Fishery of the short-necked clam Paphia undulata 43 Fishery of the short-necked clam Paphia undulata in Southern Negros Occidental, Central Philippines Karen A. Villarta * and Annabelle G.C. del Norte-Campos Marine Biology Lab, College of Arts & Sciences University of the Philippines Visayas, Miagao, Iloilo *Corresponding author: karenvillarta@yahoo.com ABSTRACT INTRODUCTION Like many finfish and invertebrates, shellfish are known to be good sources of protein for most of the coastal communities in the country. They also contribute to the total fisheries production in the country. However, these resources, including bivalves, are harvested at an increasing rate in most of our coastal areas, an obvious result of the swelling population in coastal areas as well as the constant demand of fishery resources in both the local and export markets. Consequently, bivalve aquaculture experiments are being attempted in various places to offset the exhaustion of natural beds by overexploitation (FAO, 1998). It is known that some bivalve species are popular delicacies served not only locally but in neighboring countries as well. The short- necked clam Paphia undulata (Figure 1), locally This study documents the fishery of the short-necked clam Paphia undulata in coastal waters of southern Negros Occidental. Catch and effort estimates were determined based on daily records of compressor divers gathered between February-July 2008 in Himamaylan City and July 2008-May 2009 in the town of Hinigaran. Fishing and marketing practices in both areas were also documented and population biology information noted. Compared to earlier conditions, present fishing patterns show a worsened stage of overexploitation primarily characterized by collection of predominantly small and immature (mostly <45 mm shell lengths) sizes. Intensity/duration and location of fishing also varied due to both abundance and demand factors. The difference in sizes of clams and the varying fishing durations in each area suggest a non-uniform pattern of settlement resulting most likely from differential larval recruitment, the likely factors causing the local boom and bust fishery. The larger and long term extent of the effect of these factors can only be further investigated by parallel 2-3 year fishery-dependent and -independent surveys. Keywords: Paphia undulata, catch, catch rates, Central Philippines known as “nylon shell” in western Visayas is a commercially important invertebrate resource in the Philippines and is in fact one of the most sought after bivalve species in the region. It is usually sold live or chilled/frozen in the local markets while its meat is processed for the export trade. FAO (1988) reported that Paphia undulata constituted about 4.1% of the total world and Asian landings (excluding Japan) of the most important mollusk species in Asia for the year 1986 alone. However, there is a lack of parallel information for recent years thus the values can not updated. In Negros Occidental, particularly in the towns of Hinigaran and Himamaylan, P. undulata is harvested from mudflats through compressor diving. Agasen et al. (1998) did an assessment of the species in the same Science Diliman (January-June 2010) 22:1, 43-51