The Role of Epigenetics in Aquaculture: Influencing Fish Traits through Feed
By: Kaja Skjærven, Institute of Marine Research (IMR)
Fish farmers have a powerful tool at their disposal: the feed they provide can significantly influence the traits of the fish they cultivate. Recent research highlights the importance of epigenetics—how environmental factors affect gene expression—in the aquaculture industry.
Understanding Epigenetics
The term “epi”, derived from Greek, means “on” or “above.” Epigenetics refers to additional layers of information that modify gene expression without altering the underlying DNA sequence. These small epigenetic tags can attach to genes throughout an organism’s life, locking in the impact of environmental conditions.
Interestingly, these tags can also be inherited by subsequent generations, thus influencing various physical traits, or phenotypes. This phenomenon suggests that behavioral patterns, often deemed as ‘hard to break habits,’ might also have genetic roots.
Research Foundation: Insights from Mice Studies
One pivotal study revealed that maternal nutrition in mice can dictate the physical attributes of their offspring—specifically, whether they become yellow and overweight or brown and lean. Building on these findings, researchers began exploring how similar epigenetic influences might apply to fish, particularly in relation to their diet.
This exploration is vital for aquaculture, where the right feed can either promote favorable traits or hinder the development of resilient fish.
Experimental Findings with Zebrafish
Using zebrafish as a model, scientists tested whether parental feed influenced the traits of their young. In one experiment, parent fish were provided with a feed deficient in vitamin B, while their offspring received a balanced diet. The outcomes were revealing.
Upon reaching adulthood, the offspring exhibited lighter-colored livers and higher fat content, which is closely associated with poor health. Further analysis indicated distinct differences in the expression of genes related to fat regulation. This study clearly illustrated that epigenetic changes triggered by dietary variations could affect the health and well-being of fish offspring.
The Impact of Micronutrients on Salmon
Recent research focusing on salmon tackled several key epigenetic questions pertinent to aquaculture. Researchers observed that the micronutrients in salmon feed could influence the epigenetic tags in a dose-dependent manner, primarily affecting genes responsible for fat regulation.
Insufficient dietary ingredients could lead to enduring negative effects on fish health, underscoring the importance of appropriate nutrition.
Epigenetic Influences During Key Growth Stages
Another area of investigation was the effects of feed on growth during smoltification. The findings revealed that diet could regulate genetic expression leading up to smoltification and had a significant impact on growth during the post-smolt stage.
Optimizing feed during the pre-smolt period appears crucial for successful growth transitions, indicating that dietary influences can have long-lasting effects on fish development.
Timing of Spawning and Its Genetic Implications
The timing of spawning in salmon also emerged as a pivotal area of study. Preliminary results suggest that the timing could affect the micronutrient levels in eggs, potentially influencing the offspring’s traits.
This suggests that by adjusting environmental factors such as nutrition and temperature, farmers could potentially enhance the epigenetic profiles of their fish, to elicit desirable traits.
Examining Paternal Influence on Epigenetics
Compellingly, research has shown that paternal nutrition might also play a role in the epigenetic tags passed to offspring. Initial results indicate that the father’s dietary habits could affect the tags on DNA within gonadal tissues. While further research is needed to determine the exact mechanisms, these findings offer a promising avenue for enhancing aquaculture practices.
Conclusion: The Future of Aquaculture
In conclusion, the implications of epigenetic research for the aquaculture industry are profound. By better understanding how environmental factors like nutrition impact fish traits across generations, fish farmers can optimize their practices. The goal is clear: refine feeding strategies to ensure the old habits of broodstock do not unduly influence the next generation.
Photo: Kaja Skjærven / IMR
