Integration of fisheries and ecological data to support spatial management: The case of blackspot seabream (Pagellus bogaraveo) in the western Mediterranean Sea

Wild fish and seafood species in the western Mediterranean Sea with low safe mercury concentrations

Robust identification of potential habitats of a rare demersal species (blackspot seabream) in the Northeast Atlantic

Diversity, consistency, and seasonality in parasite assemblages of two sympatric marine fish Pagrus pagrus (Linnaeus, 1758) and Pagellus bogaraveo (Brünnich, 1768) (Perciformes: Sparidae) off the coast of Algeria in the western Mediterranean Sea.

Between 2008 and 2011, the head of 150 Euthynnus alletteratus (Osteichthyes: Scombridae) caught inshore off the southeastern Iberian coast (western Mediterranean Sea) were examined for parasites. Two monogeneans, four didymozoid trematodes and four copepods were found. Parasite abundance showed a positive relationship with the annual sea surface temperature, except for Pseudocycnus appendiculatus, but negative with the sea depth (Capsala manteri, Neonematobothrium cf. kawakawa and Caligus bonito). Prevalences and mean abundances differed significantly among sampling areas, except for C. manteri, Oesophagocystis sp. 2 and Ceratocolax euthynni, and sampling years (Melanocystis cf. kawakawa, N.cf. kawakawa, P. appendiculatus and Unicolax collateralis). Results indicate that the parasite abundances of E. alletteratus in the western Mediterranean Sea depend mainly on regional environmental variables, which can show interannual variations. The presence of pelagic parasites, i.e. didymozoids and P. appendiculatus, could indicate that E. alletteratus migrates between inshore and offshore pelagic domains. The different parasite faunas reported in E. alletteratus populations from the western Atlantic Ocean and the Mediterranean Sea appear to point out the geographical host isolation. These results suggest that E. alletteratus inhabiting the western Mediterranean Sea performs inshore-offshore small-scale migrations, and not transoceanic migrations between the western Atlantic Ocean and Mediterranean Sea.

The Mediterranean Sea (MS) is an oligotrophic basin whose offshore water column exhibits low dissolved inorganic phosphorus (P) and nitrogen (N) concentrations, unusually high nitrate (NO3) to phosphate (PO4) ratios, and distinct biogeochemical differences between the Western Mediterranean Sea (WMS) and Eastern Mediterranean Sea (EMS). A new mass balance model of P and N cycling in the WMS is coupled to a pre‐existing EMS model to understand these biogeochemical features. Estimated land‐derived inputs of reactive P and N to the WMS and EMS are similar per unit surface area, but marine inputs are 4 to 5 times greater for the WMS, which helps explain the approximately 3 times higher primary productivity of the WMS. The lateral inputs of marine sourced inorganic and organic P support significant fractions of new production in the WMS and EMS, similar to subtropical gyres. The mass balance calculations imply that the MS is net heterotrophic: dissolved organic P and N entering the WMS and EMS, primarily via the Straits of Gibraltar and Sicily, are mineralized to PO4 and NO3 and subsequently exported out of the basin by the prevailing anti‐estuarine circulation. The high deepwater (DW) molar NO3:PO4 ratios reflect the high reactive N:P ratio of inputs to the WMS and EMS, combined with low denitrification rates. The lower DW NO3:PO4 ratio of the WMS (21) compared to the EMS (28) reflects lower reactive N:P ratios of inputs to the WMS, including the relatively low N:P ratio of Atlantic surface water flowing into the WMS.

Lorance, P. 2011. History and dynamics of the overexploitation of the blackspot sea bream (Pagellus bogaraveo) in the Bay of Biscay. – ICES Journal of Marine Science, 68: 290–301. The blackspot sea bream (Pagellus bogaraveo) used to be a major species in the landings from the Bay of Biscay up to the early 1980s. Nowadays, it is only a minor bycatch. Up to the mid-1970s, more than 15 000 t of blackspot sea bream were landed annually in Spanish and French ports. Thereafter, catches declined sharply from 1975 to 1985 and have stayed at low levels ever since. Here, the full history of the fishery collapse is described, using time-series of landings dating back to the early 1900s. Fishing mortalities of the main demersal stocks (hake, anglerfish, sole) were in the range 0.2–0.5 during the last 30 years. It is likely that the blackspot sea bream stock was exploited at a similar level, which is shown here to be unsustainable. The blackspot sea bream is highly sensitive to overfishing because of its protandrous hermaphroditism, with late first maturity (8 years) as females and rather low productivity. According to a yield-per-recruit model, the biomass of fecund females (BFF) is reduced to <20% of virgin BFF for a fishing mortality around 0.2. A dynamic model assuming a simple stock–recruitment relationship fitted to the reconstructed landings explained the collapse, with estimated fishing mortalities never exceeding 0.5.

The maximum length, weight, and age information of organisms in an ecosystem, moreover, the first records of migrated exotic species are essential in terms of the basis for the studies on population dynamics, stock assessment, and biological activities. Therefore, the recording of such data may be necessary for scientific databases and new related studies. The Blackspot seabream (Red seabream - Pagellus bogaraveo), which belongs to the Sparidae family, is an important seafood which is marketed fresh and frozen around the Mediterranean and the Aegean seas. Nowadays, this species has high prices depending on market demands in domestic markets as a result of overfishing and is also cultured in northern Spain. It is classified as “Near Threatened Species” in the red list due to its decreasing population trend by the IUCN. A single specimen of the Blackspot seabream with 30.7 cm in total length and 390.00 g in total weight, which was angled in the Saros Bay with a handline by a fisherman on February 08, 2019, was obtained from a fishmonger in Çanakkale. Even though there are bigger individuals in the North-east Atlantic probably depending on polar and/or deep-sea gigantism, the mentioned measurement is the proven maximum total length of this species for the Aegean Sea up to the time.

The long term variability of the sea surface temperature (SST) of the Mediterranean basin and its sub-basins for the period 1869-2006 (138 years) is investigated using the International Comprehensive Ocean-Atmosphere Data Set (I-COADS). Analysis of the SST time-series revealed a positive trend in both basin and sub-basin scale. During the last century, the highest positive SST trend is found in the Adriatic Sea (0.0141 o C/y) and the lowest one in the Aegean sea (0.0011 o C/y). This difference in the SST evolution in the two sub-basins can be related to the shift of the Eastern Mediterranean deep water formation site during the 90s, known as Eastern Mediterranean Transient (EMT). The SST variations of the Eastern Mediterranean sub-basins (Adriatic Sea, Ionian Sea, Aegean Sea, Levantine Sea) are highly correlated to each other, in contrast to the poor correlation of the SST variations between the Eastern and Western Mediterranean Sea. Harmonic analysis has shown that a dominant period of the Mediterranean variability is similar to the deep water turnover time of the basin. Comparison with climatic indices points out a high correlation of the Western Mediterranean and Adriatic Sea SST with the NAO index, while the Eastern Mediterranean SST variations are highly correlated to the Indian Summer Monsoon Index.

Population subdivision was examined in Atlantic bluefin tuna (Thunnus thynnus) through sequencing of the control region of the mitochondrial genome. A total of 178 samples from the spawning grounds in the Gulf of Mexico, Bahamas and Mediterranean Sea were analyzed. Among the samples from these locations were 36 electronically tagged bluefin tuna that were tagged in the North Atlantic and subsequently traveled to one of these known spawning grounds during the spawning season. Bluefin tuna populations from the Gulf of Mexico and the Mediterranean Sea were found to be genetically distinct based on Φst, and sequence nearest neighbor analyses, showing that these two major spawning areas support independent stocks. Sequence nearest neighbor analysis indicated significant population subdivision among the Gulf of Mexico, western Mediterranean and eastern Mediterranean Sea. However, it was not possible to find significant pairwise differences between any sampling areas when using all samples. If only samples that had a high likelihood of assignment to a specific spawning site were used (young of the year, spawning adults), the differentiation increased among all sampling areas and the Western Mediterranean Sea was distinct from the Eastern Mediterranean Sea and the Gulf of Mexico. It was not possible to distinguish samples from the Bahamas from those collected at any of the other sampling sites. These data support tagging results that suggested distinctness of the Gulf of Mexico, Eastern and Western Mediterranean Sea spawning areas. This level of stock differentiation is only possible if Atlantic bluefin tuna show strong natal homing to individual spawning grounds.

Investigating marine species population structure in a multidisciplinary framework can reveal signatures of potential local adaptation and the consequences for management and conservation. In this study we delineate the population structure of common sole (Solea solea) in the Mediterranean Sea using genomic and otolith data, based on single nucleotide polymorphism (SNPs) markers, otolith shape and otolith trace element composition data. We correlated SNPs with environmental and spatial variables to evaluate the impact of the selected features on the actual population structure. Specifically, we used a seascape genetics approach with redundancy (RDA) and genetic-environmental association (GEA) analysis to identify loci potentially involved in local adaptation. Finally, putative functional annotation was investigated to detect genes associated with the detected patterns of neutral and adaptive genetic variation. Results from both genetic and otolith data suggested significant divergence among putative populations of common sole, confirming a clear separation between the Western and Eastern Mediterranean Sea, as well as a distinct genetic cluster corresponding to the Adriatic Sea. Evidence of fine-scale population structure in the Western Mediterranean Sea was observed at outlier loci level and further differentiation in the Adriatic. Longitude and salinity variation accounted for most of the wide and fine spatial structure. The GEA detected significant associated outlier loci potentially involved in local adaptation processes under highly structured differentiation. In the RDA both spatial distribution and environmental features could partially explain the genetic structure. Our study not only indicates that separation among Mediterranean sole population is led primarily by neutral processes because of low connectivity due to spatial segregation and limited dispersal, but it also suggests the presence of local adaptation. These results should be taken into account to support and optimize the assessment of stock units, including a review and possible redefinition of fishery management units.

Demersal fish are essential to the gastronomy and economy of the Azores (Portugal), highlighting the importance of preserving their nutritional quality, which requires further research regarding the suitability of the cooking methods applied. The aim of this study was to evaluate the proximate composition and fatty acid profile of blackspot seabream (Pagellus bogaraveo) and blackbelly rosefish (Helicolenus dactylopterus) following different cooking methods (baking, boiling, frying and grilling) in order to conclude which is most suitable for preserving the nutritional quality of each species. Parameters such as water loss (calculation), moisture and ash (thermogravimetry), total fat (acid hydrolysis with extraction process) and fatty acid profile (gas chromatography with flame ionization detection) were analyzed. One-way analysis of variance (ANOVA) was conducted to compare sample means and identify significant differences between species. The obtained results indicated that grilling retained the highest mineral content, while all cooking methods resulted in unsaturated fatty acids/saturated fatty acids ratios above recommended values, confirming the high nutritional quality of both species. Based on polyunsaturated fatty acids composition and lipid health indices (fresh-lipid quality, atherogenicity index, thrombogenicity index, health-promoting index, polyene index, and hypocholesterolemic/hypercholesterolemic ratio), grilling was the most suitable method for blackspot seabream (Pagellus bogaraveo), whereas boiling was optimal for blackbelly rosefish (Helicolenus dactylopterus). These findings highlight the impact of cooking methods on these fish species nutritional value, reinforcing their role in promoting cardiovascular health.

Simple SummaryThe response of marine fish species to external pressures highly depends on their intrinsic bio-ecological traits. Among those species of commercial interest, the deep-water Blackspot Seabream (Pagellus bogaraveo, Brünnich 1768) inhabits a large geographical range, a condition that might contribute to high resilience to fishing activity. The biology of the species has been patchily investigated in past years, and to date a complete picture of its connectivity across its distribution area (Eastern Atlantic Ocean and Mediterranean Sea) has not been available. We investigated the species’ genetic variability and differentiation at a very large geographical scale by analysing nuclear DNA markers. The absence of genetic population structuring over such a wide area was found, strengthening the hypothesis that egg and larval dispersal are fundamental in sustaining the genetic connectivity of the Blackspot Seabream.Investigations of population structuring in wild species are fundamental to complete the bigger picture defining their ecological and biological roles in the marine realm, to estimate their recovery capacity triggered by human disturbance and implement more efficient management strategies for fishery resources. The Blackspot Seabream (Pagellus bogaraveo, Brünnich 1768) is a commercially valuable deep-water fish highly exploited over past decades. Considering its exploitation status, deepening the knowledge of intraspecific variability, genetic diversity, and differentiation using high-performing molecular markers is considered an important step for a more effective stock assessment and fishery management. With one of the largest efforts conceived of and completed by countries overlooking the Atlantic and Mediterranean coasts in recent years, a total of 320 individuals were collected from different fishing grounds in the Mediterranean Sea and Atlantic Ocean and analysed using 29 microsatellite loci. We applied multiple statistical approaches to investigate the species’ connectivity and population structure across most of its described distribution area. Considering the incomplete knowledge regarding the migratory behaviour of adults, here we suggest the importance of egg and larval dispersal in sustaining the observed genetic connectivity on such a large geographical scale.

Aristeus antennatus is one of the most exploited and economically important resource for fisheries in the Western and Central Mediterranean Sea displaying low population differentiation with mitochondrial and microsatellite markers. The recent development of Genotyping-by-Sequencing (GBS) methods may contribute to the discovery of SNPs and the assessment of genetic differences between populations of this species for fisheries management. Using samples from four geographical sites in Western Mediterranean and Eastern Atlantic, 115,071 putative SNPs were detected. After the stringent quality control measures and the filtering procedure, 232 SNP loci were discovered. Finally, we selected 80 SNP subset panel for Fluidigm Dynamic array application. The results showed significant differentiation among populations from the four sampling sites. Population assignment power and patterns of population differentiation were comparable between the two SNP panels. These markers represent a useful tool for future genetic application of A. antennatus populations.

Background. The deep-water longline fishery of the blackspot seabream, Pagellus bogaraveo, is an economically important fishery in the Strait of Gibraltar, which is a very complex transition ecosystem between the Mediterranean Sea and the Atlantic Ocean with an extreme spatial and temporal variability. This paper presents a series of morphometric relations for the four most important species in this fishery. Some ecological considerations about the results are also discussed. Materials and methods. The data were collected during a gear selectivity study, using different sizes of hooks baited with sardine. Relations for weight–length, length–length, and mouth dimensions for blackspot seabream, Pagellus bogaraveo (Brünnich, 1768); Atlantic pomfret, Brama brama (Bonnaterre, 1788); blackbelly rosefish, Helicolenus dactylopterus (Delaroche, 1809); and Mediterranean horse mackerel, Trachurus mediterraneus (Steindachner, 1868) were estimated and compared with the ones reported for the same species from other areas. Results. The sample size varied from 89 for T. mediterraneus to 2180 for P. bogaraveo. The fitted L–W relations explained more than 81% of the variance. For P. bogaraveo and T. mediterraneus, the estimated allometric coefficient was higher than those reported for other areas, showing a faster increase in weight, in contrast to H. dactylopterus and B. brama that showed a slower increase in weight. Moreover, linear and highly significant relations between mouth size and fish length were found for P. bogaraveo, H. dactylopterus, and T. mediterraneus. Conclusion. In this study, the first record for total length–standard length relation for H. dactylopterus is reported based on real measurements. There has been no previous studies on the relation between the different mouth size dimensions for the studied species as well as for mouth size and body length relations for P. bogaraveo and H. dactylopterus. The difference between estimated and reported coefficients might be attributed to different environmental adaptations and to the size ranges used due to the gear-size selectivity.

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 Andalucia 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.