Chapter 22 - Scallops and Scallop Aquaculture in China

Abstract

Abstract A large number of Pectinid scallops are found along the coast of China, and scallops are among the most important marine resources for China. China leads the world in scallop aquaculture. Scallop aquaculture in China began in the late 1960s and has gone through rapid growth since the 1980s. In 2012, China produced 1.42 million tonnes of scallops from aquaculture, a 245-fold increase from 1984. Most of scallops are cultured along the northern coast with three northern provinces, Shandong, Liaoning and Hebei, accounting for 93.1% of the production. Four scallop species are commercially cultured in China including two native species, the Chinese (Zhikong) and noble (Huagui) scallops, and two non-native species, the Japanese and bay scallops. For many years, the Chinese scallop was the primary species cultured in China. Massive summer mortalities since 1998, likely caused by a variant of ostreid herpesvirus, have devastated the Chinese scallop culture, and subsequently, aquaculture of non-native bay and Japanese scallops has greatly expanded and dominated scallop production. Culture of the Chinese scallops uses primarily natural seed, while bay scallops are exclusively hatchery-produced. Japanese scallop seed were mostly produced in hatcheries, although natural seed collection is on the rise. Hatchery production is conducted in large (20–30 t) concrete tanks. Spat are collected on polyethylene screens and nursed in spat bags in shrimp ponds or selected ocean areas. Chinese and bay scallops are cultured in multi-layered lantern nets on suspended longlines. Japanese scallops are also cultured in lantern nets, although on-bottom stocking has become popular. Market sizes are reached at 8–10 months of age for bay scallops (50–60 mm), 16–20 months for the Chinese scallop (60–70 mm) and 30–34 months for Japanese scallops (90–100 mm). Japanese scallops have also been affected by serious mortalities since 2007. Most mortality occurs in two peaks between April and May after spawning, and then between August and October, during and shortly after high summer temperatures. The non-native species have contributed greatly to scallop aquaculture in China, and other non-native species are being evaluated. Although scallop aquaculture in China has been growing rapidly, its sustainable growth faces some challenges including instability in seed production, the use of coal and antibiotics in hatcheries, excessive culture density at both cage and bay levels, and increasingly frequent and serious mortalities during grow-out.