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ISSN : 1225-3480
This study compared aquaculture performance of the bay scallop (Argopecten irradians) between an inner-bay site and an outer-coastal site in the Yeosu coastal area, Korea. During the study period, seawater temperature ranged from 6.75 to 27.97°C at the inner-bay site and from 12.30 to 25.83°C at the outer-coastal site, with no significant difference between sites (p > 0.05). Salinity ranged from 31.14 to 32.70 psu in the inner bay and from 31.91 to 34.01 psu at the outer-coastal site; although salinity tended to be slightly higher at the outer-coastal site, the difference was not significant (p > 0.05). The mean daily growth rate (DGR) was higher at the outer-coastal site (8.87% day-1) than at the inner-bay site (7.59% day-1). At the end of the experiment, survival was markedly higher at the outer-coastal site (82.1%) than at the inner-bay site (11.8%), whereas mean biofouling incidence was substantially lower at the outer-coastal site (3.03%) than at the inner-bay site (11.13%). Elevated biofouling in the inner bay was identified as a key limiting factor, potentially contributing to reduced growth and increased mortality through growth retardation, space competition, and competition for food resources. Overall, the outer-coastal area of Yeosu can be classified as a priority candidate site for the introduction and expansion of bay scallop farming (high suitability), whereas the inner bay represents a high-risk area vulnerable to biofouling and environmental stressors (low suitability). These findings provide baseline information for spatial planning and management by differentiating site suitability using survival and biofouling indicators.
This study aimed to elucidate gonadal development and the reproductive cycle of Heminerita japonica inhabiting the intertidal zone of Geomundo, Jeollanam-do, Korea. From April 2013 to March 2014, the condition index (CI), gonadosomatic index (GSI), and gonadal development were examined histologically, and monthly variations in water temperature and salinity were recorded. Water temperature ranged from 10.7 to 24.6 °C, with the highest value in August 2013 and the lowest in March 2014. Salinity ranged from 31.1 to 34.4 psu, with the lowest value in August 2013 and the highest in February 2014. Monthly CI patterns were similar between females and males, peaking in November (female: 43.87 ± 4.07; male: 44.49 ± 3.53) and reaching minima in June (female: 23.77 ± 6.07; male: 23.18 ± 6.08), indicating regular seasonal periodicity. Based on histological observations, the reproductive cycle was classified into five stages: early development (October-February), late development (November-April), ripe (February-May; females February-May and males March-May), partially spawning (May-July), and degenerative/resting (June-October; females July-October and males June-October). These findings provide baseline information for the conservation and ecological study of H. japonica.
The age and growth of the soft-shell clam, Mya arenaria, were investigated based on specimens collected from the coastal waters of Namhae-gun, Gyeongsangnam-do, Korea. In the relative growth equations of shell height, shell width, and total weight against shell length, the coefficients of determination (R2) ranged from 0.8462 to 0.9276, indicating high correlations. The mean shell lengths at ring diameter were SL1.83 = 31.95 mm, SL2.83 = 42.00 mm, SL3.83 = 49.51 mm, SL4.83 = 57.06 mm, SL5.83 = 65.91 mm, SL6.83 = 75.90 mm , SL7.83 = 83.79 and SL8.83 = 90.64 mm. The corresponding mean total weights were TW1.83 = 51.50 g, TW2.83 = 66.14 g, TW3.83 = 76.88 g, TW4.83 = 87.54 g, TW5.83 = 99.90 g, TW6.83 = 113.67 g, TW7.83 = 124.43 g and TW8.83 = 133.70 g, respectively. Parameters estimated from the von Bertalanffy growth model were 173.36 mm for the asymptotic shell length (SL∞), 0.0289 year-1 for the growth coefficient (k), and –0.889 year-1 for the t0. The growth equations were expressed as SLt=173.36(1-e-0.0289(t+0.0889)) and TWt=295.87(1-e-0.0289(t+0.0889))2.9303.
This study evaluated norovirus detection in bivalves collected from a high-energy open-water (HEO) aquaculture farm located approximately 15 km offshore from Gusipo on the west coast of Korea and from comparative coastal sites. Diploid and triploid Pacific oysters (Crassostrea gigas) and pen shells (Atrina pectinata) cultured at the HEO farm, together with wild oysters from Gochang and farmed oysters from Geoje and Goheung, were analyzed for norovirus GI and GII by one-step RT-qPCR from July 2024 to November 2025. To accommodate differences in study objectives and sample characteristics, the survey was conducted in three sequential phases consisting of preliminary pooled screening, individual-based confirmation, and long-term pooled monitoring. No norovirus was detected in any shellfish samples collected from the HEO farm throughout the 17-month survey period, including the winter season when norovirus contamination is generally more prevalent. In contrast, wild diploid oysters from Gochang tested positive for both GI and GII in January 2025, and farmed diploid oysters from Geoje tested positive for GII in February and March 2025. Farmed triploid oysters from Goheung remained negative throughout the monitored period. These findings indicate that shellfish produced in the offshore HEO environment had no detectable norovirus during the study period and suggest that such environments, being physically separated from land-based contamination sources, may represent a lower-risk setting for shellfish production with respect to norovirus contamination.
