shrimp nursey value of a system be enhanced by controlling salinity regime and 

 water-marsh edge habitat? 



Eugene Turner: The issue is more complex than one salinity zone or the length of edge. 

 Conditions beneficial to brown shrimp may not be benefical to white shrimp, for 

 example. 



Donald Landry: Shrimp production is not a function of the area of saline marsh but of 

 total estuarine area, which is a function of rainfall, riverflow, etc. 



Barney Barrett: An area with a great amount of saline marsh and marsh edge may have 

 higher shrimp production than one with less, but there will be considerable year-to- 

 year fluctuatious due to rainfall, river discharge, temperature and the amount of 

 nursery area. 



Eugene Turner: The long-term average is a function of nursery ground area, which is 

 wetlands, not open water ~ for brown shrimp it is saline marsh, for white shrimp it 

 is brackish and fresh marsh. On top of that, of course, there will be year to year 

 variation. 



Mike Voisin: Because shrimp migrate and vary so much, oysters are a better gauge of 

 estuarine productivity. 



DcxKild Boesch: The point of my original question is to lead to the question of how do we 

 manage the various hydrological units of coastal Louisiana for multi-species 

 production. In some large units (e.g. Terrebonne-Timbalier basin) we may be able to 

 maintain a range of conditions suitable for shrimp, oysters, etc. In smaller areas or 

 areas where freshwater input overwhelms tidal effects (e.g. Atchafalaya Bay) it may 

 be unrealistic to expect production of all these living resources. Should we have a 

 conscious strategy of managing these large systems with salinity gradients for 

 multiple resources and other systems for a single resource? 



David Fruge: For managing large basins we should plan on freshwater diversion managed 

 to retard wetland loss, not necessarily change wetland types. We have also proposed 

 diversions along the lower Mississippi River to create new subdeltas and new marsh. 



Donald Boesch: Then you would manage for maximum wetland vegetation rather than for 

 a particular harvestable resource? 



David Fruge: The resources will occupy the niches that are provided for them. 



Donald Boesch: You would like to manage for grass and Mike Voisin for oysters, that's 

 my point. 



David Fruge: I believe controlled freshwater diversions can do both by promoting marsh 

 growth and protecting oysters from predators. The primary areas being considered 

 for diversions are at Caernarvon, upper Barataria Basin and subdeltas at the river 

 mouth. There isn't yet much opposition to these diversions. Perhaps an oyster 

 fisherman in the immediate vicinity of a diversion would lose production due to 

 pollution or the fresh water itself. Most management agencies, however, are 

 supporting freshwater diversion. 



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