Growth rate, yield and economics of Gracilariopsis bailinae (Gracilariales, Rhodophyta) using fixed bottom long-line method

Abstract

Vegetative thalli of Gracilariopsis bailinae weighing 10 g each were tied to a 5-m monofilament line with plastic strips and laid horizontally on the substrate and were observed to grow at 30 d interval for 9 months. The monthly growth rate and yield were determined and a cost and return analysis of the culture system was made. The monthly growth rate of the seaweed was significantly different (P=0.05) over culture month. The highest average growth rate was 6.7 percent/day while the lowest was 1.7 percent. The lowest and highest average yield (dry wt) was 72 g and 660 g m^-2 mo^-1, respectively.

A capital asset of P1,680, working capital of P2,980, and annual production cost of P5,860 were calculated from the culture system. An annual net returns of P31,292 was computed based on a 1,000 m² area. Return on investment is 671.50 percent while payback period is 1.7 months.