MONTHLY LHNDINGS 
JFMRMJ J RSOND 
i i i i i i i i i i i 
OYSTERS 
BLOE CRRBS 
BRIT SHRIMP 
COMM. SHRIMP 
REC. FISH 
COMM. FISH 
LOW 
MEDIUM 
HIGH 
CLOSED [=□ 
Figure 2.6. Seasonal landings by commercial (comm.) and recreational (rec.) fisheries in Galveston Bay (54,56). 
precisely where houses, industry, bulkheads and other of man's accomplishments are now located. 
Thus, the actual wetlands area will be much less than 360 square kilometers. 
What does this signify for fisheries and for estuary-dependent species in general? As sea level 
rises and marsh retreat is impeded by civilization, the acreage of wetlands accessible to fishery 
organisms and contributing to their life cycles will decline, and shortly thereafter so will the fisheries 
that are currently harvested (58). In the meantime, marshes will be inundated for increasing amounts 
of time and thus will become "drowning" marshes on the way to extinction. This is a temporarily 
beneficial situation for the various fishes, invertebrates, birds, reptiles and mammals that utilize the 
marsh surface, since marsh utilization may be promoted by increases in (1) estuarine area, (2) 
duration of flooding and thus access, and (3) marsh-open water interface for materials exchanges. In 
other words, for an interim period greater marsh access could lead to greater system productivity 
(58). 
Galveston Bay itself may be too small to detect the results of apparent sea level rise, although as 
mentioned previously shrimp catches are increasing and may be due in part to increased marsh 
access. However, on a Gulf of Mexico basis, the increased access to marshes due to drowning has led 
to detectable increases in recruitment of at least three commercial species for which a long-time series 
of data is available — gulf menhaden, brown shrimp and white shrimp (Figure 2.9) (58). From 1960 
through 1985, catch statistics and population analyses have detected a 200 percent increase in the 
number of young gulf menhaden harvested and 50 percent increases in abundances of newly 
recruited shrimps. The effects of marsh disintegration are beginning to show up. 
Freshwater Inflow and Saltwater Intrusion 
Another problem facing the Galveston Bay biota is that of controlling fresh water and the 
associated change in salt water distribution. Two species of economic importance that are especially 
influenced by fresh water are oysters and white shrimp. 
45 
