Annual changes in Japanese spiny lobster feeding activity and related causes

Feeding activity and daily feed intake of three male Japanese spiny lobsters Panulirus japonicus, 74-81 mm in carapace length, were continuously monitored from February 1998 to December 1998. Lobsters were fed on mussels Mytilus galloprovincialis during a period of 284 days. The activities of the lobsters fluctuated markedly throughout the present study, reflected their molting cycles as well as changes in water temperature. Molting occurred in summer and autumn. Lobsters showed low feed intake for about one month prior to molting, did not feed for 5-17 days just before molting, and resumed feeding 2-26 days after ecdysis. The feed intake of the lobsters increased rapidly in summer following ecdysis. When water temperature was lower than 11.8degreesC, lobsters did not ingest prey. Feed intake increased as water temperature increased, and decreased when water temperature reached 28degreesC or higher.