WWW.WAS.ORG • WORLD AQUACULTURE • MARCH 2017 59 (CONTINUED ON PAGE 60) times per day, consisting of squid, mussel meat and boiled swimming crab. The acclimation period is longer than black tiger shrimp and normally for more than one week prior to ablation. In tank rearing, the brood shrimp are very sensitive to sudden light. After ablation, brooders were stocked into other similar tanks at 3-4 shrimp/m2 at a sex ratio of 1:1. Full-strength seawater was used during the period of gonadal development. However, for spawning and nauplii hatching, water of a salinity less than 30 ppt was used. After 4-6 days, brooders were subjected to a check of gonadal development or maturation stage. Animals that reached stage III (full gonad development) were transferred to a spawning tank (250 L capacity). Spawning occurs mostly around midnight and after spawning all spawners were returned to the brood tank after dipping with iodine solution. Spawned eggs remained in the spawning tank, which was provided with mild aeration and light until eggs hatched into nauplii. One difference with black tiger shrimp is that pisang shrimp during spawning produce less lipid-like substances that can cause water quality deterioration. In practice, spawners can be reared directly in the larvae tanks and use facilities efficiently. Healthy nauplii are indicated by a rapid response to light after aeration is stopped. Nauplii are harvested with a scoop net (mesh size 150 µm) and then dipped into an iodine solution of 5-10 ppm for 30 seconds. Nauplii are then stocked into larval rearing tanks at 80 nauplii/L. About 3000 nauplii/g body weight of brooder are produced. Larval development of pisang shrimp is similar to that of black tiger shrimp, with metamorphosis from nauplii into zoea, mysis and post-larvae. About 18 days are required to produce a PL-10 postlarvae. During zoea and mysis stage, Skeletonema costatum (60,00080,000 cells/mL) and Chaetoceros sp. (150,000-500,000 cells/mL) were provided two times daily (morning and afternoon). Artificial diets were also provided and divided into four meals daily. Syafrizal et al. (2015) reported that survival of PL-12 was greater (53 percent) after being fed with Chaetoceros sp compared with S. costatum (37 percent). The higher protein content of Chaetoceros partly explains this effect (Rohani-Ghadikolaei et al. 2013). Thalassiosira sp. were also used to feed larvae during zoea and mysis stage, although no scientific data is yet available regarding the effect on post-larval survival. After the post-larvae stage, the behavior of pisang shrimp is different from black tiger shrimp. Pisang shrimp larvae cling to tank walls after PL-3 and mostly inhabit the tank bottom. This indicates that larvae are strong enough for further production scale in pond grow out. However, during post-larvae stages, the number of Artemia nauplii required by pisang shrimp is greater compared to black tiger shrimp. Regular monitoring of water quality parameters is an important task to maintain the parameters at a suitable level to support growth and survival. Because post-larvae tend to occupy the pond bottom, ammonia level should be kept below 0.1 ppm and with a sufficient dissolved oxygen concentration (> 4 mg/L). Application of cane sugar is one of the techniques used instead of routine water exchange to reduce the ammonia concentration. Additions of sugar as carbohydrate source will immobilize inorganic nitrogen into the system and stimulate the growth of heterotrophic bacteria (Avnimelech 1999, Phulia et al. 2012). Reducing water exchange is a strategy for improving biosecurity and minimize cost. Further study related to various carbon sources used and effect on various C/N ratios on larvae performance and health status are need to take into consideration. In general, larval survival at a commercial production scale ranges from 20-60 percent. Live feed, primarily diatoms, during the initial stage has an important role and is a key factor affecting larval survival. Additions of specific nutrients can enhance larval survival. Sahidhir et al. (2015) reported that additions of vitamin C can enhance post-larvae survival (Fig. 2). Grow-Out Performance Grow-out is done in mostly traditional pond systems. Seed enter ponds on incoming tides during periods of high seasonal abundance and are grown to market size. Before stocking, ponds were previously prepared through pest control and fertilizer applications. The shrimp feed on naturally available foods in the pond. After three months or less, shrimp harvest size will be around 30 g if salinity is less than 20 ppt. Trials on polyculture with tilapia in an earthen pond of 600 m2 was carried out (Sahidhir and Nur 2016). About 4,600 pisang shrimp juveniles and 100 tilapia were stocked and fed an artificial diet. Shrimp and tilapia harvest were 59 kg (983 kg/ha) and 10 kg (167 kg/ ha), respectively. Shrimp survival was 77 percent and the FCR was FIGURE 2. Enhancement of pisang shrimp post-larval survival as a function of vitamin C concentration. FIGURE 3. Growth of pisang shrimp in an earthen pond.
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