be produced by Perrin's beaked whale, known only from Californian waters. Population Status Data suggests a significant decline in abundance for Mesoplodon spp. in the California Current between 1996 and 2001. Declines are hypothesized to have occurred from the effects of incidental mortality from fishing, impacts of anthropogenic noise (Navy sonar), and ecosystem changes. Since then, the population size of Mesoplodon beaked whales has increased from a mean of 1230 in 2001 to 3439 in 2014 within California Current waters off the U.S. West Coast. Threats Perrin's beaked whales are threatened by attacks from sharks such as the cookiecutter shark (Isistius brasiliensis). As with their relatives, cookiecutter sharks attack this whale with attempts at biting off chunks of flesh. Such attacks are generally not life-threatening to the whale. It is a host of the thoracican barnacle Conchoderma auritum, and for one or several species of parasitic Phyllobothrium cestodes (possibly Phyllobothrium delphini), this species is either a primary or a dead-end host. These whales are vulnerable to naval sonar and seismic activity. Currently, there are no whaling threats for this species. Although Mesoplodon whales were never harvested commercially, there have been reports of them being taken by humans from time to time. Bycatch is likely one of the main threats to this deep-water species due to it causing harm or death to whales entangled in fishing gear. According to the IUCN, this species has the potential to become caught in certain types of fishing gear, such as deepwater gill nets, used for capturing large pelagic fish species. Plastic is also seen as a threat to Perrin's beaked whales because it has been found within the stomach contents of stranded individuals. Specimen USNM 504259 - May 22, 1975; 33°15′N 117°26′W - smallest specimen (4.1 m long), immature male USNM504260 - May 28, 1975; 33°16′N 117°26′W - adult female, probably the mother of USNM 504259 (Dalebout et al. 2002) USNM504853 - September 9, 1978; 33°07′N 117°20′W - adult male, the holotype LACM 088901 JRH 052 - December 27, 1979; 32°55′N 117°15′W - immature male LACM 096355 TMMC-C75 - September 18, 1997; 36°37′N 121°55′W - immature male LACM 097501 DSJ 2348 - October 15, 2013; 33°58′N 118°27′W - mature female Possible sightings may have also 1976 possible sightings took place on July 30, 1976 and September 9, 1978, which was the same day the holotype specimen was discovered (Mead 1981). Altogether, there is a