Tuna ranching is a value-added economic activity along the coast of Baja California in Mexico involving the live capture and transport of migrating juvenile bluefin tuna to pens located near shore, where they are fed for a period of months then harvested and shipped fresh for the high-end sushi market, which is centered in Japan but expanding elsewhere.  Ranching is nested within the entire global tuna fishing and processing business.  Little is known outside the industry about the functioning of Mexican tuna ranching, which differs in important ways compared to its Australian and Mediterranean counterparts, and does not involve the harvest of reproducing age animals. Our analysis and exploratory modeling exercise identify several factors and issues that merit closer examination. A feedback perspective can shed light on whether Mexican ranching activities have the potential to become sustainable.