By Rajesh Mirchandani
BBC News, California and Oregon
The US government will decide next week whether to issue a complete season-long ban on salmon fishing off the Pacific coast of the US.
Wild salmon is big business on the Pacific coast of the US
The proposal comes in response to a drastic collapse in fish stocks.
But fishermen's groups say it will devastate their industry and cost the local economy billions of dollars.
With a light hand on the steering wheel, captain Phil Bentivegna guides his boat, Butchie B, out of San Francisco harbour.
He has worked on the ocean for 41 years, many of them in his current role, running charter tours for sports fishing enthusiasts.
We pass dozens of other such boats, testament to this important part of San Francisco's tourist infrastructure.
But the fishing tour business is quiet these days. In fact, Mr Bentivegna tells me: "Last year was probably the slowest year I have ever had for catching salmon."
Commercial fishermen are facing tough times too.
California and Oregon, western states with considerable commercial and recreational fishing industries, are looking at the very real possibility of not being able to fish any salmon at all this year.
It could cost the local economy more than $3bn (£1.5bn).
The reason is that stocks of wild Pacific Chinook salmon - a staple food along America's west coast for hundreds of years - are in drastic freefall.
One measure of the population is the number of salmon heading from freshwater spawning grounds to the ocean, a process called "returns".
This year, the Chinook return is expected to number some 56,000; the minimum needed to keep the salmon fishing industry sustainable is at least 122,000.
In past years, returns upwards of 200,000 salmon have been common.
The recreational salmon fishing season should have opened any day now; instead a temporary ban is in place, while experts decide how to respond.
Next week, the US government is widely expected to ban all salmon fishing - affecting Chinook and also the coho salmon - off a 1,200-mile stretch of the west coast of the US for the whole season, up to seven months. An alternative option would allow very limited catches.
Duncan Maclean, who advises California's fishing industry, says fishermen realise there is no alternative.
"I'm supposed to fight for every fish we catch and I have no fight this year," he says. "I cannot justify a fishery because the numbers are so low."
For once, fishermen are not getting most of the blame. This is not simply a problem of over-fishing. There are a variety of factors at play, some natural, others man-made.
Changes in ocean conditions, perhaps brought about by global warming, mean less food for salmon to eat, so fewer make it upstream to spawn.
Those that do face risks too: river water contains pollution from agriculture and industry, a potentially toxic environment for salmon, while river levels are often low as water is increasingly diverted to irrigate crops and supply large cities such as Los Angeles.
There may be no respite ahead either.
Putah Creek is a shallow tributary of the Sacramento River, exactly the type of watercourse where most wild Pacific salmon start life.
Fish biologist Professor Peter Moyle leads a team of scientists from nearby University of California at Davis. They are pulling 20ft (6m) nets through the muddy water, then dragging them on to the bank and examining the contents.
The process, called seining, is a crude way of counting the number of young salmon in a river. In a normal year, each haul should contain between five and 10 young salmon.
"We got nothing," Prof Moyle announces, "except one little sunfish."
According to Prof Moyle, the number of young salmon this year is at best a quarter of what it should be. He, like many other experts, foresees further gloom ahead.
"The fishery is going to be shut down for at least two years," he predicts.
'Time to clean up'
Some 600 miles to the north, the mist clings to the wooded hills of Oregon and a cloud hangs over the quiet fishing port of Tillamook.
This is a town dependent on salmon and crab.
As Darus Peake, owner of the Tillamook Bay Boathouse and a state fishing adviser, says: "It's going to hurt everybody from the gas station owner on the corner to the gift shop to the motel to the restaurant... it's quite a trickle down."
Prof Peter Moyle foresees further gloom ahead for salmon fishermen
In Mr Peake's mind a salmon-fishing ban would be a quick fix for a deeper, man-made, problem.
"We have got to start looking at ourselves... we need to go back to our natural resources, clean up our natural resources and then go on from there," he says.
Back in San Francisco Bay, Mr Bentivegna is pointing out the famous landmarks like the Golden Gate Bridge and Alcatraz Island, just as he has for many years.
He is running a few sightseeing tours now, no fishing trips and expects to lose nearly half his business this year.
The prospect of a season-long ban on salmon fishing makes him fear for future generations.
"I'm glad I'm at the end of my career instead of at the beginning of my career when this is happening," he says.
"I know a couple of young skippers that are in their late 20s or early 30s with families and house payments. I really feel bad for them... I just don't think this is the industry to get into any more."