Changing maturation reaction norms and the effects of growth history in Alaskan Chinook salmon

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 595:187-202 (2018) - DOI: https://doi.org/10.3354/meps12564 Changing maturation reaction norms and the effects of growth history in Alaskan Chinook salmon Jared E. Siegel1,*, Milo D. Adkison2, Megan V. McPhee2 1South Fork Research, Inc., 44842 SE 145th St., North Bend, WA 98045, USA 2College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, 17101 Point Lena Loop Road, Juneau, AK 99801, USA *Corresponding author: derajlegeis@gmail.com ABSTRACT: We explored the nature of declines in size and age at maturity in 2 populations of Chinook salmon Oncorhynchus tshawytscha in western Alaska, USA, using multidimensional probabilistic maturation reaction norms (PMRNs) accounting for growth history. Individual growth histories informed by retrospective scale analysis were used to construct PMRNs and to describe the relative influence of different life-history periods on age at maturity. Similar results were found in both populations. Models accounting for growth history uniformly outperformed size-at-age models, suggesting the importance of growth history for the determination of maturation. The second year of marine growth was found to have a disproportionate influence on the age at maturity in both sexes. Males tended to grow more than females in length during the second year at sea, possibly as a consequence of females storing more energy in preparation for the high cost of female gonad development. Finally, we found that growth thresholds for maturation have shown a long-term decline in both sexes. This suggests that declines in the average age at maturity of western Alaskan Chinook salmon may have been caused in part by adaptation to environmental or fisheries-induced selection. KEY WORDS: Oncorhynchus tshawytschka · Size at age · PMRN · Age at maturity · Life history · Plasticity · Evolution · Retrospective scale analysis Full text in pdf format Supplementary material PreviousNextCite this article as: Siegel JE, Adkison MD, McPhee MV (2018) Changing maturation reaction norms and the effects of growth history in Alaskan Chinook salmon. Mar Ecol Prog Ser 595:187-202. https://doi.org/10.3354/meps12564 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 595. Online publication date: May 14, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.