Juan M. Afonso

Universidad de Las Palmas de Gran Canaria | ULPGC · Instituto Universitario de Sanidad Animal y Seguridad Alimentaria (IUSA)

The effects of two new anesthetics (essential oils) extracted from oregano (OO) and eucalyptus (EO) plants were studied in European sea bass (Dicentrarchus labrax) stress response and welfare parameters in comparison to the effects of clove oil (CO) that is one of the most used anesthetics in aquaculture. A time-course study on evolution of plasma...

Lack of operculum, a neurocranial deformity, is the most common external abnormality to be found among industrially produced gilthead seabream (Sparus aurata L.), and this entails significant financial losses. This study conducts, for the first time in this species, a quantitative trait loci (QTL) analysis of the lack of operculum. A total of 142 i...

Morphological abnormalities in farmed gilthead seabream (Sparus aurata) are a major problem as it entails significant economic losses. In this study, 3 large scale experiments under different conditions of spawning, offspring handling and breeders phenotype were performed to analyze the inheritance of 4 types of deformities in this species: lack of...

The growth and consolidation of the gilthead seabream (Sparus aurata) industry require improvement based on permanent and cumulative aspects, such as those derived from genetic breeding programmes. Marker Assisted Selection (MAS) by Quantitative Trait Loci (QTL) can be usefully implemented with the appropriate tools. In this study, 138 microsatelli...

The effect of two physical tagging systems, Visible Implant Elastomer (VIE) and Passive Integrated Transponder (PIT), was evaluated in red porgy (Pagrus pagrus) fingerlings, at different sizes. For VIE tagging, the weight classes were <1 and 1–5 g and no tag effect was detected on fish growth. There was a significant difference in mortality between...

In this study, for the first time on meagre (Argyrosomusregius), two efficient Multiplex PCRs, a specific (STRS) and an inter- specific (STRI), were used to genotype 17 microsatellites on meagre and reconstruct genealogy under industrial conditions. A total of 197 individuals from different sources and 95 of their descendents were analysed for vali...

Commercial gilthead sea bream feeds are highly energetic, fish oil traditionally being the main lipid source. But the decreased fish oil production together with the increased prices of this oil encourages its substitution by vegetable oils, imposing new nutritional habits to aquaculture species. Partial replacement of fish oil by vegetable oils in...

Octopus vulgaris is a species of demand in the market with the potential to diversify European aquaculture. However, this species develops complex social interactions under culture conditions, which may have negative effects on its growth, survival and profitability. In order to understand its behaviour under such conditions, individual tagging sys...

In this study, heritabilities for body composition traits, their genetic correlations with growth traits and the genotype–environment interaction (G×E) were estimated at 509days (harvest size) for the first time in gilthead seabream (Sparus auratus L.), from the offspring in two different production systems (cages and tanks) in the Canary Islands....

In this study, for the first time on gilthead seabream (Sparus auratus L.), genetic parameters for growth and carcass traits were estimated at 509 days (harvest size), and for growth only at another three ages (130, 165 and 330 days). A total of 867 offspring from an industrial mass spawning of 66 broodstocks were analysed. Parental assignment was...

This study examines the utility of Passive Integrated Transponder (PIT) tagging system in fingerlings of gilthead seabream, Sparus auratus L. Two different body positions (abdominal, dorsal) and four weight classes (2–3 g, 3–4 g, 4–5 g, 5–8 g) were tested in three experiments. Tag loss rate, as well as its effect on growth and mortality rates, was...

The present work evaluates, on one hand, two anaesthetic agents to facilitate octopus handling concluding that a 1.5% of ethanol (96%) in sea water (22ºC) shows rapid anaesthetic-recovery time, indicating its suitability for this species. On the other hand, a protocol for implanting Octopus vulgaris with subcutaneous PIT tags is established and aft...

In this study, the use of Visible Implant Elastomer (V.I.E.; Northwest Marine Technology Inc.) and Passive Integrated Transponder (P.I.T.; EiD Ibérica SA - TROVAN) tags in red porgy (Pagrus pagrus) were evaluated, as tag methods to know the genealogy under culture. For VIE tags, 0.5 and 2 g weight classes were tested, without any effect of the tag...

Gilthead sea bream (Sparus aurata L) pass through the period of sexual maturation while being intensively reared for commercial purposes. This process affects growth and food conversion efficiency. In an attempt to reduce this problem several lighting regimes have been utilized which impede gonad development by increasing the length of the day. A f...

Instrumental quality parameters related to freshness were evaluated for gilthead sea bream (Sparus aurata) after different storage periods on ice (2, 4, 7 and 11 days of storage) for one, four and eight days of pre-slaughter starvation. The study was carried out on 360 gilthead sea bream from five different groups reared on a commercial fish farm....

Skeletal deformities constitute a major problem for aquaculture industry by decreasing the final value of the fish. An analysis of skeletal malformations in 11,640 fish was performed considering families and triplicates per family. Thirtynine different skeletal abnormalities were detected, such as lordosis, vertebral fusion, absence of one or both...

To discover the relation between mitochondrial DNA (mtDNA) polymorphism and the geographic population structure of Drosophila subobscura previously established for other genetic traits, a wide Paleartic survey was carried out. A total of 24 nucleomorphs was observed among 261 isofemale lines assayed by 11 restriction endonucleases with 38 different...

We analyzed the genetic polymorphism of eight red cell enzymes in samples from different geographical areas of Tenerife and the Iberian peninsula. The gene frequency heterogeneity found within the Tenerife samples was at the same level as that of Tenerife-mainland comparisons. The presence of the Negroid G6PD A+ allele in the Tenerife samples is ev...

The genetic polymorphism of eight red cell enzymes was examined in three samples from Gran Canaria and one from Equatorial Guinea. The presence of African genes in the Gran Canaria population showed an African admixture estimated to 6–9%. The genetic distance between Gran Canaria and Equatorial Guinea was 0.033, and that between Gran Canaria and th...

The genetic polymorphism of eight red cell enzymes was examined in three samples from Gran Canaria and one from Equatorial Guinea. The presence of African genes in the Gran Canaria population showed an African admixture estimated to 6-9%. The genetic distance between Gran Canaria and Equatorial Guinea was 0.033, and that between Gran Canaria and th...

Genetic polymorphism of seven red cell enzymes was examined in two Canary Island populations and in an Iberian peninsula sample. The more isolated insular population shows a considerable gene frequency heterogeneity when compared with the peninsular sample but both are within the range of European populations. The presence of certain rare alleles n...

Three North-west African populations ofDrosophila melanogaster were analyzed for chromosomal and enzyme polymorphism as well as for gametic associations between non allelic elements mapped on the same chromosome arm. Strong geographic heterogeneity was found between populations, both for enzyme and chromosomal polymorphism. Out of the 43 possible c...