A comparison between the catching efficiency of two milkfish fry collecting gears and their respective modifications

An experiment was conducted along the shore of Culasi, Antique in Panay to compare the milkfry (Chanos chanos) catching efficiency of the ordinary fry seine against its innovation and the ordinary sweeper against its 2 modifications. Results show that it is possible to replace the wings of the presently used sweeper and the ends of the fry seine with a coarse-meshed netting. This improvement decreases the water resistance of the gears and thus enables fry gatherers to use larger ones thereby giving more catch

Experiments on the induced spawning and larval rearing of the milkfish, Chanos chanos (Forsskal) in 1979

This paper summarizes the results of the experiments on the induced breeding and larval rearing of milkfish during the 1979 season

Review of SEAFDEC/AQD finfish seed production research

Research on seed production of several foodfishes has been a continuing activity of SEAFDEC/AQD since 1976. Fry and juvenile production methods of these fish commodities are in various stages of advancement. For instance, advances in the development of hatchery rearing, particularly feeding and water management schemes, have made mass production of milkfish (Chanos chanos) seed a reality, resulting further in the application of the technology in commercial hatcheries. Recent studies now focus on assessing the quality of hatchery seed stocks of milkfish vis-a-vis wild seed during nursery and grow-out culture. Likewise, sea bass (Lates calcarifer) seed production has undergone significant improvements since the technology was introduced in the Philippines in 1982. Fatty acid-enrichment of a zooplankton diet can enhance growth and survival of sea bass fry, although other cheaper alternatives and early weaning to formulated diet preparations are currently being tested. Hatchery fry production of grouper (Epinephelus salmoides and E. suillus syn. E. coioides) and snapper is in its infancy, but trials complemented by research on their larval feeding habits and requirements are underway to establish reliable methods of rearing larvae of these species. Although fairly well-established, seed production of rabbitfish (Siganus guttatus) requires further improvement in determining an appropriate zooplankton diet to ensure adequate growth and survival of larvae. Hatchery fry production of tilapia (Oreochromis sp.), carps (Aristichthys nobilis, Hypothalmichthys molitrix) and, to a certain extent, catfish (Clarias macrocephalus) can already be categorized as a flourishing industry in some parts of the Philippines. Nonetheless, SEAFDEC/AQD continues to conduct research on these freshwater species, with particular emphasis on nutrition and feed development during the nursery production phase. Together, results of past and on-going research studies ensure that seed supply of these important foodfishes become adequate and sustainable for the grow-out

Effects of different fat sources on the egg quality of grouper, Epinephelus suillus

Abstract only.The effect of different fat sources on the egg quality of grouper, Epinephelus suillus eggs was evaluated. Fish in three tanks, each containing 3 females and 1 male, were fed various types of feeds namely: trash fish (control), trash fish + cod liver oil (treatment 1) and trash fish + SELCO, a lipid emulsion containing high levels of highly unsaturated fatty acid (HUFA) (treatment 2). Approximately 77.9 million eggs spawned from January to October 1992 by the control group, 40.0 million by fish in treatment 1, and 36.4 million by the treatment 2 group. Egg production (0.45 million eggs/kg BW) among the control group was significantly higher than treatment 2. Egg production of treatment 1 (0.06-0.36 million eggs/kg BW) was not significantly different (P treatment 1 > treatment 2. There were no differences detected in the egg and oil globule diameters among the treatments. Crude protein and lipid levels of floating (good) and sinking (bad) eggs collected in February to March 1992, and August to September 1992 were similar in all treatments. Unfed larvae from treatment 1 survived until the fifth day after hatching while those in the control and treatment 2 groups lasted only until the third day. These results suggest that supplementation of cod liver oil and SELCO in the trash fish diet of E. suillus broodstock does not influence egg production, fertilization and hatching rates, and egg quality

Effect of various salinity levels and stocking density manipulation methods on the survival of milkfish fry (Chanos chanos Forsskal) during storage

ThesisThesis, 1980Thesis (M.Sc.), University of the Philippines, 198

Changes in Na+, K+-ATPase activity and gill chloride cell morphology in the grouper Epinephelus coioides larvae and juveniles in response to salinity and temperature

The activity of the enzyme Na+, K+-ATPase and morphological changes of gill chloride cells in grouper, Epinephelus coioides larvae and juveniles were determined 6–48 h after abrupt transfer from ambient rearing conditions (30–32 ppt, 26.5–30°C) to different salinity (8, 18, 32, 40 ppt) and temperature (25, 30°C) combinations. Na+, K+-ATPase activity in day 20 larvae did not change at salinities 8–32 ppt. Activity decreased significantly (P <0.01) after exposure to 40 ppt at 25–30°C, which was accompanied by an increase (P < 0.05) in density and fractional area of chloride cells. Enzyme activity in 40 ppt did not reach a stable level and larvae failed to recover from an osmotic imbalance that produced a low survival at 25°C and death of all larvae at 30°C. Enzyme activity and chloride cell morphology in day 40 groupers did not change in 8–40 ppt at 25°C and 8–32 ppt at 30°C. A significant decrease and a subsequent increase in Na+, K+-ATPase activity in 40 ppt at 30°C was associated with the increase in chloride cell density resulting in an increased fractional area but a decreased cell size. Enzyme activity and chloride cells of day 60 grouper were unaffected by abrupt transfer to test salinities and temperatures. These results demonstrate that grouper larvae and juveniles are efficient osmoregulators over a wide range of salinities. Salinity adaptation showed an ontogenetic shift as the larvae grew and reached the juvenile stage. This development of tolerance limits may reflect their response to actual conditions existing in the natural environment