What is a question about this article? If the question is unanswerable, say "unanswerable".

According to research published in 1999 by Alan Green and the Center for Public Integrity (CPI), loopholes in the ESA are commonly exploited in the exotic pet trade. Although the legislation prohibits interstate and foreign transactions for list species, no provisions are made for in-state commerce, allowing these animals to be sold to roadside zoos and private collectors. Additionally, the ESA allows listed species to be shipped across state lines as long as they are not sold. According to Green and the CPI, this allows dealers to "donate" listed species through supposed "breeding loans" to anyone, and in return they can legally receive a reciprocal monetary "donation" from the receiving party. Furthermore, an interview with an endangered species specialist at the US Fish and Wildlife Service revealed that the agency does not have sufficient staff to perform undercover investigations, which would catch these false "donations" and other mislabeled transactions.

What organization prevents animals from being sold to zoos or collectors?
unanswerable