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.

Modeling shelter abundance for juvenile Atlantic salmon in a residual flow reach of a hydro power plant using SSIIM 2

2021 ◽  
Author(s):  
Spyros Pritsis ◽  
Nils Ruther ◽  
Kordula Schwarzwälder ◽  
Anastasios Stamou
Keyword(s):  
Grain Size ◽  
Atlantic Salmon ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Sediment Supply ◽  
Substrate Composition ◽  
Juvenile Atlantic Salmon ◽  
River Reach ◽  
Bed Changes ◽  
Shelter Availability

<p>Nowadays, the aquatic biodiversity is highly under pressure due to anthropogenic changes of the rivers such hydraulic structures changing the diversity of flow and aquatic fauna as well as sediment continuity. This can have severe consequences on the fish population in the river reach. Fish are strongly depending on a certain substrate composition throughout all their life stages. Juveniles for example are depending on a certain availability of shelter in the substrate in order to survive this stage.</p><p>Therefore, we investigate the effects of changes in the sediment composition at a hydropower plant in Switzerland on the availability of potential shelter for juvenile fish. By utilizing the observed correlation between parameters describing the fine tail of a riverbed’s grain size distribution and shelter abundance for juvenile Atlantic salmon, we predict the available shelter in a river reach by using a 3D hydrodynamic numerical model directly coupled to a morphodynamic model. The initial substrate composition was assumed to be spatially uniform, its parameters based on a grain size distribution curve derived from collected sediment samples.</p><p>This model can now be used for habitat improvement scenario modeling. Based on the assumption that a specific mixture of sediment coming from upstream travelling through the river reach will positively influence the potential shelter availability, different scenarios can be investigated. The baseline for comparison was the simulation of the bed changes without any sediment supply from upstream. The baseline discharge was set to 100 m<sup>3</sup> /s and was applied for 24 hours. The resulting bed changes create a map of the potential shelter availability of this grain size mixture. Then, two scenarios with sediment inflow from the upstream boundary were simulated. One coarse and one fine mixture of sediment were chosen as inputs, with the goal of investigating their impact on shelter abundance. The former designed to have a positive effect while the latter expected to reduce interstitial voids in the substrate and have a negative effect on available shelter.</p><p>The investigation is conducted as part of the EU Horizon 2020 funded project FIThydro (funded under 727830)</p>

scholarly journals Density-independent use of shallow riverine areas in juvenile Atlantic salmon

2019 ◽  
Vol 76 (7) ◽  
pp. 1161-1170 ◽  
Author(s):  
Michael Puffer ◽  
Ole Kristian Berg ◽  
Frøydis Bolme Hamnes ◽  
Vidar Bentsen ◽  
Wouter Koch ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Experimental Studies ◽  
Aquatic Organisms ◽  
Fish Size ◽  
Juvenile Atlantic Salmon ◽  
Four Seasons ◽  
Sink Effect ◽  
Source Sink ◽  
Diurnal Regulation

Habitat use of aquatic organisms is essential to evaluate effects of many environmental challenges like effects of hydropower regulation, where stranding may occur under hydropeaking (rapid dewatering of shallow river areas). Experimental studies as well as observations from nature with juvenile Atlantic salmon (Salmo salar) show that the proportion of the population that uses shallow depth was both independent of population density and decreases with fish size. Experiments were conducted both in the presence and in absence of older fish, during day and night, and during all four seasons. Juvenile salmon from deep areas may therefore distribute into the shallow areas even when fish density becomes reduced. Thus, low density does not lead to reduced stranding risk, and shallow areas may therefore function as a sink in a within-generation source–sink dynamic under a repeated hydropeaking scenario. The sink effect of rapid dewatering in shallow areas may be mitigated by seasonal and diurnal regulation of hydropeaking activity, but dewatering may still result in extinction of weak populations.

Greater Dispersal of Wild Compared with Hatchery-Reared Juvenile Atlantic Salmon Released in Streams

1969 ◽  
Vol 26 (7) ◽  
pp. 1867-1876 ◽  
Author(s):  
Philip E. K. Symons
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Release Site ◽  
Wild Fish ◽  
Atlantic Salmon Salmo Salar ◽  
Juvenile Atlantic Salmon

When wild juvenile (parr) Atlantic salmon (Salmo salar L.) caught by electrofishing, and an equal number of hatchery-reared parr, matched for size with the wild ones, were released at three sites in unfamiliar streams containing resident parr, more hatchery-reared than wild parr could be observed by skin-diving in the areas 1 and 2 weeks later.Observed mortalities of wild parr were not sufficiently higher than those of hatchery parr to explain this result. Nor could a higher proportion of wild parr be found hiding compared with hatchery parr when one release site was electrofished a week after the release. Wild parr were found in greater numbers at points farther from one of the release sites than were hatchery-reared parr, and also more wild fish passed through a salmon counting fence approximately 100 m from a fourth release site than did hatchery-reared parr.This greater dispersal of wild parr from the release site compared with hatchery parr has important consequences to estimates of comparative survival between the two stocks.

Implications of temporal and spatial scale for Atlantic salmon (Salmo salar) research

1998 ◽  
Vol 55 (S1) ◽  
pp. 9-21 ◽  
Author(s):  
Carol L Folt ◽  
Keith H Nislow ◽  
Mary E Power
Keyword(s):  
Atlantic Salmon ◽  
Salmo Salar ◽  
Multiple Scales ◽  
Spatial Scales ◽  
Effective Means ◽  
Research Strategies ◽  
Atlantic Salmon Salmo Salar ◽  
Temporal And Spatial ◽  
And Migration ◽  
Dependent Processes

The Atlantic salmon (Salmo salar) is a model species for studying scale issues (i.e., the extent, duration, and resolution of a study or natural process) in ecology. Major shifts in behavior and habitat use over ontogeny, along with a relatively long life span and large dispersal and migration distances, make scale issues critical for effective conservation, management, and restoration of this species. The scale over which a process occurs must be linked to the research design and we illustrate this with a discussion of resource tracking by Atlantic salmon. Identifying scale inconsistencies (e.g., when a process is evident at one scale but not another) is shown to be an effective means by which some scale-dependent processes are understood. We review the literature to assess the temporal and spatial scales used in Atlantic salmon research and find most current studies appear to sacrifice spatial and temporal extent for increased resolution. Finally, we discuss research strategies for expanding the temporal and spatial scales in salmon research, such as conducting multiple scales studies to elucidate scale inconsistencies, identifying mechanisms, and using techniques and approaches to generalize across studies and over time and space.

scholarly journals The spatial scale of density-dependent growth and implications for dispersal from nests in juvenile Atlantic salmon

Oecologia ◽  
2010 ◽  
Vol 165 (4) ◽  
pp. 959-969 ◽  
Author(s):  
Sigurd Einum ◽  
Grethe Robertsen ◽  
Keith H. Nislow ◽  
Simon McKelvey ◽  
John D. Armstrong
Keyword(s):  
Atlantic Salmon ◽  
Spatial Scale ◽  
Density Dependent ◽  
Juvenile Atlantic Salmon ◽  
Dependent Growth
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