Now showing items 1-7 of 7

    • Article

      Growth of juvenile milkfish Chanos chanos in a natural habitat 

      S Kumagai, TU Bagarinao & A Unggui - Marine Ecology Progress Series, 1985 - Inter Research
      A population of juvenile milkfish, C. chanos (Forsskaal) was studied in a small mangrove lagoon in Naburut Island, central Philippines. Several size groups of milkfish occurred in the lagoon as a result of its periodic connection with the sea. Body-weight to fork-length relation was: log W = - 5.2991 + 3.2388 log L, similar to that of pond-cultured specimens. In Naburut lagoon, juvenile milkfish take in primarily blue-green algae, as well as mangrove and seagrass debris, diatoms and detritus. The condition factor of fish caught during the day from May to Nov. stayed constant, indicating that lagoon conditions for growth in terms of food did not change markedly during the year. The monthly size-frequency distribution shows that juvenile milkfish in the lagoon grew at a rate of 7 to 9 mm wk super(-1) in 1979. Compared with pond-cultured specimens, their growth rate was lower during the first month but higher during the second month in the nursery. The limited area and depth of Naburut lagoon probably set the limit to the size of juvenile milkfish; these can be sustained there to just 150 to 180 mm fork length.
    • Article

      Occurrence and distribution of milkfish larvae, Chanos chanos off the western coast of Panay Island, Philippines 

      T Bagarinao & S Kumagai - Environmental Biology of Fishes, 1987 - Springer Verlag
      The occurence and distribution of milkfish larvae (∼3–17 mm TL) off western Panay Island, Philippines are reported based on 594 plankton net tows made in April and May 1980. Forty-two tows yielded 44 larvae, together with 1149 milkfish eggs by 98 tows. About 70% of the larvae of all stages came from stations less than 100 m deep and 1–2 km from land. Younger larvae up to 6 mm and about 1 week old occurred at stations of various distances from shore, while older larvae occurred only near shore. About 48% of larvae of all stages were caught by surface tows; younger larvae occurred also in deeper layers (20 and 30 m). Larval abundance increased towards May. Younger larvae tended to occur during the quarter moon periods and older ones during the full and new moon periods.
    • Conference paper

      The occurrence of milkfish Chanos chanos fry in Pandan Bay, Antique, from 21 May to 25 June, 1975 

      S Kumagai, AC Villaluz, LB Tiro Jr. & WE Vanstone - In Proceedings of the International Milkfish Workshop Conference, May 19-22, 1976, Tigbauan, Iloilo, Philippines, 1976 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Milkfish fry were collected at the Pandan shoreline and 500 meters offshore. While shore-caught fry were uniform in size those captured offshore varied in size and stage of development.
    • Article

      Occurrence of milkfish, Chanos chanos (Forsskal) eggs around Panay Island, Philippines 

      T Senta, S Kumagai & NM Castillo - Bulletin of the Faculty of Fisheries, Nagasaki University, 1980 - The Faculty of Fisheries, Nagasaki University
      A total of 551 milkfish eggs was collected by horizontal tows with a fish larval net in the waters around Panay island during the period from April 1976 to June 1979. The maximum number obtained by a single tow was 33 eggs. Most of the eggs were collected from Cuyo East Pass, with some from the waters around the Cagayan Islands and a single egg from the Sibuyan Sea. Almost all the eggs were collected during the period frim March to June, with a peak in April, one month ahead of the peak of fry occurrence.

      Very often milkfish eggs occurred in shallow waters around islands or close to the coasts, while they were sometimes found at locations remote from land and as deep as 900 m. Water temperatures and salinities at locations shere milkfish eggs were found ranged from 26.7 to 30.8°C and from 32.9 to 34.5 ppt. The eggs were rather evenly distributed from the surface to at least 20 m down. The eggs found in the early morning collections were in the early stages of development; those found later in the day were more advanced. It seems that spawning of mikfish takes place at midnight, and that the incubation period of eggs in the wild is about 20 hours.
    • Conference paper

      Preliminary observation on the number of vertebra in milkfish, Chanos chanos (Forskal) 

      T Senta & S Kumagai - In Proceedings of the International Milkfish Workshop Conference, May 19-22, 1976, Tigbauan, Iloilo, Philippines, 1976 - Aquaculture Department, Southeast Asian Fisheries Development Center
      The existence of races and/or subpopulation in milkfish, a widely distributed species, is suggested by many workers. Comparison of mean numbers of vertebrae is one of the useful method of distinguishing subpopulations. The present paper reports the results of preliminary studies made on the vertebral counts of milkfish fry collected from several areas. The results obtained, though not conclusive, suggest the scope for further study in the line.
    • Article

      Results of drift card experiments and considerations on the movement of milkfish eggs and larvae in the northern Sulu Sea 

      S Kumagai & TU Bagarinao - Fisheries Research Journal of the Philippines, 1979 - Fisheries Research Society of the Philippines
      For a period of one year beginning December 1977, drift card experiments were conducted off the western and southwestern coasts of Panay Island to determine the surface currents in the area.

      Of a total 2,384 drift cards released during the study, 382 (16.02%) were recovered, 92% of them within 30 days following dispatch. The surface currents in the study area are strongly influenced, in direction and speed, by the prevailing monsoon winds. During the NE monsoon period, the surface currents move away from the coast; during the SW monsoon, toward and/or parallel to the coast. Based on the results, the probable movement and transport of milkfish eggs and larvae from the spawning ground to the fry collection ground are also discussed.
    • Article

      Studies on the habitat and food of juvenile milkfish in the wild 

      S Kumagai & TU Bagarinao - Fisheries Research Journal of the Philippines, 1981 - Fisheries Research Society of the Philippines
      Juvenile milkfish (Chanos chanos ) were collected from several different wild environments in Panay Island and neighboring islands. The fish were measured and the food ingested examined. Conditions of milkfish habitats were also described. It was found that the fish can live and grow in almost any kind of coastal wetlands of calm and rich sediments, such as coralline lagoon, mangrove lagoon, estuary, and bay. In the waters where plant materials were rich at the bottom, the fish fed on them and their intestines were significantly long, while in other waters where less plant materials were available at the bottom, the fish fed but with considerable amount of animal elements and possessed shorter intestines. These differences are considered as adaptations of the fish to different habitats.