Growth is one of the most important physiological parameters for a sustainable and profitable aquaculture industry. However, a common problem in fish farming is juvenile dissimilar growth that can reduce the market value of harvested fish, increase the production cost, cannibalism and disease susceptibility. As a mitigation strategy in intensive production, frequent grading procedures are employed in the larval and juvenile stages, however, this practice is not financially viable for other production systems. Since growth is related with hereditary genetics, it is essential to better understand genes and regulatory mechanisms controlling this relevant economical trait. This project aims at developing a prediction tool, composed of a panel of biomarkers, including differentially expressed genes and other physiological markers, between fast and slow-growing fish. This tool is designed to improve rearing efficiency, activity sustainability and, most importantly, will help farmers to make informed decisions.
Several gilthead seabream and seabass trials have been conducted at the Aquaculture Research Station of Olhão (EPPO/IPMA). Each trial began when the initial batch started showing growth dissimilarities on weight sampling. After the sampling, fish were sorted into small and big fish, according to the batch average weight. Each condition was separated into tanks on a flow-through system and fed with a commercial diet, four times a day, until apparent satiety. Density was always kept the same, regardless the treatment, in each trial.
Liver, muscle and intestine samples were collected from 6 fish from each treatment for differential gene expression analysis, in each trial. Total RNA was extracted, quantified and quality verified by gel electrophoresis before RNAseq.
Results showed that fast growing outperformed slow growing fishes in both species, indicating a better growth potential of some individuals. Results from the RNA Seq (genes differentially expressed among small and big fish) will be selected to integrate a panel of biomarkers for the construction of the decision tool.
These results are relevant for aquaculture production and genetic prediction programs and can be used as biomarkers for growth. Additionally, it will offer quick and reliable results for farmers and researchers.
Acknowledgments: This study was funded by the project NanoPEIXE - Identification of biomarkers for the creation of a selection tool for giltheads with different growth profiles in aquaculture productions (ALG-01-0247-FEDER-070032).