Reprodução induzida de ariacó, Lutijanus synagris (LINNAEUS, 1758), em cativeiro

Abstract

The lane snapper, Lutjanus synagris, part of the family Lutjanidae, considered snappers fish, has a high commercial value and a high demand in the State of Ceará. The aim of the current thesis was to perform the induced spawning of lane snapper, through hormonal treatment, and to describe the embrionary development and larvae rearing of this species, aiming its breeding at experimental level. The work was developed between March 2008 and December 2011, at the Marine Fish Farming Research Unit of the Coastal Environmental Studies Center of Federal University of Ceará (UFC) Marine Science Institute (LABOMAR), located at Eusébio, Ceará, Brazil. A total of 243 lane snapper specimens were captured in the wild by line and hook and traps. Seventy-two broodstock were kept separately, being 24 females, chosen accordingly to the gonads development (accessed by cannulation), and 48 males ripping milt, with mean weight of 0.381±0.154 e 0.353±0.105 kg,respectively. The broodstock was distributed into three treatments with eight repetitions each. In each treatment, the females received distincts hormonal doses of 1000, 1.250 and 1.500 UI of HCG per kg of corporal weight. The females were injected HCG twice, 30 and 70% of the total doses, in between 24 hours. All treatment males were marked so they would be different from females and were injected a sole 500 UI of HCG dose at the same time at the females’ second dose. The females started to spawn between eight and twelve hours after the last dose. Dissolved O2, temperature and salinity mean values at spawning time were 6.2±0.11 mg/L, 28±0.29 ºC e 35±0.64 ‰, respectively. The fertilized eggs presented the following features: spherical shape, transparency, narrow perivitelinic space, light corium, homogenic and non seguimented vitelo, no pigmentation and buoyants with visible oil droplet.The oocyts, eggs and oil droplets mean diameter for treatment 1 (1000 UI/Kg) were: 425±16, 659±10 e 139±2 μm; for treatment 2 (1250 UI/Kg) were: 427±15, 661±14 e 140±5 μm; for treatment 3 (1500 UI/kg) were: 422±10, 667±20 e 141±5 μm, respectively. The females which received the 1250 UI of HCG/Kg hormonal dose (treatment 2) were the ones that spawned the greatest number of eggs, 556,661.0±209,171.0. The females which were induced with 1000 UI of HCG/Kg (treatment 1) spawned the smallest number of eggs, 405,797.0±230,812.0. The females which were induced with 1000 UI of HCG/Kg (treatment 1) presented the best fertilization rate with 75±10%, followed by the ones that were induced with the doses of 1250 and 1500 UI of HCG/Kg, with 66±7 and 65±17% respectively. The lutjanids embrionary and larval development were similar to other pelagics teleosts bred all over the world. The L. synagris hatching was registered until the 30º day after eclosion (DAE). The present study suggests that further researches should be carried out to elucidate information about larvae dietary in order to obtain better survival rates, especially in the 30 first DAE.