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