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, <i>Caranx ignobilis</i> (Forsskål, 1775) was induced spawned at the National Fisheries Research and Development Institute, Taal, Batangas, Philippines to assess the possibility of captive breeding. <i>Caranx ignobilis</i> 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 &lt; 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 &gt; 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 <i>C. ignobilis</i> in the Philippines and an initial step towards developing the seed production technology for this new aquaculture species.