Transplantation and Culture of the Yesso Scallop <i>Mizuhopecten</i> ( =  <i>Patinopecten</i> ) <i>yessoensis</i> in Southeast Sea of Korea

This study aimed to assess the survival and growth rates of Yesso scallop Mizuhopecten ( = Patinopecten ) yessoensis spat transplanted from the East Sea and cultured in both inner and outer areas of Goseong Bay, Korea, using idle Bay scallop ( Argopecten irradians ) aquaculture facilities during the off‐season (November–June). Additionally, economic feasibility of this cross‐cultivation approach was evaluated. Yesso scallop spat with a mean shell length of 17 mm were stocked in lantern nets in both inner and outer areas of Goseong Bay in October 2020 and monitored monthly until June 2021. Environmental parameters, including surface seawater temperature (SST), dissolved oxygen (DO), and chlorophyll‐a concentration, were continuously recorded. High survival rates (92%–100%) were observed at both sites, and scallops reached marketable sizes (shell length 62.0–65.0 mm; total weight 25.6–28.5 g) by June. The final shell length and total weight were 65.0 mm and 28.5 g in the inner bay, and 62.0 mm and 25.6 g in the outer bay, respectively; although these differences were statistically significant, the overall size and weight achieved in both areas were similar and commercially acceptable. Economic analysis demonstrated a return on sales (ROS) of 49.8% and a benefit–cost ratio (BCR) of 2.0 for Yesso scallop cross‐cultivation, exceeding those of conventional Bay scallop monoculture. These findings indicate that utilizing existing aquaculture infrastructure for Yesso scallop production during the Bay scallop off‐season is both biologically viable and economically advantageous, providing a practical strategy for optimizing facility use and revitalizing Yesso scallop aquaculture in Korea.