Date of Award

Spring 5-6-2022

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Masters of Science in Bioscience (MSB)

Department

Marine Biology

Advisor

Walter Golet

Second Committee Member

John Logan

Third Committee Member

Gayle Zydlewski

Abstract

Traditional stock assessments require, in part, accurate knowledge of growth relationships to estimate a variety of aspects involved in population conservation management of exploited species. In addition, the local distribution and condition of top pelagic predators is driven by detection of abundant forage aggregations and along with traditional stock assessments, should be considered for effective management of marine populations. Empirical analyses of these data are severely lacking for bigeye (Thunnus obesus) and yellowfin (Thunnus albacares) tuna in the Atlantic Ocean, especially for the former. Given historical studies’ observations of these two top predators use as biological samplers due to their wide-ranging habitats throughout the world’s oceans, analyses of forage and trophic dynamics may provide vital and cost-effective information to be used in pelagic ecosystem-based management and health indication. With the objectives of determining and updating growth relationships and assessing spatio-temporal variability and other factors influencing forage and trophic dynamics in the northwest Atlantic Ocean, liver, muscle, otolith, and stomach tissues were collected from 318 bigeye and 797 yellowfin tuna captured in commercial longline and recreational rod and reel fisheries from 2018-2020. Through the use of annual otolith ageing, stomach content identification, and stable isotope analysis methods this study aims to provide a comprehensive examination of vital aspects necessary for improved management of bigeye and yellowfin tuna in the northwest Atlantic and to contribute to their conservation in the Atlantic Ocean as a whole.

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