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Freshwater clams, better known as pokea clams in Indonesia, are among the important economy-generating resources whose population continues to decline in line with the increase in fishing activities. The present study aims to determine the age group, growth, mortality, and exploitation rate of pokea clams. This research was conducted in the estuary segment of Laeya River, Southeast Sulawesi, Indonesia, from March 2016 to February 2017. Pokea samples were taken using a traditional fishing tool called Tangge. Data on age groups, growth, mortality (natural, fishing, and total) and exploitation rate were processed using the Bhattacharya method, the von Bertalanffy inverse function, the width converted catch curve, and Pauly's empirical formula, respectively, accommodated in the FiSAT II program version 3.0. The results showed that the male and female pokea were spread out in 1 and 2 size groups. Male pokea was dominated by 2 size groups, whereas the female pokea was dominated by 1 size group. The growth of the male and female clams followed the equations Lt = 83.89 - (83.89-0.025)[e.sup.-0.54t] and Lt = 77.38 - (77.38-0.025)[e.sup.-0.52t]. The male natural mortality (M), fishing mortality (F), and total mortality (Z) were 2.04 [y.sup.1] 0.91 [y.sup.1], and 2.94 [y.sup.1], respectively, whereas the natural mortality, fishing mortality, and total mortality of the female clams were 1.51 [y.sup.1], 0.90 [y.sup.1], and 2.41 [y.sup.1], respectively. In general, the male and female pokea clams in the Laeya River are overexploited, with the exploitation rates of 0.69 and 0.63, respectively. KEY WORDS: Batissa violacea var. celebensis, population, clam, pokea, size groups, growth, Sulawesi, Indonesia, INTRODUCTION Freshwater clams are a type of bivalve that can be found living on the bottom in the estuary of a large river in Southeast Sulawesi (Bahtiar et al. 2012a). [...]

Meretrix meretrix is one of the economical shellfish that has been exploited in Kendari Bay, Indonesia. Several studies have been done, but its growth pattern and condition index are not fully known. This study aims to determine its growth pattern and condition index at the Kambu River estuary, Kendari Bay. This research was conducted for 6 months from August 2021 to January 2022. Clams were collected using a rake, cleaned, and brought to the laboratory to be measured for length and weight using calipers and scales with an accuracy of 0.1 mm and 0.01g, respectively. Furthermore, the clam meat was dried using an oven and weighed. Data on growth and condition index were analyzed using simple regression and the Mann-Whitney test, respectively. The results showed that the growth of M. meretrix was in negative allometric conditions, with b values in males and females in the range of 2.20-3.00 and 1.86-2.73, respectively. The condition index of male and female clam ranged from 1.86-2.62 and 1.66-2.41, respectively, and differed significantly by month. The results of the Mann-Whitney test on clam showed that there was no significant difference between August-November and December-January. In conclusion, male and female clam had relatively different patterns based on the observation period, while the condition index was in the skinny and medium category. [ABSTRACT FROM AUTHOR]

Mangrove clams are found in the soft substrates of the mangrove forest, where they reproductively adjust to the conditions in the aquatic environment. This study aimed to determine the reproductive biology pattern, such as sex ratio, gonad maturity level, gonadosomatic index, fecundity and size of the first maturity of mangrove clams. The samples included 80 ind./month collected manually from the mangrove ecosystem for one year. The reproductive biology patterns were calculated using standard formulas, each analysed using the χ2 test, semi-quantitative descriptive evaluation and non-linear regression. The results showed that more males than females were collected, accounting for 80.0–96.5% and 3.4–20.0%, respectively. Furthermore, both sexes' gonad maturity developments coincided. The mangrove clam's mature gonads are discoverable all year by observing the gonadosomatic index IV and spawning monthly occurrence. Their maturity peaked (levels III and IV) in February–April, indicated by a high index value ranging from 3.9–18.2 and 4.3–21.9 for the male and female mangrove shells, respectively. The male clams also had smaller sizes at maturity than females at 3.0 and 5.2 cm lengths, respectively. The food (organic sediment) availability was an essential environmental parameter in developing gonadal maturity. [ABSTRACT FROM AUTHOR]

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