Search results for "Salmo"

Epizootiology of protozoans in farmed salmonids at northern latitudes

1997

Abstract Protozoan ectoparasites were examined in a northern salmonid fish farm over a 10-year period, June 1984–May 1994, by the same researcher, with similar catching and sampling procedures throughout. Husbandry procedures remained constant during the study, e.g., fingerlings were kept in steel tanks and yearlings in both steel tanks and earth ponds. Ichthyobodo necator, Chilodonella hexasticha and Ichthyophthirius multifilurs infections were treated with formalin, salt and malachite green-formalin baths, respectively, whenever any parasites were found. Altogether 10 790 randomly sampled salmon (Salmo solar), sea trout (S. trutta m. trutta) and brown trout (S. trutta m. lacustris) were s…

Nocturnal drift of mayfly nymphs as a post-contact antipredator mechanism

2000

SUMMARY 1. The predominantly nocturnal constrained drift of stream invertebrates is commonly regarded as a behaviour that avoids encounters with visually foraging fish in the water column. The alternative explanation, that drift peaks are caused by bottom-feeding, nocturnal predators, has rarely been tested. 2. We examined these hypotheses by collecting invertebrate drift in five streams in northern Finland: one with brown trout (Salmo trutta, a drift-feeding fish), one with alpine bullhead (Cottus poecilopus, a benthic fish), one with both species, and two fishless streams. 3. Drift by Baetis mayflies was aperiodic or slightly diurnal in both fishless streams on all sampling occasions. In …

Toxicity of 4-chloro-o-cresol to fish. Light microscopy and chemical analysis of the tissue

1979

Finnish salmon resistant to Gyrodactylus salaris: a long-term study at fish farms.

1996

Abstract The occurrence of Gyrodactylus salaris on Baltic salmon ( Salmo salar ), sea trout ( S. trutta m. trutta ) and brown trout ( S. trutta m. lacustris ) was examined from 1984 to 1993 at 4 fish farms (A, B, C and D) that produce smolts for stocking in northern Finland. No G. salaris was found on the sea or brown trout, but it did occur on salmon for 6–7 years at farms B, C and D, the prevalences of infection being 9.5%, 17.7% and 8.8% for salmon yearlings and smolts during that time, respectively, but less than 1.2% for fingerlings at farms B and C. Only brood stock salmon were infected at farm A in 4 years. The abundances of G. salaris increased during the second winter of each year …

Parasitofauna del salmonete de roca (Mullus surmuletus) en el Mediterráneo español: variabilidad espaciotemporal y su implicación pesquera

2015

En el presente trabajo se ha realizado un estudio de la fauna de metazoos parásitos del salmonete de roca, Mullus surmuletus, en el Mediterráneo español. Se trata del estudio más detallado y completo hasta la fecha sobre los parásitos de este teleósteo en esta región. Además, en este trabajo investigamos las ventajas y limitaciones del uso de los parásitos como marcadores poblacionales y como herramientas para trazar el origen de las capturas de salmonete de roca con el fin de ayudar a gestionar y manejar esta especie que actualmente se encuentra sobreexplotada. Para ello se analizaron 1204 peces durante el período 2003-2006: 1000 procedentes de 5 puertos del Mediterráneo español (de norte …

Peinture et poésie dans Peindre d’André Salmon

2007

Estudio de las relaciones entre la pintura y la creación poética en la obra "Peindre" (1921) de André Salmon.

Histopathological responses of newly hatched larvae of whitefish (Coregonus lavaretus s.l.) to UV-B induced toxicity of retene

2003

Positively phototactic fish larvae may be exposed to increased ultraviolet-B (UV-B) radiation alone or, potentially and in addition, to polycyclic aromatic hydrocarbons (PAHs) such as retene (7-isopropyl-1-methylphenanthrene) at the egg or larval stages. Suspended and sedimental particulate material near pulp and paper mills may act as sources of retene in chemically contaminated lake areas. In laboratory conditions whitefish larvae were pre-exposed to retene (10, 32 and 100 microg/l), with relevant controls, and irradiated in semi-static tests for 3 h once a day (2 consecutive days) with two UV-B doses (CIE-weighted 2.8 or 5.4 kJ per m(2) per day) or with visible light only. These UV-B dos…

Exposure to increased ambient ultraviolet B radiation has negative effects on growth, condition and immune function of juvenile Atlantic salmon (Salm…

2008

Atlantic salmon (Salmo salar) parr were exposed in two outdoor experiments, ranging in duration from 52 to 137 days, to spectral treatments: (1) natural sunlight (=present ambient UVB level), (2) solar radiation supplemented with enhanced UVB radiation from lamps simulating 20% or 8% stratospheric ozone loss or (3) UVB-depleted sunlight achieved by screening with Mylar-D film. The growth, condition and immune function of the salmon were quantified after treatments. Exposure to enhanced UVB radiation retarded growth, and decreased hematocrit value and plasma protein concentration. Further, enhanced UVB radiation affected plasma immunoglobulin concentration. The results demonstrate that juven…

Relationship between the endangered freshwater pearl mussel Margaritifera margaritifera, its salmonid host and co-infectants

2018

The relationship between the freshwater pearl mussel (hereafter FPM), Margaritifera margaritifera, and its salmonid host — pivotal for the conservation of this endangered bivalve — is characterized by a long parasitic stage (up to 11 months) and excessive host specificity. This thesis focuses on this relationship by experimentally studying the effect of FPM infection on the growth and resistance of salmonid fish and how the infection influences vulnerability of the host to other parasites and diseases, as well as how exposure of the host to other parasites affects vulnerability to FPM. Infection with FPM results in (i) reduced growth of the host, brown trout, during the parasitic period. Gl…

Effect of glochidia infection on growth of fish : freshwater pearl mussel Margaritifera margaritifera and brown trout Salmo trutta

2019

AbstractEffect of freshwater mussels’ (Unionoida) glochidia on the growth of fish host has remained poorly studied. We compared the specific growth rate of the juvenile, PIT-marked brown trout (Salmo trutta) between uninfected controls to those experimentally infected (average initial intensity of infection 8000 fish−1) with Margaritifera margaritifera glochidia, kept in high and low feeding. Growth and mortality of fish were monitored for 10 months. Our hypothesis was that glochidiosis would impair the growth of fish. According to our hypothesis, infected fish gained statistically significantly less weight than the control fish throughout the experiment. A proportional increase in weight o…