scholarly journals Spatial distribution of limited resources and local density regulation in juvenile Atlantic salmon

2009 ◽  
Vol 78 (1) ◽  
pp. 226-235 ◽  
Author(s):  
Anders G. Finstad ◽  
Sigurd Einum ◽  
Ola Ugedal ◽  
Torbjørn Forseth
Keyword(s):  
Spatial Distribution ◽  
Atlantic Salmon ◽  
Local Density ◽  
Limited Resources ◽  
Density Regulation ◽  
Juvenile Atlantic Salmon

Effects of discharge and local density on the growth of juvenile Atlantic salmon Salmo salar

2010 ◽  
Vol 76 (7) ◽  
pp. 1751-1769 ◽  
Author(s):  
M. A. K. Teichert ◽  
E. Kvingedal ◽  
T. Forseth ◽  
O. Ugedal ◽  
A. G. Finstad
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Local Density ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon

Spatial distribution correspondence of a juvenile Atlantic salmon Salmo salar cohort from age 0+ to 1+ years

2012 ◽  
Vol 81 (3) ◽  
pp. 1059-1069 ◽  
Author(s):  
A. Foldvik ◽  
M. A. K. Teichert ◽  
S. Einum ◽  
A. G. Finstad ◽  
O. Ugedal ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon

scholarly journals Interactions between local population density and limited habitat resources determine movements of juvenile Atlantic salmon

2017 ◽  
Vol 74 (12) ◽  
pp. 2153-2160 ◽  
Author(s):  
Maxim A.K. Teichert ◽  
Anders Foldvik ◽  
Sigurd Einum ◽  
Anders G. Finstad ◽  
Torbjørn Forseth ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Local Population ◽  
Experimental Studies ◽  
Release Site ◽  
Limited Resources ◽  
Key Factors ◽  
Juvenile Atlantic Salmon ◽  
Dependent Processes ◽  
Shelter Availability ◽  
Stream Salmonid

Competition for limited resources and the resulting density-dependent processes are key factors in driving stream salmonid population dynamics. Here we test for the combined effects of density and shelter availability on the movement of juvenile Atlantic salmon (Salmo salar) in a Norwegian river. Individually marked, hatchery-reared salmon juveniles were released at 26 sites along a 2.5 km long stretch and recaptured after 12 months. The spatial variation in shelter availability and density of salmonids was quantified prior to the release. We found no effect of released fish number on the number of marked salmon moving more than 12.5–112.5 m away from their release site. However, the ratio of pre-experiment fish density per shelter was positively related to the number of movers. Thus, fish that were released at sites where the amount of shelter was low relative to the density of the pre-experiment population were more likely to move. These results support the prediction from smaller scale experimental studies that shelter availability may act to determine local carrying capacity in stream-living salmonid populations.

Effects of spawning distribution on juvenile Atlantic salmon (Salmo salar) density and growth

2011 ◽  
Vol 68 (1) ◽  
pp. 43-50 ◽  
Author(s):  
Maxim A.K. Teichert ◽  
Anders Foldvik ◽  
Torbjørn Forseth ◽  
Ola Ugedal ◽  
Sigurd Einum ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Local Density ◽  
Habitat Characteristics ◽  
Individual Growth ◽  
Dominant Factor ◽  
Atlantic Salmon Salmo Salar ◽  
Local Densities ◽  
Spawning Sites

We test whether the spatial distribution of spawning sites in a natural population is related to the density and individual growth rate of juvenile stream-dwelling salmonids. For this purpose, fine-scale data on the spatial distribution of Atlantic salmon ( Salmo salar ) nest sites, juvenile densities and body size, and habitat characteristics were combined. The area of nests summed over reaches of 25 m in length was positively correlated with local young-of-the-year (YOY) densities and was the strongest predictor of local densities. In turn, increased YOY densities were related to slower growth, and YOY density was the strongest predictor of YOY size. Measured habitat variables had little effect on YOY density over the spatial scale examined, which suggests that redistribution of YOY salmon according to habitat preferences was limited. The distribution of spawning sites was therefore the best predictor of local densities and subsequently YOY growth. Thus, during the YOY stage when dispersal is limited, patchy spawning distributions combined with local density-dependence may be the dominant factor responsible for spatial variation in growth.

Food acquisition and growth of juvenile Atlantic salmon (Salmo salar) in relation to spatial distribution of food

Aquaculture ◽  
1996 ◽  
Vol 143 (3-4) ◽  
pp. 277-289 ◽  
Author(s):  
Even H. Jørgensen ◽  
Bjørn M. Baardvik ◽  
Robert Eliassen ◽  
Malcolm Jobling
Keyword(s):  
Spatial Distribution ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Food Acquisition ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon

Spatial distribution of juvenile Atlantic salmon (Salmo salar) in a subarctic river: size-specific changes in a strongly seasonal environment

2004 ◽  
Vol 61 (12) ◽  
pp. 2329-2338 ◽  
Author(s):  
Aki Mäki-Petäys ◽  
Jaakko Erkinaro ◽  
Eero Niemelä ◽  
Ari Huusko ◽  
Timo Muotka
Keyword(s):  
Spatial Distribution ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Low Velocity ◽  
Atlantic Salmon Salmo Salar ◽  
Seasonal Environment ◽  
Juvenile Atlantic Salmon ◽  
Boreal Streams ◽  
Management Schemes ◽  
Time Of Year

We examined seasonal variation in the spatial distribution and habitat preference of juvenile Atlantic salmon (Salmo salar) in a subarctic river characterized by near-zero water temperatures for 7–8 months a year. Size-specific differences in habitat use were pronounced in summer but disappeared at the onset of winter, when the habitats preferred by small (≤6 cm) and larger (7–17 cm) salmon overlapped heavily. Small salmon favoured low-velocity habitats during all seasons, and in summer and autumn they mainly occupied shallow microhabitats along stream margins. In winter and spring, small salmon preferred deeper habitats farther away from the shoreline. Larger salmon favoured deeper habitats in all seasons, but they only occupied slowly flowing areas at low water temperatures. Since all salmon size classes were closely associated with deep and low-velocity habitats in winter and spring, this time of year may represent a size-selective bottleneck for Atlantic salmon populations. Therefore, management schemes aiming to enhance salmonid habitats in boreal streams must rest on the knowledge of season- and size-specific habitat requirements of salmonid species.

scholarly journals Do galactic bars depend on environment?: an information theoretic analysis of Galaxy Zoo 2

2020 ◽  
Vol 501 (1) ◽  
pp. 994-1001
Author(s):  
Suman Sarkar ◽  
Biswajit Pandey ◽  
Snehasish Bhattacharjee
Keyword(s):  
Spatial Distribution ◽  
Mutual Information ◽  
Local Density ◽  
Statistical Significance ◽  
Distribution Functions ◽  
Cumulative Distribution ◽  
Host Galaxy ◽  
Data Sets ◽  
Data Set ◽  
Information Theoretic

ABSTRACT We use an information theoretic framework to analyse data from the Galaxy Zoo 2 project and study if there are any statistically significant correlations between the presence of bars in spiral galaxies and their environment. We measure the mutual information between the barredness of galaxies and their environments in a volume limited sample (Mr ≤ −21) and compare it with the same in data sets where (i) the bar/unbar classifications are randomized and (ii) the spatial distribution of galaxies are shuffled on different length scales. We assess the statistical significance of the differences in the mutual information using a t-test and find that both randomization of morphological classifications and shuffling of spatial distribution do not alter the mutual information in a statistically significant way. The non-zero mutual information between the barredness and environment arises due to the finite and discrete nature of the data set that can be entirely explained by mock Poisson distributions. We also separately compare the cumulative distribution functions of the barred and unbarred galaxies as a function of their local density. Using a Kolmogorov–Smirnov test, we find that the null hypothesis cannot be rejected even at $75{{\ \rm per\ cent}}$ confidence level. Our analysis indicates that environments do not play a significant role in the formation of a bar, which is largely determined by the internal processes of the host galaxy.

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