But nights on the lake can be uncomfortable and even dangerous, for any number of reasons — wind and pirates, among others. Last year, as a single mother, Ms. Karikumutima had no choice but to bring her infant baby out on the wooden boat with her at night, lying the baby down on a blanket in the hull of the canoe while she paddled from one net to another in the cold and the rain. The intense physical work and danger that comes with fishing on Lake Kivu, along with reinforcement from traditional gender roles, kept women from fishing for generations, tending to backyard farms instead. But in post-genocide Rwanda, that seems to be changing.

Today, women form an essential part of the national market for Lake Kivu fish. Besides fishing on the lake at night, women also gather along the shores in the early morning to buy the fish the fisherwomen deliver. They then haul those fish home to their small villages, or sell the fish to cooperatives. At the cooperatives, other women manage drying stations, where the fish are turned into a more compact, shriveled-up product that’s easier to transport. Women transport the fish across the country, in buckets and sacks, and they also sell the fish in urban markets all around the country, to landlocked Rwandans. The fish economy has created opportunities for women to form collectives and income.

Bonifrida Mukabideri often fishes with Ms. Karikumutima and is a founding member of Projet Pêche, a fishing cooperative in Kibuye, a resort town along the banks of Lake Kivu , made up of 87 women. “A lot of women have used the cooperatives to fight poverty. Here in Rwanda we now have the idea that women and men can do every job,” said Ms. Mukabideri, who supports 10 children, and has found a confidence boost by being a part of the cooperative. “I am very proud to be a part of the cooperative. Now a woman can say: ‘I can build a house by myself. I can look after my family properly. And even if my husband dies, we can live a better life.’”