Search results for "Fish"
showing 10 items of 3164 documents
�ber den Saccus vasculosus einiger Teleosteer
1954
I. Der Saccus vasculosus der Makrele, zeigt, abgesehen von seiner Lage, keine Besonderheiten gegenuber dem anderer Teleosteer. Unerklart mussen vorlaufig die dunkelgefarbten Granula im Epithel bleiben. Sie nur als Farbniederschlage zu deuten, erscheint nicht befriedigend, da sie nur im Saccus vorkommen. II. Der verschiedene Fullungszustand von Capillaren einerseits und Blutsinus andererseits im Saccus von Sebastes norvegicus lenkt unsere Aufmerksamkeit auf die noch nicht ganz geklarten Blutgefasversorgungsverhaltnisse des Saccus. Es ist an die Moglichkeit verschiedener Blutversorgung von Sinus und Capillaren zu denken, wie auch Scharrer (1948) vermutete. III. Die phasenkontrastoptischen Beo…
Untersuchungen zur Eiproduktion beim Zebrabärbling (Brachydanio rerio, Ham.-Buch.)
1986
Zusammenfassung Die Untersuchungen zur Eiprodukcion beim Zebrabarbling zeigen, das in der Zahl der abgelegten Eier erhebliche mdividuelle Unterschiede bestehen. Die Gruppengrose hat im Bereich von 2 Weibchen und 4 Mannchen bis 8 Weibchen und 16 Mannchen keinen Einflus auf die Eizahl, die zwischen 40 und 100 Eier je Weibchen und Tag schwanken kann. Die Eiablage erfolgt in einem Zyklus von zwei Tagen. Eine Trennung der Geschlechter beeinflust sowohl die Zahl als auch die Qualitat der abgelegten Eier. Verwendet man die Eizahl als Parameter in einem Reproduktionstest, dann mus die Gesamteizahl, die Zahl der im Korper denaturierten und die Zahl der unbefruchteten Eier erfast werden. Summary Egg …
Comparing RADseq and microsatellites for estimating genetic diversity and relatedness : Implications for brown trout conservation
2019
The conservation and management of endangered species requires information on their genetic diversity, relatedness and population structure. The main genetic markers applied for these questions are microsatellites and single nucleotide polymorphisms (SNPs), the latter of which remain the more resource demanding approach in most cases. Here, we compare the performance of two approaches, SNPs obtained by restriction-site-associated DNA sequencing (RADseq) and 16 DNA microsatellite loci, for estimating genetic diversity, relatedness and genetic differentiation of three, small, geographically close wild brown trout (Salmo trutta) populations and a regionally used hatchery strain. The genetic di…
Survey On Competence and Administration of Supervisory Board Activities in German Stock-Listed Companies
2017
Abstract According to the agency theory (Jensen & Meckling 1976), it is expected that there exists a positive relationship between corporate governance and company performance which is also generally assumed in recent research (Dignam & Galanis 2016). This relationship is investigated in the study performed by the author of this paper. Two different approaches were chosen in parallel: (1) quantitative data analysis, based on financial figures and corporate governance variables, and (2) a survey of supervisory board members of listed German companies. This paper is about the results of structured interviews with 30 supervisory board members. The survey confirms that corporate governa…
Modeling of Hardy-Weinberg Equilibrium Using Dynamic Random Networks in an ABM Framework
2023
Hardy-Weinberg equilibrium is the fundamental principle of population genetics. In this article, we present a new NetLogo model called “Hardy-Weinberg Basic model v 2.0”, characterized by a strict adherence to the original assumptions made by Hardy and Weinberg in 1908. A particularly significant feature of this model is that the algorithm does not make use of the binomial expansion formula. Instead, we show that using a procedure based on dynamic random networks, diploid equilibrium can be achieved spontaneously by a population of agents reproducing sexually in a Mendelian fashion. The model can be used to conduct simulations with a wide range of initial population sizes and genotype distr…
Embryonic development in corkwing wrasse, Symphodus melops
2019
Corkwing wrasse, Symphodus melops, is one of the main species used as cleaner fish to combat sea lice infestation in salmon aquaculture; however, there is little knowledge about its biology. Here, we describe the embryonic development of this species and examine the viability of the eggs under three temperature regimes. The experiments were conducted at three water temperature regimes, 12, 15, and 18°C, which resemble common sea water temperatures registered during the spawning season of corkwing wrasse at different latitudes along the Norwegian coast. Corkwing wrasse spawn small spherical eggs of 0.75–0.80 mm in diameter (mean 0.78, CV = 3.6%) with several oil droplets and go through eight…
Assessment of the interpretability of data mining for the spatial modelling of water erosion using game theory
2021
Abstract This study undertook a comprehensive application of 15 data mining (DM) models, most of which have, thus far, not been commonly used in environmental sciences, to predict land susceptibility to water erosion hazard in the Kahorestan catchment, southern Iran. The DM models were BGLM, BGAM, Cforest, CITree, GAMS, LRSS, NCPQR, PLS, PLSGLM, QR, RLM, SGB, SVM, BCART and BTR. We identified 18 factors usually considered as key controls for water erosion, comprising 10 factors extracted from a digital elevation model (DEM), three indices extracted from Landsat 8 images, a sediment connectivity index (SCI) and three other intrinsic factors. Three indicators consisting of MAE, MBE, RMSE, and…
Breeding-related seasonal changes in immunocompetence, health state and condition of the cyprinid fish, Rutilus rutilus, L.
2003
Seasonal changes in immunocompetence are predicted by the hypothesized trade-off between reproduction and self-maintenance, whereby immune function is a measure of self-maintenance and reproductive effort is seasonally dependent. We examined seasonal patterns in immunological, haematological and body condition parameters for male and female freshwater fish. In two different populations, the relative size of the spleen and the chemotaxic migration activity of head kidney granulocytes decreased immediately before and after spawning, respectively. Those decreases were accompanied by an increase in haematocrit values shortly before and after spawning in both populations and a decrease in the re…
Calibrating accelerometer data, as a promising tool for health and welfare monitoring in aquaculture: Case study in European sea bass (Dicentrarchus …
2021
Abstract Both the conventional and organic aquaculture sectors have grown rapidly over the past few years. Moreover, welfare has attracted increased attention on the part of both consumers and governments. However, fish welfare assessment is complex and thus needs to adapt measurements that are easily applicable to aquaculture conditions. In this study, in addition to classical welfare indicator measurements (physiological stress indicators and growth performance), we recorded the swimming activity data using acoustic transmitters to evaluate the welfare of European sea bass (Dicentrarchus labrax) fed a conventional vs. an organic diet. Prior feeding trial, the swimming activity recorded by…
Effect of Cold Smoking and Natural Antioxidants on Quality Traits, Safety and Shelf Life of Farmed Meagre (Argyrosomus regius) Fillets, as a Strategy…
2021
Aquaculture has been playing a leading role over the years to satisfy the global growing demand for seafood. Moreover, innovative techniques are necessary to increase the competitiveness, sustainability and profitability of the seafood production chain, exploiting new species from the aquaculture, such as meagre (Argyrosomus regius), to develop value-added products and diversify their production. In the present work, the effectiveness of cold smoking combined with antioxidants (SA) compared to cold smoking alone (S) on meagre fillets, the quality and shelf life were investigated. Sensory, biochemical, physical–chemical and microbiological analyses were performed on the smoked fillets during…