly nourish the larvae, stress shock syndrome, and the high deformation rates. We analysed 633 dusky grouper larvae and juveniles (0.2–7.2 cm total length, TL), sampled during two larval rearing cycles carried out in 2001 and 2002 in Italy. The specimens at different development stages were stained in toto for bone and cartilage and examined for skeletal anomalies during dusky grouper ontogenesis. The incidence of anomalies in groupers hatched from the same egg batch but reared using two different methods (green waters and semi-intensive rearing) and three stocking densities (8, 16 and 28 larvae/l) was compared, with a view to providing tools for identifying the most appropriate larval rearing method in order to at least limit the onset of skeletal anomalies. Our results suggest that during development no particular skeletal anomaly patterns (or fate) can be clearly identified as a high variability was observed in malformation typologies and the regions affected. No significant differences in the morphological quality between groupers reared using semi-intensive (LV02 lot) and green water (GW02-01 lot) methodologies were observed, whilst groupers reared at the highest stocking density (28 larvae/l) showed the highest frequency of deformed individuals (75.8%), the highest malformation charge (average of 5.5 anomalies per deformed individual), the largest range of anomaly typologies (38), and the highest incidence of individuals with at least one severe anomaly (30.9%). Whilst in green waters no evident effects of larvae density were observed on survival rates, the survival rate in large volume reared individuals (17.5%) was considerably higher with respect to those reared in green waters (0.2%) at 7–8 larvae/l. This indicates that the semi-intensive methodology should be considered more effective in enhancing the survival rate of dusky grouper larvae.

A dual underwater camera system connected, synchronized and powered via cable to a waterproof transportable computer, was developed. This device was used for acquiring tuna images during the transfer from fishing net to a floating cage, thus validating the potential advantages of the use of underwater video monitoring. Two images per second were recorded during tuna transfer and stored for biometric analyses, which were carried out by means of a software tool based on Artificial Neural Networks (ANNs). The ANN was trained to convert distance between pixels in each pair of images into distance between points in the real objects, automatically correcting the estimates for distance from the cameras and aspect. The ANN-based software tool allowed analysing tuna transfer images, providing biometric information of about 1000 tunas. The results were compared to conventional assessment methods.

Despite research efforts addressing artificial propagation, dusky grouper aquaculture still relies on experimental trials owing to the low survival rates of larvae and juveniles, thus rendering mass rearing difficult to attain. Although some authors suggested that the preys offered to the early larval stages represent the major problem facing the rearing of all grouper species, very little information is available in literature on larval development and the behaviour of dusky grouper. The objective of this study was to investigate the trophic preferences of larval stages of the dusky grouper by rearing using a semi-intensive technology. Larvae were reared in pilot scale mesocosms (60 m 3 ) from 3 to 35 days post hatching. The rearing system was supplied with wild zooplankton collected in a natural coastal lagoon in order to augment the chances of satisfying the larvae's feeding requirements; the feeding preferences were analyzed during ontogenesis. The relationship between mouth gape and dimensions of preys, considered as 3-D objects, was investigated to identify possible critical factor. The results of this study suggested a sequence of suitable food items from the beginning of exogenous feeding until day 35 post hatching. In particular, dusky grouper larvae actively select copepod nauplii in the size range between 2 and 12 mm in TL, and Artemia salina nauplii for TL larger than 9 mm. The rearing approach applied seemed to be promising. Indeed, while previous rearing trials of dusky grouper failed within ten days or finished at 30 days post hatching with a lower percent of survivors, this paper reports the best survival rate reported for this species (10% ± 7.0 survivors at 35 days post hatching). Finally, mouth width was observed to be the limiting factor in the selection of prey, while the smallest prey size plays a critical role in determining ingestion. Our results contribute to clarifying some aspects of the larval ecology of this species, furnishing some suggestions for its cultivation.

Bluefin Tuna ( Thunnus thynnus L.) is a fish species of high nutritional and commercial value that is increasingly farmed in the Mediterranean basin. Oxidative stress research in aquaculture is particularly important in the assessment of both the health of farmed fish and seafood quality. Reactive oxygen species (ROS) are able to start the lipid peroxidation process which is potentially dangerous in fish, since they contain a high percentage of n-3 polyunsaturated fatty acids, in particular C20:5 n-3 and C22:6 n-3, which account for most of seafood's nutritional quality. The study of the antioxidant system and how the various components interact to delay post-harvest lipid peroxidation covers both the improvement of quality and the extension of shelf life of the fresh tuna product. In this study, hepatic antioxidant enzymes (catalase—CAT, superoxide dismutase—SOD and glutathione peroxidase—GPx) and lipid peroxidation levels (TBARS) of wild and sea cage-reared tunas were investigated. The aim was to examine the possible oxidative stress state of wild tunas killed by different fishing methods, compared with reared specimens exposed to different periods of confinement but killed by the same method. No significant differences between wild specimens were found in relation to catching techniques. A significant depletion was observed in liver SOD activity in reared tunas (5.00 U/mg protein) in comparison with wild specimens (5.90 U/mg protein). No differences in liver CAT activity between wild and reared tunas were found. In reared specimens we observed an oxidative stress state indicated by an increase in GPx activity (104.70 U/mg protein and 0.83 U/mg protein in reared and wild tunas, respectively). A significantly higher liver lipid content was observed in reared tunas, but no significant differences between wild and reared tunas in terms of TBA reactive substances content were found (2.03 vs 2.02 micromol TBARS/mg lipid). Our results suggest that the increased GPx activity leads to the suppression of lipid peroxidation in liver of reared tunas. This is the first time that antioxidant enzyme activities have been assayed in Bluefin Tuna and the stress state seems to be related to the diet of reared specimens rather than to their confinement, as indicated by the absence of differences in the antioxidant activities related to the period of confinement.

The definition of a remote system in the monitoring of fin fish growth rate and shape change relies on the development of the appropriate optical ranging system and the automation of data collection. Among the available technologies, a dual camera optical ranging system is presented as the most suited for fish size remote estimation. Images are collected via a submergible low-priced dual camera module connected to a portable waterproof PC equipped with two frame grabbers. Two images are synchronically collected and, with the system parameters (focal length of both cameras, distance between the two cameras, vertical and horizontal tilt and relative rotation of the two cameras), are used to collect data of fish size and shape. A Neural Network is built to correct the error of measurement. A geometric algorithm is developed to filter fish images and elliptic Fourier analysis of automatically collected fish outline coordinates is proposed as a tool of shape analysis. For all other fish orientations, landmarks (homologous points) are collected on fish outlines and evident structures: landmark configurations relative to each fish are then rotated using the system parameters. The proposed system can be used in the monitoring of sea-based fish farming facilities, especially those which are permanently submerged, reducing mortality and stress due to fish sampling and limiting divers intervention. By its application in the study of wild population, the system can be useful in the characterization of fish communities and population dynamics, supporting traditional visual census techniques with a tool which allows for continuous, remote and automatic data collection.

In this study, skeletal descriptors of wild and reared juveniles of sharpsnout sea bream (Diplodus puntazzo) and pandora (Pagellus erythrinus) were compared to assess the quality of farmed individuals. A total of 1016 wild and reared juveniles of sharpsnout sea bream and pandora were inspected for skeletal abnormalities and a qualitative evaluation of aquaculture production was achieved. The applied approach was based on the analysis of meristic character counts, and incidence and pattern of skeletal anomalies. Correspondence Analysis (CA), Multi-Response Permutation Procedure (MRPP) and Indicator Species Analysis were performed on a data matrix. Such methodology allowed the identification of different levels of disturbance generated by the captive conditions.

A large number of juvenile, sub-adult and adult individuals of Sparus aurata were collected in two adjacent Mediterranean coastal lagoons, Lake Fogliano and Lake Caprolace, located on the central Tyrrhenian coast of Italy. A comprehensive analysis of the feeding habits of this species was carried out using both univariate and multivariate statistical methods. The results showed that qualitative and quantitative changes in the diet of this species take place within the first months of development. Considerable feeding differences between sub-adult and adult individuals of two bream populations were found in the different coastal lagoons: specimens from Fogliano showed a significantly less diverse trophic spectrum, whereas specimens from Caprolace tended to feed on a larger variety of prey. The ecological significance of these differences and their implications for ecosystem management and conservation are discussed.

Gilthead sea bream from different Mediterranean hatcheries show a consistent number of skeletal anomalies, mainly in the hemal and caudal body regions. Four hundred and twenty-two hatchery-reared sea bream from Italy, France and Spain were checked for skeletal malformations and meristic counts. The same skeletal descriptors were examined in 72 wild-caught sea bream. Correspondence analysis (CA) was performed to rank groups of hatchery-reared sea bream according to their skeletal abnormalities. The position of each group on the first correspondence axis with respect to the wild-caught specimens was used as a larval quality indicator. Wild phenotype similarity was also tested performing meristic counts and inter-groups meristic differences were illustrated. Results highlighted a quality gap between wild-caught and hatchery-reared specimens, with the only exception being sea bream larvae that were reared in semi-intensive conditions. This larval monitoring method is proposed as a tool for evaluating hatchery larval quality at a morpho-anatomical level.

The definition of a remote system in the monitoring of fin fish shape variability relies on the appropriate shape analysis tools. In this paper, different methods are proposed and compared. Growth trajectories, computed using geometric morphometrics, allow the pattern of size-related shape change and visualize growth allometry to be analyse. Geometric morphometrics is used to describe shape change in three samples (507 5100 days after hatching) of 119 individuals of the Sparid Diplodus puntazzo. The results are potentially interesting but the method still relies on the manual detection of homologous landmarks (coordinates of points located unambiguously on each specimen’s profile or structure) which are basic for such analysis. In an attempt to proceed towards the remote estimation and the automation of data collection, two alternative approaches are tested. In particular, Elliptic Fourier analysis and Bezier function were applied to the same samples, and results compared with geometric morphometrics. Fourier analysis’ growth curves are very similar to geometric morphometrics’ ones and allows for an appropriate visualisation of global shape changes. At the same time, Fourier methods can be applied to remotely and automatically detected profiles. This method is thus considered as the best candidate in the context of automated fish shape monitoring. The Bezier method performed poorly, both in terms of statistical output and shape visualization.

Data on the concentrations of some blood constituents of captive Adriatic sturgeon, Acipenser naccarii, a primitive bony fish, are reported. Serum osmolality, Na+, K+, Cl−, Ca2+, cortisol, glucose and total protein concentrations were measured. The effects of anaesthesia, temperature, crowding and prolonged handling stress were tested on a group of 12 4-year-old sturgeons sampled repeatedly. The anaesthetic dose of MS 222 (140 mg l−1) induced significant osmolality elevation in the sturgeon. After exposure to colder temperature (17 versus 25°C), cortisol and Cl− concentrations significantly decreased. The cultured sturgeon did not seem susceptible to crowding and prolonged handling stress, since neither the serum cortisol and glucose levels nor the other blood parameters were affected by these stressors. Results are compared with the few available data on other chondrostean fish and with those on teleosts.

1. 1. Kidney, oesophagus and gill Na + -K + ATPase activity and serum Na + , K + and Cl − concentrations are evaluated in European sea bass during experimental acclimation to fresh water. 2. 2. Kidney and oesophagus ATPase increase in low salinity and reach a maximum in fresh water. 3. 3. Gill ATPase decreases during the acclimation trials and rises again to normal values after a 3-week stay in fresh water. 4. 4. Na + and K + serum concentrations decrease during the trials and increase back after a 3-week stay in fresh water. 5. 5. The correlations between enzymatic activities, serum ion concentrations, morphological changes and environmental salinity are discussed.

This paper describes the embryonic and larval developmental stages of Chelon labrosus, a prominent species among the Mugilidae, a family of high interest in the ecological management of coastal extensive aquaculture systems. Its high commercial value makes it the most important mullet in the Italian northern Adriatic “vallicoltura”. The success of induced reproduction techniques enabled us to describe its developmental stages, which were recorded by camera lucida drawings and presented as developmental tables. Histological and scanning electron microscopy observations were also carried out. Development may be divided into four periods: embryonic, pre-larval, larval and juvenile, each one characterized by typical anatomical and physiological features. At hatching, C. labrosus larvae are rather underdeveloped, in comparison with other marine farmed species, but the sense organs develop rapidly as well as the mouth. At 12 days the larva already has a juvenile head on a larval body. The juvenile stage is reached precociously, at 60 days, so that C. labrosus had a high performance in the rearing trials which were carried out.

Survival of 23% (length 31.2 mm) was achieved for fry of Chelon labrosus reared in earthen ponds from Day 20 to Day 58, compared with 31.2% (24.6 mm) for the indoor controls. Pond conditions were: temperature range 20.6–27.5° C, dissolved oxygen range 6.2–8.0 ppm, and water exchange rate 1 l/s. Natural food organisms available in the pond were supplemented with nauplii of Artemia salina and copepods. Comparisons are made with traditional culture practices for Mugilidae, and the significance for developing countries is discussed.