It the pig is on the property of the poster (which the o.p. appears to suggest) and the law permits harvesting the pig without permit, it seems likely that it is the property of the o.p. The trapper may have a claim of civil interference if she manipulates the trap but since she has made a presumably good faith attempt to contact the trapper without success she can make the argument for necessity of action, both to remove a nuisance and out of concern formthe animal’s well being (e.g. unexperienced tastiness).
As for sympathy to the animal, feral (not “wild”) pigs are not native to the islands. They can be quite destructive to flora, fauna, and property as well as a potential hazard to people (unusual but sows are quite protective of litters). The animal was trapped specifically because of its nuisence potential and should be taken as intended. Wildlife (or in this case, feral) populations of animals have to be managed for the well being of ecosystems as well as protecting people and property.
Stranger