MARINE MAMMAL COMMISSION - Annual Report for 1998 



research and monitoring and factors monk seal protec- 

 tion needs into management decisions related to public 

 use of refuge areas. 



Other key agencies and groups whose activities, 

 programs, or responsibilities bear on monk seal 

 recovery include the Army Corps of Engineers, the 

 Coast Guard, the Navy, the State of Hawaii, the 

 Western Pacific Regional Fishery Management 

 Council, the University of Hawaii and the University 

 of Hawaii's Sea Grant Program, the Hawai'i Wildlife 

 Fund, and the Center for Marine Conservation. As 

 discussed in past annual reports, the Marine Mammal 

 Commission was instrumental in initiating the monk 

 seal recovery program late in the 1970s and has since 

 continued to provide advice and assistance to the 

 National Marine Fisheries Service and other agencies 

 on monk seal recovery needs. Important issues in 

 1998 are discussed below. 



Population Trends and Survival 



Little is known about Hawaiian monk seals or their 

 population status before the 1950s. It generally is 

 acknowledged that the species was heavily exploited 

 in the 1800s during a short-lived sealing venture. 

 What is thought to be the last Hawaiian monk seal 

 taken by commercial sealers was killed in 1824 by the 

 crew of the brig Aiona. Some seals were killed for 

 food by shipwreck victims and other transient visitors 

 to the islands. 



The first attempt at estimating Hawaiian monk seal 

 numbers was made in 1958, when a total of 1,206 

 seals was counted. Between then and the mid-1970s, 

 the overall population size declined by about 50 

 percent. During this period, colonies at the western 

 end of the archipelago between Kure Atoll and Laysan 

 Island declined by at least 60 percent, and the colony 

 at Midway Island all but disappeared. Most human 

 activity was concentrated at the westernmost atolls of 

 the chain during this period, suggesting that human 

 disturbance contributed to the decline. The Navy 

 undertook a major expansion of its air facility on 

 Midway Atoll during the 1950s, and in 1960 the 

 Coast Guard established a LORAN station at Kure 

 Atoll that was occupied year-round. As described in 

 the previous annual report, ownership of Midway 

 Atoll was transferred from the Navy to the U.S. Fish 



and Wildlife Service in 1996, and the atoll is now 

 managed as the Midway Atoll National Wildlife 

 Refuge. The Coast Guard closed the LORAN station 

 at Kure Atoll in 1992 and removed most of the man- 

 made strucmres by 1993. 



The decline in monk seal numbers seemed to have 

 slowed by the early 1980s, due primarily to a seven- 

 fold increase in monk seal counts at French Frigate 

 Shoals between the 1960s and mid-1980s. However, 

 the overall population again began to decline in the 

 late 1980s and early 1990s. The downward trend was 

 driven primarily by the colony at French Frigate 

 Shoals, which has been declining significantly since 

 1989. In the mid-1990s total monk seal numbers 

 appear to have stabilized at about 1,300 to 1,400 

 individuals. However, the poor juvenile survival 

 experienced in recent years, especially at French 

 Frigate Shoals, is expected to initiate a renewed 

 population decline because fewer females will be 

 entering the breeding population. 



The poor juvenile survival rate at French Frigate 

 Shoals does not appear to be due to direct human 

 disturbance. Rather, evidence indicates that limited 

 prey availability may be a factor. The small size of 

 pups at weaning, the absence of apparent disease- 

 related deaths, the low female reproductive rate, and 

 the delayed age of first reproduction at this location 

 support this hypothesis. 



Aggressive behavior or mobbing of females and 

 immature seals by adult males also is a source of 

 mortality. This can be a direct result of injuries 

 inflicted by the aggressive males or as a result of later 

 shark attacks on wounded seals or pups chased into 

 the water by aggressive males. During the 1997 field 

 season at French Frigate Shoals, 14 incidents of adult 

 male aggression toward pups were documented, and 

 eight pups subsequently died. Two adult males were 

 identified as being responsible for most of these 

 injuries. After similar behavior by the same animals 

 was observed again in 1998, the two offending males 

 were translocated to Johnston Atoll, located about 

 1,125 km (700 miles) south of French Frigate Shoals, 

 on 8 June 1998. At the end of 1998 neither animal 

 had been resighted at French Frigate Shoals, and the 

 incidence of injury or death caused by aggressive 

 behavior had declined dramatically at this site. 



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