The mechanics of mass occurrence and recruitment strategy of milkfish Chanos chanos (Forsskal) fry in the Philippines
MetadataShow full item record
The daily and hourly catch of milkfish Chanos chanos (Forsskal) fry in the coast of Hamtic, Panay Island in the Philippines was recorded over a period of 16 weeks, and correlated with time, location, types of gear, and lunar and tidal variations. About 4000 fry were marked and released, scanning electronmicroscopy was employed to examine the feeding habit of the fish. The results obtained suggest an active process governing the occurrence and movement of fry in coastal waters. The appearance of the fry is related to the developmental stage of the fry and is subject to lunar modulation. Interaction with predators in coastal waters has produced diverse and selective antipredator adaptations, such as body transparency, the use of timing (seasonality, tidal conditions), and distribution patterns. The maximization of resource utilization and minimization of resource sharing also occurs in a seasonal basis. High mortality rate in shallow coastal waters is counteracted by high recruitment rate and specific behavioural and physiological adaptations to ensure successful and fast colonization of backwaters. It is suggested that higher food availability in the nursery ground exerts a stronger selective pressure over predation, and act as the major force in the migration from offshore to shore waters.
Contribution No. 107 of the Aquaculture Department, SEAFDEC.
CitationBuri, P., & Kawamura, G. (1983). The mechanics of mass occurrence and recruitment strategy of milkfish Chanos chanos (Forsskal) fry in the Philippines.
PublisherKagoshima University Research Center for the South Pacific
Showing items related by title, author, creator and subject.
Conference paperLV Benitez - In RD Fortes, LC Darvin & DL de Guzman (Eds.), Fish and crustacean feeds and nutrition : Proceedings of the seminar-workshop on fish and crustacean feeds and nutrition held on 25-26 February 1985 at UPV, Iloilo City, 1989 - Philippine Council for Aquatic and Marine Research and DevelopmentThis paper reviews recent work on milkfish nutrition. Substantial progress had been made towards understanding the digestive physiology of milkfish. Major enzaymes envolved in the digestions of carbohydrates, protein and lipids had been detected in the pyloric caece, intestines and pancreas of milkfish. The most active carbohydrates were involved in the hydrolysis of α - glocosidic bonds. Intestinal amylase activity consistently reached the peak at about noon when milkfish gut was full. This confirms that milkfish is s daytime feeder. No cellulase activity was detected in any region orf the digertive treat although the fish relies heavily algae and other plant source for food. Trypsin, chymotrypsin and general proteases were also detected in milkfish digestive tract. A powerful milkfish trypsin inhabitor was detected in the filementous algae, Chaetomorpha brachygona which is predominant species in lumot. Lipass in the pancreas and intestines had two pH optima, suggesting a physiologic versatility for lipid digestion in milkfish. There is a limit information on the nutrient requirement of milkfish. Most studies showed that milkfish fry has a dietary requirement of 40% protein, and 7-10 lipid. Studies on the protein-energy requirement of fingerlings suggested that 30-40% protein, 10% fat and 25% carbohydrates are required. Subsequent studies showed an optimum protein energy to total metabolizable energy ratio of 44.4%. Amino acid test diets for milkfish had been formulated to contain white fish meal, gelatin and approprate amino acid mix.
Lactate dehydrogenase isozyme patterns during the development of milkfish, (Chanos chanos (Forskal)) PD Requintina, LM Engle & LV Benitez -
Kalikasan, The Philippine Journal of Biology, 1981 - University of the Philippines at Los BañosPolyacrylamide disc gel electrophoresis was done to determine the lactate dehydrogenase (LDH) isozyme patterns for fry (5-3 mg), fingerling (6-12 g), pond-size (150-250 g) and adult (6-9 kg) milkfish. The patterns were tissue specific; the different tissues examined, viz., eye, liver, heart, and skeletal muscle had different expressions of LDH isozymes. The resolved patterns appeared to be products of LDH gene loci A, B, and C. Subunits A and B were present in all tissues. A4 and B4 were predominant in skeletal and heart muscle, respectively; the two associated non-randomly in vivo and formed only the heteropolymers A3B and AB3. A liver band, L4, was most conspicuous in the fingerling, pond-size, and adult; it was assumed to be coded by locus C. A negatively charged band, X4, was detected in fully developed ovary and in fry homogenized as whole individuals, but it could not be resolved in tissues of fingerling. Six-mo old stunts and 3-mo old fingerlings had similar LDH patterns for all tissues examined. The patterns for 11-mo old stunts and fingerlings also were similar but the one for the eye of the former was the same pattern resolved for the eye of adults. There was no change in the LDH isozyme patterns of milk fish stunted for 6 mo under different salinity levels (0-5, 15-20, 32-35 ppt).
Conference paperEO Tan, DL de Guzman, LC Darvin & MC Balgos - In JV Juario, RP Ferraris & LV Benitez (Eds.), Advances in milkfish biology and culture: Proceedings of the Second International Milkfish Aquaculture Conference, 4-8 October 1983, Iloilo City, Philippines, 1984 - Published by Island Pub. House in association with the Aquaculture Dept., Southeast Asian Fisheries Development Center and the International Development Research CentreDevelopment and directions in milkfish (Chanos chanos ) research in the Philippines from 1976 to the present are reviewed and analyzed. The problems of milkfish culture are dichotomous: low productivity vis-a-vis seasons of glut and price fluctuations. To intensify fish production extensive research has been conducted on fertilizer management, reclamation of acid sulfate soils, and pond construction and engineering. Research efforts have also been heavily directed toward increasing fry production through artificial propagation, improvement of fry collecting gear, and increasing fry survival through nutrition, control of parasites, and proper handling. Research on improved icing, packaging, and processing techniques along with market analysis are necessary for maximizing economic returns.