Search results for " Trout"

Cardiovascular, ventilatory and haematological responses of brown trout (Salmo trutta L.), to the combined effects of acidity and aluminium in humic …

1995

Two year old brown trout (Salmo trutta L.) were exposed for 7 days to pH 4.7 alone and with aluminium at concentrations of 0.28 and 0.45 mg l−1, respectively, in the water of River Rutajoki, Central Finland. The labile aluminium accounted for less than 30% of the total added amount in the humic water. During the exposures the fish were monitored by a non-contact bioelectronic monitoring system which records heart and ventilation rates of the fish. Terminal blood samples were obtained to evaluate the degree of stress. No mortality occurred during any of the exposures. Acid stress alone and with aluminium caused an immediate acute response in heart and ventilation rates, which remained higher…

Shoaling behaviour of fish under parasitism and predation risk

2008

Shoaling is a common antipredatory adaptation in several fish species. However, parasite infections may alter shoaling behaviour of fish by impairing fish sensory/motor systems and by reducing the net benefit of shoaling. In an experimental study, we investigated whether Diplostomum spathaceum (Trematoda) eye flukes alter shoaling behaviour of rainbow trout, Oncorhynchus mykiss, and if this has an interaction with predation risk. The parasite reduces the vision of fish by inducing cataract formation, which in previous studies has been shown to alter fish escape responses and crypsis. We found that the shoals of infected fish contained fewer individuals and they divided into separate groups …

Bioelectronic monitoring of parasite-induced stress in brown trout and roach

1996

A non-contact bioelectronic monitoring system was used to record changes in heart rate, ventilation rate and swimming activity in brown trout Salmo trutta and roach Rutilus rutilus, following exposure to two species of cercariae of digenean trematodes: Diplostomum pseudospathaceum which is a common parasite in the lens of fishes and xiphidiocercariae of Plagiorchis elegans, a parasite of anatid birds, both of which have the snail Lymnaea stagnalis as their first intermediate host. Swimming activity increased significantly in roach exposed to Diplostomum cercariae at densities as low as 3.8l−1 and remained elevated for 24–36 h post exposure. Brown trout showed no response when exposed to low…

Prevention of fungal infestation of rainbow trout (Oncorhynchus mykiss) eggs using UV irradiation of the hatching water

2013

Abstract Fungal infestation by water mold Saprolegnia spp. causes great losses in aquaculture and fish egg hatching. To find a safe and effective alternative for the fungal prevention, we studied continuous disinfection of the inlet water by UV irradiation and ozonation combined with low concentration hydrogen peroxide (H 2 O 2 ) treatments in a rainbow trout ( Oncorhynchus mykiss ) egg hatching system. High dose of UV irradiation (400 mWs/cm 2 ) of the inlet water decreased the mortality of rainbow trout eggs from the 77.3% to 14.3% in a 28 day trial. UV irradiation did not modify water quality parameters, while combination of UV irradiation and H 2 O 2 caused up to fivefold increase in th…

Intercohort competition causes spatial segregation in brown trout in artificial streams

1999

When together in a flume, 13-cm LS (age-1) trout appeared to increase their activity and behaved more aggressively, whereas 10-cm LS (age-0) trout tended to move less and were rarely aggressive in the presence of the larger size class. Both size classes were less mobile and preferred lower water velocities in winter than in summer, and increased their use of instream cover in winter. When both size classes were present, only small trout decreased their use of low water velocities and cover. The results indicate that intercohort competition may cause spatial segregation among size groups of brown trout, especially in winter when trout attempt to minimize their maintenance costs.

Effects of soybean meal based diet on growth performance, gut histopathology and intestinal microbiota of juvenile rainbow trout (Oncorhynchus mykiss)

2006

Abstract Effects of soybean meal (SBM) based diet on growth performance, histology of the intestinal epithelium and on the gut microbiota of juvenile rainbow trout (Oncorhynchus mykiss) were investigated on two trials lasting for 8 weeks (Trial I) and 18 weeks (Trial II). The microbiological characterization was done both with conventional plating techniques, biochemical profiling and length heterogeneity analysis of PCR amplified 16S rDNA (LH-PCR). Typical histological changes were found after 18 weeks of SBM feeding (Trial II). Mean height of simple foldings were significantly higher within the group fed with fish meal (FM) based diet. These changes were not, however, reflected in the app…

Gut microbiota changes in rainbow trout, Oncorhynchus mykiss (Walbaum), during organic acid feed supplementation and Yersinia ruckeri infection

2013

Gut microbiota (GM) composition of vertebrates are considered to influence health parameters including immunological parameters in the host but knowledge of these issues in fish are sparse. We have performed a 45 day experimental study elucidating effects of dietary supplementation of organic acids (Mera Cid) and immunostimulants on the GM composition of rainbow trout Oncorhynchus mykiss (Walbaum) and investigated its association with blood parameters and disease resistance (against enteric red mouth disease (ERM) caused the bacterium Yersinia ruckeri). A total of 640 fish received either 1) basic fish feed without organic acids or immunostimulants, 2) fish feed with immunostimulants (β6glu…

High dietary inclusion level of fresh herring impairs growth of rainbow trout, Oncorhynchus mykiss

1998

Abstract One-year old rainbow trout (initially 350–670 g) were fed for 15 weeks diets containing various amounts of water (23–67%). This was achieved by replacing fish meal with Baltic herring. The growth of rainbow trout, whether measured as wet weight, protein or energy, was impaired when 50–55% dietary water was fed. The fish compensated for increasing dietary water content by consuming more diet so that the dry matter intake of the diets with 23 and 67% water were equal. Partitioning of growth into protein and lipid as well as protein and energy retention efficiencies were unaffected by dietary water. It is suggested that there is a metabolic cost of consuming more food when compensatin…

The fate aspects of pharmaceuticals in the environment : biotransformation, sedimentation and exposure of fish

2012

Taimenen mädin säilyvyys ja alkioiden kasvu Savijoen kipsinlevitysalueella

2019

Pelloille tehtävän kipsinlevityksen vesistövaikutuksia tutkittiin Helsingin yliopiston ja Suomen ympäristökeskuksen yhteishankkeessa ”SAVE - Saaristomeren vedenlaadun parantaminen peltojen kipsikäsittelyllä”. Hanke oli ympäristöministeriön rahoittama hallituksen kärkihanke. Siinä missä kipsin, eli kalsiumsulfaatin, levitys on vähentänyt pelloilta tulevaa fosforikuormitusta, se on toisaalta nostanut pilottialuetta halkovan Savijoen sulfaattipitoisuuden kolminkertaiseksi. Suuren sulfaattipitoisuuden tiedetään olevan haitallista vesieliöille, kuten kaloille. Näin ollen Jyväskylän yliopisto selvitti kipsinlevityksen vaikutuksia taimenen (Salmo trutta) varhaisten elinvaiheiden säilyvyyteen ja ka…