DAMAGE OF AQUATIC FAUNA DURING THE COLLECTION OF SHRIMP (PENEAUS MONODON) POST LARVAE IN THE TIDAL WATER OF MONGLA RIVER (RAMPAL), BAGERHAT

Abstract

The study was conducted in Mongla tidal river (Rampal) of Bagerhat district from November 2014 to October 2015 to assess the abundance of black tiger shrimp (Penaeus monodon) post larvae (PL) and to quantify the damage of different aquatic fauna during collection of P. monodon PL. Observation was also made on the distribution of aquatic organisms with the variation of water quality parameters and season. Insignificant variation in water temperature, pH, salinity and hardness was found but salinity and hardness showed great fluctuation during the study period. Regression analysis shows that the abundance of P. monodon PL was significantly (p˂0.05) related to water temperature, pH, salinity and hardness. It was found that about 401 other shrimp larvae, 382 fin fishes and 1717 other macrozooplankton were killed during the period of collection for only one PL of P. monodon. During the survey period around 0.16 million man days/year were estimated to be involved in shrimp PL collection activities and on average 6.3 million of P. monodon PL were collected annually from the studied area. It was also calculated from the present study that about 29,874 million of other shrimp species, fin fishes and macrozooplankton were destroyed annually by the shrimp seed harvesting process in Mongla river. Therefore, the results obtained from the study imply that present seed collection practice caused severe damage of other valuable aquatic fauna, which directly affect the biodiversity of tidal waters, natural productivity, improvement of mother stock and environment friendly of coastal and marine water.