Ingression, abundance and settlement dynamics of Penaeid shrimp postlarvae in backwaters and adjacent tidal ponds in Cochin, India

Dynamics of penaeid postlarval ingression and settlement the backwaters of Cochin were studied. Postlarval recruits were constituted by Metapenaeus dobsoni(70.8-78.40%)Penaeus indicus (7 .5-24.6%), M. rnonoceros (3.8-4.6%) and P. monodon (0.3-0.4'%). Their composition varied with location and season. Postlarval abundance and ingression were influenced by diel, tidal, lunar and seasonal factors. Ingression is mainly nocturnal in all species with nearly 84% of the activity during night hours. Abundance and ingression peaked up during high tides at night with major peaks coinciding with spring rides of full and new moon. It also followed a generalized seasonal pattern with two well-defined peaks for all species. It was pre-monsoon followed by post-monsoon for P. indicus and M. momoceros and postmonsoon followed by pre-monsoon for M. dobsoni. Slze of the recruits were relatively small during pre-monsoon and post-monsoon and large during monsoo