On the beach at Joal, a major fishing centre south of Senegal's capital, Dakar, women watch as the pirogues (fishing canoes) unload their catch. The women are far from happy. The nets are almost empty, but they expect worse when a Russian factory opens in Senegal to convert fish into meal. It will be the last straw for their fish-drying and curing business.

The trade, traditionally plied by women, is essential to preserve the seafood, which is sold on to consumers inland. But today they will not be able to buy a single crate of fish. Some say there are times when they have no work for a whole month.

The situation has deteriorated significantly since Chinese, Korean and Russian factories started springing up along the coast, producing meal for fish farming and stock breeding in Europe and Asia. Over the past three years, 11 plants have been built near the beaches where local fishermen land their catch, between Kayar, north of the capital, and Joal, which accounts for about a third of the country's coastline.

In Joal (population 40,000) the mood has been tense since the construction of the new Russian factory, Flash Africa, was announced. A plot of land has already been fenced off. Marianne Teneng Ndaye, who heads the trade federation representing women fish-processors at Joal-Fadiouth, has called for a day of protest. "The Koreans turned up five years ago but they only took ribbon fish, which didn't bother us," she says. "But now they are buying fresh sardinella, what are we going to eat? The Russian factory aims to produce 46 tonnes of meal a day. It will need 460 tonnes of fish to do that, but since 2010 the Joal fishing boats haven't ever landed more than 200 tonnes a day. It'll be the death of us."

"The price of fish has doubled in just a few years," complains Khadi Diagne, another fish-processor. She says she cannot afford to pay the $12 it now costs for a 50kg crate and that her income has been halved in three years. "Here they count on the mothers to feed the family," she adds.

In winter there used to be plenty of fish in the coastal waters, but now stocks are dwindling, fuelling local resentment of the competition from foreign factories. The problems started in the 1990s when the first large foreign trawlers appeared, some fishing illegally, others with a licence. The number of pirogues also started increasing. For the Senegalese, most of their animal protein intake comes from the sea, so the country's food security is now at stake.

Five hundred women in Joal work full-time salting, grilling and drying mackerel, anchovy and sardinella, known locally as yaboy and the prime ingredient in Senegalese cooking.

Some mornings thousands of women and children come out to sort and cut up the catch. In addition, there are salt merchants and farmers who deliver cartloads of straw used in the smoking process, adding up to tens of thousands of people who will be affected by the arrival of Flash Africa. In turn, consumers will be deprived of dried fish, sold on markets as far afield as Benin over 1,000km away.

The leader of the town council, Paul Ndong, sees things differently. "Everyone is in agreement – the local council, the population, the fishermen and the property developer," he asserts. "There will be 170 jobs for young people at the factory. And the owners have promised to refurbish the town hall, install electricity and build a maternity hospital." But what will happen if there is no more fish to dry? "That's impossible," he retorts. "They won't only source their fish in Joal, but all over the place." And if the women are complaining they are short of work, "it's because there are no longer as many fish in the sea".

Last month President Macky Sall met representatives of the local fishing industry. Thousands of people – the industry employs about 600,000 people in Senegal – turned out in a show of support for the firm stand on illegal fishing taken by the minister of fisheries, Haidar al-Ali. His non-profit organisation Oceanium is steadily spreading the message that the ocean must be managed sustainably. "We need to put our heads together to find ways of gradually bringing the fish back," says Diapa Diop, the under-secretary for traditional fishing. "We must create protected marine areas, wildlife refuges for certain species and review the permits granted to factories. If our people no longer have enough to eat, we must stop exporting."

This article appeared in Guardian Weekly, which incorporates material from Le Monde