Destruction of habitat is the major cause for loss of biodiversity. This volume presents the population ecology of Atlantic salmon and brown trout and how it is influenced by the environment in terms ...of growth, migration, spawning and recruitment.
The response of a brown trout habitat modification Needham, Robert J; Gaywood, Martin; Tree, Angus ...
Canadian journal of fisheries and aquatic sciences,
11/2021, Letnik:
78, Številka:
11
Journal Article
Recenzirano
Globally, freshwaters are the most degraded and threatened of all ecosystems. In northern temperate regions, beaver (Castor spp.) reintroductions are increasingly used as a low-cost and ...self-sustaining means to restore river corridors. River modifications by beavers can increase availability of suitable habitat for fish, including salmonids. This study investigated the response of a population of brown trout (Salmo trutta) to reintroduced Eurasian beaver (Castor fiber) habitat modifications in northern Scotland. The field site comprised two streams entering a common loch; one modified by beavers, the other unaltered. Electrofishing and PIT telemetry surveys indicated abundance of post-young-of-the-year (post-YOY) trout was higher in the modified stream. Considering juvenile year groups (YOY and post-YOY) combined, abundance and density varied with year and season. In the modified stream, fork length and mass were greater, there was a greater variety of age classes, and mean growth was positive during all seasons. Beavers had profound effects on the local brown trout population that promoted higher abundances of larger size classes. This study provides important insight into the possible future effect of beavers on freshwater ecosystems.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The study focuses on the microanatomy and ultrastructural changes in the trunk kidney interstitium cells and nephrons in parr, smolt, and spawning brown trout (Salmo trutta Linnaeus, 1758) sampled in ...Luga River and Solka River, the tributaries of the Baltic Sea. Regardless of the type of cells or their structure, there were changes in their areas and in the number and structure of organelles responsible for the transport, synthetic, and energetic functions of cells. Our data on the morphology of the nephron combined with data on its physiology suggest a fundamental change in kidney function during the parr-smolt transformation before migration; this could be a pre-adaptation for a successful life in saltwater where urine output is sharply reduced. Thus, detected structural features of the trunk kidney in S. trutta are cytological markers of the migration process. The numbers of lymphocytes, neutrophils, and eosinophils with segmented nuclei increased from parr to smolts and then to spawners; only monotypic specific granules in neutrophils were found in smolts and spawners. Cells with radially arranged vesicles were described for the first time in S. trutta renal interstitium. Their origin has not yet been established. The shape of these cells changed from spherical to trihedral during fish maturation. All the above ultrastructural changes of renal interstitium cells could be considered cytological markers of cell maturity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Metal(loid) bioaccumulation in acanthocephalans (Dentitruncus truttae) and intestines of fish (Salmo trutta) from the Krka River, influenced by industrial and municipal wastewaters, was investigated ...in relation to exposure to meta(loid)s from fish gut content (GC), water, and sediment to estimate potentially available metal(loid)s responsible for toxic effects and cellular disturbances in biota. Sampling was performed in two seasons (spring and autumn) at the reference site (river source, KRS), downstream of the wastewater outlets (Town of Knin, KRK), and in the national park (KNP). Metal(loid) concentrations were measured by ICP-MS. The highest accumulation of As, Ba, Ca, Cu, Fe, Pb, Se and Zn was observed mainly in organisms from KRK, of Cd, Cs, Rb and Tl at KRS, and of Hg, Mn, Mo, Sr and V at KNP. Acanthocephalans showed significantly higher bioaccumulation than fish intestine, especially of toxic metals (Pb, Cd and Tl). Metal(loid) bioaccumulation in organisms partially coincided to exposure from water, sediments and food, while in GC almost all elements were elevated at KNP, reflecting the metal(loid) exposure from sediments. Seasonal differences in organisms and GC indicated higher metal(loid) accumulation in spring, which follows enhanced fish feeding rates. Higher number of acanthocephalans in the intestine influenced biodilution process and lower concentrations of metal(loid)s in fish, indicating positive effects of parasites to their host, as supported by high values of bioconcentration factors. Fish intestine and acanthocephalan D. truttae were confirmed as sensitive indicators of available metal fraction in conditions of generally low environmental exposure in karst ecosystem. Since metal(loid) accumulation depended on ecological, chemical and biological conditions, but also on the dietary habits, physiology of organisms and parasite infection, continuous monitoring is recommended to distinguish between the effects of these factors and environmental exposure when assessing dietary associated metal(loid) exposure in aquatic organisms.
To study the influence of temperature (4, 6, and 12degreesC) on the development of brown trout (Salmo trutta) from hatching to the end of metamorphosis, an analysis of allometric growth patterns was ...conducted to identify two different groups of individuals, namely developmental phases at total lengths (TL) ranging from 2.72 cm at 4degreesC to 2.22 cm at 12degreesC. Then, a multitrait approach considering different variables like the survival rate, development time, morphometric characteristics, energetic value, and skeletal mineralization was conducted on these two groups. Results indicated that the first growth phase was slower at 4degreesC, whereas the second was also slower at this temperature, even though swimming behavior was already present. However, at 12degreesC, fry showed a delay in their development (i.e., lower levels of skeletal mineralization and energetic content) during the first growth phase, but they compensated during the second growth phase, reaching the same size in TL when compared with the other temperatures (4 and 6degreesC); fry at 12degreesC showed low energy reserves. Our study demonstrated that the use of an allometric analysis to identify different developmental stages coupled with a multitrait approach was more efficient than a classical distinction between biological stages (hatching, emergence, first food intake, and exogenous feeding), and this procedure is of interest when evaluating the impact of rearing conditions on early development in fish.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The shallow Lake Skjerja was originally one of the most outstanding brown trout lakes on the Hardangervidda mountain plateau. During the period 1973–1985, the annual yield was on average 3.35 kg ...ha-1. In the mid-1980s, Eurasian minnow established a dense population in the lake. Since 1994, 5304 kg of Eurasian minnow have been removed with baited traps, which correspond to an annual mean catch of 177 kg year-1 or 1.12 kg ha-1. The competition for food, in addition to longer food chains, has had a strong negative impact on the brown trout production, with an annual yield reduced to 1.07 kg ha-1, or 32% of the historical catches (1973-1985). The total removed biomass of the two fish species correspond to 65% of the brown trout yield before the invasion of the Eurasian minnow. In Lake Skjerja, the two crustacean species Gammarus lacustris and Lepidurus arcticus, have historically been staple food items for brown trout. Fishing with baited traps on the minnows, and the presence of a large fraction of predatory brown trout, may have reduced the predation pressure on the two crustacean species, and they are still a part of the brown trout diet. The availability of fish as food has resulted in a significant increase in the presence of large individuals of brown trout with maximum weights above four kg. Despite reduced annual yield of brown trout, Lake Skjerja is still a popular fish destination with nearly 200 big-sized brown trout (mean annual weight 1065 grams) landed annually. On Hardangervidda, an increase in air temperature has been observed since the 1980s, with a corresponding change in water temperature which may benefit Eurasian minnow. In warm summers, water temperature approaches 14°C which has proved to be near to the upper thermal threshold for Lepidurus arcticus.
Passage of hydropower plants by upstream-migrating salmonid spawners is associated with reduced migration success, and the need for knowledge of fish behavior downstream of dams is widely recognized. ...In this study, we examined fishway passage of landlocked Atlantic salmon (Salmo salar) in River Klaralven, Sweden, and brown trout (Salmo trutta) in River Gudbrandslagen, Norway, and the influence of prior experience on passage success in 2012 and 2013. Fishway trap efficiency varied from 18% to 88% and was influenced by river discharge. Most salmon (81%) entered the fishway trap on days without spill, and salmon moved from the turbine area to the spill zone when there was spill, with small individuals showing a stronger reaction than large fish. Analysis of fish with and without prior trap experience showed that a higher percentage of the "naive" fish (70% of salmon and 43% of the trout) entered the fishway traps than the "experienced" ones (25% of the salmon and 15% of the trout). Delays for fish that entered the trap ranged from 3 to 70 days for salmon and 2 to 47 days for trout.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In Romania, the salmon breeding is the second branch of pisciculture as importance, but the obtained production is very small (about 1240 to; ANPA, 2005) and enough limited as bred species (brown ...trout - Salmo trutta fario, brook trout - Salvelinus fontinalis and rainbow trout - Oncorhynchus mykiss). The brown trout (Salmo trutta fario L.) and the huchen (Hucho hucho L.) represent two species with big economical, biological and culinary value, and to capitalize and promote the Romanian aquatic and endemic potential we consider timely and necessary that these ones to breed in specialized farms, with a view to diversity the fish production and to preserve the biodiversity. In the project, our consortium proposes projection and building of a pilot station for brown trout (Salmo trutta fario L.) and huchen (Hucho hucho L.) breeding in space and environment controlled, hall type, with control possibility of medium parameters. By application of modern and performed fish breeding system it can be promoted new methods, techniques and technologies, which have as final aim the obtaining of some diversity fish productions, and evidently superior given to those obtained in present days in trout farms from Romania.
Salmonids are members of the Salmonidae family which includes the subfamily Coregoninae, subfamily Thymallinae and subfamily Salmoninae. This family includes fish of interest for aquaculture and ...sport fishing. The salmonids from the natural environment on Romanian territory are Salmo trutta fario, Salmo labrax, Salvelinus fontinalis fontinalis, Hucho hucho, and Thymallus thymallus. Gene flow from fishery populations to those in the natural habitat may create substantial problems to natural species which leads to a reduction of inherited genetic diversity and of environment adjustment due to a loss of natural capacity to adapt. Due their characteristics, microsatellites prove themselves usefull in population genetics studies. Aim of our study is to evaluate the genetic diversity of two populations of brown trout from Făgăraş Mountains using nuclear markers. For this purpose we analyzed the polymorphism of nine microsatellite loci (BS131, Str60, Str73, Str15, Str543, OmyFGT, Ssa85, Ssa197, Strutta12) in two brown trout population from Făgăraş Mountains. We successfully amplified all microsatellite loci obtaining allele peaks of different sizes. The number of allele ranged beetwen 1 (Str73) and 26 (OmyFGT). The analyzed trout populations show a relatively high degree of genetic diversity, being also characterized by a low level of inbreeding among individuals. This technology has great potential for investigating the genetic diversity of the wild population and, also, might be extended to aquaculture studies.
•Primary hepatocyte spheroids from brown trout were maintained for over 30 days.•Spheroids were exposed (96 h) to 10 and 100 µM of 5α-dihydrotestosterone (DHT).•DHT influences different lipidic ...pathways in hepatocyte spheroids from brown trout.•Hepatocyte spheroids are a promising model for fish in vitro studies.
Three-dimensional (3D) fish liver cultures mimic the in vivo cellular microenvironment, which is ideal for ecotoxicological research. Despite that, the application of these cultures to evaluate toxic effects in fish is scarce. A 3D model of brown trout (Salmo trutta f. fario) primary hepatocyte spheroids was optimized in this study by using DMEM/F-12 with 15 mM of HEPES, 10 mL/L of an antibiotic and antimycotic solution and FBS 10% (v/v), at 18 °C with ∼100 rpm. The selection of optimal conditions was based on a multiparametric characterization of the spheroids, including biometry, viability, microanatomy and immunohistochemistry. Biometric and morphologic stabilization of spheroids was reached within 12-16 days of culture. To our knowledge, this study is the first to culture and characterize viable spheroids from brown trout primary hepatocytes for over 30 days. Further, the 3D model was tested to explore the androgenic influences on lipidic target genes after 96 h exposures to control, solvent control, 10 and 100 µM of 5α-dihydrotestosterone (DHT), a non-aromatizable androgen. Spheroids exposed to 100 µM of DHT had decreased sphericity. DHT at 100 µM also significantly down-regulated Acox1-3I, PPARγ and fatty acid synthesis targets (i.e., ACC), and significantly up-regulated Fabp1. Acsl1 was significantly up-regulated after exposure to both 10 and 100 µM of DHT. The results support that DHT modulates distinct lipidic pathways in brown trout and show that this 3D model is a new valuable tool for physiological and toxicological mechanistic studies.
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