Search results for "trout"

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 …

Species differences, influence of dose and application on biotransformation of phenol in fish.

1983

1. The metabolism of phenol in goldfish (Carassius auratus), rainbow trout (Salmo gairdneri) and goldenorfe ide (Leuciscus ideus melanotus) was compared. All three species produced phenyl sulphate, quinol sulphate and phenyl glucuronide. 2. The dose dependence of metabolism of phenol in goldfish was investigated. When the concn. of phenol was increased from 0.2 to 2 mg/l medium, that glucuronylated increased from 7 to 16% and that sulphated decreased from 63 to 47%. 3. The influence of mode of exposure on metabolism of phenol in goldfish was examined. Dietary exposure and uptake from medium was compared with i.p. injection. There was less metabolism in the order: dietary exposure greater th…

Signals of major histocompatibility complex overdominance in a wild salmonid population

2009

The major histocompatibility complex (MHC) contains the most variable genes in vertebrates, but despite extensive research, the mechanisms maintaining this polymorphism are still unresolved. One hypothesis is that MHC polymorphism is a result of balancing selection operating by overdominance, but convincing evidence for overdominant selection in natural populations has been lacking. We present strong evidence consistent with MHC-specific overdominance in a free-living population of Arctic charr (Salvelinus alpinus) in northernmost Europe. In this population, where just two MHC alleles were observed, MHC heterozygous fish had a lower parasite load, were in better condition (as estimated by a…

Startup and effects of relative water renewal rate on water quality and growth of rainbow trout (Oncorhynchus mykiss) in a unique RAS research platfo…

2018

Abstract The aquaculture industry is growing fast but facing two major challenges: a shortage of suitable locations for growth and the need to reduce environmental impacts. One solution for both these challenges is inland production through recirculating aquaculture systems (RAS). The RAS technique is rather new, and several practical issues need to be solved. In this study, an experimental platform, consisting of ten individual RAS units, was built for small-scale testing of different RAS designs and operation methods, and two preliminary experiments were conducted. In the first experiment, the capability of different chemical additions (sodium nitrite, ammonium chloride and/or cane sugar)…

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…

Immunostimulants in prevention of columnaris disease of rainbow trout, Oncorhynchus mykiss (Walbaum).

2009

Transmission, infectivity and survival of Diplostomum spathaceum cercariae

2003

The transmission dynamics of the cercariae of Diplostomum spathaceum were investigated under laboratory conditions using cercariae collected from naturally infected Lymnaea stagnalis. Cercariae were kept in a constant temperature of 20 °C and the survival and infectivity to naïve young rainbow trout recorded at 3-h intervals until few cercariae were alive. Mortality initially remained constant but increased rapidly after 20 h. While a model of constant mortality fitted the survival data, an age-dependent model provided a better fit and implied that cercariae tended to carry similar quantities of resources and once these were exhausted the cercariae died. Cercarial infectivity also showed an…

Influence of rearing conditions on Flavobacterium columnare infection of rainbow trout, Oncorhynchus mykiss (Walbaum).

2005

The influence of rearing conditions on Flavobacterium columnare infection of rainbow trout, Oncorhynchus mykiss (Walbaum), was studied experimentally in the laboratory and at a fish farm. In experiment I, the effect of parasitic infection on columnaris disease was studied using F. columnare carrier fish. The fish were exposed to Diplostomum spathaceum cercariae and a set of other stressors in order to induce clinical columnaris infection. Parasitic infection and other stressors failed to induce the disease. Disease occurred when the fish were challenged with F. columnare, but D. spathaceum infection did not enhance the severity of the infection. In experiment II, the influence of rearing de…

Infection of brown trout with Diphyllobothrium dendriticum procercoids.

1997

The aims of this experimental study were to develop a practical method of controlling the number of Diphyllobothrium dendriticum procercoids delivered to a fish host; to examine the effect of different procercoid doses (3, 7 and 15) on the plerocercoid level in fish; and to examine the potential mortality caused by plerocercoids. The experiment was terminated after 2 months. The prevalence of infection at the lowest dose level, 17.2%, was statistically significantly lower than at medium and high levels, 63.3% and 56.7%, respectively. The mean intensity increased slightly along with the dosage. The contribution of D. dendriticum to the death of a few fish could not be proved. It is concluded…