Floating raft culture of Gracilaria verrucosa for optimum yield performance on the coast of Cox’s Bazar, Bangladesh

The present study was meant to describe the very first description of Gracilaria verrucosa culture using a floating raft culture method on the coast of Cox’s Bazar, Bangladesh. The effects of different factors such as rope materials, culture type, raft shape, seeding intensity, harvesting phase, and water depth on the biomass production of seaweed were evaluated during a 90-day culture period. Different water quality variables such as temperature, pH, DO, salinity, TDS, transparency, alkalinity, ammonia, nitrite, nitrate, and silica were measured at every 15-day interval throughout the culture period. The seasonal appearance of epiphytic algae and cost-benefit analysis of seaweed culture was also performed. We found the range of biomass production (3.03–13.37 kg/m 2 ) and DGR (3.08–4.72% d − 1 ) to be satisfactory in the floating raft culture method. A total of eight epiphytic algal species were recorded, which resulted in major challenges for the growth of Gracilaria . The cost-benefit analysis showed about a $1051 profit for a six-month culture period in 20 rafts. Our research concluded that farming G. verrucosa in the floating raft method, when certain critical factors are considered, can become a profitable sector for large-scale seaweed production in our coastal area.