Side scan sonar in oyster management

Abstract

Oyster harvest from Mississippi reefs provide jobs for numerous fishermen and contribute substantially to the economy. Proper management of these reefs is vital for continued harvest. Enhancement management techniques (i.e. cultch planting and/or cultivation) should helps to ensure even greater future production. Cultch planting is a key component of management measures conducted by the Mississippi Department of Marine Resources (MDMR). Cultch plants are typically evaluated with sounding poles, tongs, dredges or scuba equipment. These methods are not very efficient when surveying large areas for coverage rates or distribution of materials. Using side scan sonar to monitor cultch plants has a number of advantages over these methods. Side scan sonar can cover large areas in less time, provide accurate measurements of coverage, and simultaneously provide differential GPS coordinates. Information acquired from side scan sonar provides a long-term record, which can be used to detect changes due to environmental catastrophes, vessel groundings and/or harvest pressure. A side scan sonar survey was performed before cultch planting on the St. Joseph cultch plant site located in the western MS Sound. The side scan sonar was also used to evaluate two barge groundings sites. The data was processed and input in a mosaic software program for further analysis. This paper will demonstrate the abilities of side scan sonar as a tool for oyster reef management.