Exploitation of the window-pane shell Placuna placenta in the Philippines
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Abstract
The 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.
Suggested Citation
Gallardo, W. G., Siar, S. V., & Encena II, V. (1995). Exploitation of the window-pane shell Placuna placenta in the Philippines. Biological Conservation , 73(1), 33-38. https://doi.org/10.1016/0006-3207(95)90057-8
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0006-3207Collections
- Journal Articles [1266]
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Madrones-Ladja, Jocelyn A.; Aldon, Eva T.; Baliao, Dan D. (College of Agriculture, University of the Philippines Los Baños, 2012)The Panay Gulf in central Philippines once supported a substantial ‘kapis’ Placuna placenta (Linnaeus) population that was among the six major sources for this species. However, stock depletion began in the late 1980s because of overexploitation and destructive fishing practices. To recover the declining ‘kapis’ fishery along the Gulf, a broodstock transplantation program was initiated in 1999. Results from a survey of the Gulf prior to this program confirmed reports of resource depletion. Four (4) transplantation sites (S) with natural soft-muddy substrata in adjacent coastal towns, namely, Tigbauan (S1 and S2), Guimbal (S3) and Oton (S4) were established and stocked with 3200 (1:1 male to female ratio) sexually mature ‘kapis’ broodstock collected from nearby Negros Island in March–October 1999. Transplant survival along the sites ranged 80–100%. Spontaneous spawning by ‘kapis’ transplants occurred from March 1999 (15 d after first stocking) through May 2000. Larvae (5 larvae per L) began to appear at S1 15 d after transplantation and progressively increased in density to 23 larvae per L in November 1999. During this period, local divers reported big patches of ‘kapis’ juveniles [shell length (SL), 38 ± 11 mm] at S4. Sex ratio of recruits was 3:2 (male: female). Larvae became abundant off the nearby coasts with a strong recruitment pulse at 160 larvae per L at S4 by January 2000. Likewise, transplants taken to the laboratory were induced to spawn by photochemical method, and thus validated the spawning that occurred in transplantation sites. Juvenile recruits were of variable sizes, indicating that spawning was not simultaneous. Sexually mature juvenile recruits (40% female, 90% male) were already observed in January–February 2000. The recruitment apparently resulting from these transplants was local, dispersion ranging from zero to a few kilometers distance from transplantation sites. ‘Kapis’ harvest began in 2007 for local market consumption while commercial harvest was done in 2010 with approximately 600 tons. The repopulation of ‘kapis’ along Panay Gulf after a decade indicated the success of the restocking program which was attributed to the suitability of the species, reproduction of transplants and the proper management of the newly established resource by the coastal fishers who are members of a local organization (FARMC) with the support of local government units (LGUs). -
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