Aquaculture in sea cages is exposed to adverse weather events, which can cause enormous damage to aquaculture facilities, as occurred during Storm Gloria in the southeastern Spanish Mediterranean in January 2020, causing massive fish escapes.
A team of scientists from the University of Alicante, the University of Bergen, and the Mediterranean Institute of Advanced Studies (IMEDEA-CSIC) evaluated the potential use of metabolic and lipid biomarkers to distinguish between wild gilthead sea bream (Sparus aurata) and their counterparts escaped from fish farms.
The problem: Escaped fish and sustainability
Aquaculture, the farming of fish in controlled environments, plays a vital role in meeting our demands for seafood products. However, extreme weather phenomena such as storms can damage these facilities and cause fish escapes. These escaped fish can disrupt the delicate balance of wild populations and ecosystems.
Escaped fish can wreak havoc on marine ecosystems. They can:
- Interbreed with wild populations, potentially altering the genetic stock.
- Compete for food and habitat, affecting native fish populations.
- Spread diseases to wild fish and even other fish farm populations.
Researchers have been developing a range of strategies to prevent fish escape from aquaculture facilities, including deep learning, and improvements in facility design, among others.
Biomarkers for better tracking
Scientists are addressing the challenge of escaped fish with cutting-edge techniques: metabolomics and lipidomics. These analyze small molecules within fish tissues, revealing metabolic profiles. Think of it as a unique fingerprint.
These profiles can uncover changes caused by environmental factors, pollutants, or even the difference between wild and farmed fish. This information is incredibly valuable, with applications such as:
- Diagnosing diseases in fish.
- Understanding the impact of pollutants on fish health.
- Tracing the origin of food: perfect for identifying escaped farm fish!
Case study of sea bream
Gilthead sea bream (Sparus aurata), a highly prized fish in Mediterranean aquaculture, is a good example. Due to intensive aquaculture and declining wild populations, ensuring traceability and preventing fraud is critical.
This study investigated the potential use of metabolomic and lipidomic techniques to identify biomarkers that distinguish wild sea bream from escaped farm fish. Researchers analyzed the muscle composition and fat deposits of fish obtained from:
- Fish markets in the Spanish Mediterranean (potentially containing wild and escaped fish)
- Aquaculture facilities
By comparing metabolic and lipid profiles, scientists hope to develop a reliable method of biomarkers to identify fish based on:
- Wild sea bream: Fish that have lived freely in the ocean.
- Escaped farm-bred sea bream: Fish bred in aquaculture that escaped into the wild.
- Farm-bred sea bream: Fish bred entirely in aquaculture facilities.
The solution: Fatty acids and muscle chemistry
The study, which used a technique called nuclear magnetic resonance (NMR), revealed intriguing differences in the muscle chemistry of fish. Wild sea bream contained higher levels of:
- Taurine and trimethylamine N-oxide (TMAO): These natural compounds may be related to the fish’s diet and adaptation to the oceanic environment.
- Omega-3 fatty acids: These “healthy fats” abound in wild fish due to their natural food sources.
On the other hand, escaped and farmed sea bream exhibited higher levels of omega-6 fatty acids, likely reflecting the different food sources used in aquaculture.
The future: Towards better traceability of seafood products
The findings of the study are immensely promising for the future of sustainable aquaculture products. By identifying these biomarkers, authorities and consumers can have greater confidence in the origin of their sea bream. This can:
- Empower consumers: Knowing whether their sea bream is wild-caught enables them to make informed decisions that support ocean health.
Conclusion
While further research is needed to refine and validate this technique, this study represents a significant advancement in identifying fish origin biomarkers. As research continues, consumers and the aquaculture industry can move closer to a future where sustainable seafood options are available.
Reference (open access)
Badaoui, W., Marhuenda-Egea, F. C., Valero-Rodriguez, J. M., Sanchez-Jerez, P., Arechavala-Lopez, P., & Toledo-Guedes, K. (2024). Metabolomic and Lipidomic Tools for Tracing Fish Escapes from Aquaculture Facilities. ACS Food Science & Technology.
