Doctoral Thesis
Sustainable Alternatives to Fishmeal in Yellowtail Kingfish (Seriola lalandi) Diets: Evaluating Single-Cell Proteins and Black Soldier Fly Meal for Growth Performance and Health
Doctor of Philosophy (PhD), Murdoch University
2025
Abstract
As global aquaculture continues to expand, the demand for sustainable and effective fishmeal alternatives becomes increasingly critical. Fishmeal, despite its nutritional advantages, poses significant environmental and economic challenges due to overfishing and price volatility. This thesis explores the potential of sustainable protein sources, specifically black soldier fly (BSF) meal and single-cell proteins (SCP) derived from methanotrophic and hydrogenotrophic bacteria, to replace fishmeal in yellowtail kingfish (YTK, Seriola lalandi) diets.
The research is structured into a series of growth trials, biochemical analyses, and gene expression studies aimed at evaluating the effects of these alternative proteins on YTK growth performance, feed conversion efficiency, health parameters, and gut microbiome composition. BSF meal demonstrated efficacy as a fishmeal alternative, with comparable growth and health outcomes at 25% and 50% replacement levels. Despite some palatability challenges at higher levels, BSF meal improved gut microbial diversity, promoting beneficial bacterial taxa. Similarly, it was found that SCP derived from methanotrophic bacteria can replace up to 75% of fishmeal without causing adverse health effects, though mild inflammatory responses in the hindgut were observed at higher inclusion levels. Enhanced lipid digestibility and a more diverse gut microbiome were noted, indicating potential health benefits associated with SCP inclusion at moderate levels. However, palatability remains a challenge, particularly at higher levels, necessitating further research into diet formulation and attractants.
Comparative analysis of methanotrophic and hydrogenotrophic SCP revealed only slight differences in amino acid profiles and digestibility, and in a longer study, the results were positive, indicating that both types can be effectively utilised in YTK diets.
The findings of this thesis underscore the viability of BSF and SCP meal as sustainable fishmeal replacements in YTK diets. While palatability and long-term health effects remain areas for further investigation, this research contributes valuable insights into the development of eco-friendly and scalable aquafeeds. By advancing the understanding of alternative protein sources, this work supports the transition towards more sustainable practices in the aquaculture industry.
Details
- Title
- Sustainable Alternatives to Fishmeal in Yellowtail Kingfish (Seriola lalandi) Diets: Evaluating Single-Cell Proteins and Black Soldier Fly Meal for Growth Performance and Health
- Authors/Creators
- Luke W Pilmer
- Contributors
- Alan Lymbery (Supervisor) - Murdoch University, Centre for Sustainable Aquatic EcosystemsGavin Partridge (Supervisor) - Murdoch University, Centre for Sustainable Aquatic Ecosystems
- Awarding Institution
- Murdoch University; Doctor of Philosophy (PhD)
- Identifiers
- 991005807949207891
- Murdoch Affiliation
- Centre for Sustainable Aquatic Ecosystems
- Resource Type
- Doctoral Thesis
UN Sustainable Development Goals (SDGs)
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