Lazy? This is an OP letter from an aquatic biologist.
Natural predators of salmonids are not the problem, eliminating them all will not improve salmon stocks. These predator-prey relationships have evolved for hundreds of thousands of years, the balance is always shifting but humans have pushed that balance too much for it to bounce back. Northern pikeminnow is just a conveniently labelled culprit while the real issues are ignored.
Predators like Northern pikeminnow are natural selectors. They prey on salmonid eggs and juveniles, which is in fact not a bad thing. This selection over time strengthens the salmon populations. The problem is when you start building dams like the Columbia River where habitats become more desirable for northern pikeminnows so they thrive in that environment, their predatory efficiency increases and so does the population. The problem is when you harvest too many salmon and the population can no longer withstand the natural predation.
Some population control of NPM may help in the short run, but it is not a long term solution for saving salmonids.