SUMMARY:The waters surrounding the Balearic archipelago are considered to be prime spawning habitats of the bluefin tuna (Thunnus thynnus) and other tuna species such as albacore (T. alalunga) in the Mediterranean. During the 2003 bluefin and albacore spawning season, a tuna larval survey (TUNIBAL 0703) was carried out to assess the distribution of bluefin larvae in relation to hydrographic mesoscale features. Tuna larvae were collected by means of surface plankton tows with a bongo gear with a quadrangular mouth measuring 1 m diagonally. The otolith microstructure of 157 and 71 field-captured larvae of Mediterranean bluefin and albacore, respectively, were analyzed to estimate the daily growth pattern. Furthermore, biochemical analysis to estimate DNA, RNA and protein content was done on another batch of 114 bluefin and 132 albacore larvae. The size range included pre-flexion to post-flexion larvae, from 2.8 to 8.6 mm in body length. bluefin and albacore larvae grew linearly in standard length (0.35 and 0.33 mm/day, respectively) and potentially with respect to dry weight. No significant differences between species were observed in the size-weight relationship, or in the allometric relationship of body size and weight to otolith radius. However, the relationship of DNA and RNA to body size and weight showed a significant difference between species. Bluefin tuna larvae showed a greater nucleic acid content than albacore larvae. Protein content showed no significant differences with respect to body length.Keywords: bluefin tuna, albacore tuna, larvae, Mediterranean, growth, RNA/DNA, proteins. RESUMEN: CRECIMIENTO Y CONTENIDO DE LARVAS DE ATÚN ROJO (THUNNUS THYNNUS) Y ATÚN BLANCO (THUNNUS ALALUNGA).-Las aguas de las Islas Baleares representan una de las zonas más importantes de puesta del atún rojo (Thunnus thynnus) y de otras especies asociadas, como el atún blanco albacore (T. alalunga). En julio del 2003, época de puesta del atún, se realizó la campaña TUNIBAL, con el fin de delimitar las zonas de puesta del atún rojo, así como su relación con el modelo de circulación en el área. Las larvas de atunes se muestrearon mediante arrastres superficiales con una red Bongo de boca cuadrangular (1 m en diagonal). Para el estudio del crecimiento diario, 157 larvas de atún rojo y 71 larvas de atún blanco fueron analizadas. Para el estudio de la condición larvaria (DNA, RNA y proteínas), 119 larvas de atún rojo y 138 larvas de atún blanco fueron analizadas. Se analizaron larvas desde estados de pre-flexión a post-flexión, desde 2.8 a 8.6 mm de longitud estándar. Las larvas de atún rojo y atún blanco crecen linealmente en longitud estándar (0.35 y 0.33 mm/día respectivamente) y potencialmente en peso seco. No se encontraron diferencias significativas en la relación talla-peso, o en la relación del radio del otolito con talla o peso. Sin embargo, la relación entre DNA y RNA con talla o peso mostró diferencias significativas entre especies, siendo el atún rojo el que mostró mayores contenidos en ácidos nucleicos. No obstante,...

summaRY: the feeding habits of the axillary seabream, Pagellus acarne (Risso, 1810), from the Gulf of tunis were investigated in relation to season, sex and fish size (juveniles tl<14.5 cm and adults tl≥14.5 cm). a total of 536 specimens (males, females, unsexed and hermaphroditic), ranging between 11.0 and 25.2 cm tl, were collected with trammel nets from June 2005 to July 2006. their stomach contents were analysed. of the total number of examined stomachs, 279 stomachs were empty (Vacuity index, VI = 52%). the VI did not reveal significant seasonal differences when all of the specimens were analysed together; however, significant seasonal variations were observed for females. the diet of the axillary seabream was composed of 36 different prey species. the most important prey were arthropoda, mollusca and echinodermata. Both the dietary indices and the spearman's coefficient of correlation indicated seasonal variations in the diet. the diet was more diversified in adults than in juveniles. the axillary seabream fed on a wide range of prey items, endofauna and nekton, and can be considered a carnivorous and euryphagous predator.Keywords: Pagellus acarne, diet, dietary indices, Gulf of tunis, central mediterranean.Resumen: La dieta de Pagellus acarne (Sparidae) en el golfo de Túnez, Mediterráneo central. -se estudió la dieta del aligote, Pagellus acarne (Risso, 1810), del golfo de túnez en función de las estación del año, del sexo y de dos grupos de talla: juveniles (lt <14.5 cm) y adultos (lt ≥14.5 cm). entre junio 2005 y julio 2006 se recolectaron con trasmallos, un total de 536 ejemplares (machos, hembras, sexos no determinados) cuya longitud total oscilaba entre 11 y 25.5 cm. se analizó el contenido estomacal; 279 estaban vacíos (índice de vacuidad, Vi = 52.0%). este índice no reveló diferencias significativas en relación a la estación del año. sin embargo, se observaron importantes variaciones estacionales para las hembras. se identificaron un total de 36 especies de presas en la dieta. las más frecuentes eran artrópodos, moluscos y equinodermos. los índices de alimentación calculados, así como la aplicación del coeficiente de correlación de spearman, mostraron variaciones estacionales. el análisis específico de las presas evidenció que la dieta de los machos era diferente a la de las hembras y era más variada en los adultos que en los juveniles. P. acarne se alimenta de un amplio espectro de presas, endofauna y necton, y podría considerarse como depredador carnívoro y eurífago.Palabras clave: Pagellus acarne, dieta, índices de alimentación, golfo de túnez, mediterráneo central. ,[667][668][669][670][671][672][673][674][675][676][677][678] Barcelona (spain) issn: 0214-8358 Scientia Marina73(4) december 2009

The effects of solar and experimental drying on the protein concentration and total fatty acid (TFA) content of the muscles of Atherina boyeri (sand smelt) were studied. The percentage of protein was 18.3% for fresh fish and 14.2% for sun-dried fish, while TFA content was 4.9 g/100g and 0.5 g/100g. After the drying experiment, the percentage of protein was 23% and the fatty acid (FA) content was 2.8 g/100g. The results show that natural or experimental drying favors saturated fatty acids. The n-3 polyunsaturated fatty acids (PUFAs) are less sensitive to heat than the n-6 PU-FAs. From a nutritional point of view, it seems that the drying conditions, where parameters are T = 50˚C, moisture = 30% and air speed = 2 m/s, would be the most beneficial for the preservation of sand smelt.

For the first time, an otolith shape analysis was used to investigate the stocks of saddled bream (Oblada melanura, Linnaeus, 1758) in three fishing zones along the Tunisian coast (Bizerte, Kélibia and Sayada). Otolith shape analysis was used on 30 otoliths for each site, sampled during the spawning period. Using elliptic Fourier descriptors (EFD) the quantization of the shape otolith was investigated by SHAPE and multivariate statistical procedures. Considering the environmental and the genotypic aspects, the preliminary results of the otolith shape analysis showed dissimilarity in silhouette of otoliths of saddled bream stocks collected from the north (Bizerte), the north-east (Kélibia) and the east (Sayada) of the Tunisian coast. Therefore, these three groups could be considered as three sub-units of the Tunisian stock, which should be managed separately.

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