Browsing by Author "Gallardo, Wenresti G."
ArticleThe window-pane shell Placuna placenta or 'kapis' has great economic importance in the Philippines. The translucent shell is used in the manufacture of lampshades and other shellcraft items exported to Europe, USA and Japan. Due to its high demand, excessive and uncontrolled gathering of kapis has been noted over the past years. Its possible depletion has been a concern; thus, a nationwide survey on the status of the fishery was conducted in 1993. There are 27 kapis beds in the Philippines, six of which are considered the major sources of kapis shells. Kapis shells are gathered by (1) handpicking (in shallow areas); (2) compressor diving (in deeper areas); and (3) dredging. Because of open access to the fishery, anybody can exploit the resource. Kapis stocks are declining in most beds, while in others they are already low as a result of excessive gathering, pollution, siltation, and destructive methods of fishing such as trawling. To prevent further depletion, establishment of sanctuaries, bans on trawling and other destructive means of fishing, strict enforcement of existing regulations, community-based fishery management, and further research on seed production, restocking, and transplantation are recommended.
ArticleWG Gallardo, VC Encena II & NC Bayona -
Community Development Journal, 1995 - Oxford University PressRapid Rural Appraisal (RRA) was conducted in the fishing village of Lakaran, in the municipality of Dumangas, Iloilo province to identify the resources, livelihood, problems, opportunities, and socioeconomic condition of the villagers prior to the conduct of farmer participatory research on mussel farming. RRA tools such as the construction of the village transect, seasonal calendar and wealth ranking were used.
Restocking of windowpane shell, Placuna placenta in a depleted bed off Tigbauan, Iloilo, the Philippines JA Madrones-Ladja & WG Gallardo - In J Hylleberg (Ed.), Proceedings of the 10th International Congress and Workshop of the Tropical Marine Mollusc Programme (TMMP), 20-30 October 1999, 2000 - Phuket Marine Biological CenterThe Tigbauan coast, Iloilo, the Philippines, has been depleted of the natural population of the windowpane shell, Placuna placenta Linnaeus, 1758, since the early 1980's. To support the declining P. placenta industry of the Philippines, restocking of depleted natural beds has to be done. This work aimed at assessing the suitability of the area for restocking of this valuable bivalve species. Immature P. placenta broodstock (71.6 ± 6.2 mm) and juveniles (40 ± 10mm) were stocked in a 40 m2 muddy bottom area off Tigbauan. Growth , survival, and reproduction of the animals were monitored monthly for 3 months. All juveniles were found dead after a month covered with sand and silt. However, broodstock remained alive. Broodstock samples, taken after a month, spawned after exposure to UV-light irradiated sea water. Survival rate, shell length and body weight increment of the broodstock after 91 days were 51%, 15.0 mm and 12.6 g, respectively. P. placenta veligers were found in the plankton one month after spawning and until the end of the three-month rearing period. Net productivity of the area ranged from 0.03-0.32 ml O2/l. Phytoplankton species and macrobenthic organisms, such as Ophelina acuminata Oersted, 1843, Halophila johnstoniae Busk, 1852 and sipunculans, associated with P. placenta in the natural habitat were also collected in the area. Restocking of the depleted bed is still feasible by using adult animals to naturally repopulate the area.
ArticleWG Gallardo, MTR de Castro & RT Buensuceso -
Veliger, 1992 - California Malacozoological Society, Inc.The window pane oyster, Placuna placenta (Linnaeus, 1758), is a highly valuable bivalve species inhabiting the muddy bottom of coastal bays from the Arabian Sea on the west through the Indian Ocean and Malayan Seas to the coast of China on the east (Hornell, 1909). In the Philippines, P. placenta is extensively collected from the wild because of the high demand for its translucent shell, which is fashioned into various articles exported to the United States and Europe. As a result of overharvesting, P. placenta population in some natural beds are already depleted. Therefore, there is a need to conserve this resource through aquaculture. Hatchery techniques should be developed to produce seeds for reseeding and farming purposes. At the Aquaculture Department of the Southeast Asian Fisheries Development Center (SEAFDEC/AQD), Placuna placenta has been induced to spawn by water flow manipulation (Young, 1980). Other methods such as the addition of gametes, temperature shock, and salinity shock are presently being tried. With these induced spawning methods, there is a need to have a high degree of certainly as to the sex of the animal being used. Further, it is important that the method of sexing does not involve sacrificing the animal. However, it has been reported that sexes in P. placenta can be determined only by gonad histology. Rosell (1979) stated that male and the female P. placenta, which are dioecious, are distinguishable upon histological examination of the gonads, but they are without apparent sexual dimorphism. Macsuci et al. (1980) reported that the sex of P. placenta cannot be differentiated except by microscopic examination. Nevertheless, if gonad color, as seen through the translucent shell, could be proven to be a highly reliable basis for sexing, then this method would be useful in broodstock selection. Therefore, this study was conducted to investigate the use of gonad color for sexing P. placenta broodstock.