Depth Distribution of Striped Bass and Other Fish in Lake Texoma (Oklahoma-Texas) during Summer Stratification

In May and June 1982, before stratification, echolocator charts indicated that fish in the main basin of Lake Texoma (Oklahoma-Texas) were distributed from the surface to the bottom. With the onset of stratification and oxygen depletion in the hypolimnion in July, fish moved upward in the water column, avoiding anoxic conditions near the bottom. Stratification (defined more conspicuously by dissolved oxygen and conductivity than by temperature) became progressively more distinct in late summer, and by August temperatures in the epilimnion were greater than 28 C and dissolved oxygen in the hypolimnion was less than 2 mg/liter. Echolocator charts indicated that fish were concentrated immediately above the chemocline (8–12 m deep) where water temperature was 28.5 C and dissolved oxygen was 7.2 mg/liter. This concentration of fish included subadult and adult striped bass Morone saxatilis, which are known to congregate in the main basin of Lake Texoma during the summer. Despite the high temperatures in the epilimnion, and low oxygen conditions in the hypolimnion, no mortality of adult striped bass was observed. Although the available data indicate that a temperature-oxygen “squeeze” is typical in Lake Texoma in numerous summers, the reservoir has a large population of striped bass with many individuals larger than 5 kg.