Good Environment Management of cage farming using a coupled 3D hydrodynamic particle tracking model - A case study from Pizhala, Cochin, India

Hydrographic conditions such as water level, velocity, adequate\r\nwater circulation and stratifications have a strong influence on the\r\nmanagement of fish cage culture in the estuarine environment. In\r\nthis study, a 3D hydrodynamic model was used to identify the areas\r\nof the mixed and stratified water column and to use this in\r\nconjunction with particle tracking models for appropriate site\r\nselection for cage culture. A Lagrangian method was used to\r\nsimulate the instantaneous release of \"particles\" emulating discharge\r\nfrom fish cages to show the behaviour of waste in terms of water\r\ncirculation and water exchange. Model simulation at Pizhala cage\r\nfarm revealed that desirable water exchange is experienced in the\r\nmonsoon and pre-monsoon period. There have existed strong\r\nspring-neap variability in the water level with an average range of\r\n0.7 m with a speed of \u003c 0.12 m/s in pre-monsoon and \u003c 0.24 m/s\r\nin monsoon. This consistent flow patterns in the Pizhala region helps\r\nin the replenishment of oxygenated water and removal of waste\r\nproduced beneath the cages, and it is corroborated by the\r\nLagrangian particle transport model experiment coupled with Finite\r\nVolume Community Ocean Model (FVCOM) in the study.