By Frances Harrison
BBC, in Bandar Anzali, Iran
It is a rosy-tinted dawn and Nazagha Razania is out on his fishing boat on the Caspian Sea checking the nets.
Nazagha Razania remembers the plentiful catches of his youth
This is the height of the sturgeon season but his boat has only caught one fish in the last two months.
Today there is a sense of optimism because there has just been a storm which they hope has driven the fish into the nets, but so far all they have found is bits of driftwood and old shoes.
Caviar is among the most expensive wild foodstuffs in the world - but the fish that produce the little black eggs are rapidly disappearing.
Ninety percent of caviar comes from wild sturgeon in the Caspian Sea where overfishing since the collapse of the Soviet Union has caused havoc.
So endangered is the sturgeon that the US has just banned imports of the most expensive caviar - beluga - in the hope this will prompt producers to do more for conservation.
"In four or five years there will be no caviar fish left - maybe just one or two here or there," says the 40-year-old fisherman Nazagha, who remembers how plentiful the catch was when he was young.
Then he corrects himself, saying: "Actually it's already over; nothing comes out of the sea."
"How can the fishing company afford to pay our salaries when we don't catch any fish?" Nazagha worries.
He believes his will be the last generation of caviar fishermen - now the sturgeon are like gold he says.
Caviar is one of the world's most expensive wild foodstuffs
One of the fishermen from Nazagha's boat had to stay up all night to guard their nets from poachers.
They show us the poacher's nets which are much finer and have entangled two baby sturgeon less than a year old.
A sturgeon can take up to 20 years to mature and produce eggs.
In the distance Nazagha spots a poacher and races after him.
At first the poacher thinks we are the patrol boat and tries to speed off but when they realise we are not they stop for a chat.
"Salaam, Haji," they greet each other as friends. They live in the same village and know each other.
"Of course we're not catching sturgeon - we're catching white fish," says the poacher, grinning.
Unemployment is rife here and many fishermen have no choice but to poach if they are to feed their families. The black market price is 10 times the legal one for caviar.
Iranian researchers now believe the only way to save the caviar industry is for all five Caspian Sea states to invest in alternative livelihoods to reduce the poverty that forces people to poach.
The director of the Sturgeon International Research Centre in Iran, Mohammad Pourkazemi, says the crisis began with the collapse of the Soviet Union and the lack of state control over the industry.
Poaching does take place in Iran but here they believe it is far worse in the former Soviet states where the mafia is involved.
"Without improvement in the socio-economy and the governmental cost for implementation and enforcement it won't be possible to save the species," says Dr Pourkazemi.
Large numbers of young sturgeon are released into the Caspian
In huge halls outside Dr Pourkazemi's office, there are rows and rows of fish tanks with clouds of mosquitoes buzzing over them.
Every year Iran releases 24 million sturgeon fingerlings into the Caspian Sea but it is not easy - only between 1% and 3% survive in the wild and it costs millions of dollars.
Dr Pourkazemi says every year there is a 20% to 30% reduction of sturgeon stocks in the Caspian which means the species could be extinct within 15 years.
The sturgeon dates back to the time of the dinosaurs but today hunger for profit has created a caviar crisis.