A transformative approach to ageing fish otoliths using Fourier transform near infrared spectroscopy: a case study of eastern Bering Sea walleye pollock ( Gadus chalcogrammus)

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Helser, Thomas E., Benson, Irina, Erickson, Jason, Healy, Jordan, Kastelle, Craig, Short, Jonathan A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2019
• Subjects: Bering Sea
• Online Access: http://dx.doi.org/10.1139/cjfas-2018-0112; http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjfas-2018-0112; http://www.nrcresearchpress.com/doi/pdf/10.1139/cjfas-2018-0112

We investigated the use of Fourier transform near infrared spectroscopy (FT-NIRS), which is a method of measuring light absorbance signatures, to derive ages from eastern Bering Sea walleye pollock (Gadus chalcogrammus) otoliths. This approach is based on a predictive model between near infrared spectra in the otolith and fish age, which is calibrated and validated. The advantage of FT-NIRS over traditional methods is the speed and repeatability with which age estimates are generated. The application of FT-NIRS to walleye pollock otoliths yielded r 2 values between 0.91 and 0.95 for the calibration models and good validation performance (between 0.82 and 0.93). This approach can be expected to predict fish age within ±1.0 year of age 67% of the time. When comparing approaches, the FT-NIRS had as good or slightly better precision (75% agreement) than the traditional ageing (66% agreement) and showed little or no bias at age before 12 years of age. Once the predictive FT-NIR model is calibrated and validated, age estimates using FT-NIRS can be done at 10 times the rate compared to traditional methods.