José Antonio Hernando

Lipid, protein, and calorie content of different Atlantic and Mediterranean fish, shellfish, and molluscs commonly eaten in the south of Spain

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 Folchs method and gravimetry), protein concentration (Kjehldals 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.

Biology, Conservation and Sustainable Development of Sturgeons

Taxonomy and Biogeography.- The Regression of Sturgeons in Southern Europe.- Analysis of Mitochondrial and Nuclear DNA Markers in Old Museum Sturgeons Yield Insights About the Species Existing in Western Europe: A. sturio, A. naccarii and A. oxyrinchus.- Morphological and Morphometric Characters in Sturgeon Taxonomy and Phylogeny.- Molecular Markers and the Study of Phylogeny and Genetic Diversity in North American Sturgeons and Paddlefish.- Forensic Strategies Used for DNA Extraction of Ancient and Degraded Museum Sturgeon Specimens.- Mechanisms of Polyploid Evolution in Fish: Polyploidy in Sturgeons.- Biology and Aquaculture.- Histological, Histochemical and Ultrastructural Changes in the Digestive Tract of Sturgeon Acipenser naccarii During Early Ontogeny.- The Developmental Anatomy of the Heart of the Sturgeon Acipenser naccarii.- Observations on the Brain Development of the Sturgeon Acipenser naccarii.- Hormonal Induction of Ovulation In Vitro in Sturgeon Fishes.- Dispermic Androgenesis as a Method for Recovery of Endangered Sturgeon Species.- Influence of Temperature on the Sterlet (Acipenser ruthenus L.) Ovarian Follicles State.- On Nutrition and Feeding Studies as the Basis for the Culture of Different Sturgeon Species.- Recovery and Conservation.- Restoration of Adriatic Sturgeon (Acipenser naccarii) in Italy: Situation and Perspectives.- Acipenser sturio Recovery Research Actions in France.- Conservation of the Sturgeon Fish in Lower Volga.- Experience of Conservation of Acipenser naccarii in the Ticino River Park (Northern Italy).- Identification of Sturgeon Caviar Using DNA Markers.- International Trade in Caviar and Business Perspectives in Russia.- The Ecological Problems of Introduction and Reintroduction of Sturgeons.- Hydrological and Production Characteristics of the Main Basins for Reproduction and Fattening of Sturgeons.- Towards the Definition of Optimal Size-Weight Standards of Hatchery-Reared Sturgeon Fry for Restoration.- Acceptability and Prerequisites for the Successful Introduction of Sturgeon Species.- Prerequisites for the Restoration of the European Atlantic Sturgeon, Acipenser sturio and the Baltic Sturgeon (A. oxyrinchus x A. sturio) in Germany.- Sturgeon Recovery Plan in the Rhone River (France): Preliminary Results on Species Determination and Habitat Suitability.- Main Steps and Proposals for a Recovery Plan of Sturgeon in the Guadalquivir River (Spain).

The Regression of Sturgeons in Southern Europe

Analysing historical citations and the specimens preserved in museums, as well as zoological collections in France, Portugal, Spain, and Italy, the historical and current distributions of sturgeons in southern Europe have been studied, using morphological and genetic techniques. Errors were found in the classification of specimens of non-Adriatic origin, and 13 specimens were found to be classified as Acipenser sturio when they were in fact Acipenser naccarii. Of the 86 specimens considered valid, 44 had been captured in the Adriatic and 42 from other parts of the study area (Spain, France, Mediterranean Italy, Portugal, and Sweden). A. sturio is considered to have been present throughout Europe and currently is an endangered population in the Gironde-Garonne-Dordogne basin (France), while A. naccarii is considered endemic to the Adriatic. However, the data gathered show that it had a much broader distribution than the current one, extending at least from the French Atlantic to the Adriatic Sea.

Morphometric relations for body size and mouth dimensions for four fish species in the Strait of Gibraltar

Background. The deep-water longline fishery of the blackspot seabream, Pagellus bogaraveo, is an economically important fishery in the Strait of Gibraltar, which is a very complex transition ecosystem between the Mediterranean Sea and the Atlantic Ocean with an extreme spatial and temporal variability. This paper presents a series of morphometric relations for the four most important species in this fishery. Some ecological considerations about the results are also discussed. Materials and Methods. The data were collected during a gear selectivity study, using different sizes of hooks baited with sardine. Relations for weight–length, length–length, and mouth dimensions for blackspot seabream, Pagellus bogaraveo (Brunnich, 1768); Atlantic pomfret, Brama brama (Bonnaterre, 1788); blackbelly rosefish, Helicolenus dactylopterus (Delaroche, 1809); and Mediterranean horse mackerel, Trachurus mediterraneus (Steindachner, 1868) were estimated and compared with the ones reported for the same species from other areas. Results. The sample size varied from 89 for T. mediterraneus to 2180 for P. bogaraveo. The fitted L–W relations explained more than 81% of the variance. For P. bogaraveo and T. mediterraneus, the estimated allometric coefficient was higher than those reported for other areas, showing a faster increase in weight, in contrast to H. dactylopterus and B. brama that showed a slower increase in weight. Moreover, linear and highly significant relations between mouth size and fish length were found for P. bogaraveo, H. dactylopterus, and T. mediterraneus. Conclusions. In this study, the first record for total length–standard length relation for H. dactylopterus is reported based on real measurements. There has been no previous studies on the relation between the different mouth size dimensions for the studied species as well as for mouth size and body length relations for P. bogaraveo and H. dactylopterus. The difference between estimated and reported coefficients might be attributed to different environmental adaptations and to the size ranges used due to the gear-size selectivity.

A simple method to estimate the significance level of the catch probability in the catch removal method in river fish populations

Abstract This work presents a method for estimating the significance level of the capture probability when the capture removal method is used in riverine fish populations. The method is based on adjustment of the linear relationship between capture probability and an index of capture efficacy. With this method the population size, the statistic χ2 and the significance level of the capture probability can be estimated. This is a simple technique which can be applied in the field at the time of sampling. It does not require the use of computers and can determine in situ whether the catch is valid to calculate the population density.

Morphological development in the first life phase of Adriatic sturgeon Acipenser naccarii under controlled conditions: MORPHOLOGICAL DEVELOPMENT IN A. NACCARII

Early development of the Adriatic sturgeon Acipenser naccarii from its free embryo after hatching (stage 36), until late embryo stage, when the transition to exogenous feeding starts (stage 45) is described. Special emphasis is given to morphological development and description of the different structures that are formed at each life stage. After hatching, free embryos still present embryonic characteristics, little pigmentation and an ovoid yolk sac. The mouth begins to open on the second day post hatch (dph) and is fully open at 3 dph. The head begins to separate from the body at 4 dph and straightens at 6 dph. The first fins to appear are the pectoral fins on the yolk sac and an embryological fin fold that extends from behind the head to the posterior part of the yolk sac. All other fins will develop from this fold. At 7 dph the caudal fin begins to take a heterocercal form and dorsal scutes are observed. This study provides information that will assist aquaculturists by establishing a reference for the normal development of A. naccarii, which may be useful for evaluating the suitability and quality of fish produced for restocking.