Association ofofWUdlifeand Wildlife and Human Society

BiosphereConservation 1 (1) :45-48, 1998

Halarachnidmites infesting respiratory tract of Steller seathelions

Keaji Konishi and Keaji Shimazaki

Research institute ofIVbrth Pacijic Fisheries, Hbkkaido Uhiversic" 1-1, Minatocho 3 chome, Hbkodate, Hbkkaido, 041 Japan

Abstract sea lions Steller (Eumetopiasjubattts) are infested by many parasites through various routes, including preclator-prey relationships and contacts with other sea lions. However, we know little about the life histeries of these parasites. Ihis paper discusses a nasal (Orthohatarachne attenuata) that infests the respiratory tract of

Stel]er sealions. Of22 sea 1ions sampled around Hokkaido in 1996, the nasal cavities of 12 were infested with the

. An average of 23 mites were found in each infested . Ihere was no correlatien between the age ofthe

sea lions and the number ofmites they contained. The heads of9 pups were also examined to cleterrnine when first infestation occurred. No pups were infested and none had inflamed nasal cavities. Key words: Eumetapiasjubatus, , mite, parasite, pinniped

INTRODUCI'ION that of the pinnipeds; this suggests that the lice may

have evolved with each host, although there is no evi-

Steller sea lions (Eutnetopiasjubatus) range from dence about the evolutional background of the lice.

the coast of northern Japan, across the North Pacific However, we need to know the biologica] chaTacteris-

to southeTn California and are cleclining in numbers tics of the mites before they can be used as conspicu-

over most of their range (Loughlin et al., 1992). As ous indicators of Ste]ler sea lions, In the present pa-

the population continues to decline, particularly in the per, we discuss a species of mite that can be used as a

western Pacific Ocean, it becomes essential to deteT- b{o-indicator of Steller sea lions.

mine the cause of the decline and to elucidate the rela- The genera Hdlarachne and Orthohatarachne,

tionships that may influence management decisions and which infest the respiratory tract ef their hosts, are

guide future research. However, even seemingly simple widely distributed among pinnipeds and sea otters: O.

studies, such as counting, tagging and collecting attenuata and O. dimunuata commonly infest Otaridae

samples, are difficult. Thus, it is often useful to obtain (e.g. Kenyon et al., 1965; Fay & Furman, 1982). They information by more indirect means. In that regard, are generally believed to be transmitted between hosts

parasites are a useful resource of information and have through the sneezing, coughing or smelling behavior

been used as an alternative method for studying host of the hosts, and heavy infestation by these mites can

species, especially in recent fish surveys. Forexample, cause impairment in the hosts (Kim et a],, 1980; Ne]son

Nagasawa & Maruyama (1987) reported the abundant et al., 1977). Steller sea lions are also infested with differences of parasites on brown sole (Limanda these two species (Newell, 1947). TTiese species prob- heneensteini) between two areas. Furthermore, Kim et ab]y coevolved with their hosts over a long period as a], (1975) docurnented that lice infest the skin of pin- estimated by the host specificity (Furman, 1979). Thus,

nipeds. The geographical variation of the lice matched Orthohalarachne spp. have coevolved with Otarid spe-

This article was presentcd at the Tbdo (Steller sea lion) Symposium. Sapporo, March, 1997, orgunized by Ohtaishi, N. and K. NNlada.

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sea lion skulls which were used afterwards for a sepa-

rate study. The pharynges of 12 were infested d .. with O. attenuata (Fig. 2), The mites were preserved - ･l ' in 70% ethanol and iclentified to species with amicro- scope.

In the second part ofthe study, we boarded the Rus-

sian vessel Daria and visited four major Steller sea

RcbunIs, v lion rookeries on the Kuril Islands such as Antsiferova

Island, Lovushki Rocks, Raykoke Island and Brat

en. Chirpoev Island, to collect dead Steller sea lion pups

from the rookeries during earlyJuly in 1996. We col-

lected 3 from Antsiferovo, 3 from Lovushki, 1 from Shakotan Raykoke and 1 from Brat Chirpoev (Fig. 3). VVe col- lected only pups that had Tecently died. [[1ie heads were

removed and sent to the KamchatTybvod Laboratory

in Petropavlovsk Kamchatky, where we examined the

nasal cavities and the pharynges to determine whether

pups were infested with mites or not. Fig. 1. Sites where Stel]er sea lions were collected in the first part The data of the age of each anirnal were supplied ofstudy. by Isono (1997)

cies and could show moTpho]ogica] ancl genetic varia- tions if the host populations have separated into dif-

ferent stocks.

Thus, mites may possibly be used to assess the stocks or populations of the Steller sea lion. However, we know ]itt]e about the life histories of these mites. Ki.･ ,ii 1i> In this study, we first examined the state of mites in e li,I.,l,. StelleT sea lions of different age. Second, we exam- k smm ined when initial infestation by mites occur in new- f /i) J! born pups to determine the influence of transmission i: from mothers to l pups. ,, x'Lli MATERIALS AND METHODS i li, 1ii ii iiL ･[' ii From January to March in 1996, the 22 Ste]ler sea ! ]ii// / lions examined in this study were collectcd by shoot- ii1 [, /,, 11 i ,/B contTol at two sites: off ,t- ing for population Rebun Is- li land and off the Rausu Peninsula in Hokkaide, Japan i[. tl 1). The heads were removed, frozen and sent to (Fig. t ,1 11 1,, the laboratory. In this study, we co]lected mites only L. .i

from the pharynx, because of the difficulty of collect- Fig. 2. 0rthohatarachne attenuata Banks. A, female dorsal view; all mites the nasal cavity without cutting the ing from B, rnale dorsal view (scale bar represents e,5mrn).

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tween sea lion age and the number of mites present.

Few mites were collected from 11 and 13-year-old

animals, but a 12-year-old sea lion was heavily infested.

This suggests that the nurnbeT efthe mites could change dramatically.

In the second part of study, no mites were found frem nasal cavities or pharynges of pups collected at

the Kuril Islands. FurthermoTe, none of the sea lions

had eroded or infiamed skin; all had healthy mucus

membranes, indicating that these anima]s had never

been infested by mites,

Since this survey was conducted in early July, the

pups were about one month old. In a previous in vitro

study, ]arval mites molted twice and became adults

after 15 days (Furman & Smith, 1973), so 1-month-

old pups aTe old enough to be infested.

DISCUSSION

Steller sea lions were infested by at least 2 years of

age, possibly even earlien The number of mites did

not appear to increase with increasing sea lion age.

These results are probably due to the transmission sys- Fig. 3. Sites where dead Steller sea lion pups were collected in the tem of the mites, however, there are some other pos- second part of the study in early july, 1996. The islunds we sible explanations, including low productivity of the visited are in the midd]e to northern purt ofthe Kuri] ]sland, mites, loss of larvae during transmission to other hosts and include the major Stellersea lion rookeries,

and a host immune response caused by the mites.

These factors would increase the morta]ity of the mites.

RESUIilrS In 7 Steller sea lions from Alaskan waters examined by Fay & Furman (1982), all were infested with

In the first part of this study, O, attenuata was found halarachnid mites. They also examined 99 harbor seals

in the pharynges of 12 of the 22 Steller sea lions ex- (Phoca vitulina) from Alaskan waters to determine the amined (Fig. 2). As reported in other articles, only adult frequency of occurrence ofhalarachnid mites. About

O. attunuata were found. About 95% of the mites were 75% of the seals were infested, including a 3-month-

females. The numbers of mites in each sea lion ranged old pup, The number of mites (Hb larachne halichoeri)

from 1 to 79 (Table 1), There was no correlation be- ranged from 5 to 59 adults, and 6 to 87 larvae. More-

1lable 1.Number of O, attenuata (female adu]ts) found in pharynges of Steller sea lions and the ages of the sea lions. SamplingnumberofStellersea1ions 12345678910

' Age of Stelter sea lion (years} 27343223454214686131111279133 N=10Average26.3 No,ofO.attenuata

' From data supptied b)' T. Tsono, Research 1nstitutc of North Pacific Fisheries, Hokkaido University.

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over, no correlation occurTed between the age of the Pallas,andotherpinnipedsofAlaskanwaters,Jour-

harbor seals and the number of mites, similar to our nal of Wildlife Diseases, 18:63-67.

results. Nthough the genera are different, the trans- Furman, D. P. (1979) Specificity, adaptation and par-

mission routes are thought to be similar, There are allel evolution in the endoparasitic of

many oppotunities for mites to be transferred between mammals. Recent Advances in Acarology, 2:329-

sea lion mothers and pups, however the pups that we 337.FuTman, examined were not infested duTing the first month af- D, P & A.W. Smith (1973) in vitro develop-

ter birth. There are some possible explanations, such ment of two species of Orthohalarachne and adap- as behavioral difference between mother and pup, and tations of the life cycle for endoparasitise in mam-

amongjuveniles or adults. Nevertheless, further stud- mals, JouTnal ofMedical Entomology, 10:415-416.

ies are Tequired to address the question of mite trans- Isono, T. (1997) The development of external mor-

mission and its re]ationship to sea lion behavior. phology, skull and canines of the Steller sea lion.

HalarachnidmitesaregeneTallybe)ievedtoevolvewith M.C. thesis, Hokkaido Univ,, Sapporo, 80p.

their hosts (Furman, 1979) and appeaT to have estab- Kenyon, K.W., C. E. YUnker, & I. M. Newel] (1965) The lished a reasonably benign association with their hosts. Nasal mites (Ha]achnidae) in the Sea Otter.

The above results support this hypothesis. Although, Journal of Parasitology, 51:960.

Keyes Popu- host-specific relationship show evidence of parallel Kim, K. C.,VL L Haas,& M. C. (1980) evolution between halarachnid mites and Steller sea lations, microhabitat preference and effects of in- lions, it･is of much interest to clarify the mite festation of two species of Orthohalarachne evolutional history using morpholegical and DNA (Halarachnidae: Acarina) in the northern .

analysis for comparison with that of the Steller sea Jollrnal of Wildlife Diseases, 16:45-51, lion. Kim, K, C., C. A. Repenning & G.V: Morejohn (1975) Specific antiquity of the sucking lice and evolution ACKNOWLEDGMENTS of Otariid seals. Rapports et Proces-Verbaux des Reunions Conseil International Pour Uexploration

NVb thank the hunters for providing the samples, and de la mer, 169:544-549.

Dr. Bower and Dr. Loughlin for correcting the English Loughlin, T, R., A. S. Perlov & VA, V]adimirov (1992) of total number text. The first part of study was supported financially Range-wide survey and estimation

by the Sasagawa Scientific Research Grant frorn the of Steller sea lions in 1989. Marine Mammal Sci-

Science Society. ence, 8:220-239,

The second part of our study was conducted in con- Nagasawa, N. & S, Maruyama (1987) Occurrence and nection with Russian research related to the branding effects of Hbemobaphes diceraus (Copepoda:

of Steller sea lions in July, 1996. We appreciate the Pennellidae) on Brown So]e Limanda heTzensteini

cooperation of Kamckatrybvod, the crew members of off the Okhotsk Coast of Hokkaido. Nippon Suisan

the Russian vessel Daria and all other participants, Gakkaishi,53:991-994.

M. Cliffbrd J, Finally, we would like to express our thanks to Pro- Nelson,WL A.,J,E Bell,C. & E.Keirans fessor Dr. Ohtaishi for organizing this symposium and (1977) Interaction of ectoparasites and their hosts.

giving us the opportunities to present this paper, Journal of Medical Entomology, 13:389-428. Newell, I. M. (1947) Studies on the morpho]ogy and REFERENCES systematicsofthefami1yHalarachnidaeOudemans, Bul]etin of the Bingham Oceanographic Col]ection,

Fay, H. E & D. R Furman (1982) Nasal mites (: pp. 235-266, Halarachnidae) in the spotted seal, Phoca largha

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