Appendix II includes species that are not presently threatened with extinction, but may become so if their trade is not regulated. It also includes species that need to be regulated so that trade in certain other Appendix-I or -II species may be effectively controlled; these species are most commonly listed due to their similarity of appearance to other related CITES species.
50 CFR § 23.4
Species are listed by the Parties in one of three Appendices to the Treaty (see subpart H of this part), each of which provides a different level of protection and is subject to different requirements. Parties regulate trade in specimens of Appendix-I, -II, and -III species and their parts, products, and derivatives through a system of permits and certificates (CITES documents). Such documents enable Parties to monitor the effects of the volume and type of trade to ensure trade is legal and not detrimental to the survival of the species.