Assessing stakeholder's experience and sensitivity on key issues for the economic growth of organic aquaculture production

Participatory management is widely recognised as a working method of paramount importance, based on the principles of knowledge sharing, accountability and legitimacy. Hence, it is broadly considered suitable for addressing issues related to the sustainable development of the seafood industry, and specifically, of the aquaculture system. A survey focused on the current EU regulatory framework was carried out to elicit stakeholders’ preferences, knowledge and experience on key issues for the development of organic aquaculture, supported by science-based regulations. The survey was completed by 65 stakeholders belonging to several categories, and it was supported by the implementation of the Analytic Hierarchy Process method. Stakeholders’ preferences were elicited on organic production methods and control systems, the quality of the environment and organic products, fish health and welfare. The views expressed by the participants revealed both competence and awareness, despite the complexity of the subject. Several ideas and useful suggestions emerged regarding unresolved technical issues. In addition, the need for a targeted communication strategy on the quality of organic aquaculture products and the necessity of fostering European/national programs to support the production and marketing of organic aquaculture products were highlighted

Muscle activity as a key indicator of welfare in farmed European sea bass (Dicentrarchus labrax L. 1758)

Groups of adult sea bass were reared at either low (10 kg m−3) or high (50 kg m−3) stocking densities respectively for 84 and 116 days. To monitor the red muscle activity, about 20 fish from both densities were surgically implanted with EMG (Electromyograms) radio transmitters, after EMG calibration during exhaustive swimming exercise (Ucrit test). Blood samples and morphometric measurements were also taken. EMG showed that the muscle activity of fish reared at 50 kg m−3 was on average twofold higher than fish kept at lower density. Cortisol was significantly more elevated at higher density and haemoglobin, haematocrit and RBCC (red blood cells count) showed the same trend, while lysozyme decreased. Patterns for glucose and lactate were less clear. The results showed that the contemporary use of functional (EMG) and physiological (haematological and biochemical) profiles could give a more comprehensive view of the fish status validating the diagnosis of fish stress induced by culture practices

Calibrating accelerometer data, as a promising tool for health and welfare monitoring in aquaculture: Case study in European sea bass (Dicentrarchus labrax) in conventional or organic aquaculture

Both the conventional and organic aquaculture sectors have grown rapidly over the past few years. Moreover, welfare has attracted increased attention on the part of both consumers and governments. However, fish welfare assessment is complex and thus needs to adapt measurements that are easily applicable to aquaculture conditions. In this study, in addition to classical welfare indicator measurements (physiological stress indicators and growth performance), we recorded the swimming activity data using acoustic transmitters to evaluate the welfare of European sea bass (Dicentrarchus labrax) fed a conventional vs. an organic diet. Prior feeding trial, the swimming activity recorded by tag has been calibrated with water speed during critical swimming speed (Ucrit) tests. This calibration allowed us to increase the power of the recorded data, providing information on swimming activity with respect to the Ucrit value and on the metabolic cost of swimming. After a four-month experimental period, physiological stress indicators and growth performance did not differ significantly between the two diet groups. However, we observed a subtle difference in swimming activity: the fish in the organic diet group were more active during the feeding period in the morning. All indicators considered, our results suggest that an organic diet does not incur higher metabolic costs and does not affect the welfare of the European sea bass. Moreover, this study shows that the use of acoustic transmitters previously calibrated with physiological indicators, such as Ucrit, is a promising tool for welfare monitoring in aquaculture conditions

Nazočnost vrsta iz porodice četverozupki (Tetraodontidae) u središnjem Sredozemlju: novi podaci iz južnog Jadrana

This paper presents the first record of the Lessepsian migrant fish Lagocephalus sceleratus (silver-cheeked toadfish) on the Italian side of the south Adriatic Sea. In addition, four specimens of Sphoeroides pachygaster (blunthead puffer) were analysed. Meristic and morphometric data of the silver-cheeked toadfish and blunthead puffer are in accordance with data from the Mediterranean. The specimen of silver-cheeked toadfish was a female with gonad in resting stage and the specimens of blunthead puffer were adults (male and female) with gonads in maturing, mature/spawner and post-spawning stage. The stomach contents of the specimen of silver-cheeked toadfish were composed by Mollusca Opistobranchia and Crustacea Brachyura. Stomach contents analysis of S. pachygaster confirmed that Mollusca are the preferred prey for this species. However, the presence of Crustacea (shrimps, crabs) and fish in the stomachs indicates that the blunthead puffer has a broad and variable diet in the south Adriatic Sea. The present study suggests the presence of an established population of blunthead puffer on the continental shelf of the southeast Adriatic Sea.U radu je predstavljen prvi nalaz lesepsijske migratorne vrste Lagocephalus sceleratus (srebrenopruga napuhača) na talijanskoj strani južnog Jadrana. Uz to, analizirana su i četiri primjerka vrste Sphoeroides pachygaster (napuhača). Meristički i morfometrijski podaci dobiveni analizom primjeraka ovih dviju vrsta su u suglasnosti sa postojećim podacima iz Sredozemlja. Analizirana jedinka srebrenopruge napuhače bila je ženka, s gonadama u stadiju mirovanja, dok su jedinke napuhače bile u stadiju sazrijevanja, zrelom stadiju i izmrještenom stadiju. Sadržaj želudaca srebrenopruge napuhače sastojao se od ostataka skupina Mollusca, Ophistobranchia i Crustacea Brachyura. Sadržaj želudaca jedinki vrste Sphoeroides pachygaster potvrdio je da ova vrsta u prehrani preferira mekušce (Mollusca) kao plijen. Ipak, nazočnost ostataka rakova i kozica (Crustacea) u njihovim želucima ukazuje na raznoliku prehranu ove vrste u južnom Jadranu. Ovo istraživanje ukazuje na postojanje formirane populacije vrste Sphoeroides pachygaster na kontinentalnom šelfu jugoistočne obale Jadranskog mora

Rearing performance of Spongia officinalis on suspended

Abstract The availability of bath sponges has been recently reduced due to the depletion of natural banks due to the high fishing pressure together with some local epidemic events. At present, the commercial supply is far below the demand. The main purpose of this work was to estimate the rearing performance of Spongia officinalis var. adriatica, one of the most common Mediterranean commercial sponges, testing two different variants of culture on suspended ropes: a horizontal system placed close to the seabed, and a vertical system extended along the water column. The trials were carried out in Southern Italy (Ionian coast of Apulia, Central Mediterranean) from April 1997 to April 2000. Wild specimens of sponge were cut into pieces of different weight to test possible differences in growth and survival. During the study period, both systems resisted deterioration due to water movement and other ecological factors. In general, the growth performance (average weight, specific growth rate) did not significantly vary between the cultivation systems, nor were statistical differences in growth detected between the cuttings of different initial size. The mean growth observed was rather variable among sponge cuttings, even considering the same rearing condition and size range. The measured variations of hydrological parameters did not seem to affect survival, growth performance, or reproductive activity, which was detected almost all year round. Larger explants (about 50 g in wet weight) reached the commercial size after three years of rearing, thus identifying this initial size as the most suitable for cultivation purposes. At the end of the study period, the survival rate was 75%, with a more apparent decrease during the first year of rearing.

On the presence of Dipturus nidarosiensis (Storm, 1881) in the Central Mediterranean area

The Norwegian skate Dipturus nidarosiensis (Storm, 1881) has only recently been recorded in the western Mediterranean Sea along the coast of southern Sardinia, off Algeria and the Alboran Sea. The present study confirmed the presence of the species in the Central Mediterranean Sea by identifying morphometric, morphological features and molecular markers. Biological sampling was conducted from 2010 to 2016 on eight specimens collected through commercial landings, offshore observer programmes and scientific surveys in Adriatic and Ionian waters at depths between 320 and 720 m. The total lengths of the specimens (juveniles and adults) ranged from 268 to 1,422 mm, and their body weights ranged from 44.5 to 12,540.0 g. They showed morphometric features that corresponded to those of Norwegian skates in the Northeast Atlantic and the Western Mediterranean. In previous analyses, molecular data were obtained by mitochondrial COI sequences. The haplotype network showed the occurrence of a common haplotype (Hap_1) shared by the individuals from areas in the North Atlantic, Sardinian, Algerian and Spanish Mediterranean Sea areas but not South Africa. The occurrence of individuals in different stages of life (i.e., juveniles, sub-adults and adults) and sexual development (immature and mature) suggested the presence of a species with a permanent reproductive allocation in the deep waters of the Mediterranean, which was exposed to a low level of fishing exploitation. Indeed, the deep depth distribution of the species could be the reason for the absence of information about this species in onshore or offshore fishery data collection programmes and scientific surveys

Sardines at a junction: seascape genomics reveals ecological and oceanographic drivers of variation in the {NW} Mediterranean Sea

By evaluating genetic variation across the entire genome, one can address existing questions in a novel way while raising new ones. The latter includes how different local environments influence adaptive and neutral genomic variation within and among populations, providing insights into local adaptation of natural populations and their responses to global change. Here, under a seascape genomic approach, ddRAD data of 4609 single nucleotide polymorphisms (SNPs) from 398 sardines (Sardina pilchardus) collected in 11 Mediterranean and one Atlantic site were generated. These were used along with oceanographic and ecological information to detect signals of adaptive divergence with gene flow across environmental gradients. The studied sardines constitute two clusters (FST = 0.07), a pattern attributed to outlier loci, highlighting putative local adaptation. The trend in the number of days with sea surface temperature above 19°C, a critical threshold for successful sardine spawning, was crucial at all levels of population structuring with implications on the species' key biological processes. Outliers link candidate SNPs to the region's environmental heterogeneity. Our findings provide evidence for a dynamic equilibrium in which population structure is maintained by physical and ecological factors under the opposing influences of migration and selection. This dynamic in a natural system warrants continuous monitoring under a seascape genomic approach that might benefit from a temporal and more detailed spatial dimension. Our results may contribute to complementary studies aimed at providing deeper insights into the mechanistic processes underlying population structuring. Those are key to understanding and predicting future changes and responses of this highly exploited species in the face of climate change

Identifying priority areas for spatial management of mixed fisheries using ensemble of multi‐species distribution models

Spatial fisheries management is widely used to reduce overfishing, rebuild stocks, and protect biodiversity. However, the effectiveness and optimization of spatial measures depend on accurately identifying ecologically meaningful areas, which can be difficult in mixed fisheries. To apply a method generally to a range of target species, we devel- oped an ensemble of species distribution models (e-SDM) that combines general ad- ditive models, generalized linear mixed models, random forest, and gradient-boosting machine methods in a training and testing protocol. The e-SDM was used to integrate density indices from two scientific bottom trawl surveys with the geopositional data, relevant oceanographic variables from the three-dimensional physical-biogeochemi- cal operational model, and fishing effort from the vessel monitoring system. The de- termined best distributions for juveniles and adults are used to determine hot spots of aggregation based on single or multiple target species. We applied e-SDM to juvenile and adult stages of 10 marine demersal species representing 60% of the total demer- sal landings in the central areas of the Mediterranean Sea. Using the e-SDM results, hot spots of aggregation and grounds potentially more selective were identified for each species and for the target species group of otter trawl and beam trawl fisheries. The results confirm the ecological appropriateness of existing fishery restriction areas and support the identification of locations for new spatial management measures