Search results for "Fish"

Comparative morphometrics of sharpsnout seabream (Diplodus puntazzo Cetti, 1777), reared in different conditions

1999

The same genetic stock of sharpsnout seabream (Diplodus puntazzo), cultured in different conditions (lot A, monoculture tank; lot B, monoculture offshore cage; lot C, polyculture tank), was analysed using geometric morphometrics in order to detect changes in shape. Rearing in the offshore cage (lot B) had a significant effect on shape variation when compared to rearing in the two enclosed tanks (A and C). Fish from the tanks show a higher frequency (43.7% in lot A and 37.5% in lot C) of the so-called ‘goitred’ and ‘dorsal flat’ forms, their deformations shown by displacements in the corresponding landmarks of the infraopercular and dorsal areas. In contrast, the so-called ‘belly’ fish were …

Phenotypic plasticity in haptoral structures of Ligophorus cephali (Monogenea: Dactylogyridae) on the flathead mullet (Mugil cephalus): A Geometric M…

2015

Abstract Evaluating phenotypic plasticity in attachment organs of parasites can provide information on the capacity to colonise new hosts and illuminate evolutionary processes driving host specificity. We analysed the variability in shape and size of the dorsal and ventral anchors of Ligophorus cephali from Mugil cephalus by means of geometric morphometrics and multivariate statistics. We also assessed the morphological integration between anchors and between the roots and points in order to gain insight into their functional morphology. Dorsal and ventral anchors showed a similar gradient of overall shape variation, but the amount of localised changes was much higher in the former. Statist…

How a Fish’s Brain May Move a Fish’s Body

1990

The brainstem of the electric fish Eigenmannia virescens contains a small number of neural networks projecting directly onto the motoneuron pools of the spinal cord such that each segment is reached by at least one neuron of all the networks. Quantitative data of movement patterns, recorded from freely moving animals as well as elicited by electrical stimulation of the single networks, suggest that each network contains a full program for a particular movement, e. g. bending of the body axis to one side. By virtue of the structural relationship the programs are executable with a small number of segments. Mixing of small pieces of programs along the body axis allows for a far larger variety …

Determining suitable fish to monitor plastic ingestion trends in the Mediterranean Sea

2019

The presence of marine litter is a complex, yet persistent, threat to the health and biodiversity of the marine environment, and plastic is the most abundant, and ubiquitous type of marine litter. To monitor the level of plastic waste in an area, and the prospect of it entering the food chain, bioindicator species are used extensively throughout Northern European Seas, however due to their distribution ranges many are not applicable to the Mediterranean Sea. Guidance published for the Marine Strategy Framework Directive suggests that the contents of fish stomachs may be analyzed to determine trends of marine plastic ingestion. In order to equate transnational trends in marine plastic ingest…

An analysis based on trawl-survey data of the state of the ‘Italian’ stock of Mullus barbatus in the Sicilian Channel, including management advice

1993

Abstract Data on the relative abundance of age groups obtained by statistically designed routine trawl surveys in approximately half of the Sicilian Channel were processed with commonly available microcomputer fish population dynamics packages. The species considered was Mullus barbatus , a unit stock of which had been previously identified in the study area. Analytical and management outcomes were also assessed in relative terms. Conditions and limits on both the analyses and the outcomes are discussed with reference to the particular case study.

Helminth infestation of three fishes (Serranus scriba, Mullus surmuletus, Scorpaena porcus)from a coastal seaground in the Gulf of Palermo (Tyrrhenia…

1997

Abstract The results of a year's survey on the parasitic infestation of the gastrointestinal tract of three species of benthic fish, namely Serranus scriba, Mullus surmuletus, and Scorpaena porcus, living in a restricted coastal seaground in the N/W sector of the Gulf of Palermo, are reported and critically discussed. Fish populations were sampled monthly by means of a trammel net, according to the local fishing usage. As many as nine helminth species, five of them trematodes and four nematodes, were collected from the gastrointestinal tract of 625 individuals. Infestation was most intense in M. surmuletus, with a peak in the spring. S. scriba was especially parasitized during the spring an…

2019

Here we explore the carbon and oxygen isotope compositions of the co-existing carbonate and phosphate fractions of fish tooth enameloid as a tool to reconstruct past aquatic fish environments and harvesting grounds. The enameloid oxygen isotope compositions of the phosphate fraction (δ18OPO4) vary by as much as ~4‰ for migratory marine fish such as gilthead seabream (Sparus aurata), predominantly reflecting the different saline habitats it occupies during its life cycle. The offset in enameloid Δ18OCO3-PO4 values of modern marine Sparidae and freshwater Cyprinidae from the Southeast Mediterranean region vary between 8.1 and 11.0‰, similar to values reported for modern sharks. The mean δ13C …

La teoria que no va morir mai: Com una idea matemàtica del segle XVIII transformà el segle XXI

2014

La regla de Bayes, una teoria senzilla del segle XVIII per a l’avaluació del coneixement, rebé tot de crítiques durant la major part del segle XX, però va ser utilitzada pel Regne Unit i els Estats Units durant la Segona Guerra Mundial i la Guerra Freda. Palomares i València van representar papers importants en el seu desenvolupament durant aquells temps ombrívols. L’ús de la regla està molt estès avui dia en l’àmbit de la computació i en moltes aplicacions més. Per exemple, Bayes s’ha convertit en la clau política per a la presa de decisions basades en dades. La revolució bayesiana ha esdevingut un canvi de paradigma modern per a una era eminentment pragmàtica.

Revealing environmental synchronicity that enhances anchovy recruitment in the Mediterranean Sea.

2022

AbstractSmall pelagic fishes in the Mediterranean Sea constitute about half of the total landings, of which almost one-third is European anchovy. Anchovy abundance mainly depends on early life stage and juvenile survival and growth, which are susceptible to shifts in environmental processes. Due to the commercial importance of this species, it is necessary to elucidate the processes affecting recruitment strength for effective fishery management, using environmental indices to set more appropriate harvesting limits. Here, we constructed a simple index to capture synchronicity between enrichment and retention/concentration processes, which are known to affect anchovy abundance, during the fi…

ECONOMIC EVALUATION OF AQUACULTURE INVESTMENTS UNDER CONDITIONS OF RISK AND UNCERTAINTY IN THE MEDITERRANEAN SEA

2014

This study aims to analyze, from a technical and ec onomic point of view, the choice between alternative investments in aquaculture under condit ions of risk and uncertainty. In particular, a comparative analysis has been conducted between an inshore and an offshore farm producing European sea bass in the Mediterranean Sea. The app lied model refers to the theory of subjective probability, assigning a different probability to e xpected incomes during the investment period. Resul ts show an economic convenience of inshore with respect to offshore farming.