Impact of lunar periodicity on availability of fin and shell fish seed with special reference to Penaeus monodon in the estuarine systems of Sunderbans, West Bengal

Abstract

The seed requirement for existing brackish water aquaculture practices in India is now being met from the seed produced at hatchery as well as from natural collections. The Sunderbans in West Bengal an intricate coastline with mangrove vegetation, cluster of deltas with interlinked channels, creeks and estuaries, are treasures of fin and shell fishes. The seeds enter into these waters from offshore spawning grounds along with tidal waters. Lunar phase control the tidal amplititude and thereby regulate the influx of the seeds. The investigation carried out in six estuarine systems of West Bengal namely Hooghly, Matla, Saptamukhi, Thakuran, Vidya and Jheela portrayed the impact of lunar periodicity on availability of fin and shell fishes from these estuaries. The study depicted maximum collection on 3rd day of lunar phase. Again collection was better during full moon phase compared to New moon phase. During seventh to eleventh day of the lunar phase negligible quantity of seeds were available. All the estuaries showed similar trend of rising graph of abundance both during Full moon and New moon periods. The fish seed availability during 1st to 7th days of the Full moon and also New moon phases was prominent in respect of the total numbers hauled and percentage of fin fish, shell fish and the P. monodon. The investigation has put through a guideline towards exploitation of seeds from these open water resources more pragmatically.