Growth and production of a tropical predatory shrimp, Macrobrachium hainanense (Palaemonidae), in two Hong Kong streams

1. Macrobrachium hainanense is a predatory palaemonid shrimp (total length >7 cm) that can be abundant [density 3-5 m-2; biomass 484-606 mg ash-free dry mass (AFDM) m-2] in forest streams in Hong Kong, China. This study investigated the growth and production of M. hainanense during 2001 and 2002 in pools of two forested streams (one third- and one fourth-order). 2. The growth of tagged individuals was recorded in situ and compared with that of tagged and untagged shrimps in laboratory tanks. Field and laboratory estimates yielded similar growth rates of 0.7 mm carapace length (CL) per month, and instantaneous growth rate was 0.004 g AFDM g-1 day-1. Tagging did not affect growth in the laboratory. Cohort analysis of field populations produced similar estimates of growth to that of tagged individuals, and the growth of M. hainanense was generally slower than has been reported for other Macrobrachium species. Mass-specific growth rate of M. hainanense in the field varied with size and was two to five times higher in small individuals (