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RESEARCH ARTICLE
Contents Vol 76(10)

Advancing fish early life-history research: daily age determination of walleye pollock (Gadus chalcogrammus) with Fourier transform–near-infrared spectroscopy

Esther D. Goldstein https://orcid.org/0000-0002-0499-7288 A * , Mary E. Matta A , Charles D. Waters https://orcid.org/0000-0003-4606-3202 B , Heather K. Fulton-Bennett https://orcid.org/0000-0002-5938-9714 B , Brenna C. Hsieh A , Craig R. Kastelle https://orcid.org/0000-0002-6681-1602 A , Johanna J. Vollenweider B , Jakub T. Sliwinski C and Thomas E. Helser A
+ Author Affiliations
- Author Affiliations

A Resource Ecology and Fisheries Management Division, Alaska Fisheries Science Center, National Marine Fisheries Service (NMFS), National Oceanic and Atmospheric Administration (NOAA), 7600 Sand Point Way NE, Seattle, WA 98115, USA.

B Auke Bay Laboratories, Alaska Fisheries Science Center, NMFS, NOAA, 17109 Point Lena Loop Road, Juneau, AK 99801, USA.

C Trace Lab, University of Washington School of Oceanography, 1501 NE Boat Street, Seattle, WA 98105, USA.

* Correspondence to: esther.goldstein@noaa.gov

Handling Editor: Haseeb Randhawa

Marine and Freshwater Research 76, MF25053 https://doi.org/10.1071/MF25053
Submitted: 7 March 2025  Accepted: 28 May 2025  Published: 25 June 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing

Abstract

Context

Fish daily age information provides insight into growth, phenology and recruitment but is rarely incorporated into the decision-making process for management because of labor-intensive data collection.

Aims

We tested Fourier transform–near-infrared (FT-NIR) spectroscopy as a rapid method (~1.0 v. ~60 min per otolith for microscopic methods) to determine daily age of walleye pollock (pollock; Gadus chalcogrammus), which supports an important fishery.

Methods

We reared two annual cohorts of pollock over 3 years to accrue a comprehensive dataset for calibration models.

Key results

FT-NIR spectroscopy provided an improvement over predicting daily age from otolith weight, fish weight or fish length. A calibration model developed using microscopically aged fish had a root mean square error (RMSE) from cross validation (CV) of 12.2 days. Models developed from the full dataset with ages assigned from cohort hatch dates had a test dataset RMSE of 35.4–40.7 days and a CV RMSE of 29.4–36.9 days.

Conclusions

Spectra were affected by size-at-age, which could affect model efficacy because growth and size are influenced by environmental variability. This can be addressed with robust calibration datasets, model testing and model updating.

Implications

FT-NIR spectroscopy age prediction is likely to be sufficient to capture population-scale shifts in hatch dates of pollock.

Keywords: daily age, Fourier transform–near-infrared spectroscopy, Gadus chalcogrammus, Gulf of Alaska, LA-ICP-MS, otolith, otolith microchemistry, walleye pollock.

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