What’s the Best Way to Store Toxic 1080 Baits?

Abstract

Being able to store toxic baits could allow livestock producers to target ‘hot spots’ of predator activity, supplementing or even replacing broadscale baiting, therefore avoiding potential risk of bait-resistant populations. We compared 1080 dose recovered from dried meat baits (DMB; camel, horse and kangaroo) and sausage baits stored by different methods (shed, locked transport box, freezer, cryo-vacuumed) to identify whether they were still lethal, and address concern that freezing/thawing could result in loss of the water-soluble 1080 toxicant. We developed a bait collection method to halt microbial activity (preserving 1080 dose), allowing collection of baits manufactured under field conditions by five regional Recognised Biosecurity Groups according to their own schedule and methods. We assayed 351 baits (including 43 negative control baits, i.e., no toxicant), just over half (54%) of which were manufactured by us, using consistent meat masses, 1080 doses, and drying methods. For freshly manufactured baits, there was good consistency in bait manufacture, with no significant difference in recovered 1080. For stored baits, there was no effect of time on recovered 1080 for up to 2 months (maximum length of study), indicating different storage methods were equally effective in maintaining lethal baits. Manufactured sausage baits contained significantly more 1080 than DMB manufactured for this study, and showed substantial variability in recovered 1080 dose, which could reflect gun handling error. Storage in a locked transport box resulted in marked insect damage, likely rendering baits unattractive to target species. Freezing baits did not result in reduced 1080 dose. The majority (93%) of deployed/stored baits had a lethal 1080 dose recovered (13/192 baits were below the LD₅₀ for a 20 kg dingo). Dry shed storage is prescribed as best practice, but freezing baits does not reduce their toxic dose. Future testing for longer durations of storage would be beneficial.