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Relating juvenile spatial distribution to breeding patterns in anadromous salmonid populations
Anders Foldvik1, Anders Gravbrøt Finstad, Sigurd Einum
1Norwegian Institute for Nature Research, Tungasletta 2, NO-7047 Trondheim, Norway. a.holzschuh@agr.uni-goettingen.de
The Journal of Animal Ecology
|January 7, 2010
Summary
Maternal choice in breeding locations creates significant spatial heterogeneity in juvenile salmonid densities. This fine-scale distribution impacts population dynamics and competition, even when breeding appears uniform across the river.
Area of Science:
- Ecology
- Population Dynamics
- Conservation Biology
Background:
- Spatial heterogeneity in population density influences competition and population dynamics.
- Maternal choice of breeding sites can dictate offspring distribution, especially when juvenile mobility is limited.
Purpose of the Study:
- To quantify the spatial scale of breeding influence on juvenile densities in anadromous salmonids.
- To understand how maternal spawning decisions create fine-scale density variations within a riverine population.
Main Methods:
- Mapping redd locations and subsequent juvenile densities along a 9.2 km river reach.
- Utilizing autocorrelation and cross-correlation analyses to assess spatial relationships.
- Applying spatially explicit stock-recruitment functions to model density influences.
Main Results:
- Identified local-scale spatial patchiness in both breeding and juvenile densities, despite overall uniform breeding distribution.
- Demonstrated a strong spatial relationship between redd distribution and juvenile densities.
- Found that upstream breeding significantly influenced downstream juvenile densities within a narrow 75-150 m range.
Conclusions:
- Maternal choice of spawning locations drives substantial spatial heterogeneity in juvenile densities, operating at a much finer scale than the entire population.
- This heterogeneity in density, driven by breeding site selection, adds complexity to salmonid population dynamics and competition.
- The findings are relevant for understanding population regulation in other species with constrained juvenile dispersal.
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