Texture changes during chilled storage of wild and farmed blacspot seabream (Pagellus bogaraveo) fed different diets

The impact of changes in dietary lipids and protein sources on texture was evaluated on farmed blackspot seabream (Pagellus bogaraveo) throughout 14 days of ice storage and compared with wild fish. A commercial diet formulated with a high proportion of lipids, and two diets formulated with an important reduction of lipid levels by 60% and adding either plant protein sources (LL diet) or fishmeal (LL + diet) were supplied during growth until commercial size was attained. In the wild fish, the raw fillet hardness was significantly higher than in farmed fish during the entire ice-storage period. In the farmed fish, an increase of muscle lipid accumulation and change of fiber density were responsible for the variations in texture in the raw fillet. The highest reduction was found in fish fed with diets LL+ and LL. The texture parameters studied on the cooked fillets showed no significant differences, neither attributable to the diets nor to the ice-storage period.JUNTA ASESORA DE CULTIVOS MARINOS (JACUMAR)Postprin

Biometric parameters and biochemical composition of wild wreckfish (Polyprion americanus)

Wreckfish (Polyprion americanus) is considered to be a good candidate for European aquaculture. The main biometric parameters were recorded from 86 wild-caught fish (2.6-18 kg of total weight) for 14 months and the gonadosomatic index (GSI), hepatosomatic index (HIS) and viscerosomatic index (VSI) were obtained. Biochemical analyses of muscle, liver and gonads from wild wreckfish showed that wreckfish has a high level of protein in muscle, 84% of dry weight (DW), and low level of lipids (7% DW). Capture season, sex, size or weight of the fish did not have a strong effect on the variability observed in the levels of proteins, lipids and fatty acids of the different tissues. Reared wreckfish have more lipids in mature gonads than wild fish, which may be due to a more lipid-rich diet. However, some polyunsaturated fatty acids (PUFA) such as arachidonic acid (ARA) and docosahexaenoic acid (DHA) reached higher values in wild female gonads than in reared gonads, which could indicate the wreckfish has high requirements in these fatty acids. This study obtained valuable data on the biology and biochemical composition of wreckfish to estimate its nutritional requirements, which could be useful for the future of this species in aquaculture.European Union's Seventh Framework Programme Research, Technological development and demonstration (KBBE-2013-07)Postprint1,48

Reproduction of blackspot seabream, pagellus bogaraveo B. in captivity

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Experience with ongrowing juvenile blackspot sea bream (Pagellus bogaraveo) born in captivity, in tanks at diferent temperatures

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Multiple evidences suggest sox2 as the main driver of a young and complex sex determining ZW/ZZ system in turbot (Scophthalmus maximus)

A major challenge in evolutionary biology is to find an explanation for the variation in sex-determining (SD) systems across taxa and to understand the mechanisms driving sex chromosome differentiation. We studied the turbot, holding a ZW/ZZ SD system and no sex chromosome heteromorphism, by combining classical genetics and genomics approaches to disentangle the genetic architecture of this trait. RAD-Seq was used to genotype 18,214 SNPs on 1,135 fish from 36 families and a genome wide association study (GWAS) identified a ~ 6 Mb region on LG5 associated with sex (P < 0.05). The most significant associated markers were located close to sox2, dnajc19 and fxr1 genes. A segregation analysis enabled narrowing down the associated region and evidenced recombination suppression in a region overlapping the candidate genes. A Nanopore/Illumina assembly of the SD region using ZZ and WW individuals identified a single SNP fully associated with Z and W chromosomes. RNA-seq from 5-90 day-old fish detected the expression along the gonad differentiation period of a short non-coding splicing variant (ncRNA) included in a vertebrate-conserved long non-coding RNA overlapping sox2. qPCR showed that sox2 was the only differentially expressed gene between males and females at 50-55 days post fertilization, just prior the beginning of gonad differentiation. More refined information on the involvement of secondary genetic and environmental factors and their interactions on SD was gathered after the analysis of a broad sample of families. Our results confirm the complex nature of SD in turbot and support sox2 as its main driver.Postprin

Estimación de la utilidad de un sistema de análisis automático SCA (Sperm Class Analyzer) para el recuento y control de calidad de fitoplancton en cultivo intensivo

Durante los últimos años el sistema de cultivo de microalgas marinas ha evolucionado desde los cultivos extensivos y la producción en bolsas de grandes volúmenes para alcanzar la biomasa adecuada, pasando por sistemas de cultivo intensivo en continuo y llegando en la actualidad al uso de un sistema semicontinuo, a base de fotobiorreactores que aprovechando al máximo la luz, consigue alcanzar producciones óptimas en volúmenes y tiempos mucho más reducidos, economizando espacio, tiempo, material e incluso personal. Este experimento consistió en la validación para microalgas de un sistema de valoración y recuento automático de uso veterinario para análisisde esperma (SeA). Los resultados indican que este sistema no sólo es operativo, sino que puede ser de gran utilidad configurando la aplicacitli precisa para el análisis de los parámetros de calidad en el cultivo intensivo de frtoplancton.The marine microalgae conure system has evolved since Ihe beginning 01 aquaculture, where large volumes were produced to attain an adequale biomass, extensive culture, intensive continuous cultures and finally Ihe semi continuous systems Ihat are presently used, using photo bioreactOll, which optimize Ihe use 01 light and nutrients to attain optimal microalgae production in much lower volumes and shorter times, reducing space aIII time required, as well as costs relatedto material and hand labor. The objective 01 this experiment was to validate an automatic sperm count normally used in the veterinary industry (SeA), for rts use in microalgae count. Results indicate that the SeA is valid forthis use. Furthermore, SCAcan be of great utility and accuracy, when configured forthe analysis~ quality parameters in the intensive microalgae culture