Biology of the blood clam, Anadara rhombea (Born) in Kakinada bay

Abstract

A. rhombea occurs in small quantities in the Kakinada Bay and is incidentally collected while fishing for the more abundant A. granosa- Males attain maturity at 22 mm and females at 24 mm length. It spawns during December-April (rarely in May) and major spawning Is indicated in January-March. A single or two reproductive cycles occur during the spawning period. Increase in the ambient water temperature and salinity seem to induce spawning The proportion of males and females during different months, years and also in different length groups generally conforms to 1:1 ratio. The average monthly condition index (CI) expressed as percentage of wet flesh weight in total weight, varies from 9 6 to 15 7. The CI does not vary in relation to length. It is high before or at the beginning of spawning and low when majority of the clams hive released bulk of the gametes. In the post-spawning period the CI Is again high, probably due to the accumulation of body reserves. The estimatad values of the parameters of the yon Beitalanffy growth equation ate Lco'=90.2mm, K = 04573 per year and t" = "0 6315 yr. A. rhombea axxa'ms 47.4,63.1 and 73.1mm on completion of 1, 2 and 3 years respectively. Various morpho netric and length-weight relationships are studied