An ecological study of the Gulf Menhaden (Brevoortia patronus) in a low salinity estuary in Texas.
Holcomb, H.W., Jr.
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An ecological study of Gulf menhaden, Brevoortia patronus was conducted in the lower Trinity River, upper Trinity Bay of Texas from May 1966 to May 1968. Hydrological conditions were recorded and specimens were collected on regular semimonthly trips to the study area. A preliminary investigation as to the utilization of the area by menhaden was made in an attempt to determine the future effects of the construction of the proposed Wallisville Reservoir. Menhaden utilized the study area as a nursery ground during aall months of the year and may face seasonal temperature variations from 2.5 degrees C to 35.5 degrees C and salinity changes of 0.04 o/oo to 15.63 o/oo. Postlarval Gulf menhaden entered te study area during a November-June period with the exact time of greatest influx dependent on temperature, time of spawning, and offshore currents. Movement from the study area is during a December-February period with the exact time of movement dependent on salinity. Growth rates of postlarval Gulf menhaden in the study area agrees with the rates reported for other areas of the Gulf Coast. The construction of the proposed Wallisville Reservoir will destroy approximately 50% of the area studied for this report and which is utilized by young menhaden, while movement of the dam only five miles or more upstream would eliminate this destruction. Placement of the dam at the present site will isolate menhaden from nursery areas and will cause permanent declines in the number of menhaden utilizing the study area.