Picture a fisher heading out at dawn in a small wooden boat.

Not far offshore, a massive industrial vessel works the same waters. The coastline is a protected area for small fishing boats. But the big boats fish right along the edge, dragging a net across the seafloor that scrapes up everything in its path — not just fish, but the breeding grounds and habitat they depend on.

Over years, the fisher’s catch keeps shrinking. And with less fish, the prices keep rising at the market. Suddenly, fish is scarce within a fishing community.

That's the reality detailed by a new Conservation International study , which explains how industrial and distant-water fleets can crowd out local fishers and disrupt fragile coastal ecosystems. From the Field spoke to Melissa Cronin, the study's lead author and Elena Finkbeiner of Conservation International, a co-author, to discuss the stakes for people and nature.

A large fishing vessel hauls in a trawl net.

Let's start broad.…