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Journal Articles - UP - MSI

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1988 - 198921990 - 19971

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    Growth, mortality and recruitment pattern of the brown mussel, Modiolus metcalfei (Bivalvia: Mytilacea), in Panguil Bay, Southern Philippines
    Tumanda, Marcelino I.; Yap, Helen T.; McManus, Liana T.; Ingles, Jose A.; López, Mai G. (Elsevier BV, 1997-08)
    A stock assessment study of Modiolus metcalfei in Panguil Bay, Southern Philippines, was conducted to determine growth parameters of the species and the status of the fishery given the current harvesting efforts of this resource in the bay. Growth parameter estimates yielded mean K and Lα values of 2.04 year−1 and 62.50 mm, respectively. The recruitment pattern appeared to be unimodal, with the peak occurring during the months of May–July. Spat settlement ratios for May and July were 1.6 and 2.0 spat per live adult mussel, respectively. Settling spat showed preference to attach onto the shells and exposed byssal threads of live adult mussels. Catch curve analysis showed total mortality (Z) value of 7.64 year−1; fishing mortality (F) was 5.60 year−1. Exploitation rate was 73% of total mortality, and was attributed to intensive mussel gathering by local fishermen. Fishing mortality shows an over-exploited stock that necessitates some management intervention to maintain the sustainability of the fishery resource.
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    Fishing mortality rates of giant clams (Family Tridacnidae) from the Sulu Archipelago and Southern Palawan, Philippines
    Villanoy, Cesar L.; Juinio, Antoinette R.; Meñez, Lambert Anthony (Springer, 1988-05)
    Average size frequency distributions of Tridacna squamosa, T. gigas, Hippopus hippopus and H. porcellanus harvested from the Sulu Archipelago and Southern Palawan areas from 1978–1985 were derived from export records and a warehouse inventory of giant clam shells. Average species mortality rates (Z) were estimated and were used to approximate average fishing mortality rates (F) over the period 1978–1985. Crude estimates of exploitation rates (F/Z) indicate that populations of these species are already overexploited. These findings have serious implications in view of the fact that the Sulu Archipelago and Southern Palawan are thought to be the last strongholds of giant clams in Philippine waters.
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    Aspects of the growth, recruitment, mortality and reproduction of the scallop Amusium pleuronectes (Linné) in the Lingayen Gulf, Philippines
    Del Norte, A. G. C. (Informa UK Limited, 1988-11)
    Growth, recruitment, mortality and reproduction were investigated in the Asian moon scallop, Amusium pleuronectes (Linne) from the Lingayen Gulf, Philippines. Allometric relationships were defined by comparing different shell dimensions, as well as body weight proportions including total weight with shell, visceral weight, adductor muscle weight and gonad weight. Use of the von Bertalanffy-based ELEFAN I program yielded estimates of growth parameters equivalent to H ∞ = 106Dimshell height and K = 0.92 per year, with approximate longevity for the species of about 2 years. Recruitment, as derived using the ELEFAN II program, occurred throughout the year, but showed a pattern consisting of one major and one minor pulse separated by an 8- and 4-months interval. Fishing mortality (F = 5.3) was higher than natural mortality (M = 1.9). Spawning occurred throughout the year, with one major peak in February and one minor peak between July and September, thereby providing some biological basis to the recruitment pattern indicated. Protandry and size at sexual maturity (54 mm) in the species were confirmed.