Sea lions and buoys, a battle of wills and wit

All of National Data Buoy Center´s (NDBC) 23 Pacific coast buoy stations are in the range of Zalophus californianus californianus, a sea lion found in U.S. waters. Sea lions are very social animals that congregate in colonies on land and travel together in “rafts” at sea. In recent years, the sea lion population seemed to increase. The sea lions´ penchant for sunning themselves on buoy decks has caused considerable problems for NDBC. To stop them from causing problems on the buoys, sea lion behavior had to be understood. NDBC personnel spent considerable time learning the habits and capabilities of sea lions. With that understanding, a solution that has proven effective to date was developed. The solution, a “sea lion fence”, has been tested on the buoy at station 46050, off Newport, OR, and is being installed on ten additional buoy stations on the Pacific coast. The authors describe the problems that sea lions have caused NDBC. They discuss how the understanding of sea lion behavior led them to conclude that the animals were compressing the hatch seal and allowing water intrusion. The symptoms of water intrusion, and the results of water intrusion are included. The effect sea lions have on wave data and the approach used to analyze wave data are also discussed. Finally, they explain the “sea lion fence” design and discuss their successes as a result of its use