Search results for "Salmo"
showing 10 items of 442 documents
Evidence of energy and nutrient transfer from invasive pink salmon (Oncorhynchus gorbuscha) spawners to juvenile Atlantic salmon (Salmo salar) and br…
2021
Recent large influxes of non‐native Pacific pink salmon (Oncorhynchus gorbuscha) to North European rivers have raised concern over their potential negative impacts on native salmonids and recipient ecosystems. The eggs and carcasses of semelparous pink salmon may provide a significant nutrient and energy subsidy to native biota, but this phenomenon has not been widely documented outside the species' native distribution. We analysed the stomach contents and stable isotope values (δ15N and δ13C) in muscle and liver tissues of juvenile Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) to determine whether these native salmonids utilise marine‐derived nutrients and energy provided by…
Ecology, fisheries and management of wild brown trout populations in boreal inland waters
2010
Eutrophication of aquatic ecosystems is an increasing problem, especially threatening small and shallow freshwater lakes. While the extreme inputs of nutrients (phosphorus and nitrogen) can nowadays be reduced and controlled rather efficiently, additional measures to reverse eutrophication may be needed. These often involve biomanipulation, typically mass removal of cyprinid fish. However, the success of biomanipulations has many times been limited or short lived. The reasons for this are not well known, perhaps because the more subtle impacts of biomanipulation on the ecosystem-wide processes of lakes have not been thoroughly studied. Natural abundance stable isotopes may provide a cost-ef…
Connections between microhabitat factors and dimensions of brown trout (Salmo trutta) redds
2017
This study is part of a process of habitat restoration and management of Finnish and Swedish rivers. This study was conducted to analyse detailed and generalised data regarding microhabitat factors and dimensions of spawning redd of brown trout (salmo trutta). The objectives of this study were to analyse connections between redd dimensions, connections between redd length and microhabitat factors and to analyse the variability of redd length and microhabitat factors among catchments in order to understand spawning habitat selectivity of brown trout (salmo trutta). The study shows that the redd dimensions are positively and strongly correlated. Redd length is weakly correlated to microhabita…
Lake size and fish diversity determine resource use and trophic position of a top predator in high-latitude lakes
2015
Prey preference of top predators and energy flow across habitat boundaries are of fundamental importance for structure and function of aquatic and terrestrial ecosystems, as they may have strong effects on production, species diversity, and food-web stability. In lakes, littoral and pelagic food-web compartments are typically coupled and controlled by generalist fish top predators. However, the extent and determinants of such coupling remains a topical area of ecological research and is largely unknown in oligotrophic high-latitude lakes. We analyzed food-web structure and resource use by a generalist top predator, the Arctic charr Salvelinus alpinus (L.), in 17 oligotrophic subarctic lakes…
Photoinduced lethal and sublethal toxicity of retene, a polycyclic aromatic hydrocarbon derived from resin acid, to coregonid larvae
2004
A comparative investigation on the acute phototoxicity of retene to vendace (Coregonus albula) and whitefish (C. lavaretus), both having pelagial larvae in spring, was conducted. To test the concept of early warning of sublethal biomarkers in relation to lethality to posthatch stages, we examined the effects of ultraviolet-B (UV-B) and retene on the levels of cytochrome P4501A (CYP1A) and heat shock protein 70 (HSP70) by exposing the animals to elevated levels of these factors for 48 and 72 h, respectively. Whereas UV-B and retene on their own were not lethal, simultaneous retene and UV-B exposure caused very high mortality to both species. The median lethal concentration (LC50; i.e., the c…
Warming temperatures and ectoparasitic sea lice impair internal organs in juvenile Atlantic salmon
2021
As a consequence of climate change and open net-pen salmon farming, wild Atlantic salmon Salmo salar are increasingly likely to encounter elevated temperatures and parasite abundances during their early marine migration. Such stressors can compromise fitness by diminishing liver energy stores and impairing cardiac muscle. To assess whether temperature and infestation by salmon lice Lepeophtheirus salmonis are important correlates of liver energy stores and cardiac muscle performance in juvenile salmon, we experimentally infested fish at 3 abundances of louse infestation (zero, low, and high) and 5 temperatures (10, 13, 16, 19, and 22°C). At the end of the experiment (i.e. when sea lice reac…
Efectos de piretroides utilizados para el control del piojo de mar en la práctica de la salmonicultura sobre invertebrados no diana
2019
En la actualidad el mayor problema que enfrenta la industria salmonera a nivel mundial es la alta proliferación y diseminación del piojo de mar, un copépodo ectoparásito que alcanza altas densidades poblacionales en los centros de cultivo intensivo de salmónidos. Los insecticidas piretroides cipermetrina y deltametrina se han estado utilizado para bajar las cargas parasitarias mediante tratamientos periódicos. Los organismos marinos no diana pueden estar expuestos a estos piretroides a través del agua, los sedimentos o la ingestión de partículas orgánicas contaminadas. Los moluscos bivalvos y los anélidos poliquetos han sido ampliamente utilizados como organismos centinela de contaminación …
Jokihelmisimpukkapopulaatioiden (Margaritifera margaritifera L.) isäntäspesifisyys
2013
Jokihelmisimpukka (Margaritifera margaritifera L.) eli raakku on yksi kaikkein uhanalaisimmista akvaattisista lajeista Euroopassa. Raakku loisii osan elinkierrostaan lohikaloissa, ja tästä syystä yksityiskohtaista tietoa lajin isäntäspesifisyydestä tarvitaan lajin suojelua varten. Tässä tutkimuksessa tutkittiin kalojen sumputuskokeilla sekä laboratorioaltistuksella, onko raakku sopeutunut eri populaatioissa eri isäntäkaloihin ja onko populaatioissa sopeutumista paikalliseen isäntäpopulaatioon. Lisäksi tutkittiin vierasperäisen puronieriän (Salvelinus fontinalis Mitchill) soveltuvuutta raakkujen isännäksi. Tutkimuspopulaatioiksi valittiin Livojoen raakkupopulaatio, jonka alueella on ennen ve…
The variable food webs in cold-water lakes
2022
Jokihelmisimpukan (Margaritifera margaritifera) glokidium-toukkien kehittyminen ja lukumäärät kalaisännässä kahdessa Iijoen alueen taimenpurossa
2012
Jokihelmisimpukan (Margaritifera margaritifera L.) elämänkierron eri vaiheiden ajoitus tunnetaan heikosti, mikä vaikeuttaa mm. suojelutoimien suunnittelua. Tämän tutkimuksen tavoitteena oli havainnoida jokihelmisimpukan glokidium-toukkien kehittymistä ja lukumääriä kahdessa Iijoen alueen taimenpurossa. Erityisesti pyrimme saamaan tietoa siitä, milloin toukat kiinnittyvät kaloihin ja milloin ne irtoavat niistä. Lisäksi tavoitteena oli saada tietoa toukkien kasvunopeudesta loisvaiheessa. Tutkimus kohdistettiin kahteen lämpötiloiltaan erilaiseen puroon Iijoen alueella 9.6. ja 7.9. välisenä aikana. Tutkimuskalana käytettiin purotaimenta (Salmo trutta m. fario L.), joka on puroissa luonnostaan e…