Overfishing occurs "when more fish are caught than the population can replace through natural reproduction," according to the World Wildlife Foundation. Once this occurs, the species is no longer "sustainable." Eighty-seven percent of all the world's fish stocks that we know about are at the "breaking point," according to the Environmental Defense Fund (EDF).
The colon should be placed before the list elements introduced by what is before the colon. In this case, the "giggle gang" is the group conformed by the elements "Jana, Andrea, Erin and Samantha." All other options are incoherent with the function of a colon.