Conserving Ecosystems by Ceasing the Importation of Large Animal Trophies Act or the CECIL Act This bill addresses international wildlife conservation efforts and trophy hunting. Specifically, this bill restricts the importation of a sport-hunted trophy of a threatened species or endangered species. In addition, the bill abolishes the International Wildlife Conservation Council of the U.S. Fish and Wildlife Service. Finally, the Government Accountability Office must study the effectiveness of trophy hunting in supporting international wildlife conservation efforts.