Physiological Effects of Capturing Striped Bass in Gill Nets and Fyke Traps

Abstract

Adult striped bass Morone saxatilis were captured in 20–40-min gill-net sets in the San Joaquin River, California, and in 24–48-h fyke-trap sets in the Sacramento River as part of a tagging program. They were bled by cardiac puncture for various measurements of stress responses to capture and handling. Fish caught in gill nets were more lethargic, were kept longer out of water, and were significantly more acidotic (lower blood pH and higher lactate concentration) than fyke-trapped fish. Gillnetted fish also had a significantly higher Pco2, hematocrit, and plasma glucose and potassium concentrations than fyke-trapped fish. Both capture methods induced secondary stress responses, but responses were greater in gillnetted fish, probably because gill nets restricted buccal and opercular movements.