An animal-rights group filed a complaint today with the U.S. Department of Agriculture.

The People for the Ethical Treatment of Animals is requesting an investigation into the deaths of several pigs that perished while being transported via cargo ship from California to Hawai'i.

The group says 13 pigs died on two separate voyages during the summer and may have suffered from poor conditions, which could be in violation of the Animal Welfare Act.

The Matson Navigation Company vessels were transporting hundreds of swine from Oakland to Honolulu. Some were for human consumption and others were headed for the Army's Schofield Barracks.

The complaint is PETA's latest efforts to thwart the Army's practice of shooting live pigs and treating their gunshot wounds in a medical trauma exercise. The military says the practice is critical to learning emergency lifesaving skills.