The utility of juvenile sablefish otoliths in reconstructing life history and growth in the Gulf of Alaska

Abstract

Sablefish are commercially important, and their populations have undergone significant fluctuations over time. Juvenile growth may be a strong indicator of sablefish recruitment potential. Previous projects have reconstructed juvenile sablefish life history using otoliths; therefore, otolith analyses may be useful in predicting recruitment success. To evaluate this utility, comparisons of otolith and otolith increment measurements across structures and with fish size and growth were made. Specifically, daily age estimates from paired lapillar and sagittal otolith samples were compared to determine agreement between structures, otolith dimensions were compared to body length to support the correlation between daily increment width and somatic growth, and paired otolith samples recovered from a previous temperature and feeding ration study were used to investigate otolith increment width with known growth rates. The evidence reported herein suggests both lapillar and sagittal otoliths produce reliable age estimates, and growth planes between structures are highly correlated with somatic growth. Daily otolith increment width mirrored the results of the somatic growth study in both structures. Generally, the lapillus had fewer complications resulting in a better fit to growth and treatment data, primarily due to the lack of accessory growth centers.