dried during the summer and reflooded. The temporary drying causes pond bottoms to become 

 firm, thus reducing water turbidity and enhancing the growth of aquatic plants when the area is 

 reflooded (Chabreck 1960). 



This management procedure has been modified on Lake 4 on Rockefeller Refuge to include 

 a fishery management program. Waterways outside the impoundment are periodically sampled 

 for shrimp during the spring and summer. When post-larval shrimp are present in adequate 

 numbers, water control structures are opened on high tides so postlarvae can enter the 

 impoundment. Excellent stocking often results and growth rates are equal to those in natural 

 waters. The impoundment is open to sport fishing and numerous fishermen visit the refuge to 

 harvest shrimp and other fishery resources. 



The relationship of the duck management program to the fishery management program has not 

 been evaluated. The objectives of this study were to investigate the recreational use of impounded 

 and semi-impounded brackish marsh and to evaluate methods of enhancing recreational values. 



METHODS AND MATERIALS 



Study Area 



Rockefeller Wildlife Refuge, a State-owned area in Cameron and Vermilion Parishes in south- 

 western Louisiana, occupies about 30,876 ha of coastal marshes between the Grand Chenier-Pecan 

 Island beach ridge complex and the Gulf of Mexico. The refuge is operated by the Louisiana 

 Department of Wildlife and Fisheries and has been intensively developed for wildlife. The study 

 area includes two brackish marsh impoundments, Lakes 3 and 4, and the semi-impounded Miller 

 Lake weir area, all within the western portion of the refuge. These impoundments all border the 

 Humble Canal, a major outlet to the Gulf of Mexico. The visitor-use survey included all areas 

 accessible via Humble Canal and adjoining canals. 



Lake 3 encompasses 1,740 ha. Water levels are controlled with a concrete, variable crested, 

 reversible flap-gate control structure on the Headquarters Canal in the northeast corner of the 

 unit and are manipulated by gravity drainage. The primary management objective is the 

 propagation of important waterfowl food plants. Emergent, perennial vegetation grows on over 

 49.7% of the area; the remainder of the area is shallow ponds except for a canal 10 m wide along 

 the east side. 



Lake 4 encompasses 2,270 ha, of which 53.4% contains emergent, perennial vegetation and the 

 remainder is shallow water area. Canals border the west and south sides of the impoundment. 

 Water levels are controlled with a concrete control structure containing seven variable crested, 

 aluminum flap-gates located in the southwest corner of the unit. Wicker et al. (1983) provided a 

 detailed description of this control structure. The primary management objectives are centered 

 around the multiple-use of the unit by both estuarine fisheries species and waterfowl species. The 

 water control structure is operated to allow postlarvae shrimp and fishes to enter the unit during 

 times of peak abundance, yet water levels are maintained to produce conditions favorable to the 

 growth of widgeongrass (Ruppia maritima) and other waterfowl-food plants in the ponds and to 

 maintain water depths (0.4 m) necessary for dabbling ducks to feed. 



- The Miller Lake weir area encompasses 2,480 ha of brackish to saline marsh and shallow open 

 water bodies and receives no special management. Two weirs are located in the east levee system 

 and permit tide water from the Humble Canal to flow in and out. The weirs reduce tidal exchange 



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