Results of economic activity and problems of aquaculture development in the Possiet Bay (Japan Sea) in 2000–2015

Abstract

The Possiet Bay in the western Japan Sea is crucially important for marine aquaculture of Primorye because of the environments favorable for cultivation of many aquatic species. The local marine farms cultivate sea cucumber and several bivalve species, including the most valuable yesso scallop, which output production is counted in hundreds of tons. The number of farms in the Possiet Bay increases recently, as well as their production of seeding materials and marketable output of seafood. Cultivation of 3 bivalve species (yesso scallop, pacifc blue mussel, and pacifc oyster) and 1 holothurian species (japanese spiky sea cucumber) is considered. The seeding material is collected by the farms located in the Possiet Bay, which prefer to collect more valuable spat of the scallop and sea cucumber, while the mussel and oyster are collected in smaller amounts. In total, more than 640 million of the scallop juveniles and about 1.2 million of the sea cucumber juveniles were collected by local farms in the period from 2000 to 2015, including both the spat collected on their own collectors or bought from other vendors. Dynamics of the output is presented for these species. The greatest harvest of the marketable scallop (over 1800 t) was produced in 2006–2010, with the highest annual output over 510 t. The summary production of all marine farms in the Possiet Bay within the 15-year period (2001–2015) is estimated as 4,300 t, that exceeds the registered catch of scallop in this area in the whole history of its fshery (that was banned in the middle of 1980s). Even before the fshery opening in the early XX century, the yeaso scallop biomass in this area did not exceed 1,000 t. Dynamics of anthropogenic pressure to the Possiet Bay waters is analyzed, as well. There is concluded that yesso scallop has natural ability to considerable growth of its biomass because of high fecundity, though this potential is limited by lack of substrate for the spat settling that is successfully compensated with artifcial substrata provided by marine farms. However, the growth of scallop biomass and production causes higher phytoplankton consumption, increasing of water pollution by dissolved and particulate organic matter, and accumulation of metabolic by-products in marine organisms. Rapid development of aquaculture causes some social and ecological risks, as well, as territorial disputes, legislative problems (with harvesting permits, etc.), starfsh expansion, grazing of farmed mollusks by marine birds, destruction of aquaculture facilities in new areas located in the insuffciently closed bights by typhoons, and epizootics (most dangerous for the sea cucumbers).