Hooking mortality and physiological responses of striped bass angled in freshwater and held in live-release tubes

Mortality and physiological responses of adult striped bass Morone saxatilis angled from Lake Murray, South Carolina, and held in live-release tubes were evaluated during the spring and summer of 2003. To estimate mortality, we attached external ultrasonic transmitters to 59 striped bass (mean total length [TL] = 585 mm). Striped bass were caught with angling gear, tagged, and immediately released or held in live-release tubes for 2, 4, or 6 h prior to release. No mortality of striped bass was observed during spring. Overall mortality during summer was 83%. Mortality of summer-caught striped bass was not related to tube residence time, fish TL, depth of capture, or Surface water temperature. To characterize physiological stress, we measured the plasma cortisol, glucose, lactate, and osmolality levels of 62 additional striped bass (mean TL = 563 mm) that were angled and immediately released or angled and held in live-release tubes. Plasma cortisol, glucose, lactate, and osmolality were positively related to tube residence time. When the hematological characteristics were considered only in relation to tube residence time, responses indicative of physiological stress continued for about 150 min, after which blood chemistry began to return to normal. Live-release tubes appear to be useful for keeping striped bass alive when they are angled from cool water, but they are not effective for striped bass angled from warm water. The high summer mortality of striped bass suggests a need for restrictive fishing regulations during the summer for the Lake Murray striped bass fishery.