The Saharan country's shores are home to one of the world's largest concentrations of sea life, including fish, crustaceans, molluscs, turtles and rays.
However, despite its natural wealth and population of three million, it is one of the world's poorest nations, with two-thirds of the population surviving on less than $2 a day.
Mauritania awards fisheries agreements every five years to the European Union.
The latest deal, which ends in July, allows more than 240 foreign vessels into Mauritanian waters.
But the country's civilian government, which came to power after a bloodless coup in August, says European trawlers are depleting the country's stocks at too cheap a price and threatening the local fishing industry.
Sidi Mohamed Ould Sidina, the fisheries minister, said: "We estimate under the terms of this agreement, European fishermen catch as much as 600 million euros worth of fish each year and we receive 96-100 million euros.
"All of our deep-water potential is fished by the European Union. We just catch the dregs because our boats are very outdated and not very effective."
Harouna Diop has worked in Mauritania's small-scale fishing industry for more than 40 years and remembers when there were only six small wooden fishing boats working the waters off Nouakchott's barren coastline.
"The big ships are just an attempt to be more efficient by processing at sea and storing the fish in cold storage"
Just hours at sea were enough to fill the vessels with sardinella, horse mackerel, snapper and tuna.
Nowadays, his son can spend a week on the water and still struggle to catch enough fish to earn a living.
"There were a lot of fish before. Now there are hardly any. The big nets, the big boats have taken them all. They work night and day," said the 64-year-old.
Nouakchott's fishermen say each catch, which is roughly enough fish to fill one of the battered old Peugeot 504s that ply the route from the beach to the market in the centre of town, sells for about $370.
Half of that goes on outboard fuel, a little more on the transport into town and on food, and the rest is split among up to 25 crew members in each of the traditional, thin pirogue boats.
The fishermen's canoe-like boats and simple nets are a stark contrast to the European vessels working farther offshore.
Until recently, the Irish-owned Atlantic Dawn fished in the waters off Mauritania.
It is one of the world's largest fishing vessels, a 64-million-euro trawler cum fish-processing-plant that can store up to 7,000 tonnes of fish, or enough for 18 million meals.
"We are a people who are very close to nature. We are not a consumer society"
Sidi Mohamed Ould Sidina, Fisheries minister
With 60 crew members on board at any one time, the 144-metre ship has fished off Mauritania for six years, catching sardines and sardinella. It is known locally as "the ship from hell".
Niall O'Gorman, finance director of Atlantic Dawn, the holding company that owns the vessel, said: "We feel we're an easy target - the big ship looks like the baddie."
"The big ships are just an attempt to be more efficient by processing at sea and storing the fish in cold storage."
The Atlantic Dawn used to operate under a private agreement with Mauritania, but since August's coup it had been repeatedly boarded by the authorities and was now waiting to return under the protection of the next EU agreement, O'Gorman said.
Sidina said efforts were being made with European countries to better regulate vessels operating in Mauritanian waters.
He sympathised with calls from Nouakchott's fishermen for European countries to invest in a fishing industry in Mauritania rather than simply plucking fish from under their noses, but said the country was some way off being an economic power.
"We are a people who are very close to nature. We are not a consumer society," he said.