Namibian Jasus lalandii recruitment: size, weight and growth of pueruli and early juveniles

Abstract

Trends in size and growth of newly settled puerulus larvae and early juveniles of the rock lobster Jasus lalandii (Decapoda: Palinuridae) were determined by weekly sampling at an oyster farm at Luderitz, Namibia, over a three-month period in 1999. A high variance was observed in the ratio of carapace length (CL) to weight of newly settled pueruli and may indicate variable nutritional condition of the incoming larvae. This length–weight ratio was significantly lower than that of similar-sized juveniles; the difference was attributed to a change in morphology and improved nutritional condition of young juveniles. The size of newly settled pueruli increased significantly over the sampling period. Sizes of pueruli and juveniles overlapped broadly between 6.7 mm CL (smallest juvenile) and 10.3 mm CL (largest puerulus). Estimated growth from the puerulus to first-instar juvenile was only 0.1 mm CL (1%), indicating that small pueruli moult into small juveniles with little energy reserves available for growth. Growth rates increased to 7% and 17% of CL during the second and third moults respectively.