A Parasitological Survey of Sockeye Salmon ( Oncorhynchus nerka) and Dolly Varden ( SaZueZinus malma) from the Ozernaya River System, Kamchatka

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1 Scientific Reports of the Hokkido Slmon IItcbery No. 8: 7, Mrch 99 A Prsitologicl Survey of Sockeye Slmon ( Oncorhynchus nerk) nd Dolly Vrden ( SZueZinus mlm) from the Ozerny River System, Kmchtk Kzuy Ngsw*, Shigehiko Urw*, nd Vldimir A. D~binin*~ * Ntionl Reserch Institute of Fr Ses Fisheries, Fisheries Agency of Jpn, Orido, Shimizu, Shizuok, Jpn * Reserch Division, Hokkido Slmon Htchery, Fisheries Agency of Jpn, Nknoshim, Toyohirku, Spporo 6, Jpn * Kmchtk Reserch Institute of Fisheries nd Ocenogrphy, Petropvlovsk Kmchtsky, Kmchtk 686, Russi Abstrct.Adult sockeye slmon Oncorhynchus nerk from the Ozerny River ner the outlet of Lke Kuril were infected with Myxobolus rcticus (Myxozo) in the brin nd spinl cord nd with Philonem oncorhynchi (Nemtod) in the peritonel cvity. Some of these sockeye slmon were ffected by light viscerl dhesions. This pthologicl condition ws found in mle fish only. Myxobolus rcticus ws lso found in the brin of dult Dolly Vrden Slvelinus mlm from river flowing into Lke Kuril. There ws no substntil difference in spore mesurement of M. rcticus from slmonids mong Kmchtk (Russi), Hokkido (Jpn), nd British Columbi (Cnd). The Dolly Vrden crried Slmincol crpionis (Copepod) on the roof nd floor of the buccl cvity nd Aniskis simplex (thirdstge lrve) (Nemtod) on the viscer. Introduction Bsed on the 99 progrm of fisheries science nd technology coopertion between Jpn nd Russi, two Jpnese scientists (K.N. nd S.U.) visited Kmchtk, Russi, in August 99. The min purpose of their visit ws to get informtion on vrious spects of the biology of slmonids in Kmchtk nd to discuss with Russin scientists the promotion of slmonid reserch in both ntions, but they lso conducted with Russin scientists prsitologicl survey of slmonids from the Ozerny River system. This survey ws closely ssocited with the Interntionl North Pcific Fisheries Commission (INPFC): under the uspices of INPFC the Jpnese scientists used prsites s biologicl tgs for determining the ocen distribution of Asin nd North Americn chinook slmon Oncorhynchus tshwytsch (Ngsw nd Urw, 987; Urw nd Ngsw, 988,989,99; Urw et l., 99). Furthermore, viscerl dhesions, one of prsitic diseses of slmonids, re known to be commonly present in offshorecught sockeye slmon. nerk (Ngsw, 985, 987), but this disese hs never been Contribution A No. from the Hokkido Slmon Htchery studied for sockeye slmon tht hve returned to Kmchtk. This pper reports the preliminry results of the JpnRussi coopertive prsitologicl survey in Kmchtk. Mterils nd Methods Thirty mture sockeye slmon Oncorhynchus nerk were cught with bech seine in the Ozerny River ner the outlet of Lke Kuril on August 7,99 (Fig. ). These fish were soon brought to the lbortory of the Lke Kurd Field Sttion nd were processed by recording fork length, body weight, sex, gond weight, infection of Philonem oncorhynchi (Nemtod: Philometride), nd the presence or bsence of viscerl dhesions. Philonem oncorhynchi is custive gent of viscerl dhesions of sockeye slmon (cf. Ngsw, 985,987). The brin nd nterior prt of spinl cord were removed from ech fish nd fixed in % formlin. Two scles were lso tken from the INPFC preferred re of the body surfce of ech fish for lter ge determintion (Mjor et l., 97) Ten dult Dolly Vrden Slvelinus mlm were collected in the Vychenkiy River flowing into Lke Kuril by rod nd line on August 9, 99 (Fig. ). These fish were exmined for nemtodes in the body cvity nd for prsitic 7

2 I S M %%&H% SCI. REP IIOKKAIDO SALMON HATCHERY. NO 8, Y9 copepods on the body surfce nd in the brchil nd buccl cvities, nd when prsites were present, those prsites were removed nd fixed in % formlin. The brin ws lso tken from ech fish nd fixed similrly. The brins nd spinl cords removed from the sockeye slmon nd Dolly Vrden were brought to Jpn nd exmined for the presence of Myxobolus rcticus (Myxozo: Myxobolide) by using microscope ( x). For comprison of regionl vritions in spore mesurement of this prsite, the spores were mesured from Kmchtkn, Jpnese, nd Cndin slmonids. Results nd Discussion Nine (.%) of the sockeye slmon exmined were infected with Myxobolus rcticus in the brin nd spinl cord (Tble ). This prsite ws lso found in the brin of ll Dolly Vrden exmined (Tble ). These findings confirm the presence of im. rcticus in the Ozerny River system. According to Konovlov (97), this myxosporcn (s M. neurobius) is the most frequently occurring prsite of Kmchtkn fishes, including vrious slmonids (Oncorhynchus nerk,. kisutch, Sloelinus spp.. Prosopium cylindrceum, nd Thymllus rcticus). The spores of M. rcticus found were pershped, nd there ws no substntil difference in spore mesurement of M. rcticus from slmonids from Kmchtk (Russi), Hokkido (Jpn), nd British Columbi (Cnd) (Tble ). Another myxosporen species, M. neulobius, which is Tble. Prsites, viscerl dhesions, nd biologicl fetures of mture sockeye slmon Oncorhynchus nerk from the Ozerny River ner the outlet of Lke Kuril on August 7, 99 t, positive;, negtive. Fork Body Gond No. length weight Sex weight Age (cml (kg) (d * * Ages were recorded ccording to the Europen system Mycobolus Philonem Viscerl rcticus oncorhynchi dhesions + 8

3 NAGASAWA E l AL. PARASITES OF SALMONIDS OF KAMCHATKA biologicl tg of Columbi River chinook slmon (Urw nd Ngsw, 988,989,99; Urw et l., 99), ws not found in the Kmchtkn sockeye slmon nor Dolly Vrden. Seven sockeye slmon (.%) were ffected by light viscerl dhesions (Fig., Tble ). In cses of viscerl dhesions of sockeye slmon cught on the high ses of the North Pcific Ocen, viscerl orgns re tightly surrounded by thick connective tissue sheth (Ngsw, 985), but such conditions were never found. Only mle fish hd viscerl dhesions. All sockeye slmon exmined hrbored Philonem oncorhynchi (Fig. ). Concerning the differ Tble. Prsites nd biologicl fetures of dult Dolly Vrden Sluelinus mlm from the Vychenkiy River flowing into Lke Kuril on August 9, 99. +, positive. No Fork Body Myxobolus Slmincol length Sex rcticus crpionis (cm) weight ( 9 65, 6 5 c9 P? e * Number of copepods found + 5' Fig.. Mp of Lke Kuril, showing loctions (filled circles) smpled for sockeye slmon (Oncorhynchus nerk) nd Dolly Vrden (Sluelinus mlm). Sockeye slmon were cught in the Ozerny River (loction ) ner the outlet of Lke Kuril. Dolly Vrden were smpled in the Vychenkiy River (loction ) flowing into Lke Kuril. Tble. Spore mesurements of Myxobolus rcticus from the brin of Dolly Vrden (Slvelinus mlm) nd sockeye slmon (Oncorhynchus nerh) from Kmchtk (Ozerny River), Hokkido (Chitose River), nd British Columbi (Sprot Lke). Host (Loclity) Dolly Vrden (Ozerny River) Sockeye slmon (Ozerny River) Sockeye slmon (Chitose River) Sockeye slmon (Sprot Lke) No. of spores SL" SW*' ST" PCL*' PCW*' NC*' SW/SL PCL/SW mesured.? tO.6.7k. 8.9f.7.7i (..5.6)* (9..9) (6.87.8) (7.9.) (..5) (89) (.6.78) (.69.98).6 8.6f.6 6.6i. 8.k.6.i. 9.6f..6i..95i.9 (.55.) (7.69.8) (5.57.) (7.9.) (.8.9) (8) (.5.7) (.75.).i.6 8.i.5 6.6k. 8.i.5.i..Oi (.9.) (7.89.) (5.57.) (7.9.5) (..7) (9) (.57.7) (.86.) k.5 8. i i..96i.7 (.95.6) (7.89.8) (7.9.) (.5.) (.5..69) (.8 ) *'SL, spore length; SW, spore width; ST, spore thickness; PCL, polr cpsule length; PCW, polr cpsule width; in pm. *' NC, number of coils per polr filment. * MeniSD (rnge). 9

4 K. tt&r% SCI REP HOKKAIDO SALMN HATCHERY. No 8.99 Figs.. Photogrphs of prsitized slmonids from the Ozerny River system, Kmchtk. Sockeye slmon (Oncorhmchlcr nerk. mle, 5 cm fork length) ffected by light viscerl dhesions (rrows), Sockeye slmon (femle. 5 cm fork length) infected with Philonm oncorhpchi (rrow) on the viscer., Dolly Vrden (Sluelinus rnlm. mle, 7 cm fork length) infected with Slmrncol crpmnrs (rrow) on the roof of the buccl cvity enec m severity of visccrludhesions between offshore nd returned sockeye slmon, Ngsw (987) suggested tht viscerl dhesions re trnsitory nd dispper with fish mturtion. He lso noted tht dhesions m more commonly in mle fish thm in femle fish. Knovlov (97) reported the infection of P. oncorhynchi in sockeye slmon from severl Kmehlkn lkes, including Lke Kunl. The Dolly Vrden cmcd Slrnincolo crpinis (Copepod: Lcmeopdidc) on the rd nd floor of the buccl cvity (Fig. ). Thirdstge b c of Amh smplez (Nemtod: Amskide) were lso found on the VISCC~. Konovlov (97) found n id^^ sp. (pmbbly A. sum pler) lrve m didromous SolveLnw fmm Lke KUnl. The presence A. smplrr mdieks thl the Dolly Vrden hve returned to Lke KUnl fter suying t se Acknowledgments We thnk Dr. M i W M. Selifonov nd Dr. Vldimir I. Krpenk of the Kmchlk Reserch Insblute of Fish eries nd Ocenogrphy for their suggestions dunng our survey in Kmchtk. This work could not hve been done without the ss~stzncc of Mr. Vldimir S. Kuchercnko of the Lke K d Field Shbon. Thnks re lso due to Dr. Leo Mrglis of the Pcific Biologicl Sthon for pmvd mg the spores of M. rch from Cndin sockeye slmon. nd to Mr. Sotoo It of the Nhonl Reserch Institute of Fr Ses Fisheries for ge determintion of the Russin sockeye slmon. References Konovlov, S. M. (97): Differenritlon of locl popultions of sockeye slmon Oneorhynchus nerko (Wlbum). Nuk Publ. House. Leningrd (trnslted from Russin by L. V. Sgen, University Wshington Publictions m Fishcnes, New Ser., Vol. 6. University of Wshington Press, Settle. 975). 9 p. Mlor. R. L.. K. H. Mosher, nd J. E. Mson (97): Idenbficbon of stocks of slmon by scle fetures. In The Stock Concept m Pcific Slmon (edited by R. C.

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