Strain selection of red algae Kappaphycus alvarezii (Doty) Doty farmed using different methods in Tablolong Waters, Kupang Regency-East Nusa Tenggara Province

The main problem is facing in farming red algae Kappaphycus spp. in Kupang Regency are decreasing quality of seeds and the infection of ice-ice disease. This research aimed to analyze the growth of different strains of K. alvarezii farmed using different methods, and analyze which strains of K. alvareziii have high resistance to ice-ice disease. This research was carried on August to November 2020 in Tablolong waters, Kupang Regency. The strains used were Sacol from Sulamu and Semau, Tambalang (tissue culture) from Rote Island, and Cottonii strain from Pasir Panjang. The farming methods used were the Longline and Off-Bottom. The main data taken were wet weight and incidence as well as infection intensity of the disease. The study found that growth rates varied based on the strains and farming methods. Based on the strain, the Sacol strain from Sulamu gave a higher growth than the others. This strain grew and reached an average weight of 1087.5 grams at week 7; with an average specific growth of 4.87% per day. Based on the method, the longline method gave better growth compared to the off-bottom method. Regarding ice-ice disease, the Sacol strain from Sulamu gave higher resistance to disease compared to the other strains, with an average incidence of 27.26% and an infection intensity of 2.81%. The longline method provides higher disease resistance than the off-bottom method.