Winter diet of brown trout Salmo trutta in groundwater-dominated streams: influence of environmental factors on spatial and temporal variation

2016 ◽  
Vol 89 (5) ◽  
pp. 2449-2464 ◽  
Author(s):  
W. E. French ◽  
B. Vondracek ◽  
L. C. Ferrington ◽  
J. C. Finlay ◽  
D. J. Dieterman
Keyword(s):  
Environmental Factors ◽  
Temporal Variation ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Spatial And Temporal Variation ◽  
Winter Diet ◽  
Brown Trout Salmo Trutta

Spatial and temporal variation in the influence of density dependence on growth of stream-living brown trout (Salmo trutta)

2005 ◽  
Vol 62 (6) ◽  
pp. 1231-1242 ◽  
Author(s):  
Javier Lobón-Cerviá
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
High Growth ◽  
Spatial And Temporal Variation ◽  
Data Sets ◽  
Negative Power ◽  
Density Dependent ◽  
Brown Trout Salmo Trutta ◽  
Dependent Growth ◽  
Size At Age

The objective of this study was to investigate the extent to which, and the conditions under which, density operated on growth in stream-living brown trout (Salmo trutta). Observational data of 14 cohorts at four sites of Rio Chaballos (northwestern Spain) were examined. Consistent relationships between cohort-specific mass versus cohort-specific density and between year-to-year variations in brown trout mass at the end of five successive life stages versus mean densities corroborated one another and provided compelling evidence for the occurrence of density-dependent growth. However, density-dependent patterns varied in nature among sites to the extent that they were site-specific. A further comparison among 12 data sets revealed a smooth negative power trajectory between juvenile mass versus density. This plot suggested that detection of density-dependent growth might be facilitated in low density – high growth populations located at the steep wing relative to high density – slow growth populations. Current results emphasized the importance of density as a factor determining size-at-age and supported its operation as epiphenomena capable to obscure the effects of temperature on growth. The operation of density-dependent growth on numerical regulation of the population is further discussed.

Recruitment and survival rate variability in fish populations: density-dependent regulation or further evidence of environmental determinants?

2014 ◽  
Vol 71 (2) ◽  
pp. 290-300 ◽  
Author(s):  
Javier Lobón-Cerviá
Keyword(s):  
Environmental Factors ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Survival Rates ◽  
Fish Populations ◽  
Data Set ◽  
Site Specific ◽  
Density Dependent ◽  
Long Term Study ◽  
Brown Trout Salmo Trutta

Recently, Minto et al. (2008) , based on a fishery data set including marine, estuarine, and freshwater fishes, described higher variability in the survival rates of juveniles at low rather than at high parental density in an inversely density-dependent fashion and suggested density-dependent mechanisms underpinning those patterns. This study, based on a long-term study of brown trout (Salmo trutta; a species and habitat not included in the Minto et al. (2008) analysis), documents that survival rates in these stream-living populations exhibit a pattern that matches exactly those reported by Minto et al. (2008) . Nevertheless, hypothesis testing rejected the occurrence of stock–recruitment relationships and the operation of density-dependent recruitment regulation. The patterns elucidated for these brown trout populations can be entirely explained by the operation of two single environmental factors, namely, stream discharge in March determining annual survival rates across streams and sites and site-specific depth determining site-specific survival rates. It is open to question that exactly the same patterns can be generated by two sets of opposing factors, density-dependent (i.e., Minto et al. 2008 ) and environmental factors (i.e., this study). The consistency of this pattern suggests that survival rates and recruitment are probably determined by environmental factors across fish populations and habitats.

Use of Path Analysis to Investigate Mercury Accumulation in Brown Trout (Salmo trutta) in Norway and the Influence of Environmental Factors

1993 ◽  
Vol 50 (6) ◽  
pp. 1158-1167 ◽  
Author(s):  
Eirik Fjeld ◽  
Sigurd Rognerud
Keyword(s):  
Environmental Factors ◽  
Organic Carbon ◽  
Path Analysis ◽  
Total Organic Carbon ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Mercury Accumulation ◽  
Humic Matter ◽  
Atmospheric Depositions ◽  
Brown Trout Salmo Trutta

We studied relationships between environmental factors and mercury accumulation in resident brown trout (Salmo trutta) in 25 lakes in Norway. Our survey showed that mercury concentrations in fish are elevated in areas receiving high atmospheric depositions of mercury. A path analysis revealed that the concentrations of total organic carbon had a critical influence on the bioaccumulation of mercury. This reflects the role of humic matter in the transportation of mercury to lake water and sediments, and perhaps also a stimulating effect on the microbial methylation of mercury. Lake depth influenced the concentration of mercury in sediments, probably due to the complexation of mercury with sedimenting humic matter. The effect of such sediment on mercury concentrations in fish indicated that there exists a concentration-dependent production and release of methyl mercury to the biota. Selenium deposited from the atmosphere seemed to lower the bioavailability of mercury to fish. No effect of pH could be detected. The strong effect of total organic carbon implies that even moderate atmospheric deposition rates may result in relatively high mercury levels in fish, if other local environmental factors favour this.

scholarly journals Application of multistate modeling to estimate salmonid survival and movement in relation to spatial and temporal variation in metal exposure in a mining-impacted river

2019 ◽  
Vol 76 (11) ◽  
pp. 2057-2068
Author(s):  
Mariah P. Mayfield ◽  
Thomas E. McMahon ◽  
Jay J. Rotella ◽  
Robert E. Gresswell ◽  
Trevor Selch ◽  
...  
Keyword(s):  
Brown Trout ◽  
Salmo Trutta ◽  
Survival Rates ◽  
Cutthroat Trout ◽  
Spatial And Temporal Variation ◽  
Metal Exposure ◽  
Westslope Cutthroat Trout ◽  
Aquatic Life ◽  
Oncorhynchus Clarkii ◽  
Brown Trout Salmo Trutta

Multistate modeling was used to estimate survival and movement of brown trout (Salmo trutta) and westslope cutthroat trout (Oncorhynchus clarkii lewisi) in relation to copper concentrations in the mining-impacted Clark Fork River, Montana. Survival probability in the uppermost river segment, where dissolved copper concentrations frequently exceeded acute criteria for aquatic life (range: 31–60 days > 13.4 μg·L–1), was 2.1 times lower for brown trout and 122 times lower for westslope cutthroat trout compared with survival rates in the lowermost segment that had relatively low dissolved copper (0 days exceedance of acute concentration). Lowest survival for both species occurred in the spring–summer period when dissolved copper concentrations were elevated coincident with higher discharge. Movement among study segments was generally low, and cutthroat trout showed low movement into the uppermost river segment with the most elevated copper levels. Both species showed high rates of movement into tributaries, which coincided with their respective spawning migrations rather than as an apparent avoidance of elevated copper levels. The linkage between survival rate and level of copper exposure for both trout species suggests that additional removal of tailings deposits could improve survival rates.

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