Diverse juvenile life-history behaviours contribute to the spawning stock of an anadromous fish population

Ecology of Freshwater Fish
By: , and 

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Abstract

Habitat quality often varies substantially across space and time, producing a shifting mosaic of growth and mortality trade-offs across watersheds. Traditional studies of juvenile habitat use have emphasised the evolution of single optimal strategies that maximise recruitment to adulthood and eventual fitness. However, linking the distribution of individual behaviours that contribute to recruitment at the population level has been elusive, particularly for highly fecund aquatic organisms. We examined juvenile habitat use within a population of sockeye salmon (Oncorhynchus nerka) that spawn in a watershed consisting of two interconnected lakes and a marine lagoon. Otolith microchemical analysis revealed that the productive headwater lake accounted for about half of juvenile growth for those individuals surviving to spawn in a single river in the upper watershed. However, 47% of adults had achieved more than half of their juvenile growth in the downstream less productive lake, and 3% of individuals migrated to the estuarine environment during their first summer and returned to freshwater to overwinter before migrating back to sea. These results describe a diversity of viable habitat-use strategies by juvenile sockeye salmon that may buffer the population against poor conditions in any single rearing environment, reduce density-dependent mortality and have implications for the designation of critical habitat for conservation purposes. A network of accessible alternative habitats providing trade-offs in growth and survival may be important for long-term viability of populations.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Diverse juvenile life-history behaviours contribute to the spawning stock of an anadromous fish population
Series title Ecology of Freshwater Fish
DOI 10.1111/eff.12135
Volume 24
Year Published 2015
Language English
Publisher Wiley
Contributing office(s) Alaska Science Center Geography
Description 10 p.
First page 204
Last page 213
Country United States
State Alaska
Other Geospatial Chignik Lake system
Online Only (Y/N) N
Additional Online Files (Y/N) N