Induced spawning of giant trevally, <i>Caranx ignobilis</i> (Forsskål, 1775) using human chorionic gonadotropin (hCG) and luteinising hormonereleasing hormone analogue (LHRHa)

Abstract

The giant trevally, Caranx ignobilis (Forsskål, 1775) was induced spawned at the National Fisheries Research and Development Institute, Taal, Batangas, Philippines to assess the possibility of captive breeding. Caranx ignobilis captive broodstock, six to eight-year-old (4.83 kg mean wt) were injected with: (a) 1,000 IU human chorionic gonadotrophin (hCG).kg-1; (b) 100 μg luteinising hormone-releasing hormone analogue (LHRHa).kg-1; (c) 5 mg carp pituitary extract (CPE).kg-1; and (d) No injection (Control). Ripe female fish was given two sequence intramuscular injections at 0600 to 0700 h and 1800 to 1900 h while male fish was given half dose injection at 1800 to 1900 h. One breeding set (1 female: 2 males) were released to spawn spontaneously in each of the four units of 40-ton circular tanks, done in five replications. Successful spawning was achieved in LHRHa- and hCG-injected fish at 28–30 g.L-1 salinity and 27.6–29.25 °C in March to April of 2011 and 2012. Spawning occurred 24–52 h after 2nd injection and eggs hatched in 11–17 h. Fertilisation rate was significantly higher (P < 0.05) in LHRHa treatment (60.88 %) than hCG treatment (30.53 %). Mean spawned eggs, hatching rate and mean larvae produced were not statistically different (P > 0.05) between hCG (223,068 eggs.kg-1 breeder, 43.06 % and 41,547 larvae.kg-1 breeder, respectively) and LHRHa treatment (176,524 eggs.kg-1 breeder, 71.07 % and 56,040 larvae.kg-1 breeder, respectively). This is the first recorded captive breeding of C. ignobilis in the Philippines and an initial step towards developing the seed production technology for this new aquaculture species.