Aquaculture plays a crucial role in food production in Egypt, providing an economical source of animal protein and securing income and employment for a significant part of the population. Among the most produced species, Nile tilapia (Oreochromis niloticus) stands out as the most commonly farmed.
Scientists from Stockholm University (Sweden), The University of British Columbia (Canada), WorldFish (Egypt), Central Lab for Aquaculture Research (CLAR), The University of Tokyo (Japan), The Royal Swedish Academy of Science, and Leiden University (Netherlands) critically evaluated the potential benefits and drawbacks of pond fertilization strategies and whether the use of chicken manure (CM) in aquaculture ponds increases fish production and profitability.
Current Practices in Tilapia Farming
A common practice in Egyptian aquaculture farms raising tilapia is the fertilization of ponds with chicken manure to increase nutrient levels and promote the growth of phytoplankton, which the fish feed on. However, with reports indicating the use of antibiotics in Egypt’s poultry sector and the presence of antibiotic residues in chicken manure, a significant concern arises.
Poultry sector residues can contain antibiotic-resistant pathogens and antibiotic resistance genes (ARGs). This raises a crucial question: Are the production benefits large enough to compensate for potential health risks?
Evaluation of Benefits and Risks
An exhaustive study, based on production data from 366 aquaculture farms and pond sediments from 28 farms, evaluated potential benefits in yields and profitability for farms using CM for fertilization. Additionally, qPCRs were employed to detect the presence of three antibiotic resistance genes in pond sediments, genes that confer resistance to the antibiotics most commonly used in the poultry sector.
Key Findings
The researchers arrived at the following results:
- Yields and Profitability: The analysis showed no significant benefits in fish yields or profitability for farms applying CM.
- Nutrient Load: There was a significant risk of increased nutrient loads in ponds fertilized with CM, which could contribute to the eutrophication of local waterways.
- Antibiotic Resistance Genes: Increased abundances of the antibiotic resistance genes tetA and tetW were detected in pond sediments where CM was applied. This indicates a potential risk of ARG dissemination, which could have serious implications for public health and the environment.
- Untreated CM has been associated with mass fish deaths due to ammonia toxicity and increased pathogen levels.
Recommendations for Fish Farmers
Based on these findings, the researchers recommend that tilapia producers in Egypt and elsewhere:
- Avoid CM Fertilization: The risks to human and environmental health outweigh the potential benefits.
- Adopt Best Management Practices: Explore alternative methods to increase farm profitability while minimizing environmental impact.
Conclusion
The practice of fertilizing tilapia ponds with chicken manure does not offer significant benefits in terms of production or profitability and poses considerable risks to public health and the environment. Adopting sustainable management practices is essential to ensure safety and efficiency in Egyptian aquaculture, promoting safe and sustainable food production for the future.
Contact
Oskar Nyberg
Stockholm Resilience Centre, Stockholm University
Albanovägen 28, 106 91 Stockholm, Sweden.
Email: oskar.nyberg@su.se
Reference (open access)
Nyberg, O., Novotny, A., Sbaay, A. S., Nasr-Allah, A. M., Al-Kenawy, D. A., Rossignoli, C. M., & Henriksson, P. J. (2024). Poultry manure fertilization of Egyptian aquaculture ponds brings more cons than pros. Aquaculture, 590, 741040. https://doi.org/10.1016/j.aquaculture.2024.741040
