Journal of the Marine Biological Association of India

Volume 57 Issue 1

Ontogenetic changes in morphometry of the spiny lobster, Panulirus homarus homarus (Linnaeus, 1758) from southern Indian coast

 

E.V. Radhakrishnan, R. Thangaraja and M. Vijayakumaran
doi: 10.6024/jmbai.2015.57.1.01809-01
Abstract

 The morphometric relationships, carapace length vs total length (CL vs TL), carapace length vs weight (CL vs W), total length vs weight (TL vs W), carapace length vs carapace width (CL vs CW), carapace length vs length of third walking leg (CL vs III WL) and carapace length vs width of second abdomen (CL vs II ASW) were estimated for the Scalloped spiny lobster Panulirus homarus homarus fished from east and west coast of Tamilnadu. A total of 462 males and 350 females were measured for the study. Carapace length of lobsters ranged from 20.4 mm to 101.0 mm CL. The power function y=axb was applied in all the relationships. The first derivative dY/dCL-abCLb-1 where Y is TL was used to study the growth tendency of TL in relation to CL. A negative allometry, b<1 was found for males which was also reflected in their decreasing growth rate of TL in relation to CL. The CL vs W relationship showed a general negative allometry, b<3 in both sexes. Size at the onset of sexual maturity in male was determined based on allometric growth of third pereopod. Slopes of regression of log transformed data showed positive allometric growth of third pereopod for males (b=1.17) compared to negative allometry in females (b=0.97). Females had (b=1.04) positive allometry in second abdomen width compared to negative allometry in males (b=0.934). However, their size at maturity could not be precisely predicted as the b value of the two regression lines of immature (1.09) and mature females (1.01) did not indicate any significant deviation from 1. The size at maturity of males (63.0 mm) was determined where the two regression lines of mature and immature specimens crossed. The results obtained in the present study support the predictions of resource allocation theory in crustaceans and demonstrate marked shifts in resource allocation through ontogeny in both sexes.

 

Keywords

Panulirus homarus homarus, morphometry, allometry, growth rate, size at maturity

 

Date : 15-03-2015