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

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

Results of the study indicate that the survival rate and increase in body weight did not differ significantly at different salinity levels or at different stocking density manipulation methods. A significant interaction between salinity and stocking density manipulation could not be demonstrated statistically. There apparently is no need to reduce the salinity of the water used in storing milkfish Chanos chanos fry in order to attain higher survival as commonly believed. Sufficient food and maintenance of good water quality are more important than salinity for higher survival of fry during storage

A guide to the establishment and maintenance of milkfish broodstock

The manual describes methods used at the SEAFDEC Aquaculture Department in order to establish milkfish broodstock. It is presented under the following major section headings: Establishing broodstock farms; Farms for rearing bangus juveniles; Maturation cages for rearing broodstock to maturity; Gathering data; Spawning and egg collection; and Larval rearing.This study as well as the publication of this guide was partly supported by the International Development Research Centre of Canada under Project No. 3-P78-0033 (Phase II) and No. 3-P81-0171 (Phase III)

Identification of pen shells (Bivalvia: Ostreida: Pinnidae) collected off northern Iloilo, Philippines using their morphological characters

This study describes morphological characteristics of pen shells collected along the coast of northern Iloilo, Philippines. A total of 380 pen shell individuals with intact shells and their adductor muscles were carefully examined and measured. Eleven species were studied, namely: Atrina pectinata (Linnaeus, 1767), Atrina inflata (Dillwyn, 1817), Atrina vexillum (Born, 1778), Atrina seminuda (Lamarck, 1819), Atrina rigida ([Lightfoot], 1786), Pinna bicolor Gmelin, 1791, Pinna atropurpurea Sowerby, 1825, Pinna deltodes Menke, 1843, Pinna muricata Linnaeus, 1758, Pinna incurva Gmelin, 1791, and Pinna nobilis Linnaeus, 1758. The species were identified based on the nine characteristics of the valve for the genus Pinna and eight for the genus Atrina. These characteristics were then correlated with their adductor muscles’ morphology. Analysis of variance revealed that the three most dominant species investigated under genus Atrina, namely Atrina pectinata, Atrina inflata, and Atrina vexillum, were found to be significantly different in the eight characters of the valve (P < 0.05). Moreover, three representative Pinna species, Pinna bicolor, Pinna atropurpurea, and Pinna deltodes, were significantly (P < 0.05) different based on shell width, dorsal posterior shell margin, sulcus width, and dorsal posterior margin to dorsal nacreous margin. The observed high correlation (P < 0.05) between adductor muscle properties and different shell length characteristics for five dominant species can be used as a predictor of growth and suggests that the increase in the size of adductor muscle correlates to the increase in the size of the mentioned shell characteristics. No previous study of this kind was conducted in the Philippines. This work provides relevant information for related biological research on other pen shell species and for the management of pen shell resources in northern Iloilo and, possibly, other regions in the world

The status of seed production of grouper and other coral reef fishes in the Philippines

Initial work on seed production of grouper in the Philippines was first reported in 1986. Most of the work has been undertaken by the SEAFDEC Aquaculture Department (SEAFDEC/AQD), which concentrated on Epinephelus coioides. The achievements and results of SEAFDEC/AQD on breeding and larval rearing of grouper which including studies on sex inversion will be discussed. Directions for future research directions are also presented

Milkfish culture in brackishwater ponds

The manual is intended as a guide for operation in milkfish farming. It is presented under the following major sections: 1) Handling of fry - counting, storage and transport; 2) Pond layout and construction - selection of farm site, layout, construction, plan and specification; 3) Pond operation, culture and management - nursery pond management and rearing pond operation; 4) Harvest and post-harvest - harvest, post harvest, and processing; and 5) Economics and costing - cost of construction, cost of operation, and production/yield

Sensitivity of grouper Epinephelus coioides eggs to handling stress at different stages of embryonic development

The sensitivity of grouper Epinephelus coioides eggs to handling stress at different stages of embryonic development was investigated. Naturally-spawned grouper eggs in floating net cages were collected and handled at the early cleavage, blastula, gastrula, neurula, and eyed stages. Egg viability, hatching rate and percentage of normal larvae were significantly higher (p<0.05) in eggs collected and stocked at the eyed stage than in all other stages. An increasing sensitivity to handling stress was observed in eggs from early cleavage to gastrula, as manifested by the decreasing percentage of viable eggs, hatched, and normal larvae. Sensitivity to handling stress decreased when development reached the neurula and eyed stages. Hatched larvae from eggs handled during the blastula and gastrula stages had high mortalities during the first 3-24 hours after stocking. The results of this study show that grouper E. coioides eggs are most sensitive to handling stress during the early cleavage to gastrula phases. The results imply that harvesting or collection of grouper eggs is best done after neurulation, when the embryo has already formed optic vesicles (eyed stage), to increase egg viability and the hatching rate. It will also minimize mortalities and the occurence of abnormal larvae

Occurrence of aberrant spermatids in the freshwater sculpin, Cottus nozawae Snyder

Light and electron microscopic investigation were conducted on the spermatogenic cell in the testis of the freshwater sculpin, Cottus nozawae. Light microscopic examination showed that two types of spermatids, normal and aberrant, qxisted in the seminal lobule during the regular testicular activity. Both spermaids were mononucleate but the aberrant spermatids ha mor basophilic nucleus than the normal. Aberrant spermatids enlarged and were than released into lumen of the seminal lobules. Ultrastucturally, highly electron-bense granules occurred in the nuclear chromatin of aberrant spermatids. These increased in size becoming the core of chromatin globules which then filled the enlargeed nucleus. The aberrant spermatids when released into the lobule lumen underwent further degeneration