Search results for "Salmo"
showing 10 items of 442 documents
Effects of weekend starvation and the duration of daily feeding on production parameters of rainbow trout Oncorhynchus mykiss
2021
It would often be practical to starve the cultivated fishes over the weekends, e.g. to save in labour costs. We evaluated the possibility that domesticated juvenile rainbow trout (Oncorhynchus mykiss) could compensate for the lost growth of the 2-day weekend starvation by either hyperphagic response and/or by lower feed conversion ratio, compared to the fish fed every day in an 8-week experiment. Rainbow trout (initial weight c. 30 g, temperature 16 °C) starved during the weekends were able to increase feed intake during the weekdays clearly above the intake of the control fish after the first two weekends, also seen as an increase of the compensation coefficients over the last four weeks o…
Indice de réflexion latérale du saumon Atlantique (Salmo salar), de la truite de mer (Salmo trutta), du corégone (Coregonus lavaretus) et du brochet …
2000
L'indice de reflexion acoustique laterale (TS) de 19 saumons Atlantique (Salmo salar), 16 truites de mer (Salmo trutta), 10 coregones (Coregonus lavaretus) et 7 brochets (Esox lucius) a ete mesure en utilisant un sondeur de 200 kHz, afin d'etudier la relation entre l'indice TS et la taille, le poids et la surface du poisson. Les effets de l'angle d'incidence sur l'indice TS ont aussi ete etudies. Des modeles lineaires entre TS et le logarithme de l'indice de taille du poisson ont ete ajustes et ont montre que la meilleure prevision provient de l'indice de longueur. Classiquement, l'erreur standard de l'estimation etait de 1,2 a 2,9 dB. Les resultats des mesures de TS sur des poissons de lon…
Relationship between rat liver microsomal Δ6 and Δ5 desaturase activities and fatty acid composition: comparative effects of coconut and salmon oils …
1992
International audience; The aim of this work was to compare the effects of coconut and salmon oils on rat liver microsomal Δ6 and Δ5 desaturations, during protein restriction. A higher Δ6 desaturase activity was noted in rats fed the low-protein coconut oil diet, in comparison with that occurring in rats fed either a low-protein or normal-protein salmon oil diet. No variation was observed in Δ5 desaturase activity or in 20:4n-6/ 18:2n-6 ratio. The fatty acid composition of liver microsomal phospholipids provided evidence of higher levels of 20:5n-3 and 22:6n-3 in the normal-protein salmon oil group, when compared with the low-protein salmon oil group. No influence of experimental diets on t…
Diplostomum spathaceum metacercarial infection and colour change in salmonid fish
2004
Colour changes in two salmonid fish, the salmon (Salmo salar) and sea trout (S. trutta), were examined in relation to infection with the trematode Diplostomum spathaceum. This parasite had no effect on the rate of colour change in these fish, although species specific differences in colour adjustment times were observed. Increasing asymmetry in parasite numbers between the right and left eye, which could lead to the retention of vision in one eye, nevertheless tended to reduce the colour change time in salmon with moderate infection (P=0.08). This first experimental attempt to examine colour changes in fish in relation to eye fluke infections provides grounds for future investigations. The …
Cottus gobio Linnaeus, 1758 Community Interest Species Conservation in Upper Târnava Mare River Basin, Through Fish Populations Rehabilitation for Br…
2017
Abstract The ADONIS: CE software has been used for two fish species, Cottus gobio, of conservation interest and Salmo trutta fario, of economic interest, to design an on-site (upper Târnava Mare River) adapted support-system model for management decision-making. Habitat needs and indicators of favourable conservation status have been investigated, pressures and threats to these fish species have been determined, and management elements have been suggested. This management system allows the proper organization of management measures for the renaturation of the local natural fish associations in the local brown trout zone.
Probabilistic maturation reaction norms assessed from mark-recaptures of wild fish in their natural habitat
2014
Published version of an article in the journal: Ecology and Evolution. Also available from the publisher at: http://dx.doi.org/10.1002/ece3.1044 Open Access Reaction norms are a valuable tool in evolutionary biology. Lately, the probabilistic maturation reaction norm approach, describing probabilities of maturing at combinations of age and body size, has been much applied for testing whether phenotypic changes in exploited populations of fish are mainly plastic or involving an evolutionary component. However, due to typical field data limitations, with imperfect knowledge about individual life histories, this demographic method still needs to be assessed. Using 13 years of direct mark-recap…
The effects of dietary fumonisin B1 on growth and physiology of rainbow trout (Oncorhynchus mykiss)
2016
Kalanrehuissa on perinteisesti luotettu kalajauhoon ja -öljyyn rehujen pääasiallisina proteiinin- ja energianlähteinä. Näitä raaka-aineita on nykyään alettu korvata kasviperäisillä ainesosilla niiden edullisemman hinnan ja helpomman saatavuuden vuoksi, esimerkiksi maissilla, vehnällä ja soijalla. Pilaantuneen kasviperäisen raaka-aineen mukana rehuun pääsee haitallisia mykotoksiineja. Mykotoksiinit ovat homesienten sekundäärisiä metaboliatuotteita, joita ne pääasiassa tuottavat kilpailuun muita homeita vastaan, ja joiden on havaittu aiheuttavan kasvun heikentymistä ja sairauksia monilla eri kotieläimillä, mutta niiden vaikutuksista kaloihin tiedetään varsin vähän. Yksi yleisimmistä mykotoksi…
Hucho hucho (Linnaeus, 1758): last natural viable population in the Eastern Carpathians - conservation elements
2019
There is great variation in the conservation status of the last habitats with long-term natural viable populations of the salmon species Hucho hucho in Maramureş Mountains Nature Park, Eastern Carpathians (Romania). According to the specific guidelines for Natura 2000, 42.11% are in good conservation status, 31.57% are of average status, and 26.32% are in a partially degraded condition. In this study area, 6 main risk elements were identified related to human impact on the environment: poaching, minor riverbed mor-phodynamic changes, liquid and solid natural flow disruption, habitat fragmentation leading to isolation of fish populations, organic and mining pollution, and destruction of ripa…
Hallien (halichoerus grypus) ja itämerennorppien (phoca hispida botnica) ravinnonkäyttö Perämerellä
2011
Itämeren alueen hyljekannat ovat hiljalleen toipuneet 1900-luvun liikapyynnin ja ympäristömyrkkyjen aiheuttamasta kannanromahduksesta. Hallien ja itämerennorppien kannat ovat olleet nousussa lähes koko 2000-luvun ajan. Hylkeiden määrän lisääntymisen myötä myös ammattikalastajien hyljevahingot ovat lisääntyneet. Kalastajat väittävät elinkeinonsa olevan uhattuna, koska hylkeet vahingoittavat lohipyydyksiä, syövät saalista rysistä ja kilpailevat kalastajien kanssa samoista vähäisistä lohista. Tarkkaa tietoa lohien ja taimenten osuudesta tai osuuden ajallisesta vaihtelusta hylkeiden ravinnonkäytössä ei kuitenkaan ole. Tässä tutkimuksessa selvitettiin hallien (Halichoerus grypus) (n=63) ja norpp…
Return of the Apex Predator : How Brown Trout (Salmo trutta) Re-Establishment Shapes an Ecosystem
2021
Re-establishment of a declined apex predator fish species in a lake ecosystem may have dramatic effects on other fish and plankton community already inhabiting the ecosystem. We studied mechanistically potential impacts of re-establishment of the brown trout (Salmo trutta) in the west-central European Lake Constance focusing on two commercially important fish species: whitefish and Eurasian perch. We compared simulation model outputs from two versions of an allometric trophic network model for Lake Constance, one with and one without the trout as the apex predator. The re-establishment of the declined brown trout reduced the perch population directly by predation and indirectly by increased…