Scientists are considering all measures possible to prevent having to move species to new locations; in the case mentioned above, they had sharpshooters take-out cormorants that were eating the few remaining white fish in their natural habitat.  When left with no other option, scientists are being cautious and trying to take into account every possible negative impact of translocating a species to a new environment.  However, we still do not know everything about the ecology of an ecosystem and thus cannot understand all of the potential impacts on local native species.

Also problematic, there are a limited number of funds to relocate species to new locations and value judgments will often need to be made on which species to save.  Here we run the risk of basing those decisions on species notoriety rather than species need, as funding is often allocated to those species that are popular rather than ecologically important. 

A study by Mueller and Hellman evaluating invasive risk from assisted migrations found that intracontinental invasions, as a proxy for an assisted migration, were less likely to result in an invasive species and significant harm to an ecosystem.  However, they also estimated that both fishes and crustaceans were exceptions to this trend.

There have been success stories and failures associated with assisted migrations.  However, we have not determined whether the economic and ecological cost of those failures is worth the successful relocations.

I personally struggle with the question of whether it is better to let nature run its course when we, collectively, had a hand in its current direction and the rate of change is faster than many species can evolve.  Do desperate times call for desperate measures?  Or are we causing more problems by interfering?  

References: