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Chile is one of the main producers of seaweeds in the world; however, most of the production comes from harvesting natural beds and only 2.4% from cultures, dominated by the agarophyte Gracilaria chilensis. One of the most exploited resources is the giant kelp Macrocystis pyrifera, which is sold fresh for abalone feed and dry for alginate extraction. Recently, new possible markets are developing for this species, for example human consumption and biofuel/chemical production that could increase the demand and justify the development of a commercial cultivation system. The objective of this work was to present the recent development of the seafarming of M. pyrifera in Chile, focusing on the fundamental determinants of productivity in cultivated systems and the identification of the binding constraints to productivity. Three experimental plots (up to 21 Ha) were designed and deployed in three study areas (Caldera in northern Chile and Quenac and Ancud in southern Chile) to test different environmental conditions. During a period of 3 years, sporophytes produced in an indoor hatchery were deployed monthly, at different densities, and followed until harvest. Environmental parameters and biomass were monitored on a monthly basis. Our findings demonstrate the feasibility of Macrocystis seafarming on a large scale in Chile. Important differences in yield were observed between the study areas associated with either environmental physical or biological factors, such as the presence of herbivores. Our best production cycle reached 124 WMT Ha−1 month −1 in southern Chile, and the worst, less than 20 WMT Ha−1 month−1 in northern Chile. Finally, some direct and indirect constrains were encountered, including seeding season and depth, and the presence of pests and diseases, that are discussed.

Traditional kelp farming methods require a high amount of labor and are limited in geographic distribution – occurring mainly in nearshore, sheltered sites. To address growing global demand for sustainable biomass, the continued expansion of kelp cultivation will most likely have to move further offshore. Although many offshore cultivation trials have been done over the last 50 years, few were sufficiently robust to be viable in exposed and deep-water areas. In the North Atlantic Ocean, a Faroese company developed and tested a structural farm design that has survived in open-ocean conditions since 2010. The durable structure has withstood harsh weather events common in the Faroe Islands and thereby presents a potential strategy and method for moving kelp farming further offshore. This paper describes the primary challenges of offshore kelp farming and provides an overview of work previously done. Ultimately, the improved productivity, system survivability and scalability the MacroAlgal Cultivation Rig (Faroe Islands) and the BioArchitecture Lab cultivation grid (Chile) represent state-of-the-art and powerfully transformative strategies to pursue large-scale offshore farming to support mass production of kelp in the near future.

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