California sea lion (Zalophus californianus), one with a number 6789 branded in its hide by researchers in Astoria,Oregon. Here is an excerpt from the Oregon State website about branding. "...have been trapping and branding California sea lions in Astoria since 1997 as part of long-term study to monitor the movement, feeding habits and migration patterns of the animal in the Columbia River and along the Pacific Coast. By re-sighting individual animals throughout their lives, we can learn about age-specific survival, habitat use, age at sexual maturity, reproductive rates and longevity. All of this information is crucial to understanding sea lion life history in order to insure the overall health and well-being of the population...Branding is the only permanent way to mark a California sea lion. Wildlife managers have been hot branding seals and sea lions for over 50 years. The process is not inhumane. All of our capture and marking procedures have been reviewed and approved by our Institutional Animal Care and Use Committee, which includes experience veterinarians, species experts, and unaffiliated members of the general public, as dictated by the federal Animals Welfare Act...The hot brand is applied for 2-3 seconds to burn the hair and the very top layer of skin so the hair can’t grow back. While the process and the brand itself may look painful and raw to us, the skin of a California sea lion is very different that than of a human. It’s thicker and tougher, and has few nerve endings. Since 1997 we have branded nearly 1,400 California sea lions in Astoria. In that time, we have never had an animal die due to branding. In fact, most sea lions react very little to the branding event."