Maintenance and spawning on yellowfin tuna broodstock reared in floating net cage

Yellowfin tuna ( Thunnus albacares ) is one of the fish species that have important economic value which is expected to become one of foreign exchange that can give solution to national economy. Hatchery technology of yellowfin tuna performed at the Research Institute for Mariculture and Fisheries Extension Gondol has been successfully spawned. However, the quality and quantity of eggs produced is still not optimal. The purpose of this study was to determine the performance of spawning on yellowfin tuna broodstock reared in floating net. This research was conducted in cage with a diameter of 48.8 m with a depth of 8 m, filled 90 fishes yellow fin tuna with weights ranging between 50-70 kg per fish. Feed given is: fresh fish, squid and added vitamin C and vitamin E. The study was conducted for 11 months from January to November 2017.The results showed that the yellowfin tuna could spawn monthly. The highest spawning frequency occurred in July at 17 times. The highest total number of eggs harvested was 8,740,350 in October. Hatching rate between 50-92%. Survival activity index (SAI) is 1.8-3.5%. Survival rate of yellow fin tuna during maintenance reached 92.2%.