Physiological response of Kemp's ridley sea turtles (Lepidochelys kempii) to entanglement net capture

Abstract

Kemp's ridley sea turtles (Lepidochelys kempii) were captured in entanglement nets near Sabine Pass, Tx/La, during May through August, 1996 and 1997. Serial blood samples were collected to: 1) identify physiological effects of capture; 2) determine recovery rates from capture-induced stress; and, 3) evaluate effects of post-capture holding techniques on stress recovery. Captive Kidneys were held either on the netting boat or in an in-water cage to assess the effects of post-capture holding technique on stress physiology and subsequent recovery. Elevated plasma lactate values of 4.5 and 3.5 my were measured at capture in cage- and boat-held Kidneys, respectively. Plasma lactate increased to 6.2 mM in boat-held turtles at 1 h post-capture, while caged ridleys exhibited virtually no change (4.6 mM). The in-water treatment appeared to prevent lactate buildup while boat-held ridleys may have experienced increased breathing effort and associated stress due to their inability to achieve neutral buoyancy in tanks partially filled with seawater. Lactate levels declined in both treatment groups through the remaining post-capture sampling intervals. Baseline lactate levels were achieved in cage- and boat-held ridleys by 6 and 10 h post-capture, respectively. Capture plasma epinephrine (E) and norepinephrine (NE) levels were elevated (approximately 30-40 mM) in ridleys assigned to both treatment groups. A larger reduction in NE and E exhibited by boat-held ridleys at 1 h post-capture may have been due to their limited physical activity in a smaller holding area. Return of NE and E levels to baseline was reached by 3-6 h post-capture in both treatments. Although plasma Na+, Cl-, and glucose concentrations were not affected by entanglement netting, increased K+ levels were measured in boat-held ridleys at l h post-capture. Increased K+ and lactate levels in this treatment at 1 h post-capture suggest a stress mediated ion exchanger may exist in sea turtle cells. No significant differences were detected in plasma osmolarity between and within treatment groups. White cell counts indicate that captured ridleys were not in poor health.