Ecology of Nursery Areas 



Anthony Inglis 



The role of the inshore waters in the economy of the seas requires 

 clarification, but we know that many species of marine fishes and invertebrates 

 spend at least part of their early life histories in these rich and shallow waters. 

 The brackish streams, marshes, lagoons, and bayous, which are components 

 of estuarine systems, have even been commonly referred to as "nursery areas" 

 by both the scientist and the lay fisherman. 



Since 1957, studies have been made on the ecology of nursery hab- 

 itats in segments of the Galveston Bay system. Lufkin Bayou on the south shore 

 of West Bay was first chosen for a study on the habitat differences of the three 

 commercially important shrimps, the brown, white, and pink, but had to be 

 abandoned a year later due to dredging in the area. In 1958, Clear Lake, a 

 bay on the western shore of upper Galveston Bay, was selected because it sup- 

 ports a large and successful bait shrimp fishery. In I960, the study was ex- 

 panded to include Offatts Bayou, a deeper, more saline, and less turbid water 

 body situated in the western part of the City of Galveston on Galveston Island. 

 Offatts Bayou supports no major fishing with the exception of a winter sport 

 fishery for the spotted seatrout, Cynoscion nebulosus. In the winter of 1961, 

 the study of a fourth area. Trinity Bay, was undertaken to determine the prob- 

 able effects on the estuarine fauna of reduced Trinity River discharge due to 

 numerous engineering projects planned for the watershed. A report on the 

 Trinity Bay studies appears elsewhere in this report. 



For convenience 

 this discussion is limited 

 to the 24-month period May 

 1960 to April 1962, during 

 which field investigations 

 in Clear Lake paralleled 

 those in Offatts Bayou. Bi- 

 weekly sampling carried 

 out at each location on al- 

 ternating weeks included 

 hydrological and meteor- 

 ological observations as 

 >vell as S-nninute trawl 

 hauls for biological spec- 

 imens. Both surface and 

 bottom temperature as well 

 as salinity were measured. 



•c 



MAY JUN JUL AUG SEP OCT NOV DEC JAN FES MAR APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB MAR APR 

 1960 1961 1961 1962 



Average monthly bottom salinities and temperatures 

 for two Galveston Bay habitats. 



47 



