Journal of the Marine Biological Association of India

Volume 30 Issue 1&2

The biology of the convict surgeonfish Acanthurus triostegus triostegus ( Linnaeus ) from Minicoy Atoll, Lakshadweep.

Madan Mohan and C. S. Gopinatha Pillai

Acanthurus triostegus triostegus is the commonest acanthurid found in shallow intertidal reef flats of Minicoy Atoll and other Lakshad weep Islands. The species exhibits inward and outward movement on the reef flat along with the tides. It is a typical herbivore and feeds on filamentous and segmented algae commonly found on dead and live coral boulders.

A common formula for both male and female of the species to establish the length-weight relationship is derived as follows: Log W - = — 4. 105377+2.766371 L ogL. 

At the end of the first year the species attains a total length of 128 mm and by the end of the second year 167 mm. The ratio of males to females in the population for 1981-82 was 1 :0,99 and for 1982-83 was 1 :0.93 indicating a more or less equal proportion.

The total number of matured eggs produced by an individual per spawning varies from 32,022 to 164,013. The size at first maturity at 50% level is 87 mm TL. The species has a protracted breeding season extending almost throughout the year. It may spawn more than once in a breeding season. The settlement of postlarvae occurs in tide pools and the size at first settlement is 25 mm. Dispersal of the postlarvae from tide pools takes place after about two weeks of settlement.

Date : 30-12-1988