Animal welfare in brown trout farming: hematological results

The effect of stress resulting from fish farming has received considerable attention in this last period and fish welfare in aquaculture is a relevant topic, very important for the future of aquaculture (Watson et al., 2004; Klinger et al., 1996; Peres et al., 2004; Ron et al., 1995;Wagner et al., 1995;Watson et al., 1998). Brown trout farming is less developed then rainbow trout farming, but this kind of fish farming is increasing, mainly for fish conservation and restocking aquaculture

Quadratic Stochastic Euclidean Bipartite Matching Problem

We propose a new approach for the study of the quadratic stochastic Euclidean bipartite matching problem between two sets of $N$ points each, $N\gg 1$. The points are supposed independently randomly generated on a domain $\Omega\subset\mathbb R^d$ with a given distribution $\rho(\mathbf x)$ on $\Omega$. In particular, we derive a general expression for the correlation function and for the average optimal cost of the optimal matching. A previous ansatz for the matching problem on the flat hypertorus is obtained as particular case

Criticality and conformality in the random dimer model

In critical systems, the effect of a localized perturbation affects points that are arbitrarily far from the perturbation location. In this paper, we study the effect of localized perturbations on the solution of the random dimer problem in two dimensions. By means of an accurate numerical analysis, we show that a local perturbation of the optimal covering induces an excitation whose size is extensive with finite probability. We compute the fractal dimension of the excitations and scaling exponents. In particular, excitations in random dimer problems on nonbipartite lattices have the same statistical properties of domain walls in spin glass. Excitations produced in bipartite lattices, instead, are compatible with a loop-erased self-avoiding random walk process. In both cases, we find evidence of conformal invariance of the excitations that is compatible with SLEκ with parameter κ depending on the bipartiteness of the underlying lattice onl

Random Assignment Problems on 2d Manifolds

We consider the assignment problem between two sets of N random points on a smooth, two-dimensional manifold Ω of unit area. It is known that the average cost scales as EΩ(N) ∼ 1 / 2 πln N with a correction that is at most of order lnNlnlnN. In this paper, we show that, within the linearization approximation of the field-theoretical formulation of the problem, the first Ω -dependent correction is on the constant term, and can be exactly computed from the spectrum of the Laplace–Beltrami operator on Ω. We perform the explicit calculation of this constant for various families of surfaces, and compare our predictions with extensive numerics

A floating cage system for rearing freshwater mussels Anodonta anatina and Unio mancus in Piedmont region (NW Italy)

This research represents the first attempt in Italy to develop a cage system for adult freshwater mussel stocking, for extensive farming, that was realized from 2003 to 2005 in NW Italy. Two autochthonous species of Italian freshwater mussel were used: Anodonta anatina and Unio mancus. 5133 mussels were collected and successively stocked in floating cages in 5 different sites in a lake. This study was planned in order to determine the effect of main rearing factors for potential farming: stocking density and cage position in the water column (depth). For each species, the effects of three rearing densities and two water depths were tested. Mussel growth was measured on a monthly basis in each experimental unit throughout the study. The survival rate at the end of the experiment for both species considered was 98.4%. U. mancus resulted to be more resistant to rearing conditions and during the summer the highest mortality was registered for A. anatina. Summer mortality was between 4.8% and 20.5%. Highest mortality in U. mancus was recorded in September 2004 at 1.5 m (3.6±2.4%), while the highest mortality for A. anatina was recorded in September 2003 as 13.3%±3.8% at a depth of 1.5 m. This research showed that cage stocking is a suitable method and the optimal position of cages is at the lake thermocline. The proposed species proved to be easily utilizable for future farming or bioremediation projects, and can readily be reared up to 135 kg m^-3

Use of rice protein concentrate in rainbow trout feeding: preliminary results

During the past decades, the fishery industry has excessively used the world fish captures to produce fishmeal and fish oil in order to prepare feed for aquaculture diets. This has led to a drastic reduction of several fish populations (Hardy, 1999; FAO, 1999). At present 70% of the oil and 34% of fishmeal obtained from captures are used for aquaculture industry and, if the aquaculture production will continue to increase as predicted, in a short time it will absorb the entire world oil and fish meal production. Moreover, since fish meal still constitutes an important part of the feed formula for cultivated fish and since a further increase of fish meal availability will not be possible (Hardy, 2001), its price is expected to continue to increase (Tacon, 1998)

Finite-size corrections in the random assignment problem

We analytically derive, in the context of the replica formalism, the first finite-size corrections to the average optimal cost in the random assignment problem for a quite generic distribution law for the costs. We show that, when moving from a power-law distribution to a \u393 distribution, the leading correction changes both in sign and in its scaling properties. We also examine the behavior of the corrections when approaching a \u3b4-function distribution. By using a numerical solution of the saddle-point equations, we provide predictions that are confirmed by numerical simulations

Ecomorphology and feeding behavior of the Pleistocene South American equids (Mammalia, Perissodactyla, Equidae)

The fossil record of the South American Pleistocene presents two Equidae taxa: Hippidion Owen and Equus (Amerhippus) Hoffstetter. These equids were possibly sympatric and, although being considered closely related, present distinct cranial morphologies. This study aimed to verify possible variations on the masticatory patterns and dental wear between both genera, as well as to compare their rostral morphology and functional differences related to feeding habits. We performed quantitative analyses of macrowear and occlusion surface area of teeth from Toca dos Ossos (Bahia, Brazil). The morphofunctional analysis was conducted using photographs of specimens housed at the Museo de La Plata (La Plata, Argentina) and Museu de Ciências Naturais PUC Minas (Minas Gerais, Brazil), and based on the anatomy of the extant horse Equus caballus Linnaeus, due to its resemblance to E. (Amerhippus). Results showed that E. (Amerhippus) exhibits a more significant macrowear on the antero-posterior region of the teeth, while Hippidion has a more uniform wear. Analyses of occlusion surface area confirm the difference on the structure of dental enamel between genera, where Hippidion presents more complex folds. The morphofuctional analysis indicates that the rostral portion and the premaxillary shape of E. (Amerhippus) are similar to E. caballus. However, based on anatomical studies of the premaxillary region of other extinct ungulates, Hippidion exhibits morphological structures compatible with the presence of a vestibular proboscis and premaxillary region usually found on browsing ungulates. These results indicated that E. (Amerhippus) had the capacity to feed on more abrasive food items than Hippidion. Nevertheless, the morphofunctional dissimilarities on their skull suggest marked variations on their ecomorphological strategies. Therefore, these two different approaches corroborate our point of view that Hippidion and E. (Amerhippus), despite their possible sympatry, presented consistent mechanisms related to the reduction of niche overlap concerning the partition of food resources.Sesiones libresFacultad de Ciencias Naturales y Muse