HALOTHANE ANESTHESIA AS A METHOD OF IMMOBILIZING FREE-RANGING CALIFORNIA SEA LIONS (ZALOPHUS-CALIFORNIANUS)

Thirty free-ranging California sea lions, Zalophus californianus, incl uding 20 adult females (approximate individual weight of 100 kg) and 1 0 newborn pups (average weight 7.9 kg) were anesthetized using halotha ne and oxygen on San Miguel Island, California. The halothane was deli vered through a precision, out-of-circle vaporizer in a portable semic losed circle system anesthesia machine. Sea lions were monitored for r espiratory and heart rates, and time of capture, induction, and durati on of anesthesia were recorded. Twenty-nine of the 30 sea lions recove red uneventfully; one adult female became apneic and died despite resu scitation efforts. Adults had significantly lower heart and respirator y rates than pups, although induction, anesthesia, and recovery times did not differ between age groups.