Sodium fluoroacetate residues and carcass degradation of free-ranging feral pigs poisoned with 1080

Abstract

Sodium fluoroacetate (1080) residues in muscle and liver of free-ranging feral pigs, poisoned with 1080-treated grain in a range of habitats, were determined. The incidence of vomiting, and the degradation of poisoned carcasses were also monitored. The maximum recorded concentrations in muscle (n = 79) and liver (n = 16) were 2.42 and 4.28 µg g^–1 tissue, respectively. Mean (±s.d.) concentrations were 0.702 ± 0.535 and 0.635 ± 1.091 µg g^–1, respectively. Muscle concentration in pigs sampled within 24 h of death were similar between those pigs poisoned with wheat (0.993 µg g^–1, n = 21) and malted barley (1.012 µg g^–1, n = 20) (P > 0.05), but muscle residues may have been lower in those pigs poisoned with lupin bait (0.178 µg g^–1, n = 3). Muscle concentrations were also lower in those pigs sampled 24–48 h after death (0.481 µg g^–1, n = 13) (P = 0.004). There were no differences between the sexes (northern rangeland: mean, females 0.883, males 0.869 µg g^–1; agricultural: mean, 0.420 and 0.324 µg g^–1) (P > 0.05), but adult pigs had lower muscle concentrations than did non-adult pigs (P < 0.001). There was no evidence of vomiting by any recovered poisoned pigs (n = 85), and all but one stomach contained substantial amounts of bait and other foods. Scavengers (mainly raptors) rapidly consumed poisoned pigs weighing <16 kg, within 2 days with no apparent ill-effects. Poisoned adults (≥25 kg) were scavenged less frequently but, because of microbial action and the activity of invertebrates (e.g. fly larvae), these pigs were degraded within 7–10 days (i.e. no longer represented a potential food source for vertebrates). The levels of residues recorded were such that 1080-poisoned pig carcasses pose little potential risk to the long-term viability of non-target species.