Tracing Transgenerational Plasticity Through Ova Fatty Acid Biomarkers in Giant Kōkopu (Galaxias argenteus)

Abstract

The domestication of native fish species is emerging as a vital approach to addressing New Zealand’s unique challenges in biodiversity conservation, food security, and sustainable aquaculture. This thesis focuses on the giant kōkopu (Galaxias argenteus), one of New Zealand’s five endemic galaxiid species and a cornerstone of the culturally and economically significant whitebait fishery. As a species classified as "vulnerable" by the IUCN, G. argenteus faces ongoing threats from habitat degradation, land-use changes, and overfishing. With traditional whitebait fisheries under increasing scrutiny for their sustainability, this research explores aquaculture as a viable pathway to secure the future of G. argenteus while preserving New Zealand’s rich white baiting heritage.

Building on the domestication efforts of Manāki Whitebait, this study investigates the conditions that facilitated the first successful captive spawning of G. argenteus in 2012 and examines strategies for optimising broodstock management to improve reproductive success. A key focus of this research is the role of essential fatty acids (EFAs)— docosahexaenoic acid (DHA), arachidonic acid (ARA), and eicosapentaenoic acid (EPA)—in influencing fecundity, gamete quality, and offspring viability. These EFAs are explored in the context of their metabolic, structural, and signalling roles, revealing their critical impact on fish reproduction and larval development.

The thesis also investigates transgenerational plasticity in G. argenteus, analysing how lipid profiles shift across generations to adapt to captivity. This work demonstrates the potential for targeted dietary and environmental interventions to enhance reproductive outcomes and improve the sustainability of aquaculture systems. By integrating ecological, physiological, and aquacultural perspectives, the research highlights the capacity of aquaculture to alleviate pressure on wild populations while contributing to New Zealand’s conservation goals and white baiting traditions.

This study serves as a foundational step toward developing a sustainable aquaculture model for G. argenteus and other native species, reinforcing the importance of indigenous biodiversity and the integration of mātauranga Māori in contemporary conservation practices. It calls for continued investment in aquaculture innovation and ecological research to ensure that New Zealand remains a global leader in the sustainable management of its aquatic resources.