Quantifying size-at-age in harvested marine fish populations is a challenge with implications for both conservation and management. We describe a Bayesian hierarchical modeling approach for estimating mean and variation in size-at-age, incorporating environmental covariates. We apply
the approach to two runs of Sacramento River Chinook salmon (Oncorhynchus tshawytscha): one data-rich (fall) and one data-poor (winter). We combine information on the size of recreationally harvested
tagged fish and fishery size limits to reconstruct time-dependent marine size distributions. Our framework allows informed modeling of environmental effects on size-at-age, estimation of annual variability without overfitting, estimating size in years with limited data, and projecting sizes
in future years. We found that fall run fish are anomalously small in years following Novembers with low values of the Northern Oscillation Index (NOI). Winter run data did not include anomalously low NOI years, but typical annual variability could be quantified. Importantly, our results suggest
that it is possible to predict small size and slow growth during the upcoming fishery season on the basis of an environmental index available months in advance.
Fisheries Ecology Division, Southwest Fisheries Science Center, National Marine Fisheries Service, NOAA, 110 Shaffer Road, Santa Cruz, CA 95060, USA
Publication date: May 26, 2012
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Published continuously since 1901 (under various titles), this monthly journal is the primary publishing vehicle for the multidisciplinary field of aquatic sciences. It publishes perspectives (syntheses, critiques, and re-evaluations), discussions (comments and replies), articles, and rapid communications, relating to current research on cells, organisms, populations, ecosystems, or processes that affect aquatic systems. The journal seeks to amplify, modify, question, or redirect accumulated knowledge in the field of fisheries and aquatic science. Occasional supplements are dedicated to single topics or to proceedings of international symposia.