Abstract

This study was focused to know what happened to three bivalve resources (Ruditapes philippinarum, Mactra veneriformis, and Meretrix petechialis) at tidal flats around the Saemangeum during recent years. The population density of M. petechialis at the Yubu-do tidal flat has been gradually declined by the continuous harvesting of fishermen and reached to be a very low density of 0.6 ind./m2 . Because a very low juvenile recruitment is expected due to the lack of larval supply from a very low fertilization rate due to its low adult density, it is necessary to provide some protective sites containing dense adults of M. petechialis in order to avoid the Allee effects in Yubu-do tidal flat. In the case of the populations of R. philippinarium and Mactra veneriformis at Wi-do tidal flat, there was no natural recruitment during recent two years and few small individuals of these two species and only large individuals were found compared with those from Yubu-do and Sinshi-do, especially at the lower tidal flat due to the accumulation of fine sediments. For Ruditapes and Mactra populations, it should be necessary for a detailed a detailed monitoring study to solve problems on the survival of juveniles and recruitment failure and to know whether there are some relationships between the high mortality and recruitment failures and fine particle depositions at the tidal flats.