Search results for "Salmo"

Risupadot, putoukset ja tierummut taimenen (Salmo trutta) vaellusesteinä pienissä virtavesissä : kotiutumiskäyttäytymiseen perustuva tutkimus

2015

Virtavesissä kalojen liikkumista saattavat rajoittaa luonnostaan muodostuneet tai ihmisen rakentamat vaellusesteet. Muun muassa tienrakennuksen yhteydessä asennetut tierummut voivat estää kalojen kulun osittain tai kokonaan. Kivien tai kallion aiheuttama putous tai virran mukana kulkeutuva puuaines voivat myös synnyttää luonnollisen vaellusesteen. Suomessa vaellusesteitä on kartoitettu jonkin verran, mutta varsinaista tutkimusta on tehty vähän. Tässä tutkimuksessa tutkittiin, toimivatko risupadot, pienet putoukset ja tierummut taimenen (Salmo trutta) vaellusesteenä. Taimenet (91–383 mm) merkittiin mustepisteillä, Carlin-merkein tai rasvaeväleikkauksin ja siirrettiin esteen yläpuolelta sen a…

Symbolika księżyca w Enarrationes in psalmos św. Augustyna

2018

Niniejszy artykuł dowodzi, że Augustyn objaśniając w Enarrationes in Psalmos teksty Psalmów nie traktuje pojawiających się w nich odniesień do księżyca jedynie jako części opisów piękna stworzonego świata, ale stara się w nim dostrzec sens ukryty, którego ujawnienie służy wykładni różnych teologicznych zagadnień. Dla biskupa Hippony księżyc jest bowiem metaforą Boga Stwórcy, Chrystusa, Kościoła oraz człowieka. W odniesieniu do Boga Stwórcy księżyc ma przypominać chrześcijanom, iż Bóg stwarzając wszystko jako dobre i piękne sam jest Dobrem i Pięknem. Ponadto motyw księżyca ma wskazywać na samowystarczalność Boga, Jego wolność i niezależność. Księżyc jako metafora Chrystusa pozwala z kolei do…

Lohen (Salmo salar) kutuvaelluskäyttäytyminen Näätämöjoen vesistössä

2008

High Lipid Content of Prey Fish and n−3 PUFA Peroxidation Impair the Thiamine Status of Feeding-Migrating Atlantic Salmon (Salmo salar) and Is Reflec…

2022

Signs of impaired thiamine (vitamin B1) status in feeding-migrating Atlantic salmon (Salmo salar) were studied in three Baltic Sea areas, which differ in the proportion and nutritional composition of prey fish sprat (Sprattus sprattus) and herring (Clupea harengus). The concentration of n−3 polyunsaturated fatty acids (n−3 PUFAs) increased in salmon with dietary lipids and n−3 PUFAs, and the hepatic peroxidation product malondialdehyde (MDA) concentration increased exponentially with increasing n−3 PUFA and docosahexaenoic acid (DHA, 22:6n−3) concentration, whereas hepatic total thiamine concentration, a sensitive indicator of thiamine status, decreased with th…

Data from: Cleaner fish escape salmon farms and hybridize with local wrasse populations

2018

The genetic impact of farmed fish escaping aquaculture is a highly debated issue. However, non-target species, such as cleaner fish used to remove sea lice from farmed fish, are rarely considered. Here we report that wild corkwing wrasse (Symphodus melops), which are transported long distances to be used as cleaner fish in salmon farms, escape and hybridize with local populations. Recently, increasing numbers of corkwing wrasse have been reported in Flatanger in Norway, north of its described distribution range, an area heavily relying on import of cleaner fish from Skagerrak. Using genetic markers identified with 2bRAD sequencing, we show that, although the Flatanger population largely is …

Data from: Protection first then facilitation: a manipulative parasite modulates the vulnerability to predation of its intermediate host according to…

2011

Many trophically-transmitted parasites with complex life cycles manipulate their intermediate host behavior in ways facilitating their transmission to final host by predation. This facilitation generally results from lowering host’s anti-predatory defences when the parasite is infective to the final host. However, a recent theoretical model predicts that an optimal parasitic strategy would be to protect the intermediate host from predation when non-infective, before switching to facilitation when the infective stage is reached. We tested this hypothesis in the fish acanthocephalan parasite Pomphorhynchus laevis using the amphipod Gammarus pulex as intermediate host. Gammarids parasitized by…

Data from: Oxygen and carbon isoscapes for the Baltic Sea: testing their applicability in fish migration studies

2018

Conventional tags applied to individuals have been used to investigate animal movement, but these methods require tagged individuals be recaptured. Maps of regional isotopic variability known as “isoscapes” offer potential for various applications in migration research without tagging wherein isotope values of tissues are compared to environmental isotope values. In this study, we present the spatial variability in oxygen (math formula) and dissolved inorganic carbon (δ13CDIC) isotope values of Baltic Sea water. We also provide an example of how these isoscapes can reveal locations of individual animal via spatial probability surface maps, using the high-resolution salmon otolith isotope da…

Data from: Enriched rearing environment and wild genetic background can enhance survival and disease resistance of salmonid fishes during parasite ep…

2016

The importance and volume of aquaculture is increasing world-wide. Rearing practices play a key role in determining growth rate, survival and disease resistance in aquaculture fishes. Recent evidence suggests that in comparison with a standard stimulus-poor rearing environment, an enriched or variable rearing environment has significant positive effects on several traits underlying growth and well-being of fish. However, the effect of enriched rearing on one of the most important threats for aquaculture development, occurrence of parasitic infections, remains unknown. We used surveillance data of experimental salmonid populations of wild and hatchery origin under semi-natural parasite expos…

Data from: Proactive avoidance behaviour and pace-of-life syndrome in Atlantic salmon

2019

Individuals in a fish population differ in key life history traits such as growth rate and body size. This raises the question of whether such traits cluster along a fast-slow growth continuum according to a pace-of-life syndrome (POLS). Fish species like salmonids may develop a bimodal size distribution, providing an opportunity to study the relationships between individual growth and behavioural responsiveness. Here we test whether proactive characteristics (bold behaviour coupled with low post-stress cortisol production) are related to fast growth and developmental rate in Atlantic salmon, Salmo salar. Boldness was tested in a highly controlled two-tank hypoxia test were oxygen levels we…

Data from: Learned parasite avoidance is driven by host personality and resistance to infection in a fish–trematode interaction

2016

Cognitive abilities related to the assessment of risk improve survival. While earlier studies have examined the ability of animals to learn to avoid predators, learned parasite avoidance has received little interest. In a series of behavioural trials with the trematode parasite Diplostomum pseudospathaceum, we asked whether sea trout (Salmo trutta trutta) hosts show associative learning in the context of parasitism and if so, whether learning capacity is related to the likelihood of infection mediated through host personality and resistance. We show that animals are capable of learning to avoid visual cues associated with the presence of parasites. However, avoidance behaviour ceased after …