It’s comparatively easy to learn what is killing young salmon on their migration to the ocean, but it has proven exceptionally difficult to do much about it. So it is for double-crested cormorants on East Sand Island near Chinook, where a bird colony eats about 11 million juvenile salmon and steelhead each year. By one calculation, this resulted in 740,000 fewer returning adult salmon between 2010 and 2013.

This issue is the opposite of a mystery. The great-great-grandfathers of today’s fishermen were concerned about the same problem more than a century ago. Back then, the drastic solution was to kill everything that competed with humans for salmon, to the extent that fish-eating birds and sea mammals were drastically cut back.

Most modern residents understand the desirability of a diverse ecosystem. We want all creatures to prosper. This includes cormorants.

It’s hard to look at a hummingbird and believe it is a descendant of dinosaurs, but cormorants look as though they could be direct survivors from the Jurassic Period. With close-cropped black feathers and a sort of hunched-shoulders demeanor, when they spread their wings to dry while perched on pilings, it’s easy to see their inner-pterodactyl. They are interesting to have around.

But society is spending a vast sum on salmon recovery. At some point — and that point is now — it is time to rebalance the equation toward making sure that fewer of these expensive young salmon end up as bird food for an avian species that is obviously doing quite well in this region.

“Avian predation upon Columbia River salmon stocks has grown to become the single-largest, unchecked impact on their sustainability. … After more than a decade of research, we can no longer afford to study cormorant impacts without addressing their threats to salmon recovery,” said Paul Lumley, executive director of the Columbia River Inter-Tribal Fish Commission in Portland.

No one better understands the need for long-term balance than the river’s treaty tribes. We should all listen to them.

The U.S. Army Corps of Engineers is proposing to kill 11,000 adult cormorants on the island. Along with other steps, including making sure some eggs don’t hatch, this will bring the colony into better alignment with modern realities.

None of the rationality of wildlife management measures such as these will keep the most avid environmental groups from suing to try to block them. But mature and responsible stewardship sometimes requires assisting nature in maintaining the right balance. That is what is should happen here.