Abstract

National Marine Fisheries Service laboratories from five regions across the United States are investigating the utility of Fourier transform near infrared (FT-NIR) spectroscopy as a rapid and transformative method for estimating fish age. With increasing needs for more stock assessments to support the federal regional fishery management councils, more efficient alternatives to the conventional, labor-intensive, and time-consuming methods for providing age estimates are needed. FT-NIR spectroscopy is a well-established quality control method utilized by the food and agriculture, chemical, petrochemical, and pharmaceutical industries. Recently it has been applied to fish otoliths (Wedding et al. 2014; Helser et al. 2018; Passerotti et al. 2020), as well as shark (Rigby et al. 2016) and skate vertebrae (Arrington et al. 2021), as a novel method for estimating ages. Unlike traditional age processing methodologies, FT-NIR spectroscopy provides a rapid method to estimate fish age; however it is a secondary ageing approach. A critical component for successful implementation of FT-NIR spectroscopy relies on building predictive models, where age estimates assigned by an age reader, using traditional meth-ods, provide the input ages that allow translation of scan outputs to ages. It requires little to no sample preparation and the average scan time is approximately one sample per minute. FT-NIR spectroscopy is a non-destructive method, which means that samples will be available for future research opportunities. Perhaps even more important is that this technology could move us closer to providing more real time data for stock assessments.

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