Accidental Discharge of Brodifacoum Baits in a Tidal Marine Environment: A Case Study

Burrowing Owl Diet at a Migratory Stopover Site and Wintering Ground on Southeast Farallon Island, California

“…32 Furthermore, samples taken nine days after the spill were below the level of detection (0.02 ppm) 33 (Primus et al 2005). 34 35 Based on available evidence, the significance determination for this alternative is expected to be 36 not significant.…”

“…Empson and Miskelly (1999) found no change in the density of 2 spotties during observation, and divers did not find any dead or moribund organisms. 3 4 Eighteen tons of brodifacoum bait was accidentally spilled into the ocean at Kaikoura, New 5 Zealand in May 2001 (Primus et al 2005). No fish were found dead and of the five fish sampled 6 only a Japanese butterfish (Psenopsis anomala) tested nine days after the spill had detectable 7 residues, of 0.040 mg/L in the liver and 0.020 mg/l in the gut (Primus et al 2005 likelihood of their exposure to anticoagulants at the levels that caused mortality in the three 32 species listed above is considered negligible.…”

“…3 4 Eighteen tons of brodifacoum bait was accidentally spilled into the ocean at Kaikoura, New 5 Zealand in May 2001 (Primus et al 2005). No fish were found dead and of the five fish sampled 6 only a Japanese butterfish (Psenopsis anomala) tested nine days after the spill had detectable 7 residues, of 0.040 mg/L in the liver and 0.020 mg/l in the gut (Primus et al 2005 likelihood of their exposure to anticoagulants at the levels that caused mortality in the three 32 species listed above is considered negligible. Nevertheless precautions will be taken to minimize 33 the risk of bait drift into marine areas and monitoring of impacts to marine gastropods would be 34 incorporated into the proposed monitoring program (Section 2.10.7.7).…”

“…Residues in mussels and abalone took up to 31 months to 41 decline to concentrations below the limit of detection. This persistence of brodifacoum was 42 thought to be due to a combination of a prolonged half-life in these invertebrates and re-exposure 43 of these invertebrates to particulate brodifacoum in the high dynamic tidal marine environment 44 (Primus et al 2005 The toxicants used for rodent eradications can only effectively be delivered through a bait that 9 must be ingested orally. Animals can either ingest the toxicant by consuming bait pellets (known 10 as "primary exposure"), or by preying or scavenging on other animals that previously consumed 11 bait pellets (known as "secondary exposure").…”

Rodent control and island conservation.

“…The anticoagulants are generally less toxic to fish and invertebrates than they are to mammals and birds, but there may be risks to fish and other organisms if there is considerable run off of bait particles into aquatic environments from treated areas. However, a recent dramatic accident, in which approximately 18 tonnes of brodifacoum bait was deposited into the sea on the coast of New Zealand, has permitted a practical and large-scale assessment of the fate of brodifacoum in the marine environment (Primus et al, 2005). The principal environmental effect observed during intensive monitoring was the appearance of brodifacoum residues in certain filter-feeding molluscs and crustacea.…”