On good November mornings, Steve Dahl can pull 400 to 800 pounds of Lake Superior herring from his nets. But this was not a good morning.

Guiding his 18-foot herring skiff into the Knife River harbor, 15 miles up the shore from Duluth, Dahl figured he'd caught only about 20 pounds of the foot-long, silvery fish.

The lake herring, called cisco, typically aggregate in thick schools in the late fall when they swim to shore to spawn. But overfishing in parts of Superior regulated by Wisconsin, and a decline in fish survival, have caused cisco numbers on the Minnesota side of the lake to plummet, putting the lake's small but iconic commercial fishery in jeopardy.

The evidence of that was clear in Dahl's daily catch, about one box. "That's all we got," he said. "Yep. You just never know."

Commercial fishermen on the North Shore of Lake Superior are busy wrapping up their busiest time of the year. But they know that if things don't turn around, if solutions aren't found, their livelihoods could come to an end.

Dahl, 63, quit his job as a vocational counselor 27 years ago to fish full time. While fishing for lake herring has always had boom and bust years, this year and last have been especially tough, he said as he peeled out of bright orange waterproof bibs.

"Last year, I was down $10,000 on my annual income," he said. "So that's a little bit, that hurts a little."

Fisherman Steve Dahl's catch. Derek Montgomery for MPR News

Last year Minnesota's 25 commercial fishermen on Lake Superior caught 214,000 pounds of herring. That's down nearly 50 percent from 2012.

Herring aren't just important to commercial fishermen and to the growing number of restaurants that feature locally caught herring. They're also a vital forage fish for important sport fish like lake trout.

Fisheries researchers say there's a double whammy hitting Lake Superior's cisco.

Baby cisco aren't surviving to become adults. There hasn't been a strong year since 2003, said Cory Goldsworthy, Lake Superior area supervisor with the Minnesota Department of Natural Resources.

"A whole suite of things are impacting successful recruitment, and as usual in fisheries," he said. "You can't just say it's this one thing. It's an entire ecosystem environmental issue."

New research suggests climate change could be at least partly to blame. Low ice cover in recent years has coincided with poor cisco counts.

Fisherman Steve Dahl cleans the day's catch of cisco or lake herring. Derek Montgomery for MPR News

At the same time, there's been a surge in demand for lake herring over the past decade, with part of that driven by the local foods movement.

November is a particularly crucial time. Dahl and other fishermen typically make up to half their income in the month because of the demand for cisco eggs, which are used to make a caviar that's a Scandinavian delicacy called lojrom.

When the Baltic Sea fishery that supplied the eggs crashed, Nordic countries looked for a replacement, which they found in Lake Superior herring, said Mark Vinson, a fisheries researcher with the U.S. Geological Survey in Ashland, Wis.

"We had a perfect storm there for a while, in terms of high demand, capability of fishermen to go out and catch the fish, and also good weather."

The cisco catch increased across western Lake Superior. But it skyrocketed in waters off the shore of Wisconsin, more than tripling to more than 1 million pounds a year. From 2000 to 2007, the cisco catch in Wisconsin averaged about 359,000 pounds. Over the last seven years, it's averaged nearly 1.4 million pounds.

Herring roe or "Lake Superior Gold" as some people call it is a delicacy. Derek Montgomery for MPR News

That's because unlike Minnesota and Ontario, Wisconsin doesn't place any limits on cisco harvest in its waters.

That wasn't a problem before the new rush for roe, when Wisconsin commercial fishers focused mainly on whitefish and lake trout, Vinson said, "because it was a fish that was so abundant and there was very little demand for it."

Wisconsin commercial fishermen have historically focused on lake trout and whitefish. Herring? Not that long ago it was turned into mink food.

With the recent spike in demand, Minnesota officials have implored Wisconsin to limit its cisco catch to sustainable levels.

DNR Commission Tom Landwehr wrote a letter to the Wisconsin DNR in June saying that "based on the current age distribution of fish, the abundance of spawning Cisco will continue to decline, and subsequently, quotas will also decline until it is no longer feasible for the commercial fishery to remain open."

That would give the fish a chance to recover, said the Minnesota DNR's Cory Goldsworthy.

"We're to the point now where our quotas are so low that we're really on the verge, if we don't get a good year class, there's other management considerations such as closing the fishery down if that should happen," he said.

Fisherman Steve Dahl cleans the day's catch of cisco or lake herring. Derek Montgomery for MPR News

Minnesota has been through this before, Goldsworthy added. The state only reopened its November herring fishery in 2006, after closing it for more than forty years because of overfishing in the early 1900s.

Wisconsin DNR officials declined an interview request, saying they're meeting with the Bad River and Red Cliff Bands of Lake Superior Chippewa to negotiate possible harvest limits.

In a response to Minnesota, Wisconsin DNR Secretary Cathy Stepp wrote, "We appreciate your patience and understanding as we work to address this concern, it is a priority for our agency. We understand the impact this could have on Minnesota's commercial fishery and will work towards a solution."

Dahl, though, says it's frustrating to see his counterparts in Wisconsin harvesting unlimited cisco.

"On this side we're heavily restricted, and we've kind of taken the brunt of things," he said as he deftly filleted his daily catch.

Dahl, however, doesn't intend to stop fishing, unless he's forced to.

"Some days you think, 'what am I doing when I go out there,' [getting] pounded, beat to death, but I love it," he said. "It's in my blood."