Utilizing Free Contact Techniques with an Aggressive California Sea Lion (Zalophus californianus) to Establish Hearing Thresholds in the Open Ocean Environment

摘要

Recently a research program to measure hearing thresholds with two California sea lions (Zalophus Californians) was initiated at the Space and Naval Warfare (SPAWAR) Systems Center in San Diego, California. This research was designed to assess the effects of dive depth and the resultant increase in static pressure on auditory sensitivity to a maximum depth of one hundred meters. One of the test subjects had a well-documented history of aggression towards handlers, and was considered unsuitable for open ocean work. Due to this unpredictable nature, he was kept separate from the other working animals in an enclosure with one older non-working animal. Because he was not being utilized by any of the other programs, a decision was made to employ this particular animal for the study. A detailed training program was devised utilizing a variety of free contact and confined contact handling techniques. While working with this animal in a free contact scenario, a consistent distance was maintained which effectively eliminated all stereotypical flight of defense/ critical reactions towards the trainer. This paper will examine the results of this specialized approach and how the procedural methodology was incorporated into the experiment itself.