Exploring trophic dynamics and fish condition during autumn to understand the lack of recovery of groundfish in southern Newfoundland

Sokolowski, Monica A. (2024) Exploring trophic dynamics and fish condition during autumn to understand the lack of recovery of groundfish in southern Newfoundland. Masters thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (4MB)

Abstract

Following collapses in the 1990s, many Northwest Atlantic groundfish stocks have not recovered despite reduced fishing pressure. This leads to a key question in fisheries ecology today: Why do some stocks not recover? I address this question via analyses of condition, diet, and trophic dynamics of groundfish within Northwest Atlantic Fisheries Organization (NAFO) subdivision 3Ps. The first chapter introduces the research themes with seasonality highlighted and state of knowledge relevant to two subsequent research chapters. The second chapter uses diet and triple-stable isotope analysis (δ15N, δ13C, and δ34S) to quantify seasonal differences in southern Newfoundland Atlantic Cod (Gadus morhua) diets and condition. I report differences in both seasonal and ontogenetic patterns within this southern Newfoundland stock in condition, diet, and stable isotope values. Chapter 3 incorporates a multispecies approach using similar methods to chapter 2 alongside stable isotope mixing models to identify pre-winter trophic interactions within the southern Newfoundland groundfish community. Ontogenetic isotopic niche overlap among various species indicates potential size dependent competition among southern Newfoundland species during the autumn. This research provided pre-winter physiological condition of Atlantic cod and the trophic interactions among the groundfish community within the autumn in southern Newfoundland and supports seasonal variation among the trophic structure within southern Newfoundland that may help identify oceanographic change related productivity shifts within the ecosystem.

Actions (login required)

View Item