Novel Methods for Protecting Kappaphycus alvarezii from Herbivores: An Overview of Development and Economic Prospects

Kappahycus alvarezii is widely cultivated by Indonesian people living in coastal areas. The use of simple cultivation methods and low investment in K. alvarezii cultivation has encouraged an increase in the number of seaweed farmers. Farmers mainly use the longline method of seaweed cultivation. One of the most severe problems seaweed farmers face is the attack of fish and turtle pests. Such attacks are associated with the longline method, which is an open method that provides opportunities for grazing of the seaweed crop by fish and turtles. Confinement innovation is urgently needed to protect seaweed from consumption by various fish and turtles. In 2018, cage innovations were developed and tested with various variants, including horizontal net (Horinet), vertical net (Vertinet), long net, and basket net. This chapter explored the technical effectiveness and economic feasibility of using Horinet and Vertinet. The results showed that the growth of K. alvarezii on the Horinet, Vertinet, and longline was 5.0, 4.6, and 4.2%/day, respectively. Economic analysis of the Horinet and Vertinet systems indicated that their implementation in seaweed cultivation shows economic feasibility. From the value of the revenue/cost (R/C) ratio and other economic feasibility indices, the Horinet and Vertinet methods seemed to be feasible for commercial development as effective solutions for protecting seaweed crops from fish and turtle pests.