Chapter 11 — Species of Special Concern 



responsible management agencies to maintain and 

 expand the efforts that have been begun. The Com- 

 mission will continue working with those most in- 

 volved to ensure, to the extent possible, that this is 

 done. In this regard, the Commission plans to hold 

 its 1992 annual meeting in Florida and to devote much 

 of its meeting to a review of the status and direction 

 of manatee recovery efforts. Based on its review, the 

 Commission will provide recommendations, advice, 

 and assistance as appropriate. 



Hawaiian Monk Seal 

 {Monachus schauinslaruU) 



The Hawaiian monk seal is the most endangered 

 seal in U.S. waters. It occurs almost exclusively 

 along the chain of small, mostly uninhabited islets and 

 atolls stretching 1,100 miles northwest of the main 

 Hawaiian Islands. Although two other species of 

 monk seals have been described — the Caribbean 

 monk seal (M. tropicalis) and the Mediterranean monk 

 seal (M. monachus) — there have been no reliable 

 sightings of the Caribbean species since 1952, and the 

 Mediterranean species, which may number fewer than 

 500 animals, is one of the world's most endangered 

 seals. Thus, the fate of the entire monk seal genus 

 may depend on the survival of Hawaiian monk seals. 



The five major breeding sites for Hawaiian monk 

 seals are Kure Atoll, Pearl and Hermes Reef, Lis- 

 ianski Island, Laysan Island, and French Frigate 

 Shoals (Figure 1). Nearly half of the species' pups 

 are bom at the last site, which contains the largest 

 colony. Although monk seals likely occurred on the 

 main Hawaiian Islands before human occupation, 

 there is virtually no record of their presence in 

 Polynesian history. Recently, however, a number of 

 sightings have occurred on Kauai and, in 1991, two 

 births were recorded in the main Hawaiian Islands, on 

 Oahu and Kauai. 



Shipwrecked sailors and commercial sealers are 

 believed to have reduced the number of monk seals to 

 very low levels in the 1800s. The first systematic 

 counts of seals were made in the 1950s. By 1983, 

 when the total population (including pups) was esti- 



mated at 1,488 animals, beach counts were roughly 

 half those recorded in 1958. A new estimate of 1,752 

 seals was derived from beach counts in 1988. How- 

 ever, because of assumptions required in calculating 

 these numbers, both estimates are believed to be high. 



Population estimates have not been developed since 

 1988. In part, this is because the National Marine 

 Fisheries Service has been unable to support all the 

 field work needed for such analyses. Based on other 

 population indicators, however, Hawaiian monk seals 

 appear to have declined significantly since 1988. 



Between 1989 and 1990, total recorded births at 

 the major pupping beaches declined nearly 40 percent 

 from the 1988 level and about 30 percent from the 

 average annual level between 1983 and 1988. De- 

 clines were reported at all five major breeding sites in 

 1990. In 1991, the number of births recovered to 

 previous levels at three sites, but continued to decline 

 at the largest pupping colony (French Frigate Shoals) 

 and remained low at Lisianski Island. Total births in 

 1991 (165) remained about 30 percent below the 1988 

 level (224). In addition, at French Frigate Shoals, 

 mean beach counts of juvenile and adult seals declined 

 about 30 percent from 1989 to 1991. Although 

 immature animals have been the primary group af- 

 fected by the decline, counts decreased for all age and 

 sex classes. The data suggest a possible loss of 150- 

 200 animals from that colony. 



The cause of these recent trends is not clear. They 

 may be caused by a combination of human and natural 

 factors that differ from island to island. Among those 

 that may be at least partly responsible are interactions 

 with commercial fishing gear and fishermen, declines 

 in available prey due to over fishing or natural envi- 

 ronmental changes, entanglement in lost or discarded 

 nets or other marine debris, human disturbance on 

 pupping beaches, die-offs due to disease or naturally 

 occurring biotoxins, shark predation, and, on Tern 

 Island at French Frigate Shoals, entrapment in a 

 decaying seawall. In recent years, an additional 

 concern has been a "mobbing" phenomenon involving 

 the death and injury of adult female seals and young 

 animals of both sexes caused by overly aggressive 

 groups of male seals attempting to mate. 



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