The Roles of Extrinsic and Intrinsic Factors in the Freshwater Life-History Dynamics of a Migratory Salmonid

Peer reviewed: 
Yes, item is peer reviewed.
Scholarly level: 
Graduate student (PhD)
Final version published as: 

Bailey, C. J., D. C. Braun, D. McCubbing, J. D. Reynolds, B. Ward, T. D. Davies, and J. W. Moore. 2018. The roles of extrinsic and intrinsic factors in the freshwater life-history dynamics of a migratory salmonid. Ecosphere 9(9): e02397. 10.1002/ecs2.2397

Date created: 
2018-09-26
Keywords: 
Anadromy
Artificial nutrient addition
Fisheries
Life-history
Diversity
Long-term study
Marine-derived nutrients
Steelhead
Abstract: 

Key life-cycle transitions, such as metamorphosis or migration, can be altered by a variety of external factors, such as climate variation, strong species interactions, and management intervention, or modulated by density dependence. Given that these life-history transitions can influence population dynamics, understanding the simultaneous effects of intrinsic and extrinsic controls on life-history expression is particularly relevant for species of management or conservation importance. Here, we examined how life histories of steelhead (Oncorhynchus mykiss) are affected by weather, pink salmon abundance (Oncorhynchus gorbuscha), experimental nutrient addition, and density-dependent processes. We tested for impacts on the size of steelhead smolts (juveniles migrating to the sea), as well as their age and abundance across four decades in the Keogh River, British Columbia, Canada. Larger steelhead smolts were associated with warmer years and artificial nutrient addition. In addition, higher pink salmon abundance and artificial nutrient addition correlated with juvenile steelhead migrating at younger ages. While density dependence appeared to be the primary factor regulating the abundance of steelhead smolts, nutrient addition and temperature were positively and negatively associated with smolt production, respectively, prior to 1991, and pink salmon spawning abundance was positively associated with smolt production after 1990. Thus, this study provides evidence that the temporal dynamics of one species of salmon is linked to the juvenile life history of co-occurring steelhead. A complex interplay of species interactions, nutrient subsidies, density dependence, and climatic variation can control the life-history expression of species with complex life cycles.

Language: 
English
Document type: 
Article
File(s): 
Sponsor(s): 
Habitat Conservation Trust Foundation
Forest Renewal BC
British Columbia’s Watershed Restoration Program
British Columbia Ministry of Forests Lands, Natural Resource Operations and Rural Development
Federal Fisheries’ Habitat Restoration and Salmon Enhancement Program
Natural Sciences and Engineering Research Council of Canada (NSERC)
Liber Ero Foundation
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