Salmo trutta 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

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.

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.

Sea trout, Salmo trutta L., populations in the Slupia River basin have been affected by mass stocking with smolts and fry. This work is focused on a small-scale differentiation in sea trout populations from one basin with a strong... more

Sea trout, Salmo trutta L., populations in the Slupia River basin have been affected by mass stocking with smolts and fry. This work is focused on a small-scale differentiation in sea trout populations from one basin with a strong emphasis on the relationship between wild and hatchery origin fish. A total of 216 sea trout were genotyped at 10 microsatellite loci. Global F ST obtained by AMOVA was low at 0.0165. Pairwise F ST were significant for all tests except wild and stocked adults. The highest pairwise difference was found between the hatchery sample and Kwacza (F ST = 0.038). Analysis of the genetic structure revealed micro-geographical differentiation with four subpopulations. The quality of the artificial spawning was found not to be adequate with a high risk of adverse effects to the whole population. All future stocking actions in the basin should consider the existing population structures.

The Iberian Peninsula contains diverse populations of freshwater fish, with major river basins comprising differentiated biogeographic units. The Duero River flows through the North-Western Iberian Peninsula and is one of the most... more

The Iberian Peninsula contains diverse populations of freshwater fish, with major river basins comprising differentiated biogeographic units. The Duero River flows through the North-Western Iberian Peninsula and is one of the most important rivers within the Iberian glacial refuge. Brown trout (Salmo trutta) populate this whole basin, and studies using both allozyme and microsatellite loci have detected a geographically sorted distribution of genetic variation in this species. In this work, sequences of the mitochondrial control region obtained from 299 brown trout from the Duero River were compared with other Iberian and European datasets. Two differentiated haplotype groups were detected inside the Duero River basin. One of them was related to the Atlantic (AT) lineage that is present in Northern European populations, whereas the other comprised an unique group that was restricted to the inner region of the basin. The amount of divergence of this Duero group from the other brown trout populations studied is consistent with a new trout lineage (Duero, DU) that is endemic to this river basin and that diverged from other Atlantic populations during the Pleistocene. The distribution of the DU and AT quaternary lineages in the Duero River was consistent with the ichthyological pattern described in the basin that originated during the Miocene–Pliocene. Evidence of selective processes that favour the haplotypes of the DU lineage may explain this discrepancy.