When was the first successful open-ocean aquaculture experiment carried out?

Open-ocean aquaculture began as a serious experimental idea in the late 20th century, with pilot projects emerging from the 1970s onward. Unlike coastal pens in sheltered bays, these systems were designed for stronger currents, deeper water, and less pollution buildup. The goal was to grow seafood in ways that could reduce pressure on wild fisheries. Over time, engineering, feed management, and environmental monitoring became central to making such farms viable. The field remains important, but it also raises concerns about ecological impact and escapees.