The nation’s most influential sustainable-seafood group believes a host of once-troubled West Coast bottom fish are now recovering so well that consumers should seek them out at restaurants and markets.

Marine scientists at the Monterey Bay Aquarium said Tuesday that government regulators and fishermen had made such strides in how they manage and catch 21 species of rockfish, flounder, lingcod and sole that it listed all among the “good” or “best” seafood choices in the new edition of its popular guide.

“This is the first time we’ve really seen this happen at this scale on the West Coast,” said Santi Roberts, science manager at the aquarium.

The aquarium’s Seafood Watch guide (www.seafoodwatch.org), with its handy red, yellow and green codes, helps environmentally conscious shoppers, restaurant goers, chefs and grocers determine which species of commercial fish and shellfish are caught in the most ecologically sensitive manner.

The aquarium undertakes a rigorous, peer-reviewed evaluation for each species and urges consumers to avoid eating those not fished sustainably, while also recommending better alternatives.

Many of the species upgraded this week were deemed by the federal government in the mid-1990s or early 2000s to have been badly overfished, some to such an extent that scientists were concerned about their survival. Quotas were cut in half.

The aquarium still listed a few of the least problematic species as acceptable alternatives but urged fish lovers to completely avoid most species, particularly a wide variety of long-lived rockfish, often served as red snapper or rock cod.

But a series of major changes to management of the West Coast commercial groundfish fleet has turned around future prospects for many of these species.

“The fishermen deserve a lot of credit,” said Frank Lockhart, with the National Marine Fisheries Service’s groundfish program. “I still sometimes can’t believe how talented they are at avoiding the wrong fish and catching the right fish. ”

Overhauling the management of these fisheries, both Lockhart and Roberts said, made that task a little easier.

Many of the species, from California to Washington, are caught using trawl nets that may drag along the bottom, harming some sensitive areas.

Most were managed using massive quota systems that encouraged a race among fishermen to catch everything they could, regardless of markets. Fishermen often scooped up species they weren’t targeting and ended up tossing away many fish that weren’t salable.

But in the mid- to late 2000s, the Pacific Fishery Management Council, which oversees West Coast commercial fishing, began closing many ecologically sensitive areas to fishing. The council also divvied up quotas and redistributed them to individual fishermen as catch shares, which made it easier for fishermen to take their time and be more selective in the species they targeted. That reduced waste.

That step represented fundamental change, Lockhart said.

It allows fishermen to fish at times and in places where they know they can catch the right fish. It also allows them to work with the processors to develop markets so they can get the best possible prices.

The council started putting paid monitors on board ships with fishermen during every outing. These observers helped make sure fishermen brought up the right species from the right areas. And the council became much more conservative in setting quotas.

The result, the aquarium scientists said, is a conservation success story.

“We have excellent data on what is being caught, and things are improving,” Roberts said.

Issues remain. Species are recovering, but fishermen still have to settle for a far lower catch than in previous decades. But scientists believe the new management strategies mean those catch levels could rise again in coming years.

Sablefish, known as black cod, are still declining, though managers and aquarium scientists believe they will rebound in future years.

And some nearshore rockfish species managed by the states rather than the federal government are still in poor shape.

Still, the aquarium considers 84 percent of commercial groundfish caught along the West Coast to be either a “good” or “best” choice.

And that doesn’t even include Pacific hake, also called whiting, which it already deemed a good alternative and which accounts for the vast majority of the catch from Mexico to the Canadian border.

“This is a team effort,” Lockhart said. “Managers set up a framework that allowed the fishermen to shine, and shine they have. ”

Craig Welch: 206-464-2093 or cwelch@seattletimes.com. On Twitter @craigawelch