Watanabe: To protect the native kokanee salmon in the lake, we must allow fishing of native trout  Each mature trout eats about 250 mature kokanee annually  Lopez: The real problem is mysis shrimp, which were originally introduced into the lake as food for mature kokanee; but mysis eat plankton -- young kokanees' food  The young kokanee are starving to death
So eradicating the shrimp is preferable to allowing trout fishing
When trying to protect the food supply of a particular species, it is best to encourage the method that will have the quickest results, all else being equal.