Feasibility Study of Native Seaweed Aquaculture in Washington State

Abstract

Worldwide, the cultivation of seaweed (marine macroalgae) is growing rapidly. While the majority of this growth is in east Asia, seaweed cultivation is also increasing in North America. Washington state currently has two active in-water seaweed farms growing sugar kelp (Saccharina latissima) and one small, land-based farm growing Turkish towel (Chondracanthus exasperatus). Recently, there has been a growing, local interest in new seaweed farms. Two more in-water farms are set to start growing sugar kelp within the year (2024). In this analysis, I ask what is the feasibility of cultivating other seaweed species native to Washington, and how do they compare to the feasibility of cultivating sugar kelp? I chose nine species to evaluate: Pyropia abbottiae, Devaleraea mollis, Gracilariopsis andersonii, Ulva spp., Acrosiphonia coalita, Codium fragile, Nereocystis luetkeana, Alaria marginata, and Saccharina latissima. The feasibility of these species was evaluated and scored on a 4-point scale using five criteria: existing knowledge, global cultivation production, known temperature tolerances, future temperature tolerances, and amenability to land-based aquaculture. Three species tied for the lowest score - P. abbottiae, N. luetkeana, and A. coalita - but they had different causes for their low scores. Alaria marginata scored the next lowest due to an absence of information concerning its amenability to land-based aquaculture. All other species scored equally high, except for sugar kelp which scored highest. The results indicate that (1) sugar kelp is a good choice for an aquaculture crop in Washington regarding the chosen criteria, (2) there are other native seaweed species that are feasible for cultivation in Washington, and (3) some species are currently less feasible for aquaculture.