During the California Gold Rush there were many new immigrants who were familiar with fishing. There was a large demand for fresh food including fresh fish and shellfish among the rapidly increasing California population. Providing fresh food products were one of the most wanted and lucrative trades that developed among the California Argonauts. The small Californio population before the rush were only able to provide some beef—their main "product" before 1850 had been cowhides and tallow. After the California Gold Rush started developing a market for fresh fish, many Azorean-Portuguese turned from gold mining to fishing. Fisherman established several small fishing communities up and down the California coast selling fish in towns and cities from San Diego to Eureka. They built their own small fishing boats using the traditional "lateen" sail technology common in the Mediterranean on their fishing boats.