Wednesday, November 15, 2006

Shrimp Aquaculture in Florida; A Sustainable Model.

Kathy Stone, Florida International Univ, P.O. Box 653041, Miami, FL 33265

Beginning in the 1990’s demand for shrimp for export to industrialized nations grew substantially.  This led to intensification of shrimp farming techniques in many countries.  The perception of shrimp farming has been affected by non-sustainable operations world wide that have deforested mangrove areas for the construction of shrimp ponds and released polluted effluent into wetlands.  An organic shrimp farm in Florida is presented as a case study in environmentally sustainable shrimp farming.  Disease control and health maintenance is accomplished via manipulation of naturally occurring bacterias, nitrogen levels, oxygenation and pH.  Water is continually treated and circulated with zero discharge.  This operation also formulates its own shrimp feed which has 50% less fish meal than commercial brands.  This enterprise is not without some environmental impacts, however.  During production seasons which run roughly May through December, rainfall keeps up with evaporation rates.  During the off season, evaporation outpaces rainfall resulting in a net loss of about one foot of water per year which must be replaced from a saline aquifer.  Permits have been issued for the taking of occasional cormorants who prey on shrimp in the ponds.  Although there are minor environmental costs the potential for reducing environmental impacts of shrimp aquaculture on wetlands exists if  this system is used as a model within Florida and in other countries.  Some processes such as the recirculation of water, would necessitate a large area of land and may not be appropriate for shrimp farms that are located in close proximity to other shrimp ponds rice ponds or their water source.  Other aspects of this model such as monitoring and natural controls of oxygenation, nitrogen and pH levels may reduce effluent discharge.  Marketing shrimp feed formula with reduced fishmeal throughout Florida and worldwide, could reduce impact on ocean stocks.