Biology of the blood clam Anadara granosa (Linnaeus) in Kakinada Bay

Abstract

A. Granosa spawns throughout the year and the major spawning months vary between years. There can be 2-4 reproductive cycles in a year. Males attain first maturity at 20 mm and females at 24 mm length. The male, female ratio during different months, years and also in different length groups is 1:1. The monthly average condition index (CI) based on the percentage of wet flesh weight in total weight varies from 15.1 to 23.1 and the same expressed as percentage of dry flesh weight in wet flesh weight ranges from 17.2 to 24.2. The trends in the values obtained by these two methods are comparable. The CI does not vary in relation to length. The infestation of A. granosa by the pea ciab Pinnotheres alcocki varies from nil to 46% during different m3nths (average 10.8%). In the crabinfested clams there is no damage to the organs of the host. The CI is low in 41.1 % of the crabinfested samples when compared to the CI obtained in uninfested clams. The estimated parameters of the von Bertalanffy growth equation are Lα =73.4 nun, K = 0.5816/year and t|,= —0.4088 yr. A, granosa attains 41.1, 55.3 and 66.3 mm on completion of 1,2 and 3 years respectively. Various morphometric and lergth-weight relationships are studied.