Brown trout Research Papers - Academia.edu (original) (raw)

ABSTRACT Native species of Sardinian brown trout (Salmo trutta) have declined drastically because of the introduction of non-native salmonids, overharvesting, and habitat degradation. One approach to conservation of declining species is... more

ABSTRACT Native species of Sardinian brown trout (Salmo trutta) have declined drastically because of the introduction of non-native salmonids, overharvesting, and habitat degradation. One approach to conservation of declining species is to establish new populations through repopulation with genetically certified fish. In this study, samples of brown trout from seven rivers in Sardinia were analysed to look for the presence of pure individuals of the endemic Sardinian trout. Analyses of the mitochondrial DNA control ...

Polychlorobiphenyls (PCBs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and DDT were examined in the muscle of brown trout (Salmo trutta) from a high mountain lake located in the Pyrenees (Catalonia, Spain) that was used as a... more

Polychlorobiphenyls (PCBs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB) and DDT were examined in the muscle of brown trout (Salmo trutta) from a high mountain lake located in the Pyrenees (Catalonia, Spain) that was used as a model of these lacustrine environments. Results indicate that fish age is the main factor of variability among specimens in this population that is subjected to atmospheric inputs of the organochlorine compounds (OC). Increases of 2- and 20-fold between fish aged 1 year and 15 years old are found. The observed pattern cannot be explained in terms of fish size, condition factor, or muscle lipid content. Higher molecular weight compounds (higher lipophilicity) are better correlated with fish age than low molecular weight compounds. A transformation from 4,4′-DDT to 4,4′-DDE occurs in fish after ingestion; this results in amplified age-dependent signals, especially in male specimens. In contrast, PCB congener #180 has lower age dependence than the general OC group, which could be due to its high hydrophobicity (log Kow > 7). In any case, selective accumulation of hydrophobic compounds is already observed among younger fish (age, 1 year). Due to this effect, the relative OC composition does not reflect the main OC pollutants in the lake waters.

The aim of this study is to examine the impact of mans interventions on the present day distribution of fish in a mountain area in southern Norway, the Atna river system. River Atna originates in the Rondane mountains at altitudes of... more

The aim of this study is to examine the impact of mans interventions on the present day distribution of fish in a mountain area in southern Norway, the Atna river system. River Atna originates in the Rondane mountains at altitudes of nearly 1600 m a.s.l., and joins River Glomma at 300 m a.s.l. There are 98 lakes in the watercourse

Some of the highest recordings of radioactive fallout from the Chernobyl accident in Norway were found in the south-eastern Oppland and Hedmark counties. Cesium content and decay rates were followed in populations of brown trout and... more

Some of the highest recordings of radioactive fallout from the Chernobyl accident in Norway were found in the south-eastern Oppland and Hedmark counties. Cesium content and decay rates were followed in populations of brown trout and Arctic char in Lake Atnsjøen over the years 1986–1995. These results were compared with samples for adjacent lakes to test for between-lake variabilities within

Although dam removal has been increasingly used as an option in dam management and as a river restoration tool, there are few studies providing detailed quantitative assessment of the response of fish populations to dam removal. In this... more

Although dam removal has been increasingly used as an option in dam management and as a river restoration tool, there are few studies providing detailed quantitative assessment of the response of fish populations to dam removal. In this study, we document the response of the fish community in the Pine River, Michigan, to the gradual removal of Stronach Dam. Ten sites were sampled annually during the course of the removal (1997–2003) and for 4 years following removal (2004–2007). Before the removal of Stronach Dam, 11 fish species were found only downstream of the dam, 1 species was found only upstream of the dam, and 19 species were captured both above and below the dam. Following removal, 8 species formerly found only below the dam utilized newly available portions of the river above the dam. Most fish species (18 of the 25 evaluated) showed an increase in abundance following removal, strongly supporting the idea that dam removal reduces multiple factors limiting riverine fishes. Brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss were the primary sport fishes present in the river, and the abundance of both species increased by more than twofold over the course of the study. The abundance of white suckers Catostomus commersonii also increased significantly due to increased reproductive success. The results of this study illustrate how dam removal is a useful tool for restoration of habitat connectivity and habitat conditions and how the fish community in a coldwater stream responded to the removal.

Abstract – We compared the growth and prey consumption of juvenile hatchery and wild brown trout of similar genetic origin in 12 wire mesh cages in a natural river in North-Eastern Finland. Wild trout started feeding shortly after the... more

Abstract – We compared the growth and prey consumption of juvenile hatchery and wild brown trout of similar genetic origin in 12 wire mesh cages in a natural river in North-Eastern Finland. Wild trout started feeding shortly after the start of the experiment, and clearly earlier than novel hatchery trout, but ate less in the presence of hatchery trout. When accompanied with wild trout, novel hatchery trout started to feed earlier, consumed more live prey, and lost less weight than when in allopatry. Hatchery trout grew more slowly than wild trout. To our knowledge, this is the first study to show that hatchery trout benefit from the presence of wild, experienced trout in a complex semi-natural environment. However, our results also indicate that the benefits to hatchery fish are not transferred to wild fish, and ultimately that care should be exercised in management actions when using hatchery trout to supplement wild populations. On the other hand survival potential of the novel hatchery brown trout could be better in the wild when also undomesticated trout are present.

One hundred thirty-three Twin Cities Metropolitan area stream stations were sampled during 1998-2000. Our goal was to gain knowledge of fish communities in these rarely studied urban streams and to document their status. Seventy-two... more

One hundred thirty-three Twin Cities Metropolitan area stream stations were sampled during 1998-2000. Our goal was to gain knowledge of fish communities in these rarely studied urban streams and to document their status. Seventy-two species from 18 families were collected during the survey. Fathead minnows, central mudminnows, and green sunfish were the most frequently occurring species. Trout were collected from

Atlantic salmon and brown trout frequently co-occur in the same habitats and juveniles of both species are difficult to discriminate. Hybridization between the two taxa has also been widely documented especially in endangered populations... more

Atlantic salmon and brown trout frequently co-occur in the same habitats and juveniles of both species are difficult to discriminate. Hybridization between the two taxa has also been widely documented especially in endangered populations hence the need for species-specific molecular markers. Here we show that the microsatellite marker SsAD486 has two species-specific alleles allowing the identification of Atlantic salmon, brown trout, and their hybrids throughout the European range of these species. Since this marker is polymorphic in Atlantic salmon populations from Western Atlantic, it could also help discriminating between North American and European salmon.