Search results for "lohi"

Effect of peracetic acid on levels of geosmin, 2-methylisoborneol, and their potential producers in a recirculating aquaculture system for rearing ra…

2019

Abstract In recirculating aquaculture systems (RAS)s, off-flavors and odors, mainly caused by geosmin (GSM) and 2-methylisoborneol (MIB), can accumulate in the flesh of fish from RAS water, reducing the profitability of production. In this study, peracetic acid (PAA) was applied in three application intervals to pump sumps of rainbow trout (Oncorhynchus mykiss) reared in RAS. Using a real-time polymerase chain reaction (qPCR), the potential off-flavor producers were quantified using geoA and MIB synthase genes. Streptomyces was identified as the major GSM producer, and biofilters showed the highest number of potential off-flavor producers. Concentrations of GSM and MIB were analyzed in the …

Allee effect in a manipulative parasite within poikilothermic host under temperature change

2022

AbstractTemperature and intraspecific competition are important factors influencing the growth of all organisms, including parasites. The temperature increase is suggested to stimulate the development of parasites within poikilothermic hosts. However, at high parasite densities, this effect could be diminished, due to stronger intraspecific competition. Our study, for the first time, addressed the joint effects of warming and parasite abundances on parasite growth in poikilothermic hosts. The growth of the common fish parasite larvae (trematode Diplostomum pseudospathaceum) within the rainbow trout at different infection intensities and temperatures (15°C and 18°C) was experimentally invest…

Replacement of fishmeal with corn gluten meal in feeds for juvenile rainbow trout (Oncorhynchus mykiss) does not affect oxygen consumption during for…

2017

Abstract We compared oxygen consumption (MO 2 , mg/kg/h) of c. 80 g rainbow trout ( Oncorhynchus mykiss ) in an intermittent-flow swim respirometer at 15 °C. Before the tests the fish were grown in flow through tanks (15 °C) with either fishmeal (FM) or corn gluten meal (CGM) based diets (c. 52% protein) for a period of 3–4.5 months. Ten individuals from both treatment groups were fasted for 48 h before the swim test, which consisted of 18 loops of 210 s over three different periods: acclimation period (6 loops at 0.5 body lengths per s, BL/s), exercise period (8 loops at increased speed from 1 to 2.5 BL/s with recovery loops at 0.5 BL/s), and a recovery period (four loops at 0.5 BL/s). We …

Interactions between Rainbow Trout Eyed Eggs and Flavobacterium spp. Using a Bath Challenge Model:Preliminary Evaluation of Bacteriophages as Pathoge…

2021

The microbial community surrounding fish eyed eggs can harbor pathogenic bacteria. In this study we focused on rainbow trout (Oncorhynchus mykiss) eyed eggs and the potential of bacteriophages against the pathogenic bacteria Flavobacterium psychrophilum and F. columnare. An infection bath method was first established, and the effects of singular phages on fish eggs was assessed (survival of eyed eggs, interaction of phages with eyed eggs). Subsequently, bacteria-challenged eyed eggs were exposed to phages to evaluate their effects in controlling the bacterial population. Culture-based methods were used to enumerate the number of bacteria and/or phages associated with eyed eggs and in the su…

Spatio-temporal differences in the growth of wild and reared Atlantic salmon (Salmo salar L.) in the Baltic Sea

2013

Syönnösvaellus ja nopea kasvu ovat olennainen osa Atlantin lohen (Salmo salar L.) ekologiaa, niinpä kasvunopeuden selvittäminen on tärkeä osa kalatutkimusta. Tuottavimmat syönnösalueet tulisi tietää, jotta olisi mahdollista suojella villejä sekä kalastaa istutettuja lohia kestävän käytön periaatteella. Tämän tutkimuksen tavoitteina oli selvittää Itämeressä elävän villin ja viljellyn Atlantin lohen kasvunopeuden eroja vuosien ja merialueiden välillä. Lisäksi pyrittiin selvittämään, vaikuttavatko saalislajien runsaus, saalislajisuhteet lohen ravinnossa ja veden lämpötila kasvunopeuteen. Absoluuttinen pituuskasvu arvioitiin takautuvalla kasvunmäärityksellä suomuista vuosilta 1989–2010. Suomut …

Atlantic salmon survival at sea: temporal changes that lack regional synchrony

2022

Spatial and temporal synchrony in abundance or survival trends can be indicative of whether populations are affected by common environmental drivers. In Atlantic salmon (Salmo salar L.), return rates to natal rivers have generally been assumed to be affected primarily by shared oceanic conditions, leading to spatially synchronous trends in mortality. Here, we investigated the existence of parallel trends in salmon sea survival, using data on migrating smolts and returning adults from seven Canadian populations presumed to share feeding grounds. We analysed sea survival, using a Bayesian change-point model capable of detecting non-stationarity in time series data. Our results indicate that w…

Densities of Atlantic salmon (Salmo salar L.) fry in relation to physical habitat, spawning redd distribution and parr abundance in a small subarctic…

2014

Two small-scale surveys were conducted in a small river to examine the effects of physical habitat characteristics, spatial spawning redd distribution and abundance of older juveniles on the Atlantic salmon (Salmo salar L.) fry (age 0+) distribution 1) shortly after the emergence and 2) after the assumed main dispersal period of fry. The effect of physical habitat variables (water depth, water velocity and substratum size), spatial spawning redd distribution and densities of older juveniles were examined using multiple linear regressions. Identical models were fitted with generalized habitat suitability indices to test their applicability to predict the variation in fry densities. Clear pat…

Muhos- ja Sanginjoki lohikalojen elinympäristöinä

2006

Genetic relationships between sympatric and allopatric Coregonus ciscoes in North and Central Europe

2021

Abstract Background Sympatric speciation along ecological gradients has been studied repeatedly, in particular in freshwater fishes. Rapid post-glacial ecological divergence has resulted in numerous endemic species or ecologically distinct populations in lakes of the temperate zones. Here, we focus on the Baltic cisco (Coregonus albula) complex, to study the genetic similarity among two pairs of sympatric autumn- and spring-spawning populations from post-glacial German Lakes Stechlin and Breiter Luzin. For comparison, we included a similar pair of sympatric populations from the Swedish Lake Fegen. We wanted to explore potential genetic similarities between the three sympatric cisco populati…

Environmentally driven changes in Baltic salmon oxidative status during marine migration.

2020

The fitness and recruitment of fish stocks can be markedly affected by environmental disturbances including global warming, eutrophication and contamination. Understanding the effects of environmental stressors on salmon physiology during marine residence is of a global concern as marine survival has decreased. We present a unique combination of physiological responses - antioxidant defence and oxidative damage biomarkers, stable isotopes and contaminant exposure biomarkers - measured from adult Atlantic salmon (Salmo salar) collected at the Baltic Sea and studied in relation to environmental variables and fitness estimates. The results demonstrate that feeding populations of salmon display…