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The polychaete Hediste diversicolor is a suitable species for industrial aquaculture; however, cost-effective culture techniques need to be developed for its intensive production. The aim of this study is to evaluate the effects of worm density and substrate height and their interaction, as well as feeding frequency, on the rearing performance of H. diversicolor. Two trials were conducted. In trial 1, the effects of two substrate heights—6 and 12 cm—and two rearing densities—1000 and 4000 individuals m−2—were assessed in terms of worm growth and biomass production. Worm initial wet weight was 48 mg, and specimens were fed with commercial fish feed during a 70-day assay. The results show no interaction between rearing density and substrate height, and confirm density as a key factor in growth; however, a density of 4000 individuals m−2 results in a significant increase in production (final biomass three times higher for the highest rearing density) without affecting survival. In trial 2, the effect of three levels of feeding frequency—seven days a week; three times a week; and once a week—on growth in individuals of three weight classes—small (25–50 mg); medium (100–150 mg); large (250–350 mg)—was evaluated in a 15-day growing assay. Feeding frequency showed a major influence on the smallest size class, with the best growth indicators obtained at the highest feeding frequency. This study shows that Hediste diversicolor can be reared at a high stocking density to obtain a higher biomass production, and that feeding frequency must be considered as an important factor and adapted to the culture phase. [ABSTRACT FROM AUTHOR]

The article focuses on a study related to disinfection of Senegalese sole egg with iodine to minimizes the bacterial load without affecting the hatching rate and larval survival. Topics discussed include advantage of disinfection in prevention of disease transmission, evaluation of the disinfectant capacity and hatching rate in culture conditions, analysis of data normality and homogeneity of variance by the Kolmogorov-Smirnov and Levene methods, and importance of the egg developmental stage.

Abstract: The purpose of this study was to evaluate the total egg production of three groups of wild Solea senegalensis that were adapted to captivity (B1, B2 and B3) and to evaluate parental contribution through the allocation of larvae hatched over four spawning seasons (2007–2010). Total production, daily relative fecundity, and fertilisation and hatching rates were obtained. In addition, an analysis of egg diameter was performed. The total production resulted in 633 spawns and showed a number of differences in the floating volume rate and the hatching rate between each year. The mean relative fecundity and the fertilisation rate showed interannual stability. Significant differences in production were found between the different breeding tanks. The change in the egg diameter decreased as the breeding season progressed, and the relationship between egg diameter and time, calculated using the spawns of two females, showed a significant correlation (ρ=−0.426, p=0.000 and ρ=−0.362, p=0.000, respectively) and a significant fit to a cubic regression model (R2 =33.6, p=0.000 and R2 =54.3, p=0.000, respectively). Parentage analysis with four highly polymorphic microsatellites enabled the identification of the parents involved in each spawn, the relationships between males and females over the breeding season and between breeding seasons, and the reproductive rhythms of individual females. The percentage of individuals that participated in the spawns in each tank ranged between 8.7% (B1, 2009) and 51.7% (B3, 2008) annually. Paternity inference of progenies (n=3630 larvae) showed a high fidelity behaviour in Senegalese sole, with offspring allocated to the same couples throughout the breeding season (87–98%) and even between mating seasons in different years. The period of reproductive activity of the 4 most active females lasted from 96days (female 37, 2010) to 252days (female 35, 2009), with intervals between consecutive spawns ranging between 1 and 56days. [Copyright &y& Elsevier]

Cultivation of the common ragworm—Hediste diversicolor—has attracted a great deal of interest in recent years. Growth optimization is a key aspect for its intensive production. We have assessed the effect of body weight (Bw) and temperature (T) on growth-related parameters in common ragworm using correlation and multiple regression analyses. We used ragworms of 13 different weight classes in 15-day growing assays at 12 different temperature values. These polychaetes were stocked at a density of 1000 individuals m−2, and fed with commercial fish feed. Our results show that growth increases with T; when expressed as an absolute growth rate (AGR), growth increases as Bw increases; and when expressed as a specific growth rate (SGR), growth decreases as Bw increases. A change in the growth pattern was observed from an individual Bw of about 400 mg. Simulations performed with the equations that provided the best fit revealed that optimum T for growth changes with Bw, so that in individuals below 400 mg, optimum T is 24.9 °C, and above this temperature growth decreases. In individuals above 400 mg, growth increases slightly with temperature, but as weight increases, the effect of temperature on growth is less and less, and from a weight of 1050 mg, growth decreases as temperature increases. Mortality increases significantly at temperatures above 22 °C, especially in individuals with a Bw above 400 mg. Simulations of individual growth showed that up to 400 mg growth is quite fast at warmer temperatures, but from 400 mg to 1000 mg, the influence of T on growth rate is not significantly relevant in operational terms. This study demonstrated the huge usefulness of growth modelling for production planning. [ABSTRACT FROM AUTHOR]

This study aimed to determine the maximum time of emersion of Senegalese sole ( Solea senegalensis) specimens to form the basis for a dry sole transport procedure. For this purpose, 56 specimens (922.33 ± 29.52 g body weight) were individually placed in polystyrene boxes on a wet cloth, maintaining constant temperature (15°C) during emersion trial. Specimens ( n = 7 per group) were sampled for plasma, and mortality was monitored at different points (0, 2, 6, 12, 20, 28, 36 and 44 h of emersion), and several stress (cortisol, glucose and lactate) and metabolic (triglycerides, proteins and amino acids) parameters were assessed. After sampling, each experimental group was placed in recovery tanks for the assessment of delayed mortality and feeding performance after emersion trial. Transport periods longer than 28 h produced high stress level indicated by (i) significant increase in circulating cortisol and lactate and (ii) glucose reserves mobilization. These alterations originated physiological problems during the emersion trial that induced mortality as well as problems for recovering correct feeding performance of specimens. These results suggested that at 15°C for S. senegalensis specimens (around 900 g body weight), a waterless transport is possible without direct or delayed mortality up to 28 h. [ABSTRACT FROM AUTHOR]

Bernal, M., Ibaibarriaga, L., Lago de Lanzós, A., Lonergan, M. E., Hernández, C., Franco, C., Rasines, I., Valdés, L., and Borchers, D. L. 2008. Using multinomial models to analyse data from Iberian sardine egg incubation experiments: a comparison with traditional techniques. – ICES Journal of Marine Science, 65: 51–59.Multinomial rather than traditional models were applied to improve data analysis of incubation experiments for Iberian sardine (Sardina pilchardus) eggs. Incubation experiments were carried out in 2002 in the Gulf of Cádiz, southwestern Spain, and data were taken from the literature for the Cantabrian Sea area. Rigorous review of the traditional models revealed shortcomings in the statistical framework for modelling the developmental progression of egg stages as well as a lack of transparency of the inherent assumptions. Multinomial model results show that egg stage duration varies for all stages, with stages 3 and 4 having the shortest duration. Comparison of the results between multinomial and traditional models shows that multinomial models provide improved insight into developmental mechanisms than that can be achieved using traditional models. [ABSTRACT FROM PUBLISHER]

The aim of this study was to evaluate the effect of long term natural feeding in the subsequent reproductive status of 4 years old cultured Solea senegalensis , and to determine if the potential changes were structural or feeding dependent. To this aim, two different feeding regimes were used from one year after weaning and during the following 3 years; 1) a commercial dry food diet and 2) a natural feeding regime. After this period, the proportion of fluent males and the evolution of maturity stages of females over a breeding season were studied. A complete sperm quality analysis assessment was carried out, including individual volumes, motility, density and curvilinear, rectilinear and mean velocities of spermatozoa. Moreover, viability and apoptosis indexes were analyzed as indicator of molecular sperm membrane integrity. Additionally, a morphological characterization of the testes during the spawning season was conducted. Finally, both groups were fed with the same commercial pellets during one year to evaluate the effect of the diet of previous years on sperm quality. The results of this study showed how feeding can improve not only sperm quality and quantity, but also the proportion of fluent males and females in advanced maturity stages. All the sperm quality parameters resulted significantly higher in the group fed with a natural diet. Moreover, the number of apoptotic cells was significantly higher in the group fed with a commercial diet. According to the morphological features of the testes, the animals fed with a natural diet presented more basal position, less protuberances and irregular edges when compared with the animals fed with commercial diet. Interestingly, the progression of the spermatogenesis determined by the proportion of germ cells and the production of spermatozoa determined by the wider of the ducts system was also significantly larger in the natural diet group. After the standardization of the diets, mean volume per male and production of total motile cells were significantly higher in the group that was previously fed a natural diet, confirming structural improvements. • Long term natural feeding regime improves reproductive performance in Solea senegalensis. • A long term natural feeding regime produces structural improvements in Solea senegalensis testis. • A long term natural feeding regime enhances sperm quantity and quality. • A long term natural feeding regime increases the number of mature females. [ABSTRACT FROM AUTHOR]