The single most widely adopted conservation device in world shrimp fishing wasn’t designed to save fish. It was designed to deal with jellyfish. The rest was an accident — and it changed the industry.
Let me explain.
Shrimp trawls have a built-in problem, and it’s geometry. To catch something as small as a cold-water shrimp, you need very fine mesh. But fine mesh doesn’t discriminate. Anything that enters the net stays in the net — juvenile fish, jellyfish, whatever happens to be there. For decades, that was simply the cost of fishing shrimp: sort it out on deck, throw back what you didn’t want, and accept that much of it wouldn’t survive.
Then, in northern Norway in the late 1980s, someone got tired of the jellyfish.
The solution was almost crude: a rigid grid, angled inside the trawl, with bars spaced so that shrimp pass through into the codend while anything larger is deflected up and out through an escape opening. Built for jellyfish. Simple, mechanical, unglamorous.
And then they looked at the catch.
The fish were gone too. Not reduced — largely gone. Fish above roughly 25 to 30 centimetres simply couldn’t get through the bars, so they left through the exit instead. And the shrimp? Still there. The loss of commercial-sized shrimp came in at between zero and two percent.
That number is the whole story.
Because the usual trade-off in fishing gear is brutal: every device that lets unwanted catch escape tends to let your target escape too. One alternative tested later — a sieve panel — lost between 37 and 56 percent of the shrimp catch, which made it commercially impossible no matter how well it worked ecologically. The grid was different. It gave up almost nothing.
So the industry adopted it, and fast. Norway made it mandatory in 1991. It went international in 1993. Today it’s used in Canada, Iceland, Russia, the Faroes, the United States, Australia — the most widely adopted bycatch reduction device in shrimp fishing anywhere.
Two footnotes make it better.
The fish that escape through a grid tend to survive. That isn’t true of fish that squeeze out through the mesh of a codend, which often arrive so damaged and exhausted that escaping doesn’t save them. The grid lets them out early, near the front of the net, before that happens.
And in Canada, the grid worked so well that fisheries which had been considered impossible — grounds nobody would touch because the bycatch was unmanageable — became viable. A conservation device didn’t just reduce harm. It opened up fishing that couldn’t have existed otherwise.
There’s a lesson in that which the industry took to heart, and it’s the reason this story matters beyond the gear itself.
We tend to frame catching well and catching responsibly as opposing forces — as though every step toward one must cost you something on the other. The Nordmøre grid quietly demonstrated that this is sometimes just false — and somebody only built it because of jellyfish.
