Browsing by Author "Posadas, Ruth A."
Mass production in concrete tanks of sugpo Penaeus monodon Fabricius spawners by eyestalk ablation JH Primavera, E Borlongan & RA Posadas -
Fisheries Research Journal of the Philippines, 1978 - Fisheries Research Society of the PhilippinesTwo batches of 196 and 181 P. monodon females were ablated on one eyestalk in March and July 1977, respectively, and a control batch of 180 unablated females was stocked in July 1977. The females were stocked with males in 120-ton concrete tanks with partial flowthrough of water and fed salted mussel (Modiolus metcalfei ) at 15% body weight daily. Total number of spawnings was 82 for the March-ablated group, 3 for the July-ablated group and 4 for the July unablated group. Maturation and mortality in relation to the moult cycle and tank plus water conditions are discussed.
ArticleEggs of Penaeus monodon are classified into five different types on the basis of morphological criteria and hatching rates — A1 eggs undergo normal development with 58% hatching rate; A2 eggs show delayed and/or abnormal development with 32% hatching rate; and B, C and D eggs are unfertilized and do not hatch. Wild (unablated) females have the highest proportion of A1 eggs and highest hatching rate, followed by ablated wild stock; ablated pond stock show the lowest proportion of A1 eggs and the lowest hatching rate. There is a highly linear relationship between the percentage of A1 eggs and the hatching rate in spawnings from ablated females of both pond and wild stock. Discussion concentrates on the development of these egg types, comparison with other studies and the importance to hatchery operations of these findings.
ArticleJH Primavera, E Borlongan & RA Posadas -
SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development CenterP. 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.