Growth and moulting of captive Panulirus homarus homarus in Kenya, western Indian Ocean

Abstract

Panulirus homarus homarus is the most widely distributed of the three P. homarus subspecies and is the second most important spiny lobster in the Kenyan lobster fishery after Panulirus ornatus. Growth and moulting of lobsters held in concrete tanks with a flow‐through sea‐water system and at ambient temperatures, were monitored for 18 months (October 2001 ‐ March 2003). Both moult increment and moulting frequency were inversely correlated with size. Mean moult increment ranged from 4 mm in the 36–45 mm carapace length (CL) size class to 0.6 mm in the 86–95 mm CL size class. Mean intermoult period increased from 49 days in the 46–55 mm CL size class to 66 days in the 76–85 mm CL size class. Growth rates were 19% and 46% higher for males and females, respectively during the south‐east monsoon (low temperature) season than during the north‐east monsoon (high temperature) season. A shift in energy use from growth to reproduction rather than the influence of temperature was responsible for the variation in the growth rates between the two seasons. Marking‐induced injury caused a significant 65% growth reduction in the affected individuals. Mean moult increments calculated for most size classes of uninjured lobsters were comparable to those observed in the subtropical P. homarus rubellus reared in the laboratory in South Africa but smaller than those reported in the Indian P. homarus under similar conditions.