Officer puts out fish death theory
THE Biosecurity Queensland officer responsible for aquatic animal health believes agrichemicals and pesticides were contributing factors in the deaths and deformities at a Boreen Point fish hatchery.
Dr Roger Chong has called for better farm spray drift management.
Dr Chong’s assessment of the evidence gathered during the Noosa Fish Health Investigation Taskforce saw him submit a final report in March last year with concerns raised about even “very low” doses of pesticides possibly from a neighbouring macadamia farm.
Biosecurity Queensland’s principal veterinary officer had major concerns for the health of the Noosa River as far as the likely impact of chemicals on fish reproduction.
After studying the two-headed bass embryos produced at the Sunland Fish Hatchery, and mullet with three tails, he believed the “serious implication” was that “a common agent was causing reproductive damage to more than one species of fish in the Noosa River”.
“Normal bass fry were produced by Sunland Hatchery when non-Noosa broodstocks are used; which strongly points to the Noosa River as being the source of potential chemical toxins with mutagenic and genotoxic properties.
“Carbendazim and atrazine agrichemicals were detected in the catchment at very low levels which appear to be innocuous, but is it, given the epidemiological evidence of a potential common link?” Dr Chong’s report states.
Dr Chong reported that “evidence of liver and red blood cell pathology in affected fish pointed to potential methoxifenozide contamination of algal feeds held in uncovered tanks outside from spray drift of macadamia operations leading to acute deaths of hatched Australian bass.
“Fish that were not fed the algae on the days of agrichemical spraying did not experience similar mortalities.”
Dr Chong recommended an adverse event report be made to the regulator, the Australian Pesticides and Veterinary Medicines Authority, in relation to beta-cyfluthrin, methidathion, nonylphenol, trichlorphon/dichlorvos, methoxyfenozide and carbendazim.
“This signals the need to conduct structured research under laboratory conditions into agrichemical exposure and toxicity of these compounds on native Australian fish species, because existing label regulations do not appear to safeguard against spray drift in certain situations.
“This also involves structured monitoring of spray drift and fish health indices to evaluate actual risks of spray practices of the macadamia plantation on hatchery operations.”
“This should involve the use of sentinel fish to measure the actual contamination level of chemicals that may be applied through spray rigs at the macadamia plantation. It is important that the spraying practices reflect what is performed in the past as well as what is currently the routine.”
Dr Chong said where agrichemicals are found to have unacceptable toxicity risks to non-horticultural industry and communities under practical conditions of use, withdrawal from market is an option.