Sardina Pilchardus Research Articles

Scientific progress made towards bridging the knowledge gap in the biology of Mediterranean marine fishes.

The Mediterranean Sea is a renowned biodiversity hotspot influenced by multiple interacting ecological and human forces. A gap analysis on the biology of Mediterranean marine fishes was conducted in 2017, revealing the most studied species and biological characteristics, as well as identifying knowledge gaps and areas of potential future research. Here, we updated this gap analysis five years later by reviewing the literature containing information on the same eight biological characteristics, namely length-weight relationships, growth, maximum age, mortality, spawning, maturity, fecundity and diet, for the 722 fish species of the Mediterranean Sea. The results revealed a considerable knowledge gap as 37% of the species had no information for any of the studied characteristics, while 13% had information on only one characteristic. Out of all the biological characteristics, the smallest knowledge gap was found in the length-weight relationships (studied for 51% of the species, mainly in the eastern Mediterranean), while the least studied characteristic was mortality (studied for 10% of the species). The western and eastern Mediterranean Sea were leading forces in data collection exhibiting the narrowest gaps between current and desired knowledge. The most studied species across the entire region were the highly commercial European hake (Merluccius merluccius), red mullet (Mullus barbatus), European anchovy (Engraulis encrasicolus), European pilchard (Sardina pilchardus), common pandora (Pagellus erythrinus), and annular seabream (Diplodus annularis). The knowledge gap has shrunk by 6% during the last five years, with 40 new species having at least one study on their biology. Moreover, research has slightly shifted towards species that have been traditionally neglected, e.g., sharks, rays and chimaeras (chondrichthyans). It is recommended that research becomes less focused on commercial species and more targeted towards the identified gaps, vulnerable species (e.g., deep-sea species and chondrichthyans) and species that could potentially pose a threat (e.g., non-indigenous species) to the ecosystems of the everchanging Mediterranean Sea.

Long term oscillations of Mediterranean sardine and anchovy explained by the combined effect of multiple regional and global climatic indices

It is widely known that the abundance and distribution dynamics of populations of small pelagic clupeid fish, such as sardines and anchovies, are affected by large-scale climate variability, which may lead to changeovers to new regimes of small pelagics. However, long-distance climatic oscillations, such as El Niño/La Niña and the Pacific Decadal Oscillation, have been little explored in the Western Mediterranean Sea. We investigated the possible effects of the South Oscillation Index (i.e. the atmospheric oscillation coupled with the El Niño/La Niña) and Pacific Decadal Oscillation on fluctuations in catches of European anchovy (Engraulis encrasicolus) and sardine (Sardina pilchardus) in the Western Mediterranean Sea, and their association with regional climate oscillations (i.e. the Atlantic Multidecadal Oscillation, the North Atlantic Oscillation, the Western Mediterranean Oscillation index, and the Arctic Oscillation). The study covered two periods: (a) landings between 1950 and 2016; and (b) abundance, biomass, and physical condition (i.e., relative condition index) between 2004 and 2016. The main large-scale climatic oscillations in the region were studied using General Additive Models to investigate the relationship between a time series of species measures of European sardine and anchovy from Geographical Subarea 06. Results show that the long-term Pacific Decadal Oscillation favours sardine landings, whereas the combined effect of the Western Mediterranean Oscillation Index and the Atlantic Multidecadal Oscillation favours anchovy. We discuss potential links between the present findings and changes in the plankton community caused by prevailing winds in the region driven by long-distance climate oscillations and their impact on the reduction in small pelagic fish populations in the study area.

Oogonial proliferation and early oocyte dynamics during the reproductive cycle of two Clupeiform fish species.

Although oogonial proliferation continues in mature females in most teleosts, its dynamics and the transformation of oogonia to early meiotic oocytes during the reproductive cycle have received little attention. In the present study, early oogenesis was examined throughout the reproductive cycle in two Clupeiform fishes, the Mediterranean sardine, Sardina pilchardus, and the European anchovy, Engraulis encrasicolus. Observations using confocal laser scanning microscopy (CLSM) provided extensive information on markers of oogonial proliferation (mitotic divisions, oogonia nests) and meiotic prophase I divisions of oocyte nests (leptotene, zygotene, pachytene, diplotene) in ovaries of different reproductive phases. In sardine, oogonial proliferation persisted throughout the entire reproductive cycle, whereas in anchovy, it was more pronounced prior to (developing ovaries) and after (resting ovaries) the spawning period. Anchovy exhibited a higher rate of meiotic activity in developing ovaries, whereas sardine exhibited a higher rate in resting ovaries. The observed differences between the two species can potentially be attributed to different seasonal patterns of energy allocation to reproduction and the synchronization between feeding and the spawning season.

Cosmeceutical Potential of Extracts Derived from Fishery Industry Residues: Sardine Wastes and Codfish Frames.

The fishery industry generates large amounts of waste (20–75% (w/w) of the total caught fish weight). The recovery of bioactive compounds from residues and their incorporation in cosmetics represents a promising market opportunity and may contribute to a sustainable valorisation of the sector. In this work, protein-rich extracts obtained by high-pressure technologies (supercritical CO2 and subcritical water) from sardine (Sardina pilchardus) waste and codfish (Gadus morhua) frames were characterized regarding their cosmeceutical potential. Antioxidant, anti-inflammatory and antibacterial activities were evaluated through chemical (ORAC assay), enzymatic (inhibition of elastase and tyrosinase), antimicrobial susceptibility (Klebsiella pneumoniae, Staphylococcus aureus and Cutibacterium acnes) and cell-based (in keratinocytes-HaCaT) assays. Sardine extracts presented the highest antibacterial activity, and the extract obtained using higher extraction temperatures (250 °C) and without the defatting step demonstrated the lowest minimum inhibitory concentration (MIC) values (1.17; 4.6; 0.59 mg/mL for K. pneumoniae, S. aureus and C. acnes, respectively). Codfish samples extracted at lower temperatures (90 °C) were the most effective anti-inflammatory agents (a concentration of 0.75 mg/mL reduced IL-8 and IL-6 levels by 58% and 47%, respectively, relative to the positive control). Threonine, valine, leucine, arginine and total protein content in the extracts were highlighted to present a high correlation with the reported bioactivities (R2 ≥ 0.7). These results support the potential application of extracts obtained from fishery industry wastes in cosmeceutical products with bioactive activities.

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

A total of 1345 specimens belonging to 58 different species of wild fish and seafood from the western Mediterranean Sea were analyzed to assess total mercury levels and to estimate which species meet the EU recommendations for human consumption (0.5 μg g−1 ww) in all cases. All fish species were caught off the Mediterranean coasts and intended for human consumption. All specimens were collected from local markets located in Spain, Italy and France that sell fish caught by local fishermen (Eivissa, Menorca, Mallorca, Alacant, L'Ampolla, Ametlla de Mar, Marseille, Genoa, Civitavecchia, Alghero) at different time periods. Mercury concentrations were measured by thermal decomposition-gold amalgamator-atomic absorption spectrometry.Only thirteen species were found that did not exceed 0.5 μg g−1 ww in any specimen analyzed. These safe species were sardines (Sardina pilchardus), anchovies (Engraulis encrasicolus), blue whiting (Micromesistius poutassou), picarel (Spicara smaris), blackspot seabream (Pagellus bogaraveo), gilthead seabream (Sparus aurata), pearly razorfish (Xyrichtys novacula), surmullet (Mullus surmuletus), painted comber (Serranus scriba), brown meagre (Sciaena umbra), salema (Sarpa salpa), common dolphinfish (Coryphaena hippurus) and squid (Loligo vulgaris). These species occupy different trophic levels, have different lengths and average weights, but show a low mercury concentration than others living in the same environments.Potential human consumption of these species as sole source of fish would imply estimated weekly intakes representing between 49% and 70% of the recommended provisional tolerable weekly intake of methylmercury in the worst case.Health authorities should pay specific attention to species that do not meet EU thresholds and make appropriate precautionary health recommendations, especially for pregnant women and children.

Length Based Assessments for European Pilchard Sardina pilchardus and European Anchovy Engraulis encrasicolus, in the İzmir Bay, Aegean Sea

In the Mediterranean Sea, European pilchard Sardina pilchardus and European anchovy Engraulis encrasicolus are the most important small pelagic fish regarding their ecological role, and revenue. Here, we perform a comprehensive assessment of length-based methods for those small pelagics from İzmir Bay, Aegean Sea. Therefore, the Length-based Bayesian Estimator and Length-based Spawning Potential Ratio were used to evaluate the stock structure and status of two important small pelagic fish. The length range for Sardina pilchardus was from 7.1 cm to 17.3 cm in TL. The ratios Lmean/Lopt and Lc/Lc_opt were over 1, suggesting truncated length structure and fishing of not too small individuals. The proportion of mature individuals in the catch was far less than half (36%) suggesting that in these fisheries catch consists mostly of immature individuals. The length range for Engraulis encrasicolus was from 5 cm to 15 cm in TL. The ratios Lmean/Lopt and Lc/Lc_opt were over 1 (1.2 and 1.3, respectively), suggesting truncated length structure and fishing of large individuals. The proportion of mature individuals in the catch was over half (52%) suggesting that in these fisheries catch consists of adults. The estimated sizes at median 50% selectivity (SL50) for S. pilchardus (11.1 cm) was ∼0.6 cm shorter than its lengths at 50% maturity (L50) of 11.7 cm, which indicates that a large proportion of the catch was immature. The median estimate of the spawning potential ratio was ∼0.19 for S. pilchardus and ∼0.48 for E. encrasicolus.

A Variation in the Mortality of European Anchovy and European Pilchard After Sieving and Discarding from a Purse Seine Fishery in the Eastern Mediterranean

Discard mortality of European anchovy (Engraulis encrasicolus) and European pilchard (Sardina pilchardus) was investigated during commercial purse seine fishing operations off İzmir Bay, Turkey. In total, 6703 anchovy and 2545 sardine individuals were observed for seven days in five survival experiments carried out from March to October 2019. Only in March, fish cages were used and observed by divers. In the other trials, fish were observed in holding tanks; dead fish were collected and any surviving fish were fed. In the study, we compared the mortality of sorted and unsorted fish. The GLM model for European anchovy demonstrated a highly significant category effect (p<0.0001) and a highly significant interaction between length-related mortality and season (CL: season; p<0.0001). There were also significant differences in length-related mortality ratio according to the different categories in both seasons (p<0.0001). However, there was a highly significant interaction between mortality ratio, length, uncrowded category, and spring (p<0.005) for European pilchard. The observations showed that high mortalities occurred in the sorted fish categories of both pelagic species during the experiments.

Balık silajı üretimi için basit bir yöntem: İnokulum olarak yoğurt kullanımı

The evaluation of seafood processing wastes is an important issue in terms of both preventing environmental pollution and adding value to these wastes economically. The most practical method that can convert seafood processing waste into a valuable feed source and plant fertilizer is to make silage. In this study, the ripening times and nutritional components of fish silages prepared with direct addition of lactic acid bacteria culture (Streptococcus thermophilus), acidifying chemicals (formic acid) and yogurt, which is a fermented food, were compared. In the research, sardine fish (Sardina pilchardus) wastes (head, skin, bones, internal organs, etc.) were used in fish silage production. It was observed that all fish silages completed the ripening phase within a maximum of 10 days. It was determined that the moisture, ash, protein and lipid contents of the groups prepared with acid, bacteria and yoghurt ranged between 63-66%, 5.6-5.7%, 11.3-11.8% and 12.18-13.65%, respectively. As a result of the research, it was observed that fish silages made with the addition of yoghurt as an alternative to silages made with direct addition of pure bacterial culture or acid addition met the expectations in terms of both ripening time and nutrient components.

Diet and trophic interactions of Mediterranean planktivorous fishes

Diet and trophic interactions of seven species of planktivorous fishes: European anchovy Engraulis encrasicolus, European sardine Sardina pilchardus, round sardinella Sardinella aurita, European sprat Sprattus sprattus, red bandfish Cepola macrophthalma, damselfish Chromis chromis and bogue Boops boops were studied in the Bay of Marseille (North-Western Mediterranean Sea) from March to September 2017. Taxonomic composition and size distribution of prey were studied using stomach content analysis, and compared to prey availability determined by continuous zooplankton sampling at a fixed point. Frequently consumed items included copepods, decapod larvae and fish eggs. Comparatively, E. encrasicolus consumed more calanoid copepods (i.e. Centropages spp.), S. pilchardus, S. aurita and S. sprattus consumed more harpacticoid copepods (i.e. Microsetella/Macrosetella spp.), C. macrophthalma consumed more decapod larvae, C. chromis consumed more pteropods and B. boops consumed more benthic polychaetes. Sardina pilchardus consumed the widest diversity of prey. Prey size distribution and average prey size significantly differed among species. The prey–predator size ratio (PPSR) was highest for B. boops and lowest for S. aurita. Carbon and nitrogen stable isotope composition of species overlapped, probably due to the ingestion of particulate organic matter from the same sources at the base of the planktonic food web in the Bay of Marseille. Furthermore, trophic niche overlap supported the hypothesis of potential trophic competition between Engraulidae and Clupeidae.

Bacteria forming histamine and shelf life of sardine (Sardina Pilchardus) at different temperatures and storage time with emphasis on histopathological changes in skeletal musculature

Bacteria forming histamine and shelf life of sardine (Sardina Pilchardus) at different temperatures and storage time with emphasis on histopathological changes in skeletal musculature

Variations in nutritional quality and fatty acids composition of sardine (Sardina pilchardus) during canning process in grape seed and olive oils.

Fish canning industries generally use different oils to ensure the juicing stage of canned sardines. In this context, we tested the use of grape seed oil (GSO) which could provide several health benefits to consumers. This study compared its effects on the quality of canned sardine to that of olive oil (OO). Total polyphenols, flavonoids and non flavonoids of the tested GSO were significantly higher than those of the OO. Also, The GSO was rich in polyunsaturated fatty acid (PUFA), namely linoleic acid (65.36% of total fatty acids). The use of GSO in the sardine sardines canning process increased significantly fat, protein and ash contents after 90days of conservation. The fatty acid profile was dominated by PUFA for all the tested samples. Docosahexaenoic acid was the most abundant unsaturated fatty acid, followed by linoleic acid in GSO samples (20.86 ± 0.06% compared to 1.46 ± 0.05% in fresh sardine) and oleic acid in OO samples. Both atherogenic and thrombogenic indices decreased after the canning process in OO and GSO to less than 1. Thus GSO seems to improve the lipid nutritional quality in fresh sardine. In addition, the values for thiobarbituric acid and Total volatile base nitrogen did not exceed critical limits.

Seasonal approach to forecast the suitability of spawning habitats of a temperate small pelagic fish under a high-emission climate change scenario

Spawning habitats of cold-water, European small pelagic fishes have shifted poleward in the last three decades coincident with gradual ocean warming. We predicted present-day, season-specific habitat suitability for spawning by European sardine Sardina pichardus in the Atlantic Ocean and Mediterranean and Black Seas, and projected climate-driven changes in suitable areas from 2050-2099 under the IPCC – RCP 8.5 scenario. Sea surface temperature and distance to the coast had the greater influences in spawning habitats, reflecting the temperature- and coastal-dependent spawning of sardines. Chlorophyll-a was the third most important explanatory variable for spawning in winter to summer. Winds were predominantly important during autumn, whilst sea surface salinity was an important driver during spring and summer. Present-day, “hotspots” for spawning were identified in regions of highly productive, salty waters, where SST was between 6 and 18°C from autumn to spring or 16 and 25°C during summer and favourable winds occurred that would retain eggs and larvae closer to the coast (< 250 km). For future scenarios, forecasts indicate that environmental optima for spawning is projected to be in regions where SST varies between 11°C and 18°C from autumn to spring; and between 18°C and 24°C during summer. However, a negative relationship between phytoplankton productivity and habitat suitability induced by warming is likely to occur in the future. Projections suggest that suitable spawning habitats in all seasons will shift to higher latitudes, with a prominent range expansion along the coast of Norway during winter and autumn (> 83%). The total spawning area, however, was projected to contract in the future during spring (-10.5%) and autumn (-4.1%) due to losses of currently suitable areas along the Atlantic African Coast and Mediterranean Sea. Such regions currently support the greatest sardine stocks but climate-driven warming and decreased plankton productivity are projected to make these areas unsuitable for spawning and likely also for sardine fisheries in future.

Trophic ecology of northern gannets Morus bassanus highlights the extent of isotopic niche overlap with other apex predators within the Bay of Biscay

Understanding the linkages within complex and evolving marine food webs is essential to comprehend marine ecosystem structure and dynamics. Carbon (δ13C) and nitrogen (δ15N) stable isotope signatures are recognized to be powerful descriptors of the trophic ecology and trophic relationships within marine communities. Apex predators such as seabirds can influence the structure of communities by predating in lower trophic levels. They also convey information both over a range of spatial and temporal scales due to their high mobility and longevity, respectively. For this reason, here, we studied the trophic ecology of northern gannets and the extent of niche overlap with other apex predators within the Bay of Biscay (North-East Atlantic), a key feeding area for numerous predatory species. Mixing models indicated that northern gannets fed primarily on European anchovy Engraulis encrasicolus and on a mixed group composed of European sardine Sardina pilchardus, European sprat Sprattus sprattus, juvenile hake Merluccius merluccius, Atlantic mackerel Scomber scombrus and Atlantic horse mackerel Trachurus trachurus. Within the apex predator community, the northern gannets trophic niche overlapped the most with common guillemots Uria aalge (15.58%, based on Stable Isotope Bayesian Ellipses (SIBER)) and overlapped to a lesser extent with cetacean species occupying shelf habitats (i.e., the harbour porpoise Phocoena phocoena (9.99%) and the short-beaked common dolphin Delphinus delphis (10.37%)). Overall, the overlap found was moderate indicating trophic similarities and dissimilarities between these species. Information on trophic interactions between co-existing species is necessary for holistic environmental management, particularly in areas where several megafauna species share their foraging grounds with fisheries activity.

Diet of Adult Sardine Sardina pilchardus in the Gulf of Trieste, Northern Adriatic Sea

Food availability is thought to exert a bottom-up control on the population dynamics of small pelagic fish; therefore, studies on trophic ecology are essential to improve their management. Sardina pilchardus is one of the most important commercial species in the Adriatic Sea, yet there is little information on its diet in this area. Adult sardines were caught in the Gulf of Trieste (northern Adriatic) from spring 2006 to winter 2007. Experimental catches conducted over 24-h cycles in May, June and July showed that the sardines foraged mainly in the late afternoon. A total of 96 adult sardines were analysed: the number of prey varied from a minimum of 305 to a maximum of 3318 prey/stomach, with an overall mean of 1259 ± 884 prey/stomach. Prey items were identified to the lowest possible taxonomical level, counted and measured at the stereo-microscope. Overall, sardines fed on a wide range of planktonic organisms (87 prey items from 17 μm to 18.4 mm were identified), with copepods being the most abundant prey (56%) and phytoplankton never exceeding 10% of the prey. Copepods of the Clauso-Paracalanidae group and of the genus Oncaea were by far the most important prey. The carbon content of prey items was indirectly estimated from prey dry mass or body volume. Almost all carbon uptake relied on a few groups of zooplankton. Ivlev’s selectivity index showed that sardines positively selected small preys (small copepods < 1 mm size), but also larger preys (such as teleost eggs, decapod larvae and chaetognaths), confirming their adaptive feeding capacity.

Nematode Parasites of the European Pilchard, Sardina pilchardus (Walbaum, 1792): A Genuine Human Hazard?

Simple SummaryThe European pilchard is one of the most frequently consumed fish species in Mediterranean countries, especially in Italy and Spain, and has been reported as the cause of at least eight human anisakidosis cases in Spain since 1991, the parasitic disease caused by the ingestion of fish or cephalopods infested by the larval stage of anisakid nematodes. With the aim to shed light on the potential human parasitosis risk posed by these nematode larvae, we helminthologically analyzed a total of 350 sardines (European pilchard) captured in the Atlantic Ocean (175 sardines) and the Mediterranean Sea (175 specimens), acquired in various Spanish nationwide supermarket chains. The statistical analysis of some helminth parameters revealed a higher presence of nematodes belonging to the genus Hysterothylacium (frequency of parasitation of 24.29%; total mean parasite burden of 2.36), usually considered non-parasitic for humans (only three cases reported worldwide), when compared to nematodes of the genus Anisakis (5.71%; 0.16). The human anisakidosis risk after the consumption of raw or undercooked sardines and the role of Hysterothylacium, the most frequent nematode, is discussed, providing information to consumers. To avoid human infection by anisakid larval nematodes, the established preventive measures are confirmed and new ones are proposed.The European pilchard is one of the most frequently consumed fish species in Mediterranean countries, especially in Italy and Spain, and has been reported as the cause of at least eight human anisakidosis cases in Spain. With the aim to shed light on the potential human parasitosis risk posed by nematode larvae belonging to families Anisakidae or Raphidascarididae, a total of 350 sardines captured in the Atlantic Ocean (175 specimens) and the Mediterranean Sea (175 specimens), acquired in various Spanish nationwide supermarket chains, were helminthologically analyzed. The statistical analysis of some helminth parameters revealed a higher presence of nematodes belonging to the genus Hysterothylacium (prevalence 24.29%; mean abundance of 2.36), usually considered non-parasitic for humans (only three cases reported worldwide), when compared to nematodes of the genus Anisakis (5.71%; 0.16). The human anisakidosis risk after the consumption of raw or undercooked sardines and the role of Hysterothylacium, the most frequent nematode, is discussed, providing information to consumers. To avoid human infection by anisakid larval nematodes, the established preventive measures are confirmed and new ones are proposed, such as the consumption of sardines preferably caught in the Mediterranean and of small-sized specimens available, and the immediate evisceration after fishing.

Population Structure, Age and Growth of Sardine (Sardina pilchardus, Walbaum, 1792) in an Upwelling Environment

Information on the biological parameters of exploited fish stocks facilitates the objective assessment and management of these living resources. The sardine (Sardina pilchardus) is considered as overexploited in northwest Africa. It is a key species of the Canaries current large marine ecosystem (CCLME) of the Atlantic Ocean due to its socioeconomic importance, as well as being a key intermediary species in marine food web. A massive decline in caught fish for Senegal over half a century is also reported (61,648 t in 1994 to 7486 t in 2017). Here, we analyzed the age and growth parameters of sardines in the Exclusive Economic Zone of northern Senegal. Maximum body size was 31 cm total length (TL). A growth performance index (φ′) and a growth rate coefficient (K) of 2.65 and 0.85, respectively, were determined, with this being the first record for this country. Sardines had higher asymptotic length (L∞, 30.5 cm TL) and age (6 years) in northern Senegal compared with Morocco (Atlantic Ocean) and the Mediterranean Sea. The asymptotic length found in Northern Senegal was also higher than in other part of the CCLME and Mediterranean Sea. This difference might be attributed to differences in the pelagic habitat, environmental factors, and/or fishing pressure. This study provides new insights towards establishing management measures, especially in data-poor fisheries and should act as an advocacy to increase sub-regional collaborations.

Major population’s separation area for sardine (Sardina pilchardus) and hake (Merluccius merluccius) revealed using otolith geochemistry on the Atlantic coast of Morocco

The Moroccan Atlantic coast (21–36°N) is part of one of the most productive marine eastern boundary upwelling ecosystems worldwide. Nevertheless, information about the structure of its exploited fish populations is scarce. In this study, whole otolith elemental signatures of 111 hake (Merluccius merluccius) and 118 of sardine (Sardina pilchardus), sampled during the period June 2012 - July 2013 in 11 locations along the Moroccan coast, were analysed by solution based ICP MS. These 2 species were selected for their importance in the fisheries, their contrasted life histories, and differences in trophic behavior. Whole otolith comparisons used Ba/Ca, Li/Ca, Mg/Ca, Mn/Ca, Rb/Ca, Sc/Ca, Sr/Ca, to demonstrate the regional population structures. The linear discriminant analysis of whole otolith chemistry data of hake and sardine reached respectively 88 % and 71 % mean adequate classification, and rose to 100 % within the identified groups. The spatial variation in the elemental composition of the otoliths of the two species were significant, and all showed a clear geographic cut, thus identifying a northern and a southern group. The major split for the two species occurred in the same area corresponding to the transition zone between the northern temperate mud-shelf ecosystem and the arid ecosystem at the south (28–29°N). Complex oceanographic processes may act in this area as a barrier to planktonic dispersion favouring isolation processes that lead to distinct populations. These findings are new to hake and confirm previous studies on sardine population structure, and should be considered in fisheries management to better match management units and stock structure.

The Effect of Different Freshness of Raw Material on Lipid Quality and Sensory Acceptance of Canned Sardines.

We studied how storing fresh sardines (Sardina pilchardus) on ice for 0–15 days would affect lipid quality and sensory acceptance after the sardines were later canned. Average moisture and diacylglycerol contents showed a decreasing trend during storage time for sardines stored for to 0–10 days and an increasing trend for samples stored for 13–15 days. Total lipid and triacylglycerol average values increased with storage time of 0–10 days. In contrast, sardines stored for 13–15 days showed decreased values of lipids and triacylglycerols. Increased storage times also led to increased average saturated fatty acid (STFA) content and browning and decreased polyunsaturated fatty acid (PUFA) values and PUFA/STFA and ω3/ω6 ratios. Notably, the effect of storage time on PUFA/STFA and ω3/ω6 ratios and browning development was found significant (p < 0.05). Sensory descriptors revealed only slight quality differences with previous storage on ice for 0-10 days. In contrast, a substantial (p < 0.05) decrease (appearance and texture) was detected in samples corresponding to a 13–15-day period, such samples being considered unacceptable. Storage on ice not exceeding 10 days is recommended for sardines before being shipped to canneries for further processing. Furthermore, the use of efficient storage including preserving technologies would be desirable.

Unravelling the drivers of variability in body condition and reproduction of the European sardine along the Atlantic-Mediterranean transition

Body condition and reproduction data are broadly used to assess the health status of fish because of its implications for recruitment and ecosystem structure. Sardina pilchardus is a small pelagic distributed throughout both Mediterranean and Eastern Atlantic. Seasonal trend analysis of energy storage and reproduction was carried out in sardines from two areas along the Atlantic-Mediterranean transition: Southern Portugal-Gulf of Cádiz (POR-GC) (Atlantic Ocean) and Alboran Sea (Alb) (Mediterranean Sea) from 2019 to 2021. Energetic condition was estimated using tissue and mesenteric fat content, hepatosomatic index (HSI), and the relative condition factor (Kn). Sex, reproductive developmental stage, and gonadosomatic index (GSI) were also obtained. In addition, the oceanographic and meteorological characteristics of the areas were analysed. Results showed that seasonal Kn, tissue and mesenteric fat content, and HSI values of POR-GC specimens exceeded Alb's with summer arrival, period in which sardine acquires reserves to allocate them to reproduction. These differences could be associated to greater productivity of the former area mainly due to rivers discharges and trade winds intensification during summer (from July to September). Furthermore, gonad maturation of POR-GC stock occurred before the Alb. However, no spawning capable individuals were identified until February in POR-GC. In contrast, in Alb it was observed a remarkable fraction of spawning capable and active spawner individuals in October. We hypothesized the migration of mature individuals from POR-GC to the spawning areas located in the Alb. Seasonal genetic population studies are required to untangle it and reliably evaluate the environmental effect on the stocks.

A study of nutritional properties in European pilchard, Golden grey mullet, and Common sole caught in Mersin Bay, North-east Mediterranean Sea

European pilchard (Sardina pilchardus, Walbaum, 1792), Golden grey mullet (Liza aurata, Risso 1810), and Common sole (Solea solea, Quensel, 1806) are the commercially important fish species caught by trawl and purse seine in Mersin Bay, in the Mediterranean. This study was aimed to investigate proximate compositions, carbohydrate levels, energy contents, fatty acid profiles, and the lipid quality indexes of European pilchard, Golden grey mullet, and Common sole caught by trawl. The crude protein, lipid, moisture, and ash content were determined as proximate compositions. The protein levels were determined as the highest levels in sardine (24.08%) followed by the common sole (18.91%) and golden grey mullet (18.01%). An inverse correlation between the moisture contents and the lipid levels among the fish was observed in this study. The ash levels, carbohydrate values, and energy contents were in the following order: European pilchard &amp;gt; Golden grey mullet &amp;gt; Common sole. Palmitic acid (C16:0) and oleic acid (C18:1n9) were the highest level of fatty acids in SFA (saturated fatty acids) and MUFA (monounsaturated fatty acids) for the Golden grey mullet and Common sole, respectively. The levels of eicosapentaenoic acid (EPA) in all fish used in this study were found to be different from each other (P&amp;lt;0.05). The amount of docosahexaenoic acid (DHA) were lower than that of EPA in European pilchard and Golden grey mullet. Although the levels of EPA and DHA in fish are found to be in the range of 4.91 - 11.01% and 6.85 - 8.87%, respectively and different from each other, these two fatty acids are good for health.