Philippine Journal of Science 150 (3): 1051-1060, June 2021 ISSN 0031 - 7683 Date Received: 21 Dec 2020
Population Dynamics of the Comb Pen Shell Atrina pectinata (Linnaeus, 1767) (Mollusca, Bivalvia: Pinnidae) Collected by Diving from Shallow Areas of the Southwest Visayan Sea, Northeastern Panay Island, Philippines
Annabelle del Norte-Campos*, Switzel S. Lapara, and Kris Angeli S. Sanchez
Marine Biology Lab, Division of Biological Sciences College of Arts and Sciences, University of Philippines Visayas Miagao, Iloilo, Philippines
With the objective of determining the population dynamics of the comb pen shell (Atrina pectinata) (Mollusca, Bivalvia: Pinnidae) collected by divers in the southwest Visayan Sea, length-frequency data recorded between June 2018 and May 2019 were analyzed using the FiSAT software. von Bertalanffy growth parameters for the species were SL = 40.69 cm and K = 0.78 yr–1 the range of values for other fast-growing tropical bivalves. The estimated mean growth rate of 0.15 ± 0.05 cm d–1 likewise supports a fast growth rate and a short lifespan (< 1 yr) of the population. The recruitment pattern shows one major and minor pulse that coincides with the northeast monsoon and just prior to the southwest monsoon, respectively. Using ELEFAN II, total mortality (Z) of 2.79 yr–1 was estimated. From an averaged M/K value from the related bivalve literature (1.51) multiplied by the species’ own K, natural mortality (M) of 1.18 yr–1 was estimated, which when subtracted from the Z, gave fishing mortality (F) of 1.61 yr-1 and an exploitation rate E of 0.58, considered overexploited. Recommended management measures for more sustainable utilization of the species include non-collection of individuals smaller than the cited minimum size at sexual maturity [20 cm shell length (SL)], and a ban on the collection at least during the major spawning season deemed to be, based on the growth rate between October and December each year. Marketing of the non-adductor portion of the viscera, normally just discarded, is also recommended to increase the income of the fishers.
Keywords: Atrina pectinata, exploitation, growth, mortality, population dynamics, recruitment
INTRODUCTION – as reported by Yang et al. (2015) in Ulleungdo Island, Korea having lifespans of up to 7.5 yr. A characteristic of The comb pen shell Atrina pectinata (Figure 1), locally Family Pinnidae (pen shells) is that they are found partly known as tarab, is widely-distributed in the Indo-west embedded in heterogeneous soft bottoms, with the narrow Pacific. It ranges from the region’s tropical to subtropical anterior tip of their shell directed downwards. The outer areas (Poutiers 1998). It is tolerant to a wide range of surface color of the valves of A. pectinata is a translucent temperature (1–39 ºC) with those living in colder latitudes olivaceous tan, often tinged with darker purplish-brown or gray towards the umbones (Poutiers 1998). A. pectinata *Corresponding Author: [email protected] has 15–30 radial ribs, while the internal nacreous layer is
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Figure 1. The comb pen shell Atrina pectinata (Linnaeus, 1767) here shown with a measuring tape oriented along the anterior-posterior (SL) axis used in this study. undivided and the posterior adductor scar is completely In the study of Diocton and Adalla (2019); however, a enclosed within the nacreous area. The species can easily very small number (N = 397) of size-biased individuals be distinguished from the related co-occurring species, for the one-year study was analyzed. Aside from the poor the bicolor pen shell Pinna bicolor, which has a median representation of the natural population in their study, the radial groove that is absent in Atrina. estimation of natural mortality M was also incorrectly based on Pauly’s empirical formula, which was derived A. pectinata was ranked number one in an inventory only from fish stocks (Pauly 1980). A more correct method on commercially-important mollusk species conducted would have been to take M and K values from related in Panay Island, Philippines (del Norte-Campos et al. bivalve literature, and the mean M/K of these bivalves 2019). This inventory used a set of criteria that includes multiplied by the K of the species in question to get M, a commercial value, catch rates, sources of threats, simple arithmetic procedure (Pauly, pers.com.). frequency in markets and source sites, and literature available. It is the only mollusk species in Panay whose To ensure the long-term sustainability of the species, there adductor muscles are sold in a nearby processing plant in is a need to understand its population dynamics to assess San Dionisio, Iloilo for export to Taiwan and, therefore, exploitation that is necessary in formulating science- it rated highest in terms of commercial importance the based management guidelines. Thus, this paper aims to criterion given the highest weight in the inventory. study the population dynamics of A. pectinata from San Dionisio, Iloilo. Specifically, it aims to determine growth In Panay, Western Visayas, Philippines, A. pectinata is and mortality parameters, the recruitment pattern, and the being collected by an unregulated small diving fishery exploitation rate. – rather wasteful in that only the adductor muscles are marketed and the rest of the viscera are discarded. An annual catch of 22.1 MT yr-1 was estimated, making it the number one species (86.3%) of the four exploited MATERIALS AND METHODS species (including Placuna ephippium, Anadara globosa, and Laevistromus turturella) in the diving fishery of the Study Area and Sample Collection kg–1, this annual catch has a corresponding value of PHP The study area is located in the southwest Visayan Sea, 4.4 M yr-1. At present, 25 divers operate in the area; thus, western Visayas, Philippines (Figure 2), where a diving the annual value of the catch corresponds to an income fishery exists and catches are landed in San Dionisio, of about PHP 176T diver-1 yr-1. Most of the works on Iloilo. Diving is conducted in shallow subtidal areas, the species either cover genetics (Dong et al. 2014) and approximately 3–7 m deep with the bottom substrate reproductive biology (Yang et al. 2016). The only work ranging from coarse to fine sediment. The catches of published on its population biology in the tropics is that of a fixed number of divers (six) based in San Dionisio, Diocton and Adalla (2019) in Maqueda Bay, Philippines. Iloilo (Figure 2) were sampled every week from June
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Figure 2. Location of the study area in San Dionisio, Iloilo, Western Visayas, Philippines where pen shells were collected and measured from June 2018 to May 2019 from catches of divers operating in its coastal waters forming the southwest Visayan Sea.
2018 to May 2019, with consideration to include the The value of b was different from 3 (i.e. allometric growth) entire size spectrum. These samples were the ones if the t statistic was greater than the tabulated t value for included in the length-frequency analysis. Given the n – 2 df (Pauly 1984). bulk of the specimens, a separate random but equally sized-representative sample was taken to the lab for the Monthly measurements of SLs (L) of individuals were determination of the species’ length-weight relationship. grouped into 2.5-cm size classes and analyzed using the For this, the SLs of a total of 110 individuals were Bhattacharya (1967) method, which is useful for splitting measured to the nearest 0.1 cm using a measuring tape a composite distribution into separate normal distributions (Figure 1) and total weights (TW) to the nearest 0.01 g when several age groups (cohorts) are contained in the were taken with the use of an electronic balance. same sample. The Bhattacharya routine is incorporated in the FiSAT software (Gayanilo et al. 2005). To compute growth rates (cm day–1) by cohort, increments between Data Analysis modal lengths (mm) derived using the Bhattacharya The length-weight relationship of the species was method were divided with their respective time increments computed using Equation 1: (d). Time intervals between months were uniformly pegged at 30 d inasmuch as measurements during the (1) month were regularly made once weekly. Mean growth rates for each derived cohort were averaged to estimate where TW is measured in g, L is the SL (cm), a is the the annual mean growth rate (cm day–1) for all cohorts. intercept, and b is the slope. The von Bertalanffy growth function (VBGF) parameters To test if the computed b value was significantly different SL (cm) and K (yr–1) were estimated with a fixed starting from 3 (i.e. allometric growth), the value of the t statistic point (Sample 1, L = 22.5 mm) using ELEFAN I. To was computed (Pauly 1984): assess these growth parameters in relation to other bivalve species, the growth performance index (ø’) was computed (2) using the equation (Pauly and Munro 1984): (3) where sd(x) is the standard deviation of the log L (SL) values, sd is the standard deviation of the log W (TW) (y) where K is the growth constant (yr–1) and L is the values, r2 is the correlation coefficient, and n is the number asymptotic length in cm. of individuals used in the computation.
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Recruitment and mortality were derived using ELEFAN 1987) showed that M, as to be expected, is inversely II. Recruitment pulses are reconstructed from the size- correlated with K (i.e. natural mortality lessens with faster frequency data to determine the number of pulses each growth and vice versa), the ratio of which thus proves to year and the relative strength of each pulse. In fishery be relevant to use. Thus, from gathered M and K values biology, the most useful manner of expressing the decrease from bivalve with similar habit and habitat as A. pectinata, through time (“decay”) of a group of fish is by means of a mean M/K value was multiplied with the species’ own K “instantaneous rates.” These rates are total mortality (Z, value, to get M. Total mortality (Z) is the sum of deaths due yr–1), natural mortality (M, yr–1), and fishing mortality (F, to natural causes (M) such as predation and disease and yr–1). Total mortality (Z) was estimated using the length- fishing (F). Fishing mortality (F) was, thus, estimated by converted catch curve method, which consists of the plot subtracting M from Z. Exploitation rate (E) was computed of the natural logarithm of individuals from various age using the formula: groups (N ) against their corresponding age (t) or: t (6) (4)
Equation 4 is based on the exponential decay process equation of Beverton and Holt (1957): RESULTS (5) The SL-TW relationship of the species TW = 0.0009 SL3.71 (R2 = 0.991; N = 110) was found to be allometric
Variables of Equations 4 and 5 include Nt as the surviving (Figure 3). For the length-frequency analysis, a total of individuals in the population at time t, N0 as the initial 2,512 individuals that were measured on a weekly basis number in the cohort or population at time = 0, Z as were analyzed ranging from the existing sizes in the wild the instantaneous rate of total mortality (yr-1), a as the (8–39 cm) was analyzed. The best fit of the VBGF (Figure intercept, and b as the slope. 4) resulted in an L infinity (L ) value of 40.69 cm and an instantaneous growth constant (K) of 0.78 yr-1, which Z is estimated from the slope (b) or the descending arm of the plot, with the sign changed. Five cohorts could be followed based on the Bhattacharya Using literature values (from bivalves with similar analysis (Figure 5), giving a mean growth rate of 0.15 ± habitats, i.e. shallow subtidal, as A. pectinata) of natural 0.05 cm day–1 (Table 1). The derived recruitment pattern mortality (M) and K, a mean M/K value was computed, showed one major and one minor pulse (Figure 6). which was then multiplied with the species’ own K value The length-converted catch curve analysis gave a total to get a value of M. Ebert (1983, in Longhurst and Pauly
Figure 3. SL-TW relationship of the comb pen shell Atrina pectinata collected by diving in the coastal areas of San Dionisio, Iloilo, Western Visayas, Philippines from June 2018 to May 2019.
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Figure 4. Growth curve derived using the VBGF of the comb pen shell Atrina pectinata collected from catches of divers in the southwest Visayan Sea, San Dionisio, Iloilo, Western Philippines from June 2018 to May 2019 (VBGF growth parameters: L = 40.69 cm; K = 0.78 yr 1).
Figure 6. Recruitment pattern of the comb pen shell Atrina pectinata from the southwest Visayan Sea, Northern Panay, West- central Philippines, derived using ELEFAN II.
mortality (Z) value of 2.79 yr–1 (Figure 7). Use of the averaged M/K value (1.51) from the literature (Table 2) multiplied by the species’ K value gave natural mortality (M) value of 1.18 yr–1. This value subtracted from the Z provides a fishing mortality (F) value of 1.61 yr–1 and an exploitation rate E value of 0.58. Gulland (1971) reported
DISCUSSION Figure 5. Length-frequency distributions of the comb pen Allometric growth means that the shells of the species shell Atrina pectinata from the southwest Visayan Sea, Philippines from June 2018 to May 2019, with grow in size disproportionately to their growth in weight. superimposed modes of cohorts as identified from the This is understandable in the comb pen shell given its Bhattacharya method. inequilateral shell shape (Poutiers 1998) and lightweight
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Table 1. Growth rates of the cohorts of the comb pen shell Atrina pectinata sampled from June 2018 to May 2019 in the southwestern Visayan Sea, northern Panay, Philippines, as derived using the Bhattacharya analysis (L t – length at time t, L t + 1 – length at time t + 1, GR – growth rate).
Cohort no. L t L t + 1 Delta L Delta t GR (cm) (cm) (cm) (days) (cm d–1) 1 19.35 22.50 3.15 30 0.11 22.50 25.00 2.50 30 0.08 25.00 30.35 5.35 30 0.18 2 19.73 25.90 6.17 30 0.21 3 19.69 26.05 6.36 30 0.21 4 11.21 19.02 7.81 60 0.13 19.02 24.83 5.81 30 0.19 5 22.5 26.39 3.89 30 0.13 26.39 30.36 4.07 30 0.13 Mean GR 0.15 ± 0.05 (cm d–1)
Table 2. Literature estimates of natural mortality (M, yr–1) and growth coefficient (K, yr–1) for different shallow subtidal bivalve species (bivalves with similar habitat as A. pectinata), used to compute the natural mortality for the comb pen shell Atrina pectinata in the present study from the mean ratio of M and K (M/K). M K Species and common name (FAO 1998) M/K Literature (yr–1) (yr–1) Amusium pleuronectes 1.29 0.92 1.4 del Norte (1991) (Asian moon scallop) 1.30 0.94 1.3 Gabral-Llana (1988) 1.49 0.90 1.66 del Norte-Campos and Villarta (2008)
Tapes philippinarum 6.20 0.9125 0.22 Yap (1977) (Japanese carpet shell) Anadara granosa 1.84 1.1 1.67 Mirzaei et al. (2015) (granular ark; now Tegillarca granosa) Chlamys funebris 0.506 0.457 1.11 Soliman and Dioneda (2004) Chlamys senatoria 0.506 0.457 1.11 Soliman and Dioneda (2004) (senatorial scallop) Decatopecten striatus 0.525 0.507 1.04 Soliman and Dioneda (2004) Gari elongata 2.95 1.0 2.95 del Norte-Campos (2004) (elongate sunset clam) Paphia undulata 2.89 1.2 2.41 Agasen et al. (1998) (short-necked clam) 1.57 1.0 1.57 del Norte-Campos and Villarta (2010) 1.84 1.1 1.67 1.51 mean M/K Atrina pectinata (comb pen shell) 1.18 0.78 This study
dimensions. If growth were linear as assumed by the cited by Yang et al. (2015) using aging methods of growth Bhattacharya model, the SL would be reached in 282 bands, reported that the species can reach the mean age of days (9.4 mo) and, therefore, the lifespan of the species 5.5 yr on the west coast of Korea. The species that occur in is less than 1 yr. This fast growth and short lifespan are the Visayan Sea was not aged using annual growth bands typical of species living in the tropics. Ryu et al. (2001), as as the species does not reach this long life span in these
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on the growth of the species and its remarkable wide tolerance and plasticity (Peck et al. 2009). The resulting
on length-frequency analysis, the most usual method used among tropical species, lies within the range of values of other tropical bivalves (Table 3); this showing the appropriateness of the derived growth parameters, which – together with the short lifespan – are typical for tropical species. This observation likewise confirms the inverse relationship of growth rates and lifespan among bivalves, which is often associated with metabolic rates (Moss et al. 2016). Individuals of this species living in temperate latitudes exhibit longer longevity (mean age = 5 yr) (Yang et al. 2015). The present L estimate is, however, higher (40.69 cm) compared with that (34.65 cm) of the same species in Maqueda Bay (Diocton and Adalla 2019) – a consequence most likely of the above-mentioned lack of bigger sizes in the Maqueda Bay study. Figure 7. Length-converted catch curve of the comb pen shell Atrina pectinata derived from ELEFAN II and used to estimate The smallest (Lmin) measured individual (8 cm) occurred total mortality (Z = 2.79 yr–1). in November and December 2018, while the largest (Lmax) = 39 cm was observed in May 2019. Despite the lack of reproductive biology data in the present study, tropical habitats. The growth of tropical species is best the derived growth rate allows the assumption that the studied using length-frequency analysis (Pauly 1984), as smallest individual sampled in November as well as in was done in this paper. Instead, it is more noteworthy to December 2018 was approximately 53 d (1.8 mo) old – point out that this difference in growth rates and lifespans meaning that these were spawned in the previous month of the same species highlights the effect of temperature (October and November, respectively). Consistent with
Table 3. species from similar habitats in different tropical areas (PH – Philippines; ML – Malaysia). Species and location L K ’ Literature (cm) (yr-1) (mm) Atrina pectinata San Dionisio, Iloilo, PH 40.69 0.78 3.11 This study Maqueda Bay, PH 34.65 0.77 2.97 Diocton and Adalla (2019) Marcia hiantina 66.63 1.1 3.67 del Norte-Campos et al. (submitted) Banate Bay, Iloilo, PH Amusium pleuronectes Lingayen Gulf, PH 122 0.93 4.34 del Norte (1988) Visayan Sea, PH 100 0.94 3.97 Gabral-Llana (1988) Pilar and Capiz Bays, PH 103 0.9 3.98 del Norte-Campos and Villarta (2008) Paphia undulata Southern Negros Occidental, PH 81.5 1.2 3.9 Agasen et al. (1998) 79 1.0 3.8 del Norte-Campos and Villarta (2010) Anadara granosa (now Tegillarca granosa) Penang, ML 35.4 1.1 3.13 Mirzaei et al. (2015) Gari elongata Barotac Viejo, Iloilo, PH 93 1.0 3.94 del Norte-Campos (2004) Chlamys senatoria (WoRMS accepted name) Mimachlamys sanguinea Isla Gigantes, Carles, PH 91.88 0.65 3.74 Morillo-Manalo (2017)
1057 Philippine Journal of Science del Norte-Campos et al.: Population Dynamics Vol. 150 No. 3, June 2021 of A. pectinata in Visayan Sea, Philippines this conclusion, small individuals (or “recruits”) were yr-1) doubtful and, consequently, their fishing mortality (F observed from November 2018 until January 2019, = 1.36 yr–1) estimate. In contrast, the method to compute suggesting that the months during the northeast monsoon M employed in the present paper made use of available (October–December) constitute the major spawning bivalve literature values of M and K – two parameters season. June 2018 was a month that also showed an that are inversely-correlated (Ebert 1983, as cited by abundance of the smallest length class, further implying Longhurst and Pauly 1987). The mean M/K (1.51) arrived that another spawning season takes place in addition to at in the present study also conforms with that of Froese the major peak during the northeast monsoon, i.e. a minor et al. (2018), which is reported to be characteristic for one in April/May just before the southwest monsoon. continuously-growing species like bivalves. A protracted breeding season has also been reported in other bivalves – both marine and freshwater – such as the The population in the present study is, thus, more ark shell Scapharca inaequivalvis (Arcidae) (Ledesma- intensively overexploited (E = 0.58) than the Maqueda Fernandez and del Norte-Campos 2004), the elongate Bay population (E = 0.46). The higher annual catch for –1 sunset clam Gari elongata (Psammobiidae) (Nabuab the San Dionisio stocks (22.1 MT yr ) (Nuneza-Burgos, and del Norte-Campos 2006), and the short-necked clam pers.com) in comparison to Maqueda Bay’s 17.7 Mt –1 Paphia undulata (Veneridae) (Nabuab et al. 2010), to yr supports this finding. The total annual catch of A. –1 name a few, but all have major and minor spawning peaks pectinata in the present study (22.1 MT yr ) is relatively within the year. Pauly and Navaluna (1983) showed that small compared to that of the hammerhead oyster Malleus there is a relationship between “spawning/recruitment malleus, which showed high annual harvests of 347.8 –1 patterns” and monsoons in the tropics. Bayne (1976) MT yr (Declarador and del Norte-Campos 2004). This reported that bivalves spawn when food available is highly comparison is being made to further derive insights as available (such as during the rainy monsoon period) to M. malleus is also a bivalve likewise caught by diving in provide adequate nutrition to the planktotrophic larvae. the same fishing grounds of Panay Island. Annual catch The derived unequal (8-4-mo) recruitment pattern of one in both studies was computed by multiplying the mean –1 major and one minor pulse (Figure 6) may, thus, correlate monthly catch (kg mo ) with the number of diving days with a major and minor spawning peak that could have (fishing effort) and the total number of fishers. The higher been shown had reproductive data been available for the annual harvest of Malleus malleus can be explained by the Panay population. Diocton and Adalla (2019) stated that presence of a higher number of divers (70) targeting the the minimum size at sexual maturity of the species is species compared to the fewer (25) divers in the present 20 cm, determined in their study by plotting the relative study. The lack of studies on population dynamics and frequency of maturity over the year. How maturity was reproductive biology on the hammerhead oyster, however, determined in their study is, however, unclear in their preclude providing necessary management guidelines to paper. It is, however, unlikely that any histological ensure its sustainable exploitation, just as what has been examination of gonads was conducted as the maturity size done in the present study. was not qualified for each sex, as sexual dimorphism is rare in bivalves (Sastry 1979) and, therefore, can only be determined from histological sections of gonads. Based on the present study, however, this minimum size at maturity CONCLUSIONS AND can be reached in about 4 mo. This means that individuals RECOMMENDATIONS that spawned in the late part of the major spawning period As a result of this population’s overexploited status (= (November–December) are mature in time for the minor 0.58), sizes smaller than the reported minimum size spawning period (March–May), a prediction that remains at sexual maturity (20 cm) must not be collected. A to be verified by available reproductive biology data for closed season timed at least during the major spawning this species in San Dionisio, Iloilo. The largest observed period – assumed here to be October–December based individual (39 cm) in May 2019 could, thus, very well on the occurrence of the smallest sizes (recruits) – must have been spawned during the major spawning season. likewise be imposed. Due to the wasteful practice of just Total mortality (Z) in the present study was higher (2.79 utilizing the adductor muscle, food supply for locals can yr–1) compared to the estimate of Diocton and Adalla be augmented by the non-adductor portion of the viscera, (1.36 yr–1), which supports the higher annual catch in the which could either be sold unprocessed at lower prices or present study of 22.1 MT yr–1 vs. Maqueda Bay’s 17.7 given added value if processed, thus providing additional MT yr-1. However, their incorrect method of estimating income to the locals. This could also lessen the risks natural mortality M (i.e. based on Pauly’s empirical associated with prolonged diving hours due to the divers’ formula derived purely from fish – not bivalve – stocks practice of shucking their catch underwater in favor of (Pauly 1980). This makes their natural mortality M (1.01 the adductor muscles only. The present number (25) of
1058 Philippine Journal of Science del Norte-Campos et al.: Population Dynamics Vol. 150 No. 3, June 2021 of A. pectinata in Visayan Sea, Philippines divers exploiting the fishery should also not anymore be DEL NORTE-CAMPOS AGC, LAPARA SS, SANCHE increased in the future to prevent further overexploitation KAS. Submitted. Growth, recruitment, mortality (more intensive fishing) and ultimate decimation of the and exploitation of the hiant venus Marcia hiantina species. Obviously, reproductive biology information will (Lamarck 1818) (Mollusca: Bivalvia, Veneridae) support the results of this study. gleaned in Banate Bay, Iloilo, Western Visayas, Philippines. Philippine Journal of Natural Sciences. DEL NORTE-CAMPOS AGC, VILLARTA KA. 2008. ACKNOWLEDGMENTS Population biology of the Asian moon scallop Amusium pleuronectes Linné (Bivalvia: Pectinidae) from Pilar & This study was funded by the Department of Science and Capiz Bays, northern Panay, Philippines. UPV Journal Technology–Philippine Council for Agriculture, Aquatic, of Natural Sciences 13(Suppl.): 1–10. and Natural Resources Research and Development NICER DEL NORTE-CAMPOS AGC, VILLARTA KA. 2010. (Niche Centers in the Regions for R&D) project entitled Use of population parameters in examining changes in “Studies on the Biology and Utilization of Commercially- the status of the short-necked clam Paphia undulata Important Mollusk Species in Panay Island, Western Born, 1778 (Mollusca, Pelecypoda: Veneridae) in Visayas, Philippines.” Sincerest thanks are due to Daniel coastal waters of southern Negros Occidental. Science Pauly for his comments and advice on the computation Diliman (January–June 2010) 22: 1–8. of natural mortality (M) and directions given in terms of related literature to be cited. Maricel Janoras recorded DEL NORTE-CAMPOS AGC, BURGOS LA, VILLARTA the data in the field. KA. 2019. A ranked inventory of commercially- important mollusks of Panay, west central Philippines as a guide to prioritize research. The Philippine Journal of Fisheries 2: 119–136. https;//doi.org/10.31398/ REFERENCES tpjf/26.2.2019-0004 AGASEN EV, DEL MUNDO CM, MATIAS GO. 1998. DIOCTON RC, ADALLA EP. 2019. Some aspect on the Assessment of Paphia undulata in Negros Occidental/ biology of the pen shell Atrina pectinata (Linnaeus, Guimaras Strait waters. Journal of Shellfish Research 1767) in coastal waters of Maqueda Bay, Philippines. 17(5): 1613–1617. Journal of Marine Science Research and Oceanology 2(2): 1–6. BAYNE BL 1976. The marine mussels: their ecology and physiology. Bayne BL ed. Cambridge University DONG XX, HAI-YAN W, TAO Z, LIU JX. 2014. Press, Cambridge. 506p. Population genetic structure and demographic history of Atrina pectinata based on mitochondrial DNA and BEVERTON RJH, HOLT SJ. 1957. On the dynamics of microsatellite markers. PLOS ONE 9(4): E95436. exploited fish populations. Chapman & Hall, London. doi.10.1371/journal pone. 0095436. 533p. [FAO] Food and Agriculture Organization. 1998. FAO BHATTACHARYA CG. 1967. A simple method of species identification guide for fishery purposes. In: The resolution of a distribution into Gaussian components. living marine resources of the western, central Pacific. Biometrics 23: 115–135. Volume 1. Seaweeds, corals, bivalves and gastropods. DECLARADOR MB, DEL NORTE-CAMPOS AGC. Carpenter KE, Niem VH eds. Rome. p. 1–686. 2004. The diving fishery of Bancal Bay, northeastern FROESE R, WINKER H, CORO G, DEMIREL Panay. UPV Journal of Natural Sciences 9: 244–252. N, TSIKLIRAS AC, DIMARCHOPOULOU D, DEL NORTE AGC. 1988. Aspects of the growth, SCARCELLA G. PROBST WN, DUREUIL M, recruitment, mortality and reproduction of the Asian PAULY D. 2018. A new approach for estimating stock moon scallop Amusium pleuronectes Linné in the status from length frequency data. ICES Journal of Lingayen Gulf, Philippines. Ophelia 29(2): 153–168. Marine Science. doi:10.1093/icesjms/fsy078 DEL NORTE-CAMPOS AGC. 2004. Some aspects of the GABRAL-LLANA E. 1988. Growth, mortality, and population biology of the sunset elongate clam Gari recruitment of the Asian moon scallop (Amusium elongata (Mollusca, Pelecypoda: Psammobiidae) from pleuronectes) in the Visayan Sea, Philippines. the Banate Bay area, west central Philippines. Asian In: Contributions to Trop. Fish. Bio.: Papers by Fisheries Science 17: 299–312. Participants of FAO-DANIDA Follow Up Training
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