Kenya is staking its economy on women like Purity Marangu, who left her family to work in Saudi Arabia. They work as housekeepers, normally a safe job. But many have been assaulted, starved and worse.

On the outskirts of the coastal Kenyan city of Mombasa, a women’s organization in Jomvu Creek aims to transform livelihoods and the environment through mud crab farming. A blue economy grant is ...