Evaluating Post‐Survey Otolith Subsampling Strategies for a Small‐Bodied, Fast‐Growing Pelagic Fish for Inclusion in Stock Assessments

ABSTRACT Identifying efficient otolith subsampling strategies that maintain data quality for stock assessments is imperative given limited resources to meet age‐estimation demands of managed fish stocks. Our objective was to evaluate the performance of three different subsampling strategies: (1) fixed otolith subsampling, (2) proportional otolith subsampling with targeted supplemental sampling, and (3) hybrid otolith sampling for estimating age composition and proportions of individuals‐at‐age within length bins for Pacific sardine ( Sardinops sagax ). Proportional and hybrid strategies generally performed better than the fixed strategy. The performance of subsampling strategies was less consistent among combinations of age and length bins for estimates of proportions of ages‐at‐length than for estimates of age composition, due in part to high variation in age‐at‐length that caused uncertainty in predicted ages from lengths. We recommend the hybrid strategy that increases sample sizes at extremes of the length distribution and within length bins with multiple age classes. Processing 300–500 otoliths per year for age estimation is expected to maintain accuracy and reliability.