Reproductive
performance in induced and spontaneous spawning of the mangrove red snapper,
Lutjanus argentimaculatus: a potential candidate species for
sustainable aquaculture
A.C.
Emata-2003
Aquaculture
Research, 34(10):
849
Abstract:
A
reliable breeding technique was developed for the mangrove red snapper, Lutjanus
argentimaculatus (Forsskal 1775), to help sustain the aquaculture of
this immensely popular species in Southeast Asia. Using standardized indices
of female maturity (based on mean oocyte diameter of >/= 0.40 mm),
time of injection (1000-1130) and sex ratio (one female to two males), a
single injection of 100 µg kg-1 luteinizing
hormone-releasing hormone analogue (LHRHa) (n=16 fish), but not 50 µg kg-1
(n=five fish), successfully induced egg (62.5% success rate) and
larval (43.8%) production. Human chorionic gonadotropin (hCG) at 500 IU kg-1
(n=five fish) also failed to induce spawning, but doses of 1000 (n=22
fish) and 1500 IU kg-1 (n=15 fish) gave spawning
(77.3% and 80.0% respectively) and hatching success rates (72.7% and 60.0%
respectively) that were not significantly different from those of 100 µg kg-1
LHRHa. No spawning was observed in saline-injected controls (n=seven
fish). While mean spawning latency, egg diameter, egg production per spawn,
percent egg viability, hatching rate, percent of normal larvae and
cumulative survival of eggs to normal larvae did not differ significantly
among the effective hormones and doses, 1000 IU kg-1
hCG had a higher percentage (76.5%) of total spawns with egg production per
spawn in excess of one million than those of 1500 IU kg-1
hCG (50.0%) and 100 µg kg-1 LHRHa (40.0%). Mangrove
red snapper spontaneously spawned from March-April to November-December with
a peak of egg collection and spawning in May-June. Egg collection per spawn
ranged from 0.05 to 6.35 million. Spontaneous spawning of mangrove red
snapper exhibited lunar periodicity with spawns mostly occurring 3 days
before or after the last quarter and new moon phases and occurred
consistently between 02:00 and 04:00 hours. High fecundity and good egg
quality, coupled with the ability to respond to induce spawning or natural
spawning in captivity, provide a sound basis for improving the
sustainability of red snapper aquaculture in Southeast Asia.
(Aquaculture Department, Southeast Asian Fisheries
Development Center, Tigbauan, Iloilo 5021 Philippines. E-mail:
acemata@aqd.seafdec.org.ph)