“This is a first study [on] the subject, and as such, we must exercise caution in how the results are interpreted without further confirmation of the findings,” said the international marine ingredients organization (IFFO).
FeedNavigator reported on the findings of that scientific paper late last month. The study indicated there is a potential for fishmeal used in aquaculture feed to be a vector for antibiotic resistant genes (ARG). The Chinese scientists said they found 132 ARGs in commercially available fishmeal.
The IFFO, which represents and promotes ingredients such as fishmeal and fish oil, said while it recognizes the importance of managing antibiotics in order to protect the availability of treatments for human health, the Chinese study raises several questions.
“The work is notable as having been undertaken on a very limited sample number (5 fishmeal products; 2 terrestrial animal products), and as such is not an extensive investigation.”
A wider range of feed ingredient assessment, as part of that paper, would have been a useful comparison or control, said the marine ingredients body.
“It is possible that the presence of nutrients in the sediment (from either fishmeal or other feed ingredients) are encouraging the growth of sediment bacteria which may contain ARGs that do not originate from fishmeal,” added the IFFO.
It said that although the majority of fishmeal comes from whole fish with the pelagic species dominating, some fishmeal is produced from recycled fish trimmings. It estimates that around 33% of the total annual volume comes from trimmings: “Although some of the source of this raw material will be aquaculture byproduct, the majority is wild capture byproduct and would not come into contact with antibiotics.”
The IFFO said ARGs have been found to be present in apparently isolated locations around the world, including some very extreme environments such as permafrost and cave systems.
“They may therefore have become somewhat ubiquitous in the environment.
“The inclusion of a sample control in the paper such as other marine sediments not within the vicinity of a mariculture unit would have helped to identify whether fish farms are actually the source of the ARGs,” continued the IFFO.
It added that the use of antibiotics on farmed fish is expensive and limited.
The IFFO said the wide range of different antibiotics observed in the testing by the Chinese researcher also aligns with the suggestion that the source is not the fish farms themselves as antibiotics used as fish chemotherapeutants have tended to be limited in number.
The organization noted that some fish farms in China are notable for their proximity to human populations, and it said it may well be that any selection pressure on bacterial communities arising from antibiotic use is a result of other sources, such as sewage effluent.
The IFFO also queried some of the sampling methodology employed in the study.
“The paper shows a sample of Peruvian fishmeal, which would be entirely made from wild caught Peruvian anchoveta, to have seven different antibiotic residues present. As the sampling was conducted in China and not in Peru, we are seeking clarification of the measures taken to protect samples from contamination.”