(widgeongrass) is the dominant seagrass throughout the Mobile Bay and 

 Perdido Bay systems. It serves as a primary food source for ducks and marsh 

 birds (Stout and Lelong 1981). The most common seagrass in marine areas is 

 Halodule wrightii (shoalgrass) . It is prevalent at the entrance to Peraido 

 Bay and in Mississippi Sound (Stout and Lelong 1981). Intermingled with 

 Halodule plants, but in lesser numbers, are patches of Thalassia testudinum 

 ( turtle grass) (Stout and Lelong 1981). Thalassia is the most abundant 

 seagrass in the Gulf of Mexico as a whole, although it is less common in 

 Alabama waters. All of these grasses contribute detritus to estuarine and 

 marine systems and are important as primary producers, but their most 

 valuable function is to provide protected nursery areas for larval and 

 immature finfish and shellfish. 



The mapped grassbeds on the atlas quad sheets utilize the most recently 

 available data (Stout and Lelong 1981, 1982) but are not differentiated by 

 species. Figure 2 shows a comparison of submerged aquatic vegetation along 

 the lower Mobile Delta from 1957 to 1981. Since early inventories utilized 

 differing methodologies, exact changes in areal coverage and species composi- 

 tion are difficult to assess. However, it appears that overall species 

 diversity and total areal coverage have declined. Eurasian watermilfoil has 

 become the predominate species in Alabama and is expected to increase in the 

 future. The total area of submerged aquatic vegetation in Mobile and Baldwin 

 Counties is estimated to be approximately 5,500 acres with the largest area 

 (4,300 acres) in the Mobile Delta. Eurasian watermilfoil accounts for 

 approximately 35% of total SAV acreage (Stout and Lelong 1981). 



SHELLFISH HARVEST AREAS 



Shrimp (Panaeus spp.) 



The shrimp fishery is tne most important commercial fishery in Alabama. 

 Since 1950, when the annual catch was approximately 5,000,000 lb, the amount 

 of shrimp landed in Alabama annually has generally increased, although 

 variations in this trend have occurred (Figure 3). In 1977, a peak year, the 

 shrimp fishery landed approximately 25,000,000 lb of shrimp which comprised 

 12% of the weignt and 91% of the value of the total Alabama seafood landings 

 (Heath 1979). Landings in 1983 totaled more than 15,000,000 lb with a value 

 of over $40,000,000, 93% of the total value of seafood landings in Alabama 

 (Table 4). There is some indication that catch per unit of effort has 

 declined and that the present rate of exploitation is near maximum (Swingle 

 1977). 



Ninety-nine percent of the shrimp caught off coastal Alabama spend at 

 least part of their life cycle in tne estuaries of Alabama; Mobile Bay is 11%, 

 of this system. Three shrimp species -- brown shrimp (P^ aztecus ) , wnite 

 shrimp (P. setiferus) and, to a limited extent, pink shrimp (P. duorarum ) -- 

 are commercially important species harvested off coastal "Alabama [Heath 

 1979). All shrimp spawn offshore. Peak immigration of post-larvae into the 

 estuaries is from March to April for brown shrimp and June to September for 

 white shrimp (Christmas and Etzold 1977). Juvenile brown and white shrimp 

 leave the estuaries for deeper waters in the spring and fall, respectively 



in 



