Seafood Safety: Are Antimicrobials in Aquaculture a Hidden Risk?
"Comprehensive monitoring and resistance surveillance are crucial for protecting consumers from antimicrobial-resistant bacteria in fish and seafood."
Eating fish is often touted as a healthy choice, but could there be unseen risks lurking beneath the surface? With wild fish populations declining, aquaculture, or fish farming, is booming to meet the increasing demand for seafood. However, this rapid growth raises questions about the use of antimicrobials and their potential effects on our health.
In Australia, the aquaculture industry is expanding, focusing on species like salmon, tuna, prawns, and oysters. These farmed fish and shellfish are often raised in high densities, increasing the risk of disease outbreaks. To combat these diseases, antimicrobials are sometimes used, but this practice could lead to antimicrobial resistance, a growing threat to public health.
This article explores the concerns surrounding antimicrobial use in Australian aquaculture, highlighting the need for comprehensive monitoring and stricter regulations to safeguard consumers from the potential risks of antimicrobial-resistant bacteria in seafood.
Global AMR Burden in Aquaculture
Antimicrobial resistance has developed and spread throughout aquatic environments alongside increased use of antimicrobial chemicals in aquaculture. A 2022 global analysis identified beta-lactamases, tetracyclines, sulfonamides, macrolides, and fluoroquinolones as the most represented antibiotic classes, with Vibrio spp. and Aeromonas spp. among the most investigated resistant bacteria. Research has also examined global antimicrobial-use trends in aquaculture for 2017 and projected patterns for 2030, highlighting the need for surveillance and stewardship.
Surveillance Needs Better Evidence Chains
AMR surveillance in aquatic systems depends on diagnostic methods whose sensitivity, specificity, and traceability affect the usefulness of results. Published shrimp-aquaculture studies have used differing antimicrobial-susceptibility testing methods, culture media or panels, incubation conditions, antibiotic selections, control cultures, and protocols. These methodological differences support calls for a One Health evidence-chain review linking antimicrobial use with resistant bacteria, resistance genes, environmental and food matrices, and human exposure signals.
From Antibiotic Use to Genomic Surveillance
The history of AMR development in aquaculture is linked to widespread antibiotic use in human medicine and agriculture, including the emergence of resistance in fish pathogens after antimicrobial use began in aquaculture. More recent work has made genomic technologies central to identifying, characterizing, and monitoring antimicrobial-resistance genes. These tools provide insight into the origins, mechanisms, and spread patterns of resistance beyond what traditional approaches can show.
The Rise of Antimicrobial Resistance in Aquaculture
Antimicrobial resistance occurs when bacteria evolve to withstand the effects of drugs designed to kill them. The use of antimicrobials in aquaculture can accelerate this process, potentially leading to the development of resistant bacteria that can spread to humans through the consumption of contaminated seafood.
- Limited Surveillance: Australia lacks a comprehensive surveillance system for antimicrobial resistance in animals, including aquaculture.
- Imported Seafood Risks: Under World Trade Organization rules, Australia cannot routinely test imported seafood for antimicrobial-resistant bacteria, increasing the risk to consumers.
- Inadequate Residue Testing: The Department of Agriculture, Fisheries and Forestry conducts residue surveys, but the number of aquaculture samples tested is small and may not accurately reflect the extent of antimicrobial use.
Current Evidence on Aquaculture AMR
A Fisheries Research and Development Corporation report prepared in 2007 indicated that antimicrobial use had declined since the 1980s, which the report associated with vaccine development and improved management. More recent reviews identify overuse and improper use, regulatory shortcomings, environmental contamination, horizontal gene transfer, and co- and cross-resistance as factors contributing to AMR. A 2025 review describes antibiotic resistance in aquaculture as a threat to aquatic-animal health, the environment, and human health.
Sustainability Depends on Controlling Resistance
Aquaculture is expected to play an important role in meeting seafood needs as wild fish stocks become increasingly depleted by overfishing. The source argues that failing to address antibiotic resistance could compromise both aquaculture's sustainability and the health of aquatic and human populations. A bibliometric analysis of research from 2000 to 2025 identified antibiotic-resistance development in aquaculture, emerging challenges, and alternative solutions as major areas of investigation.
Alternatives to Antibiotic Use
Reviews of aquaculture disease management discuss alternatives intended to reduce reliance on antibiotics and limit AMR. The listed options include vaccination, bacteriophages, quorum quenching, probiotics, prebiotics, chicken egg yolk antibodies, and medicinal plant derivatives. These alternatives are presented within a broader concern that increased antimicrobial use for disease prevention and treatment has contributed to the emergence and dissemination of resistance in aquatic environments.
Protecting Consumers: A Call for Action
The Australian aquaculture industry needs to be more transparent about its antimicrobial use. Clear and consistent reporting is essential for monitoring trends and identifying potential problems.
Aquaculture Must Join One Health Planning
The Global Action Plan on AMR was established by the World Health Assembly in Geneva in 2015. Since then, most World Health Organization members have developed and implemented national action plans based on a One Health approach. The source notes that aquaculture is significant among food-producing sectors but has often been overlooked in AMR planning.
Tracking ARGs and Research Priorities
A 2023 bibliometric study examined research trends and key concepts concerning antimicrobial-resistance genes and AMR in aquaculture systems. It identified the accelerated development of ARGs and AMR in aquaculture environments, associated with antibiotic overuse, as a global concern. Bibliometric analysis can help map the field's research direction and identify priorities for future work.
A Bangladesh Case Study
Research in rural Bangladesh applied the Driver-Pressure-State-Impact-Response conceptual framework to an aquaculture case study site. The analysis combined social, microbiological, and metagenomic datasets. This approach places aquaculture AMR within a broader system that includes social conditions, microbial change, and genetic evidence.
Potential Foodborne Transmission
Antimicrobials in aquaculture are primarily used to prevent and treat bacterial infections in fish. The source reports that inappropriate use may contribute to zoonotic antibiotic-resistant bacteria and transmission of resistant strains to humans through food consumption. Another source reports resistant microbes in aquaculture land and aquatic environments, farmed animals, and seafood at the point of sale, while warning that industry antibiotic use is expected to rise with intensification and increasing disease levels.
Regulatory authorities must ensure that appropriate permits for antimicrobial use are obtained and followed. Stricter enforcement of regulations is needed to prevent the misuse and overuse of these drugs.
Investing in alternative disease management strategies, such as vaccines and improved husbandry practices, is crucial for reducing the reliance on antimicrobials in aquaculture. By working together, the aquaculture industry, regulatory bodies, and consumers can ensure the safety and sustainability of seafood production in Australia.