Tagging experiments on searanched Penaeus indicus in the Palk Bay, southeast coast of India

Abstract

An attempt has been made to study the suitability of hatchery raised and farm grown Penaeus indicus for searanching, and to study the growth and movement of ranched population in the Palk Bay and the Gulf of Mannar. The eggs released by a spawner without eyestalk ablation were raised upto juveniles through rearing in the hatchery, nursery cement tanks and in earthern ponds. The hatching rate and subsequent survival rate from nauplius-1 to PL-1 was 92.3 and 53.0 % respectively. Survival from PL-1 to PL-21 was 49.5 %. The seeds thus raised were stocked in two coastal earthern ponds at a rate of 50,000/ha and fed with pellet diet daily at the rate of 5-10 % of biomass. After 111 days, retrieval was 41.45 % in pond I and 75 % in pond II. The growth was from 22.95 mm TL to. 111.7 mm TL/10.1 g wt. in pond I and 103.06 mm TIV 8.1 g wt. in pond II. These juvenile prawns were tagged with loop tags and released in the Palk Bay off Mandapam at 3 m depth. Recovery started from the subsequent day onwards in the trawl catches of Palk Bay and Gulf of Mannar and continued upto 28 days. Of the 3,430 prawns released, only 19 were recovered accounting for <1 % recapture. Distribution and movement of tagged prawns and the prospects of searanching of P. indicus have been discussed.