Piloting the co-culture of Gracilaria verrucosa seaweed and Penaeus monodon in extensive pond systems in Java, Indonesia

With an increasing need for food for the growing global human population, more food will have to be produced sustainably with a lower impact on the environment while still being economically profitable. We studied the effect of combining seaweed cultivation with extensive shrimp farming on production, gross profit and nutrient concentrations. Pond experiments were conducted using different combinations of the agaroid seaweed Gracilaria verrucosa , and the Giant tiger prawn, Penaeus monodon , without supplemental feeding. Combined cultivation showed 18% higher seaweed production during the first cycle and 27% higher production during the second. Shrimp production was 53.8% higher in combined cultivation than in single-species cultivation. Seaweed quality in terms of agar content and gel strength did not differ between treatments. Gross profit of combined cultivation was, respectively, 156% and 318% higher compared to single-species seaweed and shrimp cultivation. As no feed was used, environmental impact was reduced using this method. Seaweed culture decreases nutrient loading in the water and pond sediment when cultured either solely or in combination with shrimp and lowered bacterial counts. Co-cultivation therefore improves the income whilst reducing the environmental impact.