Contingency Plan for Hawaiian Monk Seal Unusual Mortality Events
Contingency Plan for Hawaiian Monk Seal Unusual Mortality Events
Contingency Plan for Hawaiian Monk Seal Unusual Mortality Events
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evaluations) are per<strong>for</strong>med in the field; these preliminary findings, as well as descriptions<br />
of gross lesions or clinical signs observed, are reported to the <strong>Monk</strong> <strong>Seal</strong> Assessment<br />
Program and <strong>Monk</strong> <strong>Seal</strong> Health and Disease Program. These measures increase the<br />
likelihood of timely detection of an unusual mortality event, allowing a response to be<br />
mounted within the field season if deemed appropriate.<br />
Known causes of mortality in <strong>Hawaiian</strong> monk seals include emaciation of juveniles,<br />
tiger and Galapagos shark attacks, male aggression (individual and multiple), deleterious<br />
fisheries interactions, and entanglement in marine debris (Balazs and Whittow, 1979;<br />
Kenyon, 1981; Henderson, 1985, 1990; Alcorn and Kam, 1986; Banish and Gilmartin,<br />
1992; Hiruki et al., 1993a, 1993b; Nitta and Henderson, 1993; Starfield et al., 1995).<br />
Disturbance of pregnant or nursing females likely causes them to desert preferred<br />
pupping beaches, resulting in decreased pup survival (Kenyon, 1972; Kenyon, 1981).<br />
Maximum age is believed to be 25-30 years, but few seals live this long (NMFS,<br />
unpublished data).<br />
The influence of disease on monk seal populations is not well understood, but is an<br />
active area of research (Aguirre et al., 1999; Aguirre, 2000; Appendix A, <strong>Hawaiian</strong> <strong>Monk</strong><br />
<strong>Seal</strong> Specimen Collection Protocol and Appendix B, <strong>Hawaiian</strong> <strong>Monk</strong> <strong>Seal</strong> Necropsy<br />
Protocol). Infectious and noninfectious diseases have been reported in <strong>Hawaiian</strong> monk<br />
seals but do not appear to be impeding population recovery: all wild seals carry parasites;<br />
dental and skeletal abscesses and pathology were the apparent causes of death in one<br />
aged seal; and biotoxins may pose a serious risk (Golvan, 1959; Rausch, 1969; Kenyon<br />
and Rauzon, 1977 [cited in Kenyon 1981]; DeLong, 1978; DeLong and Gilmartin, 1979;<br />
Gilmartin et al., 1980; Whittow et al., 1980; Dailey et al., 1988). Of the 15 Marine<br />
Mammal <strong>Unusual</strong> <strong>Mortality</strong> <strong>Events</strong> (UMEs) occurring in other marine mammals species<br />
since 1992 (Dierauf and Gulland, 2001: 72-73, Table 1), infectious diseases and biotoxins<br />
were the most common diagnoses (five cases each). Other factors implicated in UMEs<br />
included fisheries interactions, ship strikes, and large-scale decadal changes in oceanic<br />
productivity (Polovina et al., 1995).<br />
In a recent review of emerging and resurging diseases in marine mammals, Miller et<br />
al. (2001) describes three ways in which wildlife species may be exposed to emerging<br />
diseases (newly evolved or newly identified as pathogens), all three of which are<br />
applicable to <strong>Hawaiian</strong> monk seals. The first is exposure via spillover from domestic<br />
species or humans. Many recent reports of transmissible diseases in marine mammals<br />
have included organisms traditionally associated with domestic animals and humans<br />
(e.g.; Brucella sp., Ewalte et al., 1994; Ross et al., 1994; Jepson et al., 1994;<br />
Mycobacterium bovis and M. tuberculosis, Forshaw and Phelps, 1991; Cousins et al.,<br />
1993; Woods et al.; 1995; Bernardelli et al., 1996). The second method of exposure is via<br />
rehabilitation or translocation of animals (e.g., Stamper et al., 1998, reports the possible<br />
spread of leptospirosis from skunks to rehabilitating harbor seals). The third way that<br />
wildlife species may become exposed to emerging diseases is through the effects of<br />
environmental phenomena such as El Niño and large-scale climate change on the<br />
proliferation or spread of infectious organisms (Fauquier et al. 1998; Harvell et al., 1999;<br />
Reddy et al. 2001). Another source of exposure to infectious diseases in <strong>Hawaiian</strong> monk