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We undertook a systematic evaluation of the lipid, protein, calorie, and fatty acid composition in 35 species of fish, shellfish and molluscs commonly consumed throughout the four seasons of the year in Andalusia, Spain. Using a portion of muscle tissue the following were measured in each study unit: total lipids (extraction using Folch's method and gravimetry), protein concentration (Kjehldal's method), total calories (direct calorimetry), and composition of fatty acids (gas chromatography). The lipid, protein, and different fatty acid concentrations found are presented in table form. There was a high degree of inter-species variability in the concentration of lipids and the various fatty acids. There was also a high degree of intra-species seasonal variability in some cases. The relative proportion of fatty acids was not independent of the total concentration of lipids, independently of the season studied. This systematic study of a large group of species shows that the cataloguing of fish as 'white' or 'blue' depends especially on the time of year they are captured. For example, in spring the mackerel (Scomber scombrus), a fish considered traditionally to be 'blue' (fatty), has the same lipid concentration as the dover sole (Solea vulgaris), commonly considered to be 'white' (little fat), and the sea pike (Merluccius merluccius) has a higher lipid concentration in autumn than the jack mackerel (Trachurus trachurus). Even greater differences existed when the fish were classified according to their richness in n-3 fatty acids. These differences in the total lipid concentration and the composition of fatty acids, as well as the inter-relations between them, may, under certain circumstances, be important for the calculation of dietary calories and nutritional values, and may explain the differences found between the various tables of food composition, as well as the divergent results in epidemiological studies on the association between fish in diets and various diseases, such as diabetes or ischaemic cardiopathy.

The goal of this study was to evaluate the chemical composition and the fatty acid profile of mantle and tentacle of male and female Sepia officinalis, sampled at four seasons from the Mediterranean sea of Tunisia. S. officinalis were found to be rich in glycogen, protein and oil, and significant differences were observed between samples. The level of saturated fatty acid and unsaturated fatty acid showed significant variability among sex and during seasons. DHA and EPA, as polyunsaturated fatty acids, were the most abundant in all samples (14.8-27.8 % and 10.4-18.3 %, respectively). Oleic acid was the most abundant monounsaturated fatty acids (1.63-4.52 %). Σn3 and Σn6 was remarkably different between seasons and among sex. This study could be suitable for the development of reliable guide of fatty acid accumulation in cephalopod. [ABSTRACT FROM AUTHOR]

The effects of season and sex on the fatty acids (FAs) and proximate compositions of the mantle of the mature common cuttlefish were evaluated. The results of the proximate composition showed that the lowest lipid content was obtained from females in winter (0.74%), whereas the highest level of lipid was found in males in autumn (0.94%; p < 0.05). The protein levels of the mantle of the mature male of common cuttlefish were significantly higher ( p < 0.05) than those found in female specimens. The FA compositions of each sex for all seasons ranged from 29.4% to 32.5% saturated FAs, 8.7-11.1% monounsaturated FAs and 48.2-54.6% polyunsaturated fatty acids (PUFAs). The proportions of n-3 PUFAs (44.0-50.6%) were higher than n-6 PUFAs (3.4-4.3%) regardless of sex and seasons. The levels of eicosapentaenoic acid in the mature common cuttlefish mantle in spring, autumn and winter were 15.9-17.8%, 16.3-17.2% and 15.7-16.8% while those of docosahexaenoic acid were 32.5-33.0%, 27.5-29.0% and 28.7-31.1%, respectively. [ABSTRACT FROM AUTHOR]

This study aims to describe the variability of albacore ( Thunnus alalunga) diet in the Northeast Atlantic and Mediterranean Sea and to identify possible relationships between this variability and the features of different feeding areas, the behavior, and the energetic needs of albacore. Stomach contents from albacore caught in five zones of the Bay of Biscay and surrounding waters ( n = 654) and three zones of the Mediterranean Sea ( n = 152) were analyzed in terms of diet composition and stomach fullness. Carbon and nitrogen stable isotope and C/N ratios were measured for white muscle and liver from albacore in the Bay of Biscay ( n = 41) and Mediterranean Sea ( n = 60). Our results showed a spatial, seasonal, inter-annual, and size-related variability in the diet of albacore. Albacore diet varied by location in the Mediterranean Sea, with a particularly high proportion of cephalopods, and low δN values in the Tyrrhenian Sea. In the Northeast Atlantic, albacore consumed a higher proportion of crustaceans and a lower proportion of fishes in the most offshore sampling zone than inshore. The digestion states of the major prey reflected a diurnal feeding activity, indicative of feeding in deeper waters offshore, whereas on the continental slope, feeding probably occurred in surface waters at night. Important seasonal and inter-annual diet variability was observed in the southeast of the Bay of Biscay, where preferred albacore prey appeared to be anchovy ( Engraulis encrasicolus). Stomach fullness was inversely related to body size, probably reflecting higher energetic needs for smaller individuals. Albacore from the Bay of Biscay had significantly lower δC and higher δN values compared with albacore from the Mediterranean Sea, indicative of regional baseline shifts, and trophic position and muscle lipid stores in albacore increased with body size. [ABSTRACT FROM AUTHOR]

Fish is the best source of polyunsaturated fatty acids (PUFA), specifically n-3 fatty acids, especially eicosapentaenoic acid and docosahexaenoic acid. The objective of the present study was to determine the fat content and fatty acid compositions of 34 marine water fish species from the Mediterranean Sea. The fatty acid compositions of fish consisted of 30.10-46.88% saturated fatty acids, 11.83-38.17% monounsaturated fatty acids and 20.49-49.31% PUFA. In most species, the following fatty acids were identified: mystiric acid (C14:0, 0.72-8.09%), pentadecanoic acid (15:0, 0.05-2.35%), palmitic acid (C16:0, 15.97-31.04%), palmitoleic acid (C16:1, 1.48-19.61%), heptadecanoic acid (C17:0, 0.31-1.84%), cis-10-heptadecenoic acid (C17:1, 0.17-2.01%), stearic acid (C18:0, 2.79-11.20%), oleic acid (C18:1n9, 2.44-28.97%), linoleic acid (C18:2n-6, 0.06-3.48%), arachidonic acid (C20:4n-6, 0.12-10.72%), cis-5,8,11,14,17-eicosapentaenoic acid (C20:5n-3, 1.94-10%) and cis-4,7,10,13,16,19-docosahexaenoic acid (C22:6n-3, 3.31-31.03%). The proportions of n-3 PUFA ranged from 12.66% for annular seabream to 36.54% for European hake, whereas the proportions of PUFA n-6 were between 1.24% for oceanic puffer and 12.76% for flathead mullet. The results of this study show that these fish species were rich in n-3 PUFA, especially, eicosapentaenoic acid and docosahexaenoic acid. [ABSTRACT FROM AUTHOR]