are on the low end of the scale for Texas estuaries (1), which are, in turn, on the low end of the range 
of estuarine production in general (44). Second, zooplankton densities (the main consumers of 
phytoplankton) are also on the low end of the ranges seen in other Texas estuaries (1). Third, salt 
marsh productivity is higher in Texas than in most other Atlantic and Gulf coast states (63). Finally, 
the macrobenthic and fish faunas are omnivores or carnivores except in their earliest larval stages 
(47). 
Habitat Utilization 
Vegetated habitats serve other functions than providing direct or indirect sources of food. Aside 
from these, wetlands function as natural water treatment plants for nutrients and wastes, provide 
aesthetic value, control biogeochemical cycles of elements such as nitrogen and sulphur, buffer 
inlands from storms and reduce flooding, and provide useful products such as lumber. Perhaps the 
most significant functions of wetlands for estuarine organisms are provision of nursery areas for 
feeding, refuge and substrate utilization by other organisms. In a Spartina altemiflora marsh, 
densities of crustaceans such as Palaemonetes pugio, Callinectes sapidus and Penaeus aztecus and 
fishes such as Lagodon rhomboides, Fundulus spp., Sciaenops ocellatus and Cynoscion nebulosus 
were all significantly higher in flooded marsh areas than in adjacent non-vegetated waters (23,49). 
During most seasons, densities of juveniles of many commercially, recreationally and ecologically 
important fishes and crustaceans are higher in vegetated habitats such as salt marshes, fresh marshes 
and seagrasses around Galveston Bay than in adjacent open waters (Figure 2.3, from 50). There are 
indications that the vegetative structure provides refuge from predators and foods (such as epiphytic 
algae and high densities of infauna) not found in open waters (50-52). The connection between 
amounts of vegetated habitats and fisheries productivity in adjacent waters has been demonstrated 
worldwide. For example, landings of brown shrimp in nearshore Louisiana waters have been 
directly linked to the amount of salt marsh vegetation present (53). Thus, wetlands habitats are quite 
valuable in many aspects. 
Fisheries 
The Galveston Bay system supports a wide variety of species in its bay and nearshore commercial 
and recreational fisheries (Table 2.12). In 1986, commercial fisheries landed more than 10,000 metric 
tons of seafood with a dockside value exceeding $26 million for the top 10 species alone (Table 2.13). 
The commercial catches were dominated by invertebrates such as brown shrimp, pink shrimp and 
white shrimp (totaling 6.8 million kilograms), blue crabs (1.4 million kilograms) and oysters (1.6 
million kilograms, whole) (54). Southern and gulf flounders and Atlantic croaker were the dominant 
finfishes. The 1986 recreational fisheries landed in excess of 280 tons, primarily of sportfishes such 
as spotted seatrout, sand seatrout, southern and gulf flounders, Atlantic croaker and redfish (55). 
Since 1960, landings of penaeid shrimp, oysters and blue crabs have been relatively stable given 
some degree of annual fluctuation (Figure 2.4) (54, 56). Some abrupt changes have been due to 
regulatory actions such as closing of bays to oyster harvesting after heavy rainfall and pollutant 
loading. An apparent upward trend in shrimp landings is in part due to increasing inshore fishing 
effort but may also indicate increasing marsh access (discussed later). Fluctuations in finfish landings 
since 1975 (Figure 2.5) (54, 55) were primarily due to regulatory actions in the face of heavy 
commercial and recreational fishing pressure on spotted seatrout (Cynoscion nebulosus) and 
redfish (Sciaenops ocellatus) in the late 1970's. Commercial landings of spotted seatrout and redfish 
were banned, thus the decline seen around 1980. The commercial fishery is now increasing, with 
flounders the dominant species and mullets, Atlantic croaker, black drum and sheepshead next in 
importance. Recreational fishing, now controlled by size and bag limits on certain species, has 
stabilized and is led by landings of spotted seatrout followed by sand seatrout, redfish, flounders and 
Atlantic croaker. 
A synopsis of commercial and recreational fisheries (Figure 2.6) indicates that landings are 
generally highest in summer and fall months, with the exception of oysters that are a winter-spring 
harvest with public reefs closed during the warm months. The blue crab fishery reaches a maximum 
in early summer. The bait shrimp fishery is most productive in summer and fall, coincidently when 
both demand and supply are highest. The bay commercial shrimp fishery has two seasons separated 
by closures: a June and July fishery for brown shrimp (Penaeus aztecus) and an August through 
39 
