That's very sad. It's a shame another home couldn't be found for them. On the other hand it seems like something has to be done. Non-native species can dessimate an area. If their interrupting the natural life cycle of a native species it must be done.

Living in the great lakes region, I see regularly what non-native species can do to local populations. Zebra mussles, Goobies, Lamprey, all are non-native and have been well on their way to dessimating the indiginous populations of fish. Look at what feral goats and cats are doing in austrailia.