Keith Fuller

Date of Award

Spring 2021

Document Type

Open Access Dissertation

Department

Biological Sciences

First Advisor

Joseph Quattro

Abstract

The accurate determination of age for fish is a vital part of both populationmanagement and ichthyological research. However, the methods which are primarily employed to age fish can be difficult, time consuming, inaccurate, or some combination thereof. Most ageing is currently done via hard parts (such as otoliths, vertebrae, or scales) which are read in a manner similar to tree rings with markings corresponding to known or presumed periods of time. Recently, Fourier transform-near infrared spectroscopy (FT-NIRS) has been investigated as a novel tool to age fish more quickly and objectively. This method works by recording the vibrational frequencies of molecular bonds in a scanned sample which are then correlated with age through partial least squares (PLS) regression models. Several fundamental questions remain before wider usage, however, including questions of sample storage, structure utility, errors introduced by reliance upon traditionally determined ages, and taxa- specific issues of age resolution. In this study, a high degree of ageing accuracy was found with FT-NIRS for Morone saxatilis and Carcharhinus isodon samples in each storage (frozen or EtOH) and preparation (raw or bleached) method investigated. Ageing was unsuccessful with mounted skate (Leucoraja ocellata) vertebral sections. Most samples of M. saxatilis were able to be aged to within 2 days of true age, and ~90% were aged to within 5. Over half of the C. isodon samples were aged to within 1 year of traditionally determined age. The surprising degree of success found using whole M. saxatilis larvae suggests further streamlining potential as well as the possibility of using FT-NIRS for nonlethal ageing in- situ. While unsuccessful at ageing the skate samples tested, the high accuracy, speed, and cross-structure applicability demonstrated here by FT-NIRS strongly justifies continued exploration into its utility within the field of fisheries science.

Rights

© 2021, Keith Fuller

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