Blue News

Wild pigs near South San Jose (Mulligan/Merc)

Wild pigs are causing increasing damage, but one obvious solution--hunting and eating them--carries risks: [bold added]

A wildlife trapper in Monterey County made an unexpected discovery after capturing a series of wild pigs in March of this year. While processing the animals, the trapper found several with blue-tinged muscles and fat tissues. The bizarre discoloration is a result of exposure to diphacinone, an anticoagulant rodenticide that is often dyed to identify it as a poison, according to the California Department of Fish and Wildlife.

In an email to SFGATE, Fish and Wildlife pesticide investigations coordinator Ryan Bourbour said that the trapper observed the wild pigs eating directly from rodenticide bait stations. The scope of the contamination appears extensive across the southern part of Monterey County and along the Salinas River, according to KSBW-TV.

...While California banned diphacinone for most uses in January 2024, agricultural operations have exemptions due to their pest control needs. That loophole has broad ecologic implications. A 2018 statewide study found rodenticide residues in 8.3% of wild pig tissue samples — and in an alarming 83% of bear samples — mainly in animals frequenting agricultural zones. Wildlife officials warn that this contamination can ripple through the food chain, since wildlife can be inadvertently consuming poisoned prey.

After confirming the presence of diphacinone in the liver and stomach contents of wild pigs with blue tissues, Fish and Wildlife’s Wildlife Health Laboratory is advising hunters to not consume meat from any animals showing discoloration. Visible signs aren’t always reliable, however. “As demonstrated by findings of exposure in nongame animals, the discoloration is not always present and is not a reliable indicator of AR [anticoagulant rodenticide] residues in meat,” the 2018 study said.

Diphacinone is already in the food chain and we can't always trust visual inspection to reveal its presence through the tell-tale blue. Wild pig will be off our menu for the foreseeable future.