Notes on ovarian rematuration of ablated sugpo (prawn) Penaeus monodon Fabricius

Extended abstract of the paper delivered by Mrs. Jurgenne H. Primavera at the Symposium on Reproductive Physiology of Fish, Paimpont, France, Sept. 19-21, 1977.To what extent spent P. monodon females can remature and spawn successive broods is an important question in terms of recycling spawners in a commercially viable operation. Corollary to this is the quantity and quality of fry from rematured females in comparison to those from first spawning. Of 347 experimental females, only 10.1% had a second spawning, and 1.4% a third spawning. To a large degree the low rate of rematuration is due to high spawner mortality - average survival period after spawning was only 6 days in a sample of 176 spawners. It took an average of 23 days after ablation for a prawn with undeveloped ovaries to mature and spawn. An ablated female may have another spawning in as little as 5 days after the previous one. Average fecundity was 180,000 eggs per second spawning, and 140,000 eggs per third spawning. The average number of eggs from first spawning ablated females was 110-120,000. Hatching rate was lower for rematuration: 44% for second spawnings, and 35% for third spawnings, as compared to 64% for first maturation

Notes on the induced maturation and spawning in four-month-old Penaeus monodon Fabricius by eyestalk ablation

The ablation technique consisted of making an incision across the eyeball to allow free flow of fluids while holding the prawn under water, squeezing the eyeball contents outwards, and pinching hard the eyestalk tissue. The cut area heals completely in about a week; no application of antibiotics is necessary. Spent spawners were tagged with thin brass rings (Rodriguez, 1976) around the unablated eyestalk for a separate experiment on rematuration. Two spawning yielding approximately 277,000 eggs were obtained three weeks after ablation, followed four days later by two more spawnings with 160,000 eggs; all four spawners weighed more than 100 g. With a hatching rate of 98% and 78% for the first and second batch, respectively, the spawnings produced viable nauplii. Water temperatures as low as 23 degree C due to a delayed cold spell in March depressed molting; weakened larvae had to be discharged at the mysis stage. Although ovarian development continued, no further spawnings were obtained due mainly to the onset of bacterial and fungal disease. Infection is initiated in injured portions of the exoskeleton, sometimes penetrating right through the muscles to the ovarian tissues. The non-flowthrough conditions and mussel meat feeding led to fouling of the culture water resulting in consecutive mortalities caused by disease. Female P.monodon held in maturation pens were ablated at the age of 15 months (Santiago, et al., 1976); they averaged only 16 g body weight after four months growth in ponds. In another experiment, pond-reared P.monodon females ranging from 50 to 80 g were ablated at approximately seven months (Aquacop, 1977). The present results show a minimum age of four months from postlarve that P.monodon is capable of ovarian development and spawning upon ablation. However, maturation is probably affected by size as well as age - the four-month old females weighed an average of 100 g in contrast to the smaller animals in the earlier experiments

Viability of Penaeus monodon eggs after simulated transport conditions

P. monodon spawners, transported from maturation pens suffer from stress which in turn may lead to lowered spawning rate or fertility. Spawning the females in the maturation site and transporting the eggs to the hatchery site is being considered as an alternative. Egg transport costs may be reduced to a minimum by using eggs from ablated spawners, transported at high density with no aeration. Experiments on higher egg densities as well as on transport of nauplii should, however, be undertaken

Prawn hatchery operations

The manual, an updated version of the 1984 SEAFDEC/AQD manual, presents the underlying principles and step-by-step instructions of prawn larval and post-larval rearing. The techniques described are not only applicable to Penaeus monodon, but may also be modified and applied to other penaeid and metapenaeid species. The following aspects are covered: Site selection; Life cycle; Hatchery design and planning; Hatchery operations; Diseases; and Economics.1st Ed

Effect of substrate types on fecundity and nauplii production of ablated Penaeus monodon Fabricius.

Contribution No. 84 of the SEAFDEC Aquaculture Department.The survival, spawning, fecundity, and nauplii production of ablated Penaeus monodon females reared in flow-through broodstock tanks with white coralline and black sand substrates for 62 days, were assessed. Prawns exposed to the white coralline substrate consistently produced eggs with significantly higher (P - 0.05) average hatching rates and total nauplii production than those exposed to the black sand substrate. No differences were observed in the fecundity, spawning and survival rates in both treatments. It was observed that nightly sampling of ablated females during experiment 2 produced a higher number of spawning (48) and total number of nauplii produced (6.8 milion) compared to twice weekly sampling in experiment I (29 spawnings and 3.0 million nauplii) for the white substrate

A prototype warm water shrimp hatchery

Reprinted June 1989 as Aquaculture Extention manual; no. 12.A description is given of the prototype warm water shrimp hatchery established and operated by SEAFDEC Aquaculture Department since 1982. Hatchery design, operation and management, larval rearing in small indoor tanks, larval rearing in large nursery tanks, routine hatchery management, harvesting and transportation and financial aspects are covered