Morphometry and population structure of non-harvested and harvested populations of the Japanese red coral (Paracorallium japonicum) off Amami Island, southern Japan

Abstract

Precious coral harvested in the Mediterranean Sea and the northern Pacific Ocean is of commercial value yet excessive fishing has led to a serious decline in its abundance. Consequently, there is now international discussion about controlling the world trade of precious coral. To explore the possibility of a sustainable fishery of Japanese red coral (Paracorallium japonicum), the morphometry and the population structure of populations in a non-harvested area and in a harvested area were investigated using a remotely operated vehicle (ROV) off Amami Island, Southern Japan, in 2009. In the harvested population, the estimated modal ages are 10 to 20 years. In contrast, the main mode in the non-harvested population extends widely from 20 to 40 years, with a small but distinct secondary mode between 50 and 60 years. Commercially collected specimens are mainly 30–40 years old. The difference in the modes of non-harvested and harvested populations suggests that harvested populations return to the pre-fishing level after at least 10–20 years of a biological rest period. This study indicates a rotational harvest is useful for sustainable management.