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1 This content only applies to transition applications that were received before 1 July The content will be relevant for these applications until 30 June For all other applications, including new applications, please visit

2 RESIDUE GUIDELINE No Introduction Residues in Abalone This residue guideline provides information on the conduct and reporting of residue studies into the treatment of farmed abalone with veterinary chemicals. The minimal residues data requirements described in this guideline reflect the minor uses of veterinary and agricultural chemicals in the abalone industry. The main objective of this guideline is to ensure that the data generated are adequate for the purpose of setting Maximum Residue Limits (MRLs) and Withholding Periods (WHPs). This guideline should be read in conjunction with the NRA Vet Requirement Series Guidelines for Registering Veterinary Chemicals (Part 5A, Residues). Growth Stages in Farmed Abalone Abalone (Haliotis sp.) are marine molluscs related to oysters, scallops and mussels. To date, abalone farming has focussed on culturing techniques for greenlip and blacklip abalone species. The life cycle and growth stages of farmed abalone are outlined in the following diagram.

3 53 Broodstock 1 Fertilised Eggs Harvest Mature/market size: 2-4 years 6 Abalone Growth Phases 2 Hatching: hours Free-swimming larvae: 4-10 days Mature abalone Larvae (Veligers) Grow-out period: months 5 Juvenile abalone (spat) 4 3 Spat growth: 8-12 months Metamorphosis: 1-2 days 1. Sexually mature adult broodstock are induced to spawn. Male and female gametes are mixed to effect fertilisation. 2. Fertilised eggs are transferred to larval rearing tanks, where they hatch into free-swimming larvae (veligers). 3. Veligers metamorphose into juvenile abalone (spat) in nursery tanks containing racks of diatom-coated plates. 4. Spat graze on diatoms in weaning tanks and/or settlement tanks until mm long. 5. Spat are transferred to grow-out tanks until market size. 6. At harvest, abalone are ~70 mm long (50 g); some are grown for a further 12 months until mm long ( g). Chemical usage in abalone farming There are no registered uses of chemicals in abalone (at the time of writing). However, there is potential for the use of veterinary drugs in abalone farming, to sedate the animals prior to handling, and to control disease and infections. Anaesthetics may be useful in minimising traumatic injury and stress during handling operations such as the removal of spat from nursery tanks, the transfer of juvenile abalone to grow-out tanks, and when sorting and grading mature molluscs. Additionally, antibiotics may be effective in combating secondary bacterial infections (vibriosis) observed when abalone are heat-stressed. Bacterial infections can occur during larval (veliger) rearing, and during grow-out in summer months where water temperatures rise above 23 C (blacklip abalone) or 25 C (greenlip abalone). Residue trial design Residue trials in abalone need to be carefully designed, to ensure that the data generated reflect the residue levels that are likely to result when chemicals are used

4 according to Best Industry Practice. The data must also be suitable for establishing MRLs and WHPs, where appropriate. The following aspects need to be considered when designing residue trials. (i) Rearing environment Trials must be carried out in an environment that mimics actual conditions (such as water flow and exchange rates, water temperature, light etc) used by the abalone industry. (ii) Dosage form Trials must address all modes of application and dosing of the chemical. These may include addition of a solution of the chemical directly to the water, or in-feed medication. (iii) Application rate The highest dose/application rate that is likely to be used in the industry should be selected for the residue trial. (iv) Number of applications Where several applications of the chemical are likely, the highest number of applications should be used in the residue trial, along with the shortest interval(s) between successive applications. (v) Withholding periods, pre-harvest intervals and sampling times Two main scenarios cover the potential uses of chemicals in abalone farming: the first involves treatment at the time of harvest (eg anaesthetics), and the second involves treatment at any time during the growth phases, prior to harvest (eg antibiotics). In the first scenario, the levels of residues present in abalone at the time of harvest must be determined, to enable MRLs to be established. In the second scenario, chemical application close to harvest would be expected to result in the highest residues. Therefore, residue trials should incorporate the shortest pre-harvest interval that would occur in practice. In some instances, the MRLs will need to be set at the analytical limit of quantitation (LOQ), to meet the strict residue import tolerances that apply in key export markets. When this is the case, it will be necessary to determine the time required for residues to decline to below the LOQ, thereby enabling an appropriate WHP to be established. Within the aquaculture industry, WHPs are typically expressed in terms of degree days e.g. a WHP of 500 degree days is equivalent to 50 days at 10 C or 25 days at 20 C. This approach is used because water temperature may affect the rates of growth and residue depletion in the treated species. Consequently, water temperature must be recorded throughout all residue decline trials conducted with abalone. Residue data will not normally be required to establish temporary MRLs where chemicals are applied prior to the grow-out period (>2 years from harvest) and abalone are a long time from maturity. 54 Best Industry Practice is defined as the application of a chemical product at a rate that gives the lowest practicable residues while still being efficacious.

5 For further information on withholding periods and analytical methods, Applicants are referred to Residue Guideline No. 10: Withholding periods, and Residue Guideline No. 19: Residue analytical method. (vi) Sample size The number of abalone required at each sampling time will depend on the size of the molluscs. In general, six abalone should be harvested and combined to give a sample of at least 50 g. Where more than one sampling time is used in the trial, the combined samples for each time point should be kept separate from other time points and clearly labelled prior to analysis. A validated analytical method must be used to quantify any residues present (see Analytical Methods below). Applicants are advised to contact the NRA Chemistry and Residues Evaluation Section prior to commencement of any residue trial on abalone, to discuss the trial protocol design. Further information on residue trials is presented in Residue Guideline No. 11: Reporting of residue trials. Metabolism and Residue definition The residue definition for a chemical is the substance(s) that is measured when determining residues in samples, and is the residue to which the Maximum Residue Limit (MRL) applies. Typically, the residue definition is based on the metabolic profile of the chemical in the target species. However, unless specific data on chemical metabolism in abalone are available, the residue definitions applicable to mammalian tissues will be acceptable for determining residues in abalone. Further information relating to residue definitions is available in Residue Guideline No. 6: Definition of residues for the purposes of setting an MRL. Analysts should refer to the NRA s MRL Standard (Table 3) at the NRA website ( for a complete list of residue definitions for agricultural and veterinary chemicals that have been approved to date. Analytical methods Appropriate analytical methods, as discussed in Residue Guidelines No. 19: Residue analytical method, and No. 26: Veterinary drug residue analytical methods, should be used. Modification of an existing method used for the determination of the chemical residues in other species is acceptable. The analytical method used should be suitable for use as a regulatory or enforcement procedure. 55 Commodity to be analysed The commodity definition for marine molluscs in both the NRA MRL Standard (Table 2) and the Codex Alimentarius Commission classification of foods and animal feeds is: IM Molluscs Whole commodity after removal of shell Therefore, the foot plus other tissues must be analysed for residues. It is not acceptable to analyse the edible portion, namely the foot, only.

6 Storage stability data Samples should be frozen as soon as possible after collection, and stored frozen at - 20 C until analysed for tissue residues. Generally, the stability of residues in food commodities needs to be demonstrated when samples are stored for 6 months or longer. However, for intrinsically less stable molecules the timeframe is shorter. Further information is presented in Residue Guideline No. 8: Stability of residues during storage. Antibiotics Applicants applying for use of antibiotics on abalone should contact the Veterinary Chemicals Evaluation Section for advice on additional data requirements to satisfy Part 10 of the NRA s Vet Requirements Series Guidelines for Registering Veterinary Chemicals. Residue Guidelines cited Residue Guideline No. 6: Definition of residues for the purpose of setting an MRL Residue Guideline No. 8: Stability of residues during storage Residue Guideline No. 10: Withholding periods Residue Guideline No. 11: Reporting of residue trials Residue Guideline No. 19: Residue analytical method Residue Guideline No. 26: Veterinary drug residue analytical methods For more information contact: Martin Merrett Phone: (02) Fax: (02)