Estimation of the larval drift of the Japanese spiny lobster in the vicinity of the Goto Islands (横浜商科大学開学四十五周年記念号) Estimation of the larval drift of the Japanese spiny lobster in the vicinity of the Goto Islands
For the last 40 years, the annual catch of the Japanese spiny lobster has remained steady at about 1,200 metric tons. Thus, constant larval recruitment is required to maintain a steady stock abundance of the spiny lobster in Japanese coastal areas. To estimate the coastal areas over which the phyllosoma of the Japanese spiny lobster (mainly Panulirus japonicus) are transported from or returned to its hatching areas, a field experiment was carried out with drift cards. This field study consisted of releasing 6,000 drift cards during the spiny lobster hatching season (June 26 - July 31, 1992) in units of 1,000 cards per week from the southeast region of the Fukuejima Island, which is in the Goto Islands. The results from this study are summarized as follows: 1) It was difficult for the drift cards to be transported by the currents to the Japan Sea. Therefore, the waters around the Goto Islands are a good habitat for phyllosoma of the Japanese spiny lobster because the prevailing current system makes transport into the less desirable habitat of the Japan Sea unlikely. 2) The current systems were likely to cause the drift cards to remain in the vicinity of the Goto Islands. Therefore, it is suggested that the lobster stock is locally retained in that area. 3) The drift cards tended to be transported along the Pacific coast of southern Japan. This then suggests that the vicinity of the Goto Islands is also an important spawning and hatching area for the Pacific stock.
横浜商科大学紀要 10, 125-143