Discharge-dependent covariation patterns in the population dynamics of brown trout (Salmo trutta) within a Cantabrian river drainage

2004 ◽  
Vol 61 (10) ◽  
pp. 1929-1939 ◽  
Author(s):  
Javier Lobón-Cerviá
Keyword(s):  
Population Dynamics ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Regional Scale ◽  
Survival Rates ◽  
River Drainage ◽  
Introduced Populations ◽  
Geographical Regions ◽  
Brown Trout Salmo Trutta ◽  
Positive Correlations

Patterns of spatial covariation in the population dynamics of brown trout (Salmo trutta) across Rio Esva (northwestern Spain) were explored by using the residuals from stock–recruitment relationships as indices of survival rates of spawner-to-recruit (STR), spawner-to-cohort size (STC), and spawner-to-spawner (STS). Positive correlations in pairwise comparisons among survival rates together with highly significant spatiotemporal variation in STC (74.3%) and STS (51.5%) explained by variation in STR provided evidence for persistent spatial covariation across the river drainage during the whole lifetime. Split-line regressions fitted to the survival rates versus river discharge in March (when trout emerge) highlighted the importance of discharge during, or just after, trout emergence as a major determinant of recruitment whose effects are reflected in the population over the lifetime and emphasized the synchrony between environmental processes and brown trout dynamics. Synchrony in recruitment is caused by hydrological synchrony that, in turn, is determined by climatic synchrony (rainfall) operating at the regional scale. The importance of discharge for recruitment is consistent with studies on native and introduced populations, suggesting its broad effect on the dynamics of stream brown trout across geographical regions.

Energetics and survival of virgin and repeat spawning brown trout (Salmo trutta)

1998 ◽  
Vol 55 (1) ◽  
pp. 47-53 ◽  
Author(s):  
Ole Kristian Berg ◽  
Eivind Thronæs ◽  
Gunnbjørn Bremset
Keyword(s):  
Brown Trout ◽  
Specific Energy ◽  
Salmo Trutta ◽  
Energy Content ◽  
Survival Rates ◽  
Total Protein Content ◽  
Energy Expenditures ◽  
Brown Trout Salmo Trutta ◽  
Investment In Reproduction ◽  
First Time

Smaller virgin spawners of a stunted population of brown trout (Salmo trutta) had higher specific energy content than repeat spawners, indicating that once maturation has started, the trout does not completely recover from its first spawning. Males had higher amounts of total and specific energy after spawning compared with females (adjusted for length differences). The greatest energy expenditures were recorded among spawning females (specific total energy losses of about 20%, which were twice the losses of male spawners). Repeat females lost 40% of their fat content. The gonads of the females accounted for 20% of the total protein content. The loss in carcass protein and fat for the spawners was greater than the corresponding loss in visceral fat and protein. Survival rates paralleled the amounts of energy expended in reproduction. Overall survival rate of first-time spawning males (females) was about 0.90 (1.00), while the corresponding value for repeat spawners was about 0.65 (0.50). It is predicted that brown trout from a stunted population should make a relatively small investment in reproduction and thus represent a case of low investment among iteroparous fish species.

The influence of hydrological and biotic processes on brown trout (Salmo trutta) population dynamics

2002 ◽  
Vol 59 (1) ◽  
pp. 12-22 ◽  
Author(s):  
Franck Cattanéo ◽  
Nicolas Lamouroux ◽  
Pascal Breil ◽  
Hervé Capra
Keyword(s):  
Population Dynamics ◽  
Brown Trout ◽  
Salmo Trutta ◽  
Growth Period ◽  
Intraspecific Interactions ◽  
Emergence Period ◽  
Trout Population ◽  
Brown Trout Salmo Trutta ◽  
High Flows ◽  
Survival Mechanisms

Hydrological and biotic forces constrain brown trout (Salmo trutta) population dynamics, but tests of their role across numerous streams are uncommon. In 30 French stream reaches, using 5–8 samples (1 per year) each, we investigated whether the year-to-year seasonal hydrology influenced annual trout densities within reaches, and whether the relationships were shared by all reaches. We also searched for intraspecific interactions between and within cohorts. Trout data were age class (0+, 1+, and adults) densities. For each year, hydrology was described using 13 variables, each computed for a reproduction, emergence, and growth period related to the biological cycle of trout. We used analyses of covariance (ANCOVA) to test how trout densities at year n – 1 and hydrology at year n influenced trout densities at year n. High flows during emergence significantly reduced the 0+ densities, consistently across the 30 reaches. Then, 1+ and adult densities were linked, respectively, to 0+ and 1+ densities from the previous year. Analyses also revealed density-dependent survival mechanisms for the 0+ cohort, suggesting intracohort competition. Therefore, hydrology constrains trout dynamics only during the critical emergence period, after which intracohort interactions regulate the 0+ density. Such mechanisms, validated across 30 environmentally different reaches, seem to be fundamental to trout population dynamics.

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.

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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