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The life history of Philonema oncorhynchi in sockeye salmon from Cultus Lake and the morphometric variation… Platzer, Edward George 1964

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THE LIFE HISTORY OF PHILONEMA ONCORHYNCHI IN SOCKEYE SALMON FROM CULTUS LAKE AND THE MORPHOMETRIC VARIATION OF THE ADULT NEMATODES by EDWARD GEORGE PLATZER B . S c , U n i v e r s i t y o f B r i t i s h Columbia , 1961 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in the Department of Zoology We accept t h i s t h e s i s as conforming to the requ i red s tandard THE UNIVERSITY OF BRITISH COLUMBIA August , 1964 In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study* I f u r t h e r agree that per-m i s s i o n f o r extensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . I t i s understood that copying or p u b l i -c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my w r i t t e n permission* Department of Zoo 1 oqy  The U n i v e r s i t y of B r i t i s h Columbia, Vancouver 8, Canada Date August,1964. I f Abstract The l i fe cycle of Phflonema oncorhynch? was studied in sockeye salmon, Oncorhynchus nerka, from Cultus Lake, British Columbia. Gravid female worms from the coelom of sockeye spawners burst in lake water releasing living first-stage larvae. These were ingested by Cyclops  bicuspidatus and developed to the infective third stage in the haemocoele. Development required 17 days at 12 C or 70 days at 8 C. Each of six hatchery-reared sockeye fingerlings were fed 14-70 copepods infected with thi.rd-stage larvae. Fourth-stage larvae were recovered from the periton-eal tissues of four fingerlings when examined four to ten days after in-fection. The later stages of development were studied by maintaining naturally infected sockeye salmon for two years in freshwater. These had early fourth-stage larvae in the parietal peritoneum and tunica advent it ia of the swim bladder when captured as downstream migrants at Cultus Lake. When the fish were 26 months old, late fourth-stage larvae were found in the peritoneal tissues. These moved into the coelom when the fish were 32 months old and moulted to the preadult stage. The comparative morphology of mature worms collected from B.C. salmonids was studied. The type spec-ies, Philonema oncorhynch? Kuitunen-Ekbaum, 1933 was obtained from the type host, Oncorhynchus nerka, in the type locality, Vancouver, B.C. Philonema were also obtained from salmonids with a freshwater l i fe cycle in a land-locked area, Kootenay Lake, which was once contiguous with the type local-ity of Philonema agubernaculum Simon and Simon, 1936. The morphology was constant for worms found in different hosts and geographical areas. Size was an unreliable characteristic and appeared to be a host-dependent varia-tion. The type specimens of Philonema agubernaculum Simon and Simon, i 1936 were examined and no differences in morphology found. 1 I X Acknowledgments The author wishes t o express h i s s i n c e r e g r a t i t u d e t o Professor J . R. Adams f o r sugges t ing and s u p e r v i s i n g t h i s s t udy . The author is indebted t o the members o f the B . C . F i s h and Game branch , the In t e rna t -iona l Salmon Commission, and Mr . Fred Jones o f Kas lo f o r t h e i r a s s i s t -ance in o b t a i n i n g f i s h , and to Professor W. S. Hoar who k i n d l y p rov ided f a c i l i t i e s f o r h o l d i n g f i s h . Th in s e c t i o n s o f copepods were prepared by M r s . Ann P l a t z e r and Mr. . L l o y d Roberts suggested the technique f o r p r e s e r v i n g female worms. Dr . Leo M a r g o l i s k i n d l y loaned t r a n s l a t i o n s o f Russ ian and Japanese l i t e r a t u r e . Thanks are extended t o Mr . R. Ju r an i c who t r a n s l a t e d seve ra l Russ ian a r t i c l e s . D r . W. W. Becklund p rov ided specimens o f Philonema from the U . S. N a t i o n a l Museum. The author wishes t o thank Miss Sue Ca l th rop f o r her e x c e l l e n t t y p i n g o f the f i n a l manusc r ip t . Iv Table o f Contents Page In t roduc t ion 1 PART I.. LIFE HISTORY OF P. ONCORHYNCH! IN CULTUS LAKE SOCKEYE SALMON 7 Methods and M a t e r i a l s 7 C o l l e c t i o n o f P. oncorhynch? l a rvae 7 C o l l e c t i o n of copepods 8 In f ec t i on and c u l t u r e of copepods 8 In f ec t i on and maintenance o f young f i s h 10 N a t u r a l l y i n fec t ed young sockeye salmon 10 F i x a t i o n , s t a i n i n g and measurement o f l a rvae 10 Sec t ions o f l a rvae in s i t u 11 Resu l t s 12 A . Exper imental i n f e c t i o n and maintenance o f Cyclops  b icusp idatus 12 B . D e s c r i p t i o n of the e a r l y developmental stages o f P . oncorhynch i in C_.. b icusp idatus 13 1. F i r s t - s t a g e l a r v a 13 2. Second-stage l a r v a 14 E a r l y second-stage l a r v a Late second-stage l a r v a 3. T h i r d - s t a g e l a r v a 15 T h i r d - s t a g e l a r v a in s i t u C . Exper imental i n f e c t i o n o f young salmon 16 1. Resu l t s o f exper imental i n f e c t i o n 16 2. D e s c r i p t i o n o f f o u r t h - s t a g e l a rvae from e x p e r i -men ta l ly in fec t ed salmon 17 V Page D. D e s c r i p t i o n o f the developmental stages o f P . oncorhynch? in n a t u r a l l y in fec ted 0 . nerka from Cu l tu s Lake 18 1. The t i s s u e phase of Philonema oncorhynch? in 0 . nerka 20 D i s c u s s i o n 21 PART I I . MORPHOMETRY ANALYSIS OF PHI LONEMA FROM B . C . FISHES 26 Methods and M a t e r i a l s 26 Resu l t s 28 Specimens from Oncorhynchus nerka 29 Specimens from Oncorhynchus nerka kenner ly i -(kokanee) 31 Specimens from Oncorhynchus ke ta 32 Specimens from Salmo g a i r d n e r i i 32 Specimens from Salmo s a l a r 33 Specimens from S a l v e l i n u s malma 3^ Specimens from S a l v e l i n u s f o n t i n a l i s 35 Specimens from Prosopium w?11?amson?i 35 D i s c u s s i o n 36 Summary B i b l i o g r a p h y 42 L i s t o f A b b r e v i a t i o n s used in Tables and F igures 46 vi List of Tables Page I. Records of Philonema spp. 48 •I.I. Measurements of JP. oncorhynchi larvae, experimental infections 51 III. . Experimental infection of sockeye salmon 53 IV. Size differences between third-stage and fourth-stage 1arvae 54 V. Developmental stages of P. oncorhynchi in Cultus Lake sockeye salmon 55 VI'. Measurements of P. oncorhynch? larvae, natural infec-t ions ~ 56 VII. Variation of anal papillae 58 VIII. .Prevalence of P. oncorhynchi in the Fraser River System 59 IX. Prevalence of Philonema in the Columbia River System 61 X. Female P. oncorhynch? from 0. nerka 63 XI. Male P. oncorhynch? from 0. nerka and 0. keta 64 XII. Ph?lonema from kokanee 65 XIII. Ph?lonema from S. gairdner? ? and S_. salar 66 XIV. Philonema from S. malma and S. fontInalIs 67 XV. . Philonema from P. wil1lamsoni i 68 v i i L i s t o f F igures Page 1. F i r s t - s t a g e l a r v a o f P . oncorhynch? 69 2. Second-stage l a r v a moult 70 3. T h i r d - s t a g e l a r v a 71 4. Thf rd - s t age l a r v a in s i t u 72 II II II II II 72 6. Cepha l i c p a p i l l a e 73 7. Anal p a p i l l a e 74 8. Adhesions in 34-month o l d sockeye salmon 75 9. Larva in swim bladder w a l l 75 10. Grav id female worms in sockeye salmon 76 11. Cysts in male sockeye salmon 76 12. Male Phi lonema. t o t a l lengths 77 13. 1 1 " » nerve r i n g d i s t ances 78 14. 1 1 " , muscular oesophagus lengths 79 15. 1 1 " , g l a n d u l a r oesophagus lengths 80 16. " " , t a i l lengths 81 17. . " " s p i c u l e lengths 82 18. Female Phi lonema. t o t a l lengths 83 19. " " , nerve r i n g d i s t ances 84 20. 1 1 " , muscular oesophagus lengths 85 21 . , " " , g l a n d u l a r oesophagus lengths 86 22. . P readu l t Phi lonema. t o t a l lengths 87 23 . " " , nerve r i n g d i s t ances 88 • » • V I I I Page 2k. P readu l t Phi lonema, muscular oesophagus lengths 89 2 5 . " " , g l a n d u l a r oesophagus lengths 90 26 . u 1 1 , t a i l and s p i c u l e lengths 9 ' 1 INTRODUCTION Kuitunen-Ekbaum (1933) found tha t adu l t sockeye salmon, Oncorhynchus  nerka (Walbaum), from E n g l i s h Bay, B r i t i s h Columbia , were h e a v i l y in fec t ed w i t h specimens of an undescr ibed nematode which were found f r e e in the body c a v i t y or entwined amongst the p y l o r i c caeca . The nematode had the c h a r a c t e r i s t i c s o f the Carnallanata f a m i l y Dracuncul idae but d i f f e r e d su f -f i c i e n t l y from the o ther d r a c u n c u l o i d genera, Dracunculus and P h i l o m e t r a , t o j u s t i f y the e r e c t i o n o f a new genus and s p e c i e s , Philonema oncorhynchi Kuitunen-Ekbaum, 1933« Kuitunen-Ekbaum desc r ibed these i n f e c t i o n s as harm-le s s t o sockeye salmon s i n c e no worms were found in the musc les . She found a l s o tha t mature female worms burs t a f t e r immersion in sea water and d i s -charged thousands o f l i v i n g l a r v a e . The l a r v a e d i ed a f t e r two days in the sea wa te r . The rup ture of the female worms was a s c r i b e d t o the c o n t r a c t i o n ,of muscle bands. In the same y e a r , Smedley (1933) desc r ibed the same spec ies o f worm from sockeye salmon c o l l e c t e d at Cul tus Lake, B r i t i s h C o l -umbia, but she adopted the name g iven by Kuitunen-Ekbaum when she learned on the eve of p u b l i c a t i o n tha t the spec ies had a l ready been de sc r i bed and named. Simon and Simon (1936) desc r ibed another new s p e c i e s , Philonema  agubernaculum, which they found in the body c a v i t y and muscle o f the abdom-ina l w a l l o f Prosopiurn w?11iamsoni ( G i r a r d ) , Salmo shas ta (Jordan) and S a l v e l i n u s f o n t i n a l i s ( M i t c h e l l ) from the waters o f Wyoming Na t iona l F o r e s t . They j u s t i f i e d the d e s c r i p t i o n of t h i s new spec ies c h i e f l y by i t s much s m a l l e r s i z e and the d i f f e r e n c e in r a t i o o f a n t e r i o r t o p o s t e r i o r oesophag-us . However, u n l i k e P . onco rhynch i . i t was noted tha t p a t h o l o g i c a l changes 2 of the gonads accompanied infections with P. agubernaculum. Salvelinus fontinalis from Lake Edward, Quebec, were found to have severe multiple adhesions of the viscera which Richardson (1937) decided were the consequence of a nematode infection. He named this nematode Philonema salvelini, but did not give any description of the specimens beyond the range of total length of several immature encysted worms. Fujita described a species from Japan, Ph?lonema ochotense, in 1937 (Fukui, 1961). Fujita (1939) described three more species of Philonema from salmonids taken from Kamchatka: Philonema konda? from Oncorhynchus  keta; Philonema tenuicauda from Oncorhynchus nerka and 0. keta; and Ph?lon- ema salvelini from Salvelinus leucomaenis. The descriptions contained full measurements of the nematodes which differed in their respective size and in the number of caudal papillae in the male. He was apparently unaware that the trivial name "salvelini" had been used by Richardson (1937) and therefore his P. salvelini was invalid. In 1940 he added a fifth species, Philonema elonqata. from the body cavity of Oncorhynchus kawamurae taken in Lake Tazawa, Akita Prefecture, Japan. This species differed from the the others only in size and number of caudal papillae in the male. Baylis (1948) described several specimens of Ph?lonema which were collected from Salvelinus alpinus subspecies taken at the mouth of the Strindberg River, East Greenland. In most respects the specimens were intermediate between P. oncorhynchi and P. agubernaculum and Baylis identif-ied them as P. oncorhynchi since he considered P. agubernaculum to be Iden-tical with P. oncorhynch? despite the generally smaller measurements. These he suggested might be due to the influence of different hosts or degree of maturity. BaylIs also found that, even though cephalic papillae had not 3 been desc r ibed p r e v i o u s l y in Philoneroa. conspicuous submedian p a p i l l a e were p r e s e n t . He a l s o noted tha t preanal p a p i l l a e were present though n e i t h e r Kuitunen-Ekbaum nor Smedley had mentioned them. Akhmerov (1955) dec l a r ed tha t Philonema agubernaculum Simon and Simon, 1936, Philonema e longa ta F u j i t a , 19^0, and Coregonema s i b i r i c a Bauer, 1946 were synonyms of Philonema oncorhynchi Kuitunen-Ekbaum, 1933. Akhmerov's d e c i s i o n was based on a s tudy of specimens from sockeye and chum salmon, S a l v e l i n u s leucomaenis and A r c t i c g r a y l i n g , Thymallus a r c t i c u s . He d i d not synonymize the o the r four spec ies desc r ibed by F u j i t a because the d e s c r i p -t i o n s were not a v a i l a b l e . The d r acuncu lo id genus Coregonema was e rec ted by Bauer in 1946 because i t possessed a gubernaculum (Akhmerov, 1955). Akhmerov d i d not f i n d a gubernaculum in these worms from A r c t i c g r a y l i n g and s a i d they were m o r p h o l o g i c a l l y i d e n t i c a l w i t h P . o n c o r h y n c h i . However, s i n c e the A r c t i c g r a y l i n g was a f reshwater f i s h he proposed tha t the nemat-odes in t h e i r coelom were a subspecies o f P . oncorhynchi which he named Philonema oncorhynch? s i b i r i c a . S p a s s k i i and Rakova (1958) agreed w i t h Akhmerov's synonyms but pub-l i s h e d a f u r t h e r d e s c r i p t i o n o f the average measurements and morphology o f Philonema o n c o r h y n c h i . In I960, Meyer proposed the binomen Philonema c a b a l l e r o n e n s e . nom. n o v . , t o r e p l a c e Philonema s a l v e l i n ? F u j i t a , 1939, s i n c e t h i s binomen was preoccupied by i t s e a r l i e r use by Richardson (1937) and hence, as a pr imary homonym, was u n a v a i l a b l e . Fukui (1961) p u b l i s h e d a summary o f the c h a r a c t e r i s t i c s o f F u j i t a ' s specimens of Phi lonema. He a l s o m i s i n t e r p r e t e d Akhmerov's synonym and s a i d that Philonema agubernaculum Simon and Simon, 1936, was synonymous w i t h 4 Philonema elongata Fujita, 1940. Fukui admitted that the worms he exam-ined from salmon were badly damaged and though they were identified as P. oncorhynchi and P. ochotense on the basis of size, he was not certain of their identity. Table I records the occurrence of Philonema sp. compiled from the 1iterature. Two attempts at solving the l i fe history of P. agubernaculum have been reported from Maine (Meyer, 1958, I960; Vik, 1964). Meyer found that freshwater Cyclops sp. ingested the larvae released by the rupture of mature £_. agubernaculum. Later, one or more larvae were found to be pres-ent in the body cavity of the copepods. Infected copepods were kept alive for a month and then fed to hatchery-reared fingerling Salmo salar. These fish were autopsied several months later but were not infected. Meyer sus-pected that Osmerus mordax was involved as an intermediate host since it was a forage fish for landlocked Atlantic salmon. He examined a large number using the pepsin-HCI digestion method but the results were negative. Vik (1964) reported that nine Philonema larvae were recovered from 450 0. mordax digested by pepsin-HCI. These were fed to a single hatchery trout from which six small P. aubernaculum specimens were recovered two months later. Vik also fed larvae to Cyclops scut ifer but they died before any development took place. He suggests that the copepod is the first inter-mediate host and the smelt may be a second intermediate host in the l i fe history of P. agubernaculum. even though the infection level is low. He also observed that in several infected Salmo salar and Salvelinus fontinalis. perforations of the body wall were present which might have been the method by which the P. agubernaculum females expelled their larvae. However, 5 Meyer (I960) suggests that gravid females of P. agubernaculum are passed out with the roe at spawning. Adult Philonema are found in the coelom but the larval site has not been reported in the literature. Bangham and Adams (195*+) reported finding larval nematodes in the swim bladder walls of salmon ids during a parasite survey of British Columbia fresh-water fishes. These larvae were called Philonema because of the characteristic oesophagus and tai l . Margolis (1963) also reported finding the same nematode larvae in young sockeye and likewise suggested it was an early stage of P. oncorhynchi. The foregoing review on the taxonomy and life history of the genus Philonema indicates that a number of aspects need clarification, namely the complete solution of the life history, investigation of host-dependent variation, host specificity, and pathology. The comparative morphology of adult worms found in British Columbia salmon ids and the life cycle of Philonema oncorhynch? in Cultus Lake sock-eye salmon are presented in this thesis. The study of the adult morphology was enhanced by the favorable situation in British Columbia because Philon- ema occurs in a number of anadromous and freshwater salmon ids, some of which occur in the same geographical regions. Cultus and Kootenay Lakes were the main collecting areas because of the availability of infected fish. The characteristics that have been used to describe species of Philonema could be evaluated by studying adult worms from different hosts and geographical areas. The life cycle was elucidated by using two approaches: experiment-Personal communication from Dr. J.R. Adams. 6 a l l y i n f e c t i n g young f i s h and f o l l o w i n g the development in a group o f n a t u r a l l y i n fec t ed f i s h . For the former , f i r s t - s t a g e l a r v a e o f Ph?lonema .i oncorhynchi were ob ta ined from g r a v i d female worms taken from Cu l tu s Lake sockeye sa lmon. Wi ld-caught copepods were in fec ted e x p e r i m e n t a l l y w i t h the f i r s t - s t a g e l a r v a e and mainta ined u n t i l the l a rvae developed to the i n f e c t i v e t h i r d s t a g e . Young ha tchery- rea red sockeye f i n g e r l i n g s were fed in fec ted copepods. Thus, the route o f i n f e c t i o n was e s t a b l i s h e d f o r Cu l tus Lake sockeye salmon. Wi th the second approach, the development o f l a r v a e in the swim-bladder per i toneum was fo l l owed by m a i n t a i n i n g a group of n a t u r a l l y - i n f e c t e d sockeye salmon from C u l t u s Lake in f reshwater and exam-i n i n g the f i s h p e r i o d i c a l l y . T h i s t h e s i s i s presented in two p a r t s , each t r e a t e d as a separa te e n t i t y . Par t I con ta ins the work on the l i f e h i s t o r y o f Ph?lonema oncorhy- nch i ?n Cu l tus Lake sockeye salmon. Par t II con ta ins the comparat ive s tudy o f the adu l t morphology. 7 PART I Life Cycle of Philonema oncorhynchi in Cultus Lake Sockeye Salmon The life history of Philonema oncorhynch? in Cultus Lake sockeye salmon, Oncorhynchus nerka. was elucidated in the following ways. Infec-tive larvae of P. oncorhynch? from spawning sockeye were used to infect copepods, Cyclops bicuspidatus. which were obtained from Cultus Lake. This copepod was used because it is the major food source for young sock-eye (Foerster, 1925). Mueller's methods (1959) for obtaining, infecting, and maintaining copepods were used with modifications. Young fish were infected by artificial feeding and killed within two weeks to try to determine the route of migration of the larvae. The later development of P. oncorhynchi in sockeye was followed for two years by autopsying natural-ly-infected sockeye from Cultus Lake at intervals. With this approach the relationship of the P. oncorhynchi life cycle to the sockeye life cycle was recorded. Methods and Materials  Collection of P. oncorhynchi Larvae. Fresh larvae were obtained from female sockeye salmon from the Sweltzer Creek fish trap at Cultus Lake, B.C. (operated by the International Salmon Commission). The fish were killed by a blow on the head and brought back to the parasitology labora-tory at the Department of Zoology, University of British Columbia. Fish, held in a vertical position with the tail up, were opened by a clean in-cision from the anus to the pelvic girdle. Each fish was then inverted and the ripe eggs allowed to flow into a pan. The incision was then con-tinued to the posterior base of the pericardial cavity. Female worms were 8 r e c o v e r e d from amongst t h e eggs i n t h e pan and from t h e body c a v i t y o f t h e f i s h where they were t h r e a d e d amongst t h e v i s c e r a . They were t r a n s f e r r e d t o R i n g e r ' s s o l u t i o n i n a P e t r i d i s h . Only g r a v i d females c o n t a i n i n g moving f i r s t - s t a g e l a r v a e were s e l -e c t e d f o r i n f e c t i o n o f copepods. F i v e g r a v i d females were t r a n s f e r r e d t o a 1000 ml Erlenmeyer f l a s k c o n t a i n i n g 500 ml o f c o l d (10°C) d e c h l o r i n a t e d tap w a t e r . A f t e r one minute t h e worms b u r s t , r e l e a s i n g t h e l a r v a e . A f t e r one hour t h e remains o f t h e female worms were removed and t h e f l a s k s s t o r e d o in a r e f r i g e r a t o r s e t a t 8 C. C o l l e c t i o n o f Copepods. P l a n k t o n was c o l l e c t e d in Smith Bay in C u l t u s Lake w i t h a W i s c o n s i n p l a n k t o n n e t , #12 b o l t i n g s i l k s c r e e n . The net was towed w i t h a rowboat and a l l p l a n k t o n c o l l e c t e d was poured i n t o a t h r e e - g a l l o n l i v e r t i n , about t h r e e - f o u r t h s f i l l e d w i t h l a k e w ater. T h i s was t r a n s p o r t e d back t o t h e p a r a s i t o l o g y l a b o r a t o r y . On a r r i v a l t h e p l a n k -t o n was a e r a t e d o v e r n i g h t i n a r e f r i g e r a t e d room at 10°C. I n f e c t i o n and C u l t u r e o f Copepods. The p l a n k t o n c o l l e c t e d from C u l t u s Lake c o n t a i n e d t h e f o l l o w i n g c r u s t a c e a n s : (a) c l a d o c e r a n s (b) E p i s c h u r a nevadens i s (c) C y c l o p s b i c u s p i d a t u s E p i s c h u r a n e v a d e n s i s and t h e c l a d o c e r a n s were p r e s e n t in low numbers and d i e d d u r i n g t h e f i r s t two days when t h e p l a n k t o n was c o n c e n t r a t e d . C_. b i c u s p i d a t u s . t h e major p l a n k t e r , was amenable t o c u l t u r e and pr o v e d t o be a ready i n t e r m e d i a t e h o s t . A sample o f t h e copepods was d i s s e c t e d b e f o r e t h e experiment t o e n s u r e t h a t t h e y were u n i n f e c t e d . 9 The copepods were concent ra ted by f i l t e r i n g the contents o f the l i v e r t i n through #12 b o l t i n g s i l k . The copepods were e q u a l l y d i v i d e d i n to t h r ee f o u r - i n c h s t a c k i n g d i s h e s , each d i s h c o n t a i n i n g approximate ly 1000 copepods. Each d i s h was inocu la t ed w i t h f r e sh P . oncorhynchi l a rvae u n t i l t he re were t h r ee l a r v a e t o each copepod and p l aced in the r e f r i g e r a t o r f o r 2k hours . A f t e r t h i s t ime a sma l l sample o f copepods was examined. If 70 per cent o f the copepods were in fec ted then the d i s h was d i l u t e d in one o f t h ree ways: ( 1 ) The contents of a d i s h were poured i n t o an e i g h t - i n c h s t a c k i n g d i s h which was then f i l l e d w i t h one l i t e r of f i l t e r e d l ake water and kept in the r e f r i g e r a t o r . (2) The contents o f a d i s h were poured in to a 16" x 12" x 6" p o l y -e thy lene wash b a s i n , c o n t a i n i n g one g a l l o n o f f i l t e r e d l ake wa te r , and o kept at 12 C on a water t a b l e . . (3) The contents o f a d i s h were poured in to a t h r ee g a l l o n museum j a r , f i l l e d w i t h f i l t e r e d l ake wa te r , ae ra t ed , and kept at 12*C on a water t a b l e . If fewer than 70 per cent o f the copepods were i n f ec t ed on the f i r s t exposure , the d i shes were r e i n o c u l a t e d w i t h l a rvae and l e f t f o r another 2k hours . Th i s was repeated u n t i l t he s tandard was met o r u n t i l too many copepods had h igh m u l t i p l e i n f e c t i o n s . The j a r s were main ta ined under the above c o n d i t i o n s and the copepods were fed w i t h a mixed c u l t u r e o f Paramecium bu r sa r ?a . P . caudatum and Euglena s p . Samples o f the copepods were examined at I n t e r v a l s t o f o l l o w the development o f the l a r v a e . 10 In fec t i on and Maintenance o f Young F i s h . Young ha tche ry - rea red 0 . nerka (e ight months o l d ) were used as exper imental h o s t s . They were an -e s t h e t i z e d w i t h MS 222 (Sandoz) and fed copepods through a p o l y e t h y l e n e stomach tube . The f i s h were kept in a smal l aquarium f o r 2k hours and then removed to a l a r g e h o l d i n g aquarium (12°C) w i t h running wa te r . The water in the smal l aquarium was f i l t e r e d t o recover r e g u r g i t a t e d copepods o r l a r v a e which might haved passed through the d i g e s t i v e t r a c t in t h i s i n t e r v a l . The number of i n f e c t i v e l a r v a e fed to each f i s h was c a l c u l a t e d in the f o l l o w i n g manner: (1) A smal l number o f copepods was examined from the l o t t o be fed t o f i s h and the mean number o f i n f e c t i v e l a r v a e per copepod determined. (2) Each f i s h was fed an exact number of copepods. Regurg i t a t ed copepods were sub t r ac t ed from the t o t a l and the dose o f i n f e c t i v e l a r v a e found by m u l t i p l y i n g the number o f copepods ingested by the mean i n f e c t i o n per copepod. Exper imental f i s h were k i l l e d at i n t e r v a l s by p i t h i n g . The organs and p a r i e t a l per i toneum were removed and shredded in separa te d i shes f o r examinat ion w i t h a d i s s e c t i n g microscope . N a t u r a l l y Infected Young Sockeye Salmon. These were ob ta ined from Cu l tu s Lake , A p r i l 1962, as downstream m i g r a n t s . A l l f i s h examined at t h i s t ime were in fec ted w i t h f o u r t h - s t a g e P . oncorhynchi l a r v a e . The smolts were mainta ined in the hatchery at the U n i v e r s i t y o f B r i t i s h Columbia and examined at i n t e r v a l s t o determine the development o f P . onchrhynchi l a r v a e . F i x a t i o n . S t a i n i n g and Measurement o f La rvae . Larvae were f i x e d It overnight in formal in-acetic acid before staining. The following modification of Goodey's lactophenol-cotton blue stain was used for staining larvae (Franklin and Goodey, 19^9): ( 1 ) A drop of 0.0025 per cent cotton blue lactophenol was placed on a clean slide and spread so that it covered one-half the area of the coverslip to be used. (2) Two glass wool fibers were arranged outside the drop for cover-glass support. (3) Larvae were transferred from the fixative to the lactophenol-cotton blue with an eyelash glued to an applicator stick. (h) The slide was heated to 70 C on an electric plate until the larvae were a dark blue color. (5) The coverslip was applied and sealed with Gurr's Glyceel. The larvae were measured on a Leitz binocular microscope (interpupillary dis-tance set at 66 mm) with an ocular micrometer. Sections of Larvae In Situ. Infected copepods were fixed in Palades osmic acid, pH 7,k (Palade, 1952) for one hour at 0°C, then rinsed in dis-tilled water and dehydrated through successive alcohols. They were embedded in Maraglas epoxy resin (Freeman and Spurlock, 1 9 6 2 ) . Sections were cut at 1.5 H w'th a Porter-Blum ultramicrotome and stained with alkaline toluidine blue, 0.1 per cent (Trump, 1 9 6 1 ) . Infected swim bladders from sockeye smolts were prepared in the fol-lowing manner for 1ight microscopy: ( 1 ) The fish were killed by pithing and the swim bladder was exposed by a mid-ventral incision. (2) The swim bladder was injected with egg albumin from one end and 12 the gas removed s imul t aneous ly by another s y r i n g e (#30 needle) from the other end. (3) A f t e r the swim bladder was i n f l a t e d i t was f i x e d w i t h a l c o h o l -f o r m a l i n - a c e t i c a c i d and embedded in p a r a f f i n f o r s e c t i o n i n g . Resu l t s A . Exper imental In fec t ion and Maintenance o f Cyclops b i c u s p i d a t u s . In a l o n g e v i t y t e s t P_. oncorhynchi l a rvae re leased by g r a v i d females remained a c t i v e in l ake water f o r 17 days at 8 ° C . Some l a r v a e d i ed the f i r s t day a f t e r r e l e a s e from female worms but t h i s may have been a r e s u l t o f overcrowding in the s tock i n f e c t i o n f l a s k s . Larvae remain suspended in water f o r a long t ime because t h e i r a c t i v e movements se rve t o ma in t a in t h e i r pos i t i o n . Shal low s t a c k i n g d i shes ensured h igh contac t between concent ra ted copepods and l a r v a e . The copepods swam about a i m l e s s l y , r e c o i l i n g on c o n -t a c t w i t h each o ther o r w i t h l a r v a e . .On c o n t a c t i n g l a r v a e , copepods were observed to ingest them head f i r s t . Copepods a l s o ingested dead l a r v a e . Infected copepods u s u a l l y con ta ined on ly one or two l a rvae in t h e i r haemocoele though as many as seven f i r s t - s t a g e l a rvae were found in some e x p e r i m e n t a l l y in fec t ed copepods. No d i f f e r e n c e in swimming behaviour was noted between un in fec ted and in fec ted copepods. Three methods were used to ma in ta in in fec ted copepods. Maintenance o f the copepods in the r e f r i g e r a t o r at 8 C was the best method w i t h about 150 t o 200 i n f ec t ed copepods s u r v i v i n g in each s t a c k i n g d i s h f o r 150 days . The p o l y e t h y l e n e dishpan method y i e l d e d 100 copepods per g a l l o n o f water a f t e r two months at 12* C . The museum j a r s y i e l d e d o n l y 10 copepods per g a l l o n of water a f t e r t h ree months at 12*^ and were invaded by c l a d o c e r a n s . 13 In a l l maintenance methods a mixed c u l t u r e o f Paramecium and Euglena was used as food and the copepods r e t a i n e d the i r i d e s c e n t g lobu le s o f o i l which are present when the copepods are taken from C u l t u s Lake . Unfed copepods l o s t the h i g h l y c o l o u r e d o i l g lobu le s becoming w h i t e and t r a n s -l u c e n t . Reproduct ion may have occur red under the maintenance c o n d i t i o n s but p ropaga t ion d i d not s i n c e no n a u p l i i o r copepodids were found a f t e r t h r ee weeks. B . D e s c r i p t i o n o f the E a r l y Developmental Stages o f P . oncorhynchi in C. bicusp i d a t u s . Three developmental stages were recognised in the in fec t ed copepods. They were des ignated f i r s t - , second- , and t h i r d - s t a g e l a rvae r e s p e c t i v e l y . The f i r s t s tage in the copepods was found to be the same form tha t escapes from the female . Two moults in the copepod a re t h e r e f o r e i n d i c a t e d . 1. F i r s t - s t a g e l a r v a . The measurements o f 28 l a r v a e re leased from a mature female worm are presented in Tab le I I . F i g u r e 1 shows the c h a r a c t e r i s t i c fea tures o f the f i r s t - s t a g e l a r v a . The o r a l opening i s conspicuous and surrounded by p a p i l -l a e . Amphids a re present p o s t e r i o r to the p a p i l l a e but are inconsp icuous . A t r i a n g u l a r d e n t i c l e i s s i t u a t e d at t he do r sa l aspect of t he o r a l open ing . The anus i s c l e a r l y demarcated on the body w a l l . Phasmids are s l i g h t l y p o s t e r i o r to the anus and are inconsp icuous . The body i s a t tenuated s h a r p l y i n to a very long and f i l i f o r m t a i l which tapers i n to a sharp p o i n t and c o n -t a i n s numerous n u c l e i . The oesophagus i s long and d i l a t e d , c o n t a i n i n g a h y a l i n e substance w i t h numerous r e f r a c t i l e p a r t i c l e s . The nerve r i n g i s p a l e s t a i n i n g and s i t u a t e d hal f -way a long the und iv ided oesophagus. A g l a n d u l a r oesophagus 14 i s not p r e sen t . The exc re to ry pore and c e l l c o u l d not be l o c a t e d . The i n t e s t i n e c o n s i s t s o f 18-30 c e l l s w i t h prominent n u c l e i and i t does not appear t o be connected t o the rectum. The g e n i t a l pr imordium c o n s i s t s o f four c e l l s which are loca t ed mid-way between the t e r m i n a t i o n o f the i n -t e s t i n e and the anus. The c e l l s o f the g e n i t a l pr imordium c o n t a i n n u c l e i w i t h very l a r g e clumps of ch roma t in . The rectum i s a t h i n - w a l l e d tube . F i r s t - s t a g e l a r v a e recovered from the haemocoele of copepods i n -fec ted f o r two days were found t o have the i n t e s t i n e u n i t e d t o the rectum and the d e n t i c l e was s t i l l p r e s e n t . F i r s t - s t a g e l a r v a e moved a c t i v e l y about in the haemocoele o f the copepods and were observed to w r i t h e a c t i v e -l y when removed from the copepod. 2 . Second-stage l a r v a . The measurements o f 10 specimens are recorded in Tab le I I . Twenty-f i v e days a f t e r exposure t o f i r s t - s t a g e l a r v a e , second-stage l a r v a e of P . oncorhynchi were recovered from the haemocoele o f C. b icusp idatus main-t a ined at 8 C. When mainta ined at 12 C, second-stage l a r v a e were recovered a f t e r 17 days . T h i s s t age o f P . oncorhynchi i s c h a r a c t e r i z e d by a sheath which i s the cas t c u t i c l e o f the f i r s t l a r v a l s t age . At the a n t e r i o r end o f the exuv iae , the t r i a n g u l a r d e n t i c l e and the moulted oesophageal l i n i n g o f the f i r s t l a r v a l s tage can be seen d i s t i n c t l y ( F i g . 2 ) . Two types o f second-stage l a r v a e were found. One was sho r t e r than the f i r s t - s t a g e l a r v a and des ignated as an e a r l y second-stage l a r v a , w h i l e the second was equ iva len t in length t o the f i r s t - s t a g e l a r v a but had a mus-c u l a r and g l a n d u l a r oesophagus, and t h e r e f o r e was des ignated as the l a t e second-stage l a r v a . 15, Early second-stage larva. Six specimens were measured, one from a copepod maintained at 12°C for 17 days and five from copepods maintained at 8°C for 58 days (Table II). The following differences were noticed be-tween this stage and the first-stage larva. (a) The dorsal denticle is not present. (b) The intestine is narrow and the nuclei bulge from the intestine's external surface. (c) The rectum is thick and swollen. (d) The tail is short and tapers rapidly into a fine sharp point. (e) A sheath is present. (f) The larvae do not move actively when in the copepod's haemocoele or when they are removed from the copepod. (g) The genital primordium could not be located. Late second-stage larvae. Three specimens were recovered from C. bicuspidatus maintained for 17 days at 12°C. The fourth specimen was obtain-ed from a C. bicuspidatus maintained at 8 C for Ih days. The differences from the previous stage are: (a) The glandular oesophagus is present and is thicker and slightly longer than the muscular oesophagus. (b) There is an increase in total body length. 3. Third-stage larva. Measurements for 17 third-stage larvae are presented in Table II and this stage is illustrated in Figure 3. Third-stage larvae were found after 70 days in C. bicuspidatus maintained at 8°C. In C. bicuspidatus maintained at 12°C, the third stage was found after 17 days. The third 16 s tage d i f f e r s from the p rev ious s tage in the f o l l o w i n g ways: (a) No sheath i s p r e s e n t . (b) The g l a n d u l a r oesophagus i s a very prominent s t r u c t u r e in the l a r v a e , occupying o n e - h a l f the length of the l a r v a e and f i l l i n g the pseudocoelom w i t h i t s great w i d t h . (c) The t a i l has rounded shoulders near the rounded t i p . (d) The l a r v a e move a c t i v e l y in the copepod's haemocoele and a l s o when r e l e a s e d . (e) The rectum i s a narrow, t h i n - w a l l e d tube . ( f ) A prominent o e s o p h a g o - i n t e s t i n a l v a l v e is present which pro t rudes in to the lumen o f the i n t e s t i n e . T h i r d - s t a g e l a r v a in s i t u . Sec t ions showed that the t h i r d - s t a g e l a r vae occupy the haemocoele o f C_. b icusp i d a t u s . The l a rvae are i n t e r -twined w i t h the copepod's organs and a l s o extend in to the most p o s t e r i o r abdominal segments. F igures h and 5 show s a g i t t a l s e c t i o n s of an in fec t ed copepod. Cross and t a n g e n t i a l l o n g i t u d i n a l s e c t i o n s through a l a r v a are p r e sen t . There is a c l o s e a s s o c i a t i o n of the l a r v a w i t h the organs o f the copepod. Some s e c t i o n s show l a r v a e in c l o s e a s s o c i a t i o n w i t h l a r g e d rop-l e t s o f o i l present in the copepod's haemocoele. -C. .Experimental I n f e c t i o n o f Young Salmon. 1. Resu l t s o f exper imental i n f e c t i o n . Experiment I was s t a r t e d on January 14, 1964, u s ing th ree sockeye as desc r ibed in the s e c t i o n on "Methods" . Tab le I I I shows the d e t a i l s o f the number fed and r ecove red . One f i s h was au tops ied a f t e r f o u r days and y i e l d e d f i v e f o u r t h - s t a g e l a r v a e from the sc rap ings o f the p a r i e t a l p e r i t o n -eum. The l a r v a e were f i x e d , s t a i n e d and measured (Table I V ) . The l a s t two 17 0 f i s h were au tops ied a f t e r n ine days . One was nega t ive w h i l e the o ther con ta ined two f o u r t h - s t a g e l a r v a e which were recovered from the p a r i e t a l per i toneum. Experiment II was s t a r t e d on January 27, 1964, u s ing four f i s h , t h ree sockeye and one coho (Table I I I ) . They were mainta ined ove rn igh t as before and removed the f o l l o w i n g morning. A t o t a l o f 30 copepods were r e -covered from the f i l t e r e d water and a l l were fed t o one o f the sockeye on January 2 9 . Th i s f i s h was mainta ined overn igh t as before and marked by c l i p p i n g the do r sa l f i n before t r a n s f e r r i n g t o the h o l d i n g tank w i t h the o ther f i s h . One sockeye was au tops ied 17 hours a f t e r feed ing to see i f l a r v a e c o u l d be recovered from the i n t e s t i n a l t i s s u e but the f i s h was neg-a t i v e . The next f i s h was autops ied at f i v e days and seven f o u r t h - s t a g e l a r v a e were found in the swim-bladder peri toneum and t h r ee in the p a r i e t a l per i toneum. These l a r v a e were f i x e d , s t a i n e d and measured (Table I I ) . The marked sockeye and the coho were au tops ied on February 8, 1964, 12 days a f t e r i n f e c t i o n . Three f o u r t h - s t a g e l a r v a e were found in the p a r i e t a l peri toneum and 11 in the swim bladder peri toneum of the marked sockeye . One f o u r t h - s t a g e l a r v a was found in the swim bladder peri toneum of the coho. The l a r v a e were f i x e d , s t a i n e d and measured except f o r the l a r v a from the coho which was l o s t (Table I I ) . 2. D e s c r i p t i o n o f f o u r t h - s t a g e l a r v a e from e x p e r i m e n t a l l y in fec ted salmon. Twenty t h ree o f the 33 f o u r t h - s t a g e l a r v a e recovered were measured. It was found tha t the four t o f i v e day i n f e c t i o n s y i e l d e d l a r v a e tha t were much s m a l l e r than those from the n ine t o ten day i n f e c t i o n s . The d i f f e r -ences were expressed in the t o t a l body leng th and in l eng th of the g l a n d u l a r 18 oesophagus. These lengths in the younger fourth-stage larvae were signif-icantly smaller than the measurements for the third-stage larvae and for the fourth-stage larvae from older infections (Table IV). The measurements of the older larvae were not significantly different from those of the third-stage larvae. The significant reduction in size of the larvae dir-ectly after infection of the fish indicated that a moult had probably occurred and on this basis the larvae in the swim bladder were designated fourth-stage larvae. No change in organ structure was observed, in the transition from third to fourth larval stages. Four to five day and nine to ten day larvae occurred both in the parietal peritoneum and tunica advent itia of the swim bladder; however, the older larvae were found predominantly in the tunica advent it ia of the swim bladder, whereas the younger larvae were distributed evenly between the two sites (Table III). D. Description of the Developmental Stages of P. oncorhynch? in Naturally  Infected 0. nerka from Cultus Lake. Yearl-ing downstream migrants were obtained from Cultus Lake in May, 1962. These fish were maintained in fresh water at the Department of Zoology aquarium, University of British Columbia, until March, 1964. Ac-cording to Foerster (1938) downstream migrants are eleven and one-half months old. These fish were sampled at intervals to determine the develop-mental course of P. oncorhynchi (Table V and VI). Two developmental stages of f_. oncorhynch? were found ?n sockeye maintained in freshwater. The earliest stage, which corresponded to the fourth-stage larva in experimental infections, was found in the swim-bladder peritoneum. This stage was also designated fourth stage. The older stage 19 was found only in the coelom and designated preadult because maturing gonads were present. The morphology of the fourth stage is similar to that of the third stage, differing only in the increase in length of the body, t a i l , muscular and glandular oesophagus, and intestine. The genital primordium could not be found in any of the specimens examined, it was noticed during dissec-tions that the larvae were capable of re-penetrating the tunica adventitia of the swim bladder after being dissected out. They could also move active-ly through the tunica adventitia of the swim bladder when disturbed by poking with a dissecting needle. No growth occurred in the fourth-stage larvae sampled during the first six months. Thereafter there was rapid growth so that eight months later large fourth-stage larvae were found. These were designated as late fourth-stage since the sexes could be recognized through the presence of rudimentary female and male gonads. The genital tract in the female was didelphic amphidelphic and the vulva was not completely formed. The uteri and ovaries appeared as a double row of cells. The male genital tract was joined to the ventral wall of the cloaca and consisted of a double row of cells. The morphology of the other body organs remained the same except for their increased length and width. This stage was later found in the coelom along with preadult worms. Four preadult worms were found during the early part of the study. They did not appear abundantly until the fish were 32 months old or 20 months after the study was initiated. Few females were found. They dif-fered from the late fourth stage in that the vulva was well developed and open, the uteri were large tubes and the ovaries were recognizable. No 20 moult was observed and this stage was designated preadult on the basis of morphological changes. Preadult males were more numerous. They had spic-ules, anal papillae, a tridentate telamon, and a well differentiated genital tract. Several male tails were removed from live preadults, mounted in Ringer's solution and studied under an oil immersion lens. Accurate counts of anal papillae could be made only when the tail was ventral side up. The preanal papillae were sessile with clearly demarcated nerve endings while the postanal papillae protruded from the cuticle and also had distinct nerve endings. The papillae occurred in pairs or singly and their positions were numbered from the posterior extremity. The number of postanal and pre-anal papillae ranged.from 17 to 19 each. One arrangement is shown in Figure 7 and the variability listed in Table VII. The sockeye which had been maintained in freshwater for 20 months exhibited severe pathology of the coelom associated with the presence of late fourth and preadult stages. Adhesions of the pyloric caeca, liver, stomach, gonads and intestine to the body wall were present in almost every fish regardless of sex. When adhesions were teased apart, preadult males were found encased in fibrous capsules. Figure 8 shows an adhesion of the pyloric caeca to the body wall with which P. oncorhynchi preadult males were associated. During the period of this study, the sockeye grew from an average fork length of 8.5 cm to 21.00cm. The weight also increased on the average from 8.0 gm to 120 gm. 1. The tissue phase of Philonema oncorhynchi in 0. nerka. Fourth-stage P. oncorhynchi larvae were found primarily in the con-21 nective tissue of the tunica advent itIa of the swim bladder and the pneum-atic duct (Fig. 9 ) . Sections of whole fish revealed that the fourth-stage larvae were also in the loose connective tissue of the parietal peritoneum. The collagenous fibers of the loose connective tissue appeared to allow free movement for the larvae. When inflated swim bladders were removed from infected sockeye smolts, larvae could be seen moving slowly through the tunica adventitia. Larvae that were freed by dissection from the tunica advent itia were capable of re-entering the tissue if they came in contact with it. In tissue sections large clear areas were noted about many larvae. The density of fibroblasts was greatest in the region of the larvae, in-dicating a tissue reaction to their presence. Discuss ion The observed life history of PhIlonema oncorhynchi is similar to th-atc reported for other dracunculoids which have a cyclopoid Intermediate host. Philometra fujlmot? Furuyama, 1932, encysted in the fins of Ophio-cephalus argus Cantor was found to utilize five species of Cyclops as inter-mediate hosts, and two weeks were required for development of the infective larvae. Dracunculus medlnensis (Linnaeus), the human guinea worm, utilizes Mesocylops leukart? as an intermediate host and requires 12-18 days to develop to the infective third-stage larva (Moorthy, 1938; Onabamiro, 1956). Dracunculus ophidensis Brackett, 1938, is found in Thamnophis slrtalis. The infective larvae develop in 15 days in Cyclops viridis. the intermediate host. Tadpoles were found to be second intermediate hosts (Brackett, 1938). MIcropleura indiva Khera, 1951, found in Lissemys punctata, used Cylops species as an intermediate host and infective larvae are formed in six days (Siddiqi and Jairajpuri, 1963). Meyer (1958, I960) and Vik (1964) reported 22 the infection of Cyclops sp. with P. agubernaculum larvae; however, they were unable to complete the life cycle in this fashion, Vik found larvae in pepsin-HCl digests of Osmerus mordax and fed them to young hatchery-raised Salvelinus fontinalis. He recovered,preaduIts after several months and suggested 0. mordax was an intermediate host but the very low preval-ence may indicate that the larvae he recovered from the smelt was an accidental infection. P. oncorhynchi differs from other dracunculoids in having a much longer developmental period both in the intermediate cylopofd and in the salmonid hosts. This fundamental difference is probably a result of the adaptation of the life history of P. oncorhynchi to that of the sockeye salmon, 0. nerka. In Cultus Lake, sockeye spawn at Lindell Beach in one to six meters of water (Foerster, 1 9 2 5 ) , beginning usually the first week of November and continuing until mid-December (Foerster, 1929). The eggs hatch during the winter and the fry are found free-swimming in the lake in early May (Foerster, 1938). They remain in the lake for eleven and one-half months. Occasionally they remain two years but rarely zero or three years (Foerster, 1 9 2 9 ) . The sockeye migrate to sea near the end of April (Foerster, 1938), remaining there two years and then return in the fall of their third year. Gravid P.concorhynch? females are passed out into the redd along with the roe and burst after one minute in the lake water. The active first-stage larvae are infective for C. bicuspidatus which is abundant throughout the lake all year (Ricker, 1 9 3 7 ) . Analysis of temperature data from 1932 to 1936 for the period November first to December 30 from 1932 to 1936 (Ricker, 1937) has shown that the mean temperature for this period 23 is 7.7*C (average for 0, 10, 20, 30 and 40 meters). Infective third-stage larvae of £ . oncorhynchi maintained experimentally at 8 C develop in seventy days. From this it is suggested that infection of sockeye fingerlings takes place during the month of January. Foerster (1925) demonstrated that C. bicusp idatus is the major food supply for young sock-eye in Cultus Lake during their lacustrine residence. Probably only the third-stage larva is infective since second-stage larvae were passed by salmon fingerlings in the experiments. It has also been shown that in-fected C_. bicusp idatus can survive at least 150 days at 8 C when fed Para-mecium. However, it is not known how long they could survive under the natural conditions of their environment, but since their swimming ability is not affected by the presence of one to seven P. oncorhynchi larvae it is suggestive that their survival is similar to that of uninfected copepods. The parietal peritoneum and the tunica advent it ia of the swim bladder are the sites of the fourth larval stage. The larvae appear most abundantly in the tunica advent i t ia . The route of migration has not been shown. However, the larvae must migrate into the intestinal walls after the copepod has been broken down by the digestive processes. Four migrat-ory routes are suggested. (1) The larvae may enter the deep visceral lymphatics and proceed to the posterior cardinal veins via the coeliaco-mesenteric and subvertebral lymph trunks. (2) Alternately, the larvae may enter the hepatic portal system and once in the circulatory system, the larvae could be transported to the swim bladder by the coeliaco-mesenteric artery where they could penetrate the vessel walls and enter the tunica adventitia. The parietal peritoneum is supplied by extensions of the seg-mental vessels from the dorsal aorta. (3) Another route may involve an 24 active migration through the intestinal wall and into the loose connective tissue of the mesentery. The larvae could disperse throughout the periton-eum in this manner since the loose collagenous tissue would not restrict the migrations of the larvae. .It has been shown that the fourth-stage larvae are spread throughout the peritoneum in naturally infected fish though" the majority are in the tunica adventitia of the swim bladder. (4) The fourth migratory pattern may involve penetration through the wall of the intestine into the coelom and then penetration into the parietal peritoneum or tunica adventitia. Observations on naturally infected sockeye from Cultus Lake have shown that the fourth-stage larva does not grow for six months after the fish migrate downstream. At this time the fish is 18 months old. There-after growth is rapid and when the fish is 26 months old late fourth-stage larvae are found in the peritoneal tissues with rudimentary gonads. This stage is found in the coelom when the fish is 32 months old and preadults also have appeared in abundance. The l i fe cycle of P. oncorhynch? is harmonious with that of the Cultus Lake sockeye. Preadult worms begin to appear one year before the sockeye is due to spawn. The mechanism by which the l i fe cycle of the worm is coordinated with that of the sockeye is not known but a relationship to the gonadal growth or maturity of the sockeye is suggested. The sockeye maintained in fresh water during the study grew substantially during the last year and their size was comparable to that reported for kokanee (VernOn, 1957). The development of pathological adhesions in male and fe-male fish appeared to be a tissue reaction to the presence of P. oncorhyn- chi . This is in contrast to andromous sockeye which show tissue reactions 25 only in the male fish. Whether the gonadotrophic, gonadal hormones, or increased growth of the fish affects the nematode is not known. Other cases in which maturation of a parasite occurs with the host have been documented by several research workers. Stunkard (1959) found that Poly- stoma stellae matures at the same time as its host, Hvla. Self (1963) found that gravid Nematobothrium texomensis are only found in gravid buffalo fish, Ictiobius bubalus. Triaenophorus nodulosus in Esox lucius is well known (Miller, 1952) and Hopkins (1959) suggested that the matura-tion of T. nodulosus may be related to temperature changes. However, Chubb (1963) suggested that other host physiology related to maturation may be involved. 26 PART II Morphometric A n a l y s i s o f Philonema from B r i t i s h Columbian Fishes The number o f caudal p a p i l l a e and the oesophageal and t o t a l body lengths have been the main c r i t e r i a used f o r taxonomic d i s c r i m i n a t i o n o f Philonema spp . However, the amount o f v a r i a t i o n has not p r e v i o u s l y been s tud i ed in a number of salmonid h o s t s . Th i s study i n v e s t i g a t e s the v a r i -a b i l i t y o f Philonema c o l l e c t e d from B r i t i s h Columbia sa lmonids . The type s p e c i e s , Philonema oncorhynch? Kuitunen-Ekbaum, 1933 was obta ined from the type hos t , Oncorhynchus ne rka , in the type l o c a l i t y , Vancouver, B r i t i s h Columbia . C o n c u r r e n t l y , Philonema were ob ta ined from salmonids w i t h a f reshwater l i f e c y c l e in a l and locked a rea , Kootenay Lake, which was once cont iguous w i t h the type l o c a l i t y of Philonema aguber-naculum Simon and Simon, 1936. In t h i s manner, the v a r i a t i o n o f Philonema found in d i f f e r e n t hosts which occur in the same or d i f f e r e n t geographica l regions cou ld be assessed . The s tudy of Ph?lonema in B r i t i s h Columbia salmonids was augmented by specimens obta ined from the H e l m i n t h o l o g i c a l C o l l e c t i o n , Uni ted S ta tes Na t iona l Museum ( U . S . N . M . ) . Th i s m a t e r i a l inc luded the types o f Philonema  agubernaculum Simon and Simon, 1936 from S a l v e l i n u s f o n t i n a l i s and Prosop- ium s p . In t h i s way, the m a t e r i a l c o l l e c t e d from B r i t i s h Columbia salmon-ids cou ld be compared d i r e c t l y w i t h specimens c o l l e c t e d throughout temper-a te North Amer i ca . Methods and M a t e r i a l s F i s h in fec t ed w i t h Philonema were c o l l e c t e d from the Frase r R i v e r system and Kootenay Lake r e g i o n . The s p e c i f i c l o c a l i t i e s are l i s t e d in 27 Tables VIII and IX with the dates of capture. Fish were autopsied in the following way: the f ish was opened with a mid-ventral incision from the anus to the base of the pectoral f ins , and the coelom examined for roundworms. The pyloric caeca were teased apart since worms were often found intertwined amongst them and the assoc-iated fat deposits. The ovaries were also teased apart since worms were occasionally found in this s i t e . The swim bladder was not inspected in mature f ish unless worms were not found in the coelom. In this case the swim bladder was dissected out along with its peritoneum and teased apart in sal ine. The tissues and saline were then examined for larvae. Philonema females were dipped in 95 per cent ethanol and transferred to 70 per cent ethanol immediately. This procedure was used because female Philonema burst if immersed f i r s t in 70 per cent ethanol. Prolonged immer-sion in 95 per cent ethanol caused shrivel l ing and loss of the cut ic le of the females. Philonema males were placed in Ringer's saline and steaming 70 per cent ethanol poured over them. A l l specimens were stored in glycer-ine-alcohol (one part glycerine to 20 parts 70 per cent alcohol) and were cleared by allowing the alcohol to evaporate slowly at room temperature un-t i l the specimens were in pure glycerine. Total lengths of Philonema males were found by projecting glycerine mounts of the worms with a Bausch and Lomb Microprojector. The images were projected onto paper and a pencil l ine traced along the midline of each worm, A stage micrometer (2.0 mm) was projected in the same manner and its length traced on the paper. A Brunning chartometer was calibrated with the micrometer tracing and was used to measure the lengths of the males. Phi- lonema females were projected with an Omega enlarger (135 mm enlarging 28 l e n s ) . T rac ings were made in the same manner as f o r the males except tha t a cen t imeter r u l e was p r o j e c t e d t o c a l i b r a t e the char tometer . A l l measure-ments o ther than t o t a l lengths were made w i t h an o c u l a r micrometer in a L e i t z b i n o c u l a r microscope at an i n t e r p u p i1 l a r y s e t t i n g o f 66 mm. A l l head mounts, both male and female , were temporary. The head was cut o f f as c l o s e as p o s s i b l e t o the p a p i l l a e and mounted in g l y c e r i n e w i t h the c o v e r s l i p supported by g l a s s r ods . The mounts were examined w i t h an o i l immersion l e n s . Male t a i l s were cut o f f j u s t a n t e r i o r t o the p r e -anal p a p i l l a e , mounted, and examined in the same way. Worms taken from salmon were des ignated as Philonema oncorhynch? in the r e s u l t s whereas worms taken from other hosts were des ignated as P h ? l o n - ema s p . The reasons w i l l be presented in the d i s c u s s i o n . Resu l t s The a n a l y s i s of morphologica l v a r i a t i o n in nematodes and o ther s o f t -bodied organisms i s h indered by the absence o f hard pa r t s which would be f r e e from d i s t o r t i o n caused by f i x a t i o n . There fo re , a constant method o f f i x a t i o n was used so tha t one might assume the degree o f v a r i a t i o n would remain c o n s t a n t . The comparat ive study of adu l t morphology was based p r i m a r i l y on s e x u a l l y mature males and g r a v i d female worms c o l l e c t e d from spawning f i s h . I f o n l y immature worms were a v a i l a b l e , then these were used f o r comparison w i t h s e x u a l l y mature worms from o the r f i s h . Large numbers o f Philonema were recovered from ikokanee, sockeye salmon, and Kamloops t r o u t so tha t comparisons c o u l d be made between worms from i n d i v i d u a l f i s h o f the same spec ies and worms from d i f f e r e n t f i s h s p e c i e s . Head p a p i l l a e were found both in male and female worms. T h e i r a r -29 rangement was constant fn a l l worms examined from d i f f e r e n t h o s t s . Caudal p a p i l l a e were shown to be q u i t e v a r i a b l e in p readu l t male P . oncorhynch J (Part I ) . It was found tha t the p a p i l l a e cou ld not be examin-ed p r o p e r l y in a l a t e r a l v iew because the t a i l was too t h i c k in the mature a d u l t . The s t r ong c o i l i n g o f the male t a i l r e s i s t e d a l l attempts t o p r e -pare proper mounts. Counts o f caudal p a p i l l a e were made never the less w i t h l a t e r a l views and the same degree o f v a r i a t i o n was encountered when male Philonema from a l l f i s h were examined. There fo re , i t was assumed tha t caudal p a p i l l a e were not a r e l i a b l e c h a r a c t e r i s t i c f o r d i f f e r e n t i a t i o n of s p e c i e s . Philonema i n f e c t i o n s were not found in the f o l l o w i n g f i s h : s t e e l -head t r o u t (Salmo g a i r d n e r i ? ) . p i n k salmon ( 0 . gorbuscha) . s p r i n g salmon ( 0 . t shawytscha) , coho salmon (0.. k i s u t c h ) (Table V I I I ) , and Ye l lows tone cu t t h roa t t r o u t (Salmo c l a r k i i l e w i s i i ) (Table I X ) . Specimens from Oncorhynchus ne rka . Sockeye salmon were sampled from Cu l tu s Lake, the mouth of the Frase r R i v e r , and Great Cen t r a l Lake on Vancouver I s l a n d . The p reva lence o f P_. oncorhynchi was 100 per cen t , 20 per cent and 100 per cen t , r e spec t -i v e l y (Table V I I I ) . The worms were u s u a l l y in t e r twined amongst the p y l o r i c caeca or l y i n g loose in the coelom of spawning f i s h ( F i g . 1 0 ) . L i v e f_. oncorhynchi were a l s o found in spawned-out female sockeye which were " w a t e r - l o g g e d . " No host r e a c t i o n was found in female sockeye except f o r two encysted f e -male worms in two f i s h . In the male sockeye , many adhesions and c y s t s were present ( F i g . 1 1 ) . When the c y s t s were opened, P . oncorhynchi were found. The p y l o r i c caeca 30 were attached to the parietal peritoneum by fibrous tissue. Thin strands of fibrous tissue were also found between the ventral surface of the liver and the parietal peritoneum. Two precocious sockeye males (jacks) were examined and the same situation found. P. oncorhynchi females taken from female sockeye in the mouth of the Fraser River had eggs in their uteri. Female worms taken from female sockeye entering Cultus Lake had many developing and first-stage larvae in their uteri. Female worms taken from spawning female sockeye in Cultus Lake had only first-stage larvae in their uteri. The sequence of develop-ment of the P. oncorhynchi larvae appears to be correlated with the prog-ressive gonadal maturation of the female sockeye. In contrast to the female sockeye, male and precocious sockeye spawners produced JP. oncorhynchi females with only eggs present or with nothing in the uteri. Male P. oncorhynchi measured from sockeye salmon showed a great variation in the total body and organ lengths amongst individual hosts (Figs, 12-17, Table XI). Examination of the figures reveals that the measurements for male worms from females, males and precocious sockeye form separate groups except for spicule lengths, which are similar. In general, male worms from jacks were the smallest while male worms from normal male sockeye were almost as large as those from female sockeye. Female f_. oncorhynchi also showed considerable variability in size when worms from individual hosts were compared (Figs. 18-20, Table X). The total body lengths of female worms from jacks and male sockeye were smaller than those from female sockeye. Organ lengths were similar in the female worms regardless of the host's sex. Extreme variations are prob-31 ably due to the small sample size from each host which was a result of the difficulty in obtaining whole worms when they were entangled amongst the pyloric caecae. One female worm collected by Rausch from Oncorhynchus nerka in Alaska, U.S.N.M., No. 56177—590A, was studied and measured. Other worms were in the collection but their poor condition did not allow study. The female worm was immature, full of unfertilized eggs and f e l l into the size range of P. oncorhynchi collected from male sockeye. No differences be-tween this worm and the P. oncorhynch? in the author's collection could be found. Specimens from Oncorhynchus nerka kennerly? (Kokanee). One female kokanee was obtained from Cultus Lake which was three years old and preparing to spawn. On autopsy it was found that the inter-nal organs were adhered firmly to the body wall with fibrous tissue. The organs were dissected away from the body wall and Philonema males were found amongst the adhesions. Dead Philonema females were found encysted on the lateral parietal peritoneum. Minute Philonema were found coiled on the swim bladder, ovaries and testes, pyloric caecae, and body wall of spawning and spawned-out kokanee examined from the Kootenay Lake region (Table IX). Occasionally they were found encysted in egg membranes. Adhesions were found only in one female and one male kokanee. Philonema found were in either of two stages, late fourth-stage larva or preadult with the exception of two maturing female worms found in an immature female kokanee. No differences were noted in infections of male and female kokanee. 32 Late f o u r t h - s t a g e l a r v a e recovered from kokanee were longer than those from anadromous sockeye mainta ined in freshwater but the organ lengths were s i m i l a r except f o r the g l a n d u l a r oesophagus l eng th ( F i g s . 22-26, Tab le X I I ) . Male p r eadu l t Philonema from kokanee were s m a l l e r than the p r e -adu l t s from sockeye salmon but the r e l a t i v e p ropo r t i ons appeared t o be the same ( F i g s . 22-26, Tab le X I I ) . Female p readu l t Philonema were a l s o much s m a l l e r than p readu l t s from sockeye salmon except f o r t a i l l ength ( F i g s . 22-26, Tab le X I I ) . The matur ing Philonema females con ta ined deve lop ing embryos and they were s i m i l a r in s i z e t o those recovered from sockeye males ( F i g s . 18-21, Tab le X I I ) . Specimens from Oncorhynchus k e t a . Four chum salmon spawners were captured in Cu l tu s Lake (Table V I I I ) . Only f i v e male P . oncorhynchi were found in the male chum and no host r e -a c t i o n was seen . The two in fec t ed chum females had o n l y encysted dead P . oncorhynchi females on the p y l o r i c caeca and o v a r i e s and the worms were c a l c i f i e d in some c a s e s . One female had e x t e n s i v e adhesions o f the l i v e r and stomach which were a t tached t o the v e n t r a l p a r i e t a l per i toneum. The measurements of the male worms from the male chum were s i m i l a r t o those o f the male P . oncorhynchi recovered from female sockeye ( F i g s . 12-17, Tab le X I ) . No measurements were made on the c a l c i f i e d female worms s i n c e the s t r u c t u r a l fea tures were o b l i t e r a t e d . Specimens from Salmo g a i r d n e r i i . The p reva lence o f Philonema in Kamloops t r o u t from Kootenay Lake 33 was low (Table I X ) . Immature t r o u t had few In fec t ions and made up the major pa r t o f the sample (35 out of 46 f i s h ) . A l l spawning t r o u t were i n f e c t e d . Adhesions were present o n l y in two in fec ted female t r o u t . One l a r v a l Philonema was recovered from the swim bladder o f an immature t r o u t at Gerrard (Table I X ) . Male Philonema from female t r o u t were s i m i l a r t o male £ . oncorhyn- ch? from j a c k sockeye w i t h respect t o a l l measurements made ( F i g s . 12-17, Tab le X I I I ) . The nerve r i n g d i s t a n c e was l a r g e r and the s p i c u l e length was s h o r t e r but c o n s i d e r a b l e ove r l ap o f the ranges o c c u r r e d . Female Philonema from female t r o u t were equ iva l en t t o female P . oncorhynchi from male sockeye w i t h respect t o t o t a l body leng th but the organ lengths were g e n e r a l l y s m a l l e r though c o n s i d e r a b l e ove r l ap o f ranges occur red w i t h a l l measurements in sockeye salmon ( F i g s . 18-21, Tab le X I I I ) . Shaw (1947) depos i ted Philonema oncorhynchi from Oregon s tee lhead t r o u t in the U . S . N . M . , No. 40004—3273A. These were ob ta ined and the measurements of two males taken (Table X I I I ) . The morphology and length measurements correspond w i t h those from Kamioops t r o u t . The head p a p i l -l ae were present and the number o f caudal p a p i l l a e was v a r i a b l e as in o ther Ph?lonema examined. Specimens from Salmo s a l a r . Philonema agubernaculum c o l l e c t e d by Dr . Meyer from landlocked A t l a n t i c salmon, Lake Sebago, Maine were ob ta ined from the U . S . N . M . , No. 46160—4225D. No males were found In the c o l l e c t i o n . E igh t females were comple te . Only one conta ined f i r s t - s t a g e l a rvae w h i l e the res t conta ined eggs o r had empty u t e r i . The females were s m a l l e r 34 in t o t a l body and g l a n d u l a r oesophagus length than female P . oncorhynchi from j a c k sockeye but the nerve r i n g d i s t a n c e and muscular oesophagus lengths were s i m i l a r (Table X I I I ) . Specimens from Sa lve l inu f r malma. Only one in fec t ed D o l l y Varden was ob ta ined from Cu l tu s Lake (Table V I | I ) . The i n f ec t ed female was immature and adhesions of the l i v e r to the p a r i e t a l per i toneum were p r e s e n t . The p reva l ence of Philonema i n f e c t i o n s in Kootenay Lake D o l l y Varden waso v a r i a b l e (Table I X ) . Mature worms were found in a spawning male which had adhesions and c y s t s c o n t a i n i n g on ly female Phi lonema. D o l l y Varden in the main l ake had few i n f e c t i o n s whereas more i n f e c t i o n s were found in f i s h taken from Meadow Creek . Severa l males and females had adhesions and cys t s as de sc r i bed above. The male Philonema from the Cu l tu s Lake i n f e c t i o n were s i m i l a r in s i z e t o male P . oncorhynchi from j a c k sockeye ( F i g s . 12-17, Tab le X I V ) . The s p i c u l e lengths d i f f e r e d but were equ iva len t t o those found in male Philonema from Kami oops t r o u t . Male Philonema from D o l l y Varden in Meadow Creek were c l a s s i f i e d as p r e a d u l t s s i n c e no f e r t i l e worms were found. The measurements agreed w i t h those o f P . oncorhynch? p r e a d u l t s from sockeye ( F i g s . 22 -26 ) . Four th - s t age l a r v a e were a l s o found in these f i s h (Meadow Creek) and corresponded to the l a t e f o u r t h - s t a g e l a rvae recovered from the coelom o f sockeye salmon ( F i g s . 22 -26 ) . The female Philonema found in the Cu l tu s Lake D o l l y Varden was s m a l l e r than any P . oncorhynch? recovered from spawning sockeye ( F i g s . 18-2 1 , Tab le X I V ) . The adu l t female Philonema from the Cooper Creek D o l l y Varden were equ iva l en t t o those from j a c k sockeye ( F i g s . 18-21) . P readu l t 35 females were found in the Meadow Creek D o l l y Varden and were equ iva len t t o the p r e a d u l t s recovered from Kootenay Lake kokanee ( F i g s . 22-26, Tab le X I V ) . Specimens from Sa lven inus f o n t i n a l i s . Type specimens o f Philonema agubernaculum were depos i ted in t he U.S .N .M. , No. 8908—M373A, by Simon and Simon (1936). One complete male and the a n t e r i o r p o r t i o n of another male were present a long w i t h one com-p l e t e and one headless female . The male measurements corresponded to those of P . oncorhynch? from male sockeye and Kamloops t r o u t (Table X I I I ) . Cont ra ry t o the d e s c r i p t i o n ° f Philonema agubernaculum males by Simon and Simon (1937), head p a p i l l a e were present and a l s o p r e - and pos t - ana l p a p i l l a e . The females con ta ined l a r v a e which were not comple te ly matured. Except f o r t o t a l body l e n g t h , the females were s m a l l e r than both Philonema  oncorhynchi in sockeye and Philonema in Kamloops t r o u t (Table X I V ) . Specimens from Prosopium w i11 i a m s o n i i . Only t h r ee un in fec ted w h i t e f i s h were obta ined from Cul tus Lake (Table V I I I ) . A l a rge number o f w h i t e f i s h were examined from Gerrard (Table I X ) . A l l the in fec ted f i s h were approaching m a t u r i t y . Abdominal adhesions were present in four w h i t e f i s h but were not a s soc i a t ed w i t h the Ph?lonema i n -f e c t i o n . The measurements of the male worms were v a r i a b l e but good compar i -sons were made w i t h male worms from Kamloops t r o u t and j a c k sockeye salmon ( F i g s . 17-17, Tab le X V ) . As in male worms c o l l e c t e d from other spec ies of sa lmonids , the s p i c u l e length was s l i g h t l y v a r i a b l e ( F i g . 1 7 ) . 36 The total body length of female worms was comparable to that of fe-male worms from male sockeye; however, the nerve ring distance and muscular oesophagus length were similar to those for female worms from Kami oops trout and jack sockeye (Figs. 18-21, Table XV). The glandular oesophagus length was shorter than that for other fertile females (Fig. 21). Philonema agubernaculum collected by Simon and Simon, 1936 from Prosopium sp. Montana, was obtained from the ILS.N.M., No. 38004—M590E. One complete female was present and the length measurements were comparable to those of female worms from jack sockeye (Table XV). Discuss ion Eight species of Philonema have been described on the basis of total body length and ratio of muscular to glandular oesophagus in both the male and female worms. The number of caudal papillae in the male worm was also used. Baylis (1948) was first to suggest that the species were morpho-logically identical and that the size differences were probably due to host differences. Akhmerov (1955) made Philonema agubernaculum Simon and Simon, 1936 and Philonema elongate Fujita, 1940 synonyms of Philonema oncorhynch? Kuitunen-Ekbaum, 1933. In his survey of parasites of Kamchatka fishes it was found that size was an unreliable characteristic and that the morphol-ogy was constant for worms found in different hosts. This study supports Akhmerov's conclusions with respect to the morphological variation in Philonema oncorhynchi. Analysis of the morphological variation in P. oncorhynchi has brought to light some interesting characteristics, e.g. the extreme varia-tion in size of worms from male and female sockeye salmon. The female worms from male sockeye salmon were much smaller than those from female 37 fish and characteristically did not contain embryos. The infertility of the female worms in male sockeye salmon is due either to the fact that the males are sterile or that the numerous eggs of the female are incapable of development. This may be a result of the environment produced by the male sockeye salmon. The infertility of P. oncorhynch? in male sockeye salmon is probably correlated with the fact that the worms in the coelom of the male cannot be released during spawning as are fertile worms in the coelom of female fish. In the latter, the ovarian membranes disintegrate, releas-ing the roe into the coelom from whence it is expelled by body contractions through the female urogenital pore. In the male fish the testes remain intact and the milt ?s expelled via the gonoducts. It is evident that P. oncorhynch? infections in male sockeye have reached a dead-end in their 1 ife cycle. The wide variation in length measurements made on P. oncorhynch? from the type host, 0. nerka, were found to overlap and encompass most measurements on Philonema taken from salmonids in two geographically sep-arated areas, Cultus and Kootenay Lakes. Adult worms taken from white-fish, Dolly Varden and Kamloops trout were generally smaller than those from sockeye but comparisons of total body length, distance to nerve ring, muscular and glandular oesophagus, tail and spicule length revealed the tremendous variability of these morphometric aspects in the genus Philonema. Examination of the type specimens for Philonema agubernaculum Simon and Simon (1936) revealed no detectable morphological differences or morpho-metric characteristics which can be used to set the specimens apart from Philonema oncorhynch?. Simon and Simon (1936) described P. agubernaculum on the basis that the worms they collected from Rocky Mountain whitefish, 38 Eastern Brook and rainbow trout were much smaller than P_. oncorhynchi and that the ratio between the anterior and posterior parts of the oesophagus was 1.0:2.7 whereas the ratio in JP. oncorhynch? was 1.0:1.1. Examination of oesophageal ratios in specimens in the present collection showed extreme variability. Many authors hesitate to use ratios of this or any body part as a criterion of species differentiation in nematodes (Barraclough and Blackith, 1962). The difference in final size of adult Philonema in the various salmonids is most likely a reflection of suitability of the environ-ment of the parasite. It has been shown in this paper that there is con-siderable difference in size between worms recovered from male and female fish of the same species. Westbrook and Scott (1955) found that Litomoso-ides carin? grew to different lengths in male and female cotton rats. The effect of host hormones appears to be the causative agent since they vould probably be the primary effectors of a difference in environment in fishes of different sex. It is reasonable to assume that, in the various salmonids that Philonema infects, a difference in hormones and body chemistry exists and the extent of this is reflected in the growth of Philonema in their body cavities. From this point of view, the sockeye is the host in which Philonema attains its largest possible size, whereas, growth in other sal-monids ceases at a lower level in the growth curve of Philonema. This in-terpretation is based on the assumption that length of infection has no bearing on the size of the parasite since worms in jack sockeye are compar-able to those from male sockeye one year older. This assumption leads to the hypothesis that maturation of Philonema is correlated with host matura-tion and consequently this is the factor which determines that all Philon- ema are physiologically alike since mature worms were found only in salmonids 39 which were in spawning condition. In the sockeye salmon, host tissue reactions to P. oncorhynch? were found mainly in the male fish. This fact may be related to the fact that the male host is a "dead-end" for the parasite. Alternately or at the same time the hormonal differences may cause an immune response to the presence of the worms in the male's coelom. The tissue reaction in the male but not the female sockeye salmon may be related to the difference in blood Cortisol and cortisone levels in the salmon, the female having double the concentra-tion found in males (Idler, 1959). Cross (1963) has shown that immune responses to Nematospiroides dub?us in rats is prevented by the administra-tion of cortisone. Fibrosis in the form of extensive abdominal adhesions were found in other salmonids, mainly Dolly Varden. The pathology was associated with the presence of Philonema in most cases though adhesions were found in a few fish which were uninfected. This may have been caused in these cases by Diphyllobothrium infections. MacLulick (1942) has reported the pathol-ogy of Ph?lonema sp. 5n lake trout, Crlstovomer namaycush, while Meyer (I960) and Vik (1964) have found massive adhesions in brook trout and land-locked Atlantic salmon from Maine. The pathology of Philonema in these salmonids may be related to their different l i fe histories, e.g. they do not die after spawning as do Pacific salmon. Vernon (1957) demonstrated that three distinct populations of kokanee were present in Kootenay Lake. Two populations spawned when three years old while the third spawned at four years. Kokanee were sampled from all populations in this study and mature Philonema were not found. The worms may fail to mature because some stimulus present in anadromous 40 sockeye is missing in the freshwater form, kokanee. The lack of an approp-r i a t e stimulus may prevent the larvae from growing to maturity . The infec-t i o n of the kokanee must come from the inoculum introduced into t h e i r feed-ing area by spawning t r o u t . 41 SUMMARY The l i f e c y c l e o f Philonema oncorhynchi was found to be s i m i l a r t o o ther d r a c u n c u l o l d l i f e c y c l e s . Sockeye salmon r e l e a s e g r a v i d female P . oncorhynchi i n t o the water w i t h the roe . The female worms b u r s t , r e l e a s -ing l a r v a e which are ingested by the in te rmedia te hos t , Cyclops b i c u s p ? d - a t u s . A f t e r two moults in the copepods haemocoele, the l a r v a e are i n f e c t -i ve to young sockeye salmon. The l a rvae migra te t o the t u n i c a a d v e n t i t i a o f the swim b ladde r , undergoing a t h i r d moult du r ing the m i g r a t i o n . In n a t u r a l l y in fec t ed sockeye salmon, the l a r v a e move to the coelom when the f i s h are 26 months o l d . Here the l a rvae moult and p readu l t s are formed. The adul t morphology of Philonema found in B r i t i s h Columbia salmon-ids was compared. The v a r i a b i l i t y o f the type s p e c i e s , Philonema oncorhyn- c h i from the type hos t , Oncorhynchus n e r k a . encompasses most o f the v a r i a b -i l i t y found in Philonema from o ther h o s t s . Examinat ion o f the types o f Philonema agubernaculum revea l s no morphologica l d i f f e r e n c e s . The d i f f e r -ences in s i z e are a t t r i b u t e d t o host-dependent v a r i a t i o n . 42 BIBLIOGRAPHY 1. AKHMEROV, A . Kh. 1955. Parasite fauna of the f ishes of the r i v e r Kamchatka. (Russian t e x t . ) Izvest. Tikhookeansk. N . I . Inst. Rybn. Khoz. Okeanogr. 43_, 99-137. 2. BANGHAM, ft. V . 1951. Parasites of f i s h In the upper Snake River Drainage and in Yellowstone Lake, Wyoming. Zoologica 3J>, 213-217. 3. BANGHAM, R. V. and ADAMS, J ; . R. 1954. A survey of the parasites of freshwater f ishes from the mainland of B r i t i s h Columbia. J . F i s h . Res. Bd. Canada H . , 673"708. 4. BARRACLOUGH, R. and BLACKITH, R. E . 1962. Morphometric re lat ionships in the genus Ditylenchus. Nematologica 8, 51 "58. 5. BAYLIS, H. A. 1948. On two nematode parasites of f i s h e s . Ann. Mag. Nat. H i s t . 24, 327-335. 6. BRACKETT, S. 1938. Description and l i f e h is tory of the nematode Dracunculus ophidensis n . sp. with a redescript ion of the genus. J . P a r a s i t o l . 24, 353-361. 7. CHUBB, J . Ci. 1963. .Seasonal occurrence and maturation of Trianoph-orus nodulosus ( P a l l a s , 1781) (Cestoda: Pseudophyl1 idea) in the p ike Esox luc ius L. of LTyn Teg i d . P a r a s i t o l . 53, 419" 433. 8. CROSS, J . H. and DUFFY, D. E'. 1963. Nematosp i roides dub ius in the abnormal host. Ann. N.Y. Acad. S c i . 113. A r t . 1, 88-99. 9. DOMBROSKI, E . 1955. Cestode and nematode infect ion of sockeye smolts from Babine Lake, B r i t i s h Columbia. J . F i s h . Res. Bd. Canada 12, 93"96. 10. FOERSTER, Ri. E . 1925. . Studies in the ecology of the sockeye salmon (Oncorhynchus nerka). Contr. Can. B i o l . 2, 335-422. 11. . 1929. An invest igat ion of the l i f e h is tory and propagation of the sockeye salmon (Oncorhynchus nerka) at Cultus Lake, B r i t i s h Columbia. #3. The downstream migration of the young in 1926 and 1927. Contr. Can. B i o l . . F i s h . 5_, 57~82. 12. 1938.. M o r t a l i t y trend among young sockeye salmon (0. nerka) during various stages of lake residence. J . F i s h . Res. Bd. Canada 4, 184-191. 13. FUJITA, T. 1939. On the Nematoda-parasites of the P a c i f i c salmon. J . Facul . Agr. Hokkaido Imp. Univ. 42, 239-266. 43 14. FUJITA, Tf. 1940. Further notes on nematodes of salmonoid fishes in Japan. Japan. J . Zoo l . . 8 , 377-394. 15. FUKUI, T. 1961. Studies on the parasites of salmonid fishes of Japan. (Japanese t ex t . ) B u l l . Yokohama Municipal Univ. Soc. 12., Natural Science #2, 1-66. 16. FRANKLIN, M!. T. and GOODEY, J . B!. 1949. A cotton-blue-lactophenol technique for mounting p lan t -pa ras i t i c nematodes. . J . . Helminth. 23_, 175 -178. 17. FREEMAN, Jl . A . and SPURLOCK, Br. .0. 1962. A new epoxy embedment for electron microscopy. J . Cel 1 B i o l . 13_, 437-442. 18. FURUYAMA, T. 1934. On the morphology and l i f e h is tory of Philometra fujimoti Furuyama. 1932. Keijo J . Med. 5_, I 6 5 - I 7 7 . 19. HADERLIE, E . C. 1953. Parasites of the fresh-water fishes of C a l i f -o r n i a . Univ. C a l i f . Publ . Zoo l . 5_Z> 303-440. 20.. HOPKINS, C. A . 1959. Seasonal var ia t ions in the incidence and dev-. elopment of the cestode Proteocephalus f i l i c o l l i s (Rud.. 1810) in Gasterosteus aculeatus (L. I 7 6 6 ) . P a r a s i t o l . 49_, 529~542. 21. IDLER, D . R . , RONALD, A . P . , and SCHMIDT, P. J:. 1959. Biochemical studies on sockeye salmon during.spawning migrat ion, V I I . Steroid hormones in plasma. Can. J . Biochem. P h y s i o l . . 37, 1227-1238. 22. KUITUNEN-EKBAUM, E . 1933. Philonema oncorhynchi nov. gen. et spec. Contr . ,Can. B i o l . F i s h . 8, 71 - 7 5 . 2 3 . MacLULICH, D. A. 1942. Parasites of trout in Algonquin Provinc ia l Park, Ontario. Can. J . Res. 20, 405-410. 24. MARG0LIS, L . 1963- Parasites as indicators of the geographical o r i g i n of sockeye salmon, Oncorhynchus nerka (Walbaum), occurr-ing in the North P a c i f i c Ocean and adjacent seas. B u l l . 11, Int. North Pac. F i s h . Comm. 2 5 . MEYER, M. C>. 1954. The larger animal parasites of the fresh-water fishes of Maine. Maine Dept. Inland Fisheries Game, Augusta. Fisheries Res. Mangt.. Div . B u l l . 1. 26. ——-—— 1958. Studies on Philonema agubernaculum. a dracunculoid nematode infect ing salmonids. J . P a r a s i t o l . 44 (Suppl .) , 42. 27. I960. Notes on Philonema agubernaculum and other related dracunculoids infect ing salmonids. Libro Homenaje al Dr. Eduardo Caballero y Caballero, Jubileo 1930-1960, 487-492. 28. MILLER, R. B. 1952. A review of the Triaenophorus problem in Can-44 adian lakes. Bull. Fish. Res. Bd. Canada 9JL* 2 9 . MOORTHY, V. N. 1938. Observations on the development of Dracunculus medinensis larvae in Cyclops. Am. J. Hyg. 27_, 437-460. 30. MUELLER, J . F. 1959. The laboratory propagation of Spirometra manson-oides (Mueller, 1935) as an experimental tool. II. Culture and infection of the copepod host, and harvesting of the procercoid. Trans. Am. Micro. Soc. 7JL 245-255. 3 1 . MUNROE, E. G. 1949. Notes on fish of the interior of the Labrador peninsula. Artie. 2_, 165-173. 32. 0NABAMIR0, Si. D. 1956. The early stages of the development of Drac-unculus medinensis (Linnaeus) in the mammalian host. Ann. Trop. Med. Paras itol. jjO, 157-166. 3 3 . PALADE, G. E. 1952. A study of fixation for electron microscopy. J. Exp. Med. 9_5_, 285-298. 34. RICHARDSON, 0. R!. 1937. Observations on the parasites of the speck-. led trout in Lake Edward, Quebec. Trans. Amer. Fish. Soc. 66| 343-356. 35. RICKER, w\ E. 1937. Physical and chemical characteristics of Cultus . Lake, British Columbia. J . Biol. Bd. Can. 3_, 363-402. 36. SELF, Js. T. 1963. The egg, miracidium, and adult of Nematobothrium texomensis (Trematoda: Digenea). J. Parasitol. 49_, 731-736. 37. SHAW, J . N. 1947. Some parasites of Oregon wild life. Oregon State College Agr. Expt. Sta. Tech. Bull. J_l_. 38. SIDDIQJ, A. H. and JAIRAJPURI, M'. S. 1963. On Micropleura indica Khera, 1951 (Nematoda: Dracunculidae) from a new host Lissemys  punctata, with studies on its life history. Z. f. Parasiten-kunde 2J3, 99-105. 39. SIMON, J . Ri. and SIMON, F. 1936. Philonema agubernaculum sp. nov. (Dracunculidae), a nematode from the body cavity of fishes. Parasitol. 28, 440-442. 40. SMEDLEY, E. M. 1933. Nematode parasites from Canadian marine and fresh-water fishes. Contr. Can. Biol. Fish. 8, 169-179. 41. SPASSKII, A. A. and RAK0VA, B. M. 1958. Nematode fauna of Pacific Ocean fishes. (Russian text.) Work from the Helminth. Lab. Akad. Nauk. U.S.S.R., 1945-57. 42. SPASSKII, A. A. and R0ITMAN, V. A. 1959. On the nematode fauna of grayling. (Russian text.) Vopr. Ikhtiol. \Z, 177-186. 45 43. STUNKARD, H. W. 1959. Induced gametogenesis in a monogenetic trematode, Polystoma stellai Vigueras, 1955. J . Parasitol. 4£, 389-391. 44. TRUMP, Br. F. , SMUCKLER, E>. A., and BEND ITT, E>. P. 1961. A method for staining epoxy sections for light microscopy. J. Ultra-struct. Res. 5_, 343-348. 45. VERNON, B. Hi. 1957. Morphometric comparison of three races of kokanee (Oncorhynchus nerka) within a large British Columbia lake. J. Fish. Res. Bd. Canada |4, 573~598. 46. VIK, R. 1964. Notes on the life history of Philonema agubernaculum Simon et Simon, 1936 (Nematoda). Can. J . Zool. 42, 511-512. 47. WESTBROOK, M. G. and SCOTT, Ji^  A. 1955. A statistical analysis of the growth in length of the filarial worms in the cotton rat. Texas Rept. Biol. Med. V3_, 537"558. 46 L i s t o f A b b r e v i a t i o n s Used in Tables and F igures F - female FLF - f o r k l eng th of f i s h GP - d i s t a n c e to the g e n i t a l pr imordium from the an t e r -i o r end L - l ength of worm LGO - length o f g l a n d u l a r oesophagus LGp - l ength of the g e n i t a l pr imordium LI - l ength o f i n t e s t i n e LMO - l eng th of muscular oesophagus LSh - l ength of sheath LTe - l ength o f t e s t i s Lv - l a r v a M - male No. - sample number NR - d i s t a n c e to the nerve r i n g from the a n t e r i o r end PM - p recoc ious male ( jack) S' - l ength of s p i c u l e SF - sex o f f i s h SW - sex o f worm T - d i s t a n c e from the anus to the t i p o f the t a i l V - d i s t a n c e from the a n t e r i o r end to the v u l v a W - number of worms measured WBA - body wid th at the anus WBNR K»!body width at the nerve r i n g WBOV - body width at the oesophago-intestinal valve WCal - width of calomus WCap - width of capitulum WGO - width of glandular oesophagus Wl - width of in tes t ine WMO - width of muscular oesophagus * In F i g s . 22-26, "S" indicates that the fourth-stage " larvae are from sockeye salmon in Table V I . Table 1. Records of Philonema spp. , compiled from the l i t e r a t u r e . Author Date Species Host Loca l i ty Kuitunen-Ekbaum 1933 Philonema oncorhynchi Oncorhynchus nerka B r i t i s h Columbia Smed1ey 1933 P. oncorhynchi 0. nerka II II Simon and Simon 1936 P. aqubernaculum Salvelinus f o n t i n a l i s . Salmo shasta. Prosop i urn wil l!amsoni i Wyoming Richardson 1937 P. s a l v e l i n i S. f on t i na l i s Quebec Fu j i t a * 1937 P. ochotense — Japan it 1939 P. kondai Oncorhynchus keta Sea of Okhotsk II 1939 P. tenuicauda 0. nerka, 0. keta II II II 1939 P . s a l v e l i n i Salvelinus leucomaenis ii tt ti 1940 P. elonqata Oncorhynchus kawamurae Japan MacLulich 1942 Philonema sp. Cristovomer namaycush Ontario Bauer * * 1946 Coreqonema s i b i r i c a Thymallus arc t icus Kamchatka Shaw 1947 P . oncorhynchi Salmo qairdneri i Oregon Bayl i s 1948 P. oncorhynch i Salvelinus alp inus Greenland Munroe 1949 Philonema sp. S. font inalIs Labrador continued -Table I, cont 'd . Author Date Spec ies Host Loca l i ty Bangham 1951 P. aqubernaculum Salvel inus namaycush;\,Salmo t r u t t a , P. wil l iamsoni i Wyoming Haderlie 1953 P. oncorhynch i S. qa i rdner i i Ca l i fo rn ia Bangham and Adams 1954 P. oncorhynch i Salmo c l a r k i i . S. q a i r d n e r i i , Salvelinus malma, 0. nerka, Oncorhynchus kisutch B r i t i s h Columbia it i i 1954 Philonema sp. Prosopium cylindraceum, P. w i l l i a m s o n i i , Acrocheilus alutaceus " II Meyer 1954 P. aqubernaculum S. f o n t i n a l i s , Salmo sa lar Maine Akhmerov 1955 P. oncorhynch i 0. nerka, 0. keta, S. leucomaenis Kamchatka Dombroski 1955 P. oncorhynchi 0. nerka B r i t ish Columbia Spasskii and Rakova 1958 P. oncorhynchi 0. nerka Kamchatka Spasskii and Roitman 1959 P. oncorhynch i Thymallus thymallus, T. arc t icus Kamchatka Fukui 1961 P. oncorhynchi — Japan ti 1961 P. ochotense — n Margolis 1963 P. oncorhynch i 0. nerka B r i t i s h Columbia, Alaska continued -Table 1, con t 'd . Author Date Species Host Loca l i ty Vik 1964 P . agubernaculum S. f o n t i n a l i s , S . •sa lar Maine Fukui, 1961. Akhmerov, 1955. vn o Table I I . Measurements of Philonema oncorhynchi larvae from experimental infec t ions . Measurements are in microns. Stage F i r s t (28) Second Third Fourth Early (6) Late (4) U / ) Young (11) * Older (12)** L 609 502 615 961 896 975 (559-656) (376-564) (552-684) (901-1020) (841-1003) (909-1066) NR 69 70 64 100 91 91 (63-80) (57-83) (54-68) (88-105) (74-103) (91-108) LMO 135 169 133 213 203 205 (114-148) (148-185) (114-171) (137-242) (160-237) (165*228) WMO 7 10 7 6 4 3 (5-14) (7 -H) (5-9) (4-8) (3-6) (3-4) LGO - 148 436 386 454 (125-180) (314-547) (308-456) (388-570) WGO 12 10 8 10 (10-13) (8-13) (7-10) (9-12) WBNR 22 25 23 15 14 16 (20-29) (23-26) (22-25) (14-17) (13-21) (14-17) WBOV 27 23 15 14 16 (23-30) (20-24) (13-16) (13 -14) (14-18) WBA 18 20 17 13 12 14 - (15-23) (17-22) (13-19) (11-14) (11-13) (1?-15) continued -Table 11, con t 'd . F i r s t Second Third Fourth s t a g e (28) , (17) ' Early (6) Late (4) Young ( 1 1 ) * Older (12) LI 113 212 221 207 202 212 (92-131) (120-257) (140-285) (171-322) (131-305) (171-228) Wl 15 10 7 6 6 6 (10-23) (7-14) (6-9) (3-9) (3-6) (3-7) T 282 120 113 109 107 105 (245-311) (103-137) (98-128) (88-128) (83-120) (74-125) LSh - 668 732 - - -(599-721) GP 269 (237-309) LGP 37 -(14-48) * Young larvae are from 4-5 day o ld infect ions. ** Older larvae are from 9"10 day old infect ions. Table I I I . Infection of hatchery-reared sockeye salmon with Phi Ion ana oncorhynch I. No. of copepods ingested Est i mated no. of t h i r d -stage larvae Durat ion of infect ion (days) Par ie ta l peritoneum Location Swim bladder wal1 Larvae recovered Kidney (per cent) Experiment A Fish 1. 17 37 4 5 - 13.5 Fish 2. 17 37 9 - - 0 Fish 3. 14 31 9 2 - 6.5 Experiment B Fish 1. 40 68 0.75 - - 0 Fish 2. 40 68 5 3 7 1 16.2 Fish 3. 70 91 10 3 11 15.4 Fish 4.* 25 32 10 — 1 3.1 * Fish 4 was a coho, others are hatcheiyreared sockeye. Table IV. Size differences between t h i r d , recently moulted 4 t h and 4 t h stage larvae. Larvae Total Length Glandular Oesophagus Length 3rd stage A. from haemocoele of C_. bicusp idatus N = 17 x = 961.4" S R 2 = 59.3 S-2 x N = 17 x = 435.7M 174.7 Recently moulted 4 t h stage larvae B. from experimentally infected 0. nerka (4-5 day infection) N = 11 x = 897.7 S* 2 = 386.6 S-^ x N = 11 x = 386.3 120.8 4 t h stage larvae C. from 9-10 day infect ion N = 12 x = 975.3 S x 2 = 149.6 N = 12 x = 453.9 S 5 2 = 171.1 A compared with B A compared with C B compared with C t = 3 . 4 4 * * t = 1.01 n . s . t = 3.43** t = 2.64* t = 0.95 n.s, t = 3 . 9 1 * * Weighed M t " test used. n . s . - not s i g n i f i c a n t . ** - s ign i f i can t at 0.01 l e v e l . *. - s i gn i f i can t at 0.05 l e v e l . 55 Table V . Developmental stages of £ . oncorhynch? found in na tura l ly infected Cultus Lake sockeye maintained in freshwater for two years. Hypo- 4th stage Preadult Date f i s h Age thet i ca l Number Larvae present stages present were of age of of f i s h -examined f i s h infect ion examined Early Late F M May, 1962 12 4 10 + _ _ June 13 5 4 + -July 14 6 4 + -August 15 7 10 -September 16 8 3 + -October 17 9 17 + .+* November 18 10 4 + -February, 1963 21 13 5 + -March 22 14 7 + +* July 26 18 6 +* August 27 19 6 + +* January, 1964 32 24 7 + + February 33 25 2 + + March 34 26 6 + + Only one found. Table V I . Measurements of Phflonema oncorhynchi from Cultus Lake sockeye salmon maintained in freshwater. Fourth Preadults Stage Early (20) Late F (8) M (9) F (2) M (10) L 1.07 (.96-1.20) 4.80 (3.85-6.33) 3.90 (3.63-4.44) 42 (26-59) 18 (11-23) NR 99 (88-105) 151 (141-203) 153 (135-185) 375 (3*4-406) 233 (185-264) LMO 223 (205-262) 349 (308-431) 313 (283-338) 748 (725-770) 450 (264-517) WMO 5 (5-6). 15 (10-21) 12 (10-12) 62 (43-80) 39 (25-48) LGO 485 (419-581) 995 (830-1384) 923 (725-1058) 1500 1286 (722-1637) WGO 14 (10-16) 45 (31-71) 41 (37-49) 164 (155-172) 121 (61-205) WBNR 17 (16-20) 54 (46-84) 46 (38-60) 333 (222-444) 156 (111-205) WBOV 18 (15-19) 55 (47-80) 52 (48-63) 347 (222-472) 195 (105-250) continued -Table VI, cont'd Fourth Preadults Stage Early (20) Late F (8) M (9) F (2) M (10) WBA 14 33 40 145 133 (11-15) (31-37) (33-44) (105-185) (50-222) 1.93 - 12.1 (1.36-2.87) (5.5-18.7) LTe - - 1.65 (1.28-2.05) 350 (314-387) WCap - - - - 14 (12-17) WCal 7 ( 6 - 7 ) T 121 245 259 660 394 (91-134) (227-258) (221-283) (515-805) (332-455) Total length, distance to vulva, testis length are given in millimeters. Other measurements in microns. Table VII. Anal papillae of male preadult Philonema oncorhynchi. Position Variability Postanal 1 Always median and single. 2 Median and single, or closely paired. 2 n II n it II 4 Median and single; paired either close or wide. 5 Always paired, either close or wide. 6 Median and single; paired either close or wide. 7 Always paired either wide or partially fused. 8 Always median and single. g ti II II II 10 Always paired, either separated or partially fused. 11 Always paired and separate. Preanal 12 Always paired and separate. 1^ " " II 14 May be paired, separate or partially fused or right member absent. 15 Paired, right member may be absent. ll ll 11 ll ll II 17 Paired, either right or left member may be absent. ]Q ll ll II II II II II II n 19 Paired, right member may be absent. 20 Paired, left member may be absent. 21 II II it II II it 22 Paired or completely absent. Table VI U . Prevalence of Philonema oncorhynch? in the Fraser River System and Vancouver Island. Host Date Loca l i ty # of f i s h examined * # of f i s h infected* Prevalence Oncorhynchus nerka Aug. , 1962 Steveston 5.5 (26,29) 11 (6,5) 20% n II Nov., 1962 Cultus Lake 11 (9,2) 11 (9,2) 100% II it Nov., 1963 Cultus Lake 11 (5,6) 11 (5,6) 100% II i i Aug., 1963 Great Central Lake 2 F 2 F 100% Kokanee June, 1963 Cultus Lake 1 F 1 F 100% Oncorhynchus keta Dec., 1962 II II 1 M 1 M 100% n II Nov., 1963 II a 3 F 2 F 66% Oncorhynchus qorbuscha Nov., 1963 II it 1 F 0 0 Oncorhynchus kisutch Nov., 1963 II II 1 F 0 0 Oncorhynchus tshawytscha Nov., 1963 Steveston 1 F 0 0 Salmo qairdneri i Nov., 1963 Steveston 10 (4,6) 0 0 Salvelinus malma June, 1962 Cultus Lake 3 (2,1) 1 F 33% n II June, 1963 ti it 1 M 0 0 continued -Table V111, con t ' d . # of f i sh # of ffsh Host Da^e Loca l i ty examined* infected* Prevalence Prosop ium wi11iamson i i June, 1962 Cultus Lake 2 F 0 0 " " June, 1963 " " 1 F 0 0 * The f i r s t numbers in parentheses are female f i sh and the second are male f i s h . Table IX. Prevalence of Philonema in the Columbia River System. Host Date Loca l i ty #of f i s h examined* # of f i s h infected* Prevalence Kokanee Sept. , 1962 Meadow Creek 90 (41 ,49) 58 (29,29) 65% Sept., 1963 u ii 10 (5,5) 8 (5,3) 80% Sept., 1962 Redfish Creek 15 (7,8) 4 (2,2) 27% May, 1963 Kootenay Lake 12 (10,2) 1 F 8% May, 1963 Duncan Lake 22 (12,10) 0 0 Sept. , 1963 Kokanee Creek 6 (3,3) 3 (2,1) 50% Sept., 1963 Goat Creek 9 (4,5) 9 (4,5) 100% Sept., 1963 Lardeau River 10 (4,6) 6 (1,5) 60% Sept., 1963 Pass Creek 1 M 1 M 100% Salmo qairdner i i May, 1963 Kootenay Lake 46 (26,20) 13 (10,3) 28% u ii Sept., 1963 Gerrard 1 M 1 M 100% Salmo c l a r k i i May, 1963 Kiakho Lake 13 (10,3) 0 0 Salvelinus malma Sept. , 1962 Cooper Creek 1 M 1 M 100% continued -Table IX, con t 'd . # of f i s h # of f i s h Host Date Loca l i ty examined infected'*' Prevalence Salvel inus malma May, 1963 Kootenay Lake 49 (30,19) -1 M .2% «• " Sept., 1963. Meadow Creek 7 (5,2) 4 (2,2) 18% ProsopIurn wi 11i amsonIi Sept. , 1962 Lardeau River I F 0 0 •« " May, 1963 Gerrard 40 (22,18) 8 (4,4) 20% " " Sept. , 1963 Meadow Creek 19 (11,8) 0 0 * The f i r s t numbers in parentheses are female f i s h and the second are male f i s h . Table X. Female P. No. SF FLF W L (mm) (run) 1 F 6 219 (199-238) 2 F 580 5 Ilk (186-322) 3 F 555 3 223 (212-244) 4 F 550 8 209 (181-234) 5 F 570 5 246 (212-289) 6 F 560 6 236 (221-258) 7 ^ PM 430 445 6 168 (138-195) 3 M 590 10 123 (81-205) 9 M 600 10 117 (83-143) NR CM) LMO 00 LGO GO 383 787 (360-415) (720-860) 384 798 (360-420) (720-890) 360 796 (750-860) 345 720 (300-420) (610-800) 388 805 (360-400) (750-830) 350 688 (330-360) (550-780) 356 685 (278-500) (500-833) 365 750 (305-415) (666-888) 404 793 (362-455) (722-944) 1822 (1660-2020) 1972 (1770-2330) 1830 (1720-2020) 1841 (1550-2100) 1914 (1380-2220) 1708 (1500-1910) 1685 (1360-2000) 1728 (1520-1840) 1789 (1600-1968) Table XI. Male P. oncorhynch i from 0. nerka and 0. keta. No. SF FLF W L NR LMO LG0 T S (mm) (mm) OO GO GO 00 00 1 F - 19 30 (22-38) 325 (178-400) 615 (425-820) 1665 (1230-2250) 385 (282-470) 327 (283-381) 2 F 580 18 38 (33-42) 358 (340-390) 650 (560-740) 1810 (1610-2080) 480 (390-600) 368 (330-530) 3 F 555 8 40 (37-47) 369 (344-412) 705 (627-812) 1956 (1776-2414) 535 (480-597) 356 (314-418) 4 F 550 11 35 (27-46) 347 (308-387) 665 (554-775) 1845 (1443-2331) 477 (320-547) 345 (326-369) 5 F 570 4 34 (31-39) 354 (326-375) 663 (603-713) 1922 (1721-2303) 518 (492-541) 347 (326-381) 6 F 560 6 34 (33-37) - - - - -7 PM 430 445 ,11 18 (9-32) 236 (172-320) 469 (320-670) 1355 (932-1626) 356 (295-517) 360 (332-381) 8 M 590 10 31 (25-39) 322 (271-369) 583 (523-677) 1698 (1443-2109) 455 (406-504) 350 (332-381) 9 M 600 10 26 (16-33) 305 (246-357) 573 (517-713) 1596 (1249-1748) 463 (394-554) 324 (295-363) 10 M* 730 5 34 (32-35) 358 (340-370) 676 (550-770) 1908 (1660-2140) 458 (420-490) 374 (320-470) Table XII* Philonema from 0. nerka kennerly? No. SF FLF (mm) SW W L (mm) NR GO LMO GO LGO GO T GO S GO 11 F 195 F 2 58 292 528 1277 (55-61) (278-305) (500-555) 12* F 395 Lv 6 8 180 326 676 312 -M 380 (5-10) (154-209) (295-357) (583-777) (228-369) F 217 M 215 F 8 19 225 419 974 489 F 235 (11-30) (197-271) (344-517) (733-1166) (344-578) M 17 12 206 365 871 291 284 (5-14) (166-246) (271-424) (638-1110) (234-351) (191-326) Sample 12 - measurements of worms from five kokanee were pooled. Table X I I I . Philonema from S. gairdneri and S. s a l a r . No. SF FLF SW W L NR LMO LGO T S (mm) (mm) (u) (u) (H) 13 F 500 F 27 149 (107-181) 306 (250-360) 585 (470-720) 1355 (1050-1750) M 22 21 (17-26) 304 (246-418) 5 1 0 (394-715) 1240 (890-1830) 329 (295-375) 311 (264-363) 14 F 790 F 23 129 (101-148) 298 (250-372) 545 (472-638) 1510 (1193-1832) - -M 10 19 (17-24) 264 (240-295) 436 (381-535) 1342 (1082-1832) 342 (283-406) 313 (234-369) 15* - M 2 24 (22-25) 295 529 (492-566) 1208 (1177-1238) 317 (301-332) 305 (301-308) 16** - F 8 41 (32-46) 313 (250-361) 583 (472-611) 935 (777-1110) - -* Steelhead t rout , Oregon; U.S.H.M. Col 1. No. 40004—3273A. Landlocked At l an t i c salmon; U.S.H.M. Col 1 . No. .46160—4225D. OTN ON Table XIV. . Phflonema from S. malma and S. f o n t i n a l i s . No. SF FLF sw W L NR LMO LG0 T S (mm) (mm) (M) GO GO GO GO 17* F 310 F 1 57 170 280 1050 - -M 4 10 (6-13) 207 (180-246) 341 (330-360) 892 (760-1010) 308 (250-390) 275 (230-300) 18 M 450 F 2 74 (67-81) 292 (250-333) 569 (500-638) 1578 (1499-1637) - -19* M F 380 340 Lv 2 10 (9-10) 185 (154-215) 329 (289-369) 988 (833-1143) 474 (332-615) -F 5 14 (12-19) 194 (148-221) 363 (295-424) 827 (583-1000) 371 (314-449) -M 6 12 (10-15) 204 (178-228) 362 (283-412) 932 (833-1000) 255 (221-289) 313 (283-338) 20** - - F 1 6 7 233 416 1000 888 -M 1 19 258 406 1176 369 332 No. 17 is from Cultus Lake, 18 and 19 from Kootenay Lake region. Brooktrout; U.S.H.M. C o l l . No. 8908—M373A, type for Philonema aqubernaculum Simon et Simon, 1936. Table XV. Philonema from Prosopium wi l l iamsoni ?. No. SF FLF SW W L NR LMO LGO T S (mm) (mm) (u) (u) (u) (u) ( U ) 21 F 202 F 5 95 280 506 951 F 243 (78-105) (222-316) (444-583) (816-1249) F 236 F 246 M 3 13 221 365 8 3 6 318 340 (13-14) (209-246) (326-387) (805-888) (301-344) (326-363) 22* - - F 1 85 305 638 1360 916 Prosopium sp . ; U.S.N.M.. Col 1. No. 38004—M590E, designated Philonema agubernaculum. 69 L I 5 0 JJ F i g . 1. F i r s t - s t a g e l a r v a o f P h i l o n e m a oncorhynch? f r o m a g r a v i d f e m a l e P_. o n c o r h y n c h i . 70 Dorsal tooth Oesophagus Exuviae of first moult Second-stage larva \ I 50 u Fig. 2, Anterior end of a second-stage larva of P. oncorhynchi showing the exuviae of the first moult. The tooth of the f irs t -stage larvae is lost with the exuviae. Flo. 3. Third-stage larva' of f_. oncorhynchi from the haemocoele of p_. b icusp idatus. Anterior and posterior regions of larva are shown. 72 F i g . k. Saggital section of £ . bicuspidatus infected with a th i rd stage larva of £ . oncorhynchi. x4no. F i g . 5. Higher magnification of larva in F i g . 4. Note Y-shaped lumen of glandular oesophagus, X2000. 73 100 / i Fig . 6 . Cephalic papil lae of a preadult male Philonema oncorhynch? from sockeye salmon maintained in freshwater. 11 Fig. ?• Caudai papillae of a male preadult Philonema oncorhynchi from sockeye salmon maintained in freshwater. Variability of the papillae is listed in Table Vl l . 75 F i g . 9. Fourth-stage larva in the tunica advent i t ia of the swim bladder from a Cultus Lake year l ing sockeye salmon, X800. 76 F i g . 10. Gravid female P . oncorhynchi in the body cavity of a spawning Cultus Lake sockeye salmon, X2. F i g . 11. Encysted P . oncorhynchi and long fibrous adhesions in spawning male sockeye salmon (Cultus Lake), X2. (8) (18) i (6) (4) (11) - (19) (10) 1 (5) (10) (22) (10) (3) :iD O. nerka J I L J_ J L _L O i __L o £ a (4) CO C > o JL E 'a. o C L _ J _ 2 3 4 5 6 7 8 9 SAMPLE 10 13 14 17 21 F i g . 12. Total lengths of male Philonema. 78 2 i r 400 _ 300 o z cr 200 LU > Z ' 100 (18) (S) (4) 1 (5) (11) (10) (10) ( 19) (11 ) o J L O. nerka J L_ O'l I (22) (10) ( 4) ( 3 ) E C a. alvel OSDJ oo Q. 1 1 2 3 4 5 7 8 9 10 13 14 17 21 SAMPLE F i g . . 1 3 . D i s t a n c e o f n e r v e r i n g from t h e a n t e r i o r end o f male P h i l o n e m a . 79 =1 8 0 0 CD z Ld ~* 6 0 0 00 Z> CD < £ 4 0 0 oo L U O ^ 2 0 0 _ i 3 CJ 00 2 0 (8) (4) (18) (11) (19) (5) (10)(10) (22) (10) (11) -I. 1 (4) (3) O. nerka o o ! _ CL J L J X J ! L 1 2 3 4 5 7 8 9 TO 13 14 17 21 SAMPLE . F i g . 14. Length of muscular oesophagus in male Phi lonema. i r 2400 r -CD Z LU _ J 00 O < I Q_ O 00 LU O < _ l Q z: < _ i O 2000 1600 1200 (8) (18) (4) (11) (19) (10) (5) (10) 800 (11) (10) ( 22) (4) (3) 400 Q narka J I L di ' D C o • J Z Im > o a to CO E D a. o i/> o L -0_ J I I _L 12 3 4 5 7 8 9 10 13 14 17 21 SAMPLE F i g . 15. Length of g l a n d u l a r oesophagus in male Phi l o n e m a . 31 600 - l r 500 (a) 3 X I— CD Z LU < 400 (1 8) (4) do) (5) (10) 300 (ID (1 9) (11) (2 2) (10) 200 O. n e r k a I t i l l ro dl o E 03 00 (4) C > 00 (3) E . 3 Q. O in O t_ Q . J I I L 1 2 3 4 5 7 8 9 10 13 14 17 21 SAMPLE Fig. 16. Tail lengths of male Philonema. 600 500 3 h -o UJ 400 300 UJ _ l U oo 200 n r (18) (8) (11) ( 4 ) <11X10) (5) (19) (10) (22) ( 3) (10) (4) O. n e r k a i I II I II C3 - S i d i _1_ Q. O m O a J L 2 3 4 5 7 8 9 10 13 14 17 21 SAMPLE 82 F i g . 17. S p i c u l e l e n g t h s o f male Philonema. 3Q0 250 200 JT) loO L L U (6) (6) (5) (5) (8) (6) £ 100 o 50 _ (10) (10) (2) (27) (23) (2) (1) (5) 0 J L O . nerka  i I O J L a. o o s_ C L 1 2 3 4-5 6 7 8 9 11 SAMPLE 13 14 17 18 21 Fig. 18. Total body length of female Philonema. 5 0 0 4 0 0 » 3 0 0 E g 2 0 0 (6) (5) (3) (6) (8) (10) (10) (6) (2) (27)(23) ( 2 ) (1) (5) 100 0 Q n e r k a I I L J L j I c o o J L J L J X £ n. o o i _ 1 2 3 4 5 6 7 8 9 11 SAMPLE 13 14 17 18 21 Fig. 19. Distance to nerve ring in female Philonema. I • • • / 85 1000 . 9 cf 1 r 600 =3. ^ 800 LU _J 00 ZD CD < O 400 CO LU O cc < 200 _ j o OO Z ) (6) (5) (3) (5) (8) (6) (10) (10) (6) (2) (27) (23) 0 O. nerka _ L c a ^. o _L J L J L (2) <=S> (D J L (5) 1 2 3 4 5 6 7 8 9 SAMPLE 11 13 14 1718 21 F i g . 20. Muscular oesophagus lengths of female Phi lonema. 86 2400 2000 h-O z -M600 CO CD < x1200 Q_ O CO LU O cr < _i Q Z < _ J CD 800 400 (5) (3) (6) (8) (6) (5) (6) (10) (10) (2) (23) (27) (1) (5) O. ngrka I L_ c D O C > a oo E Q . O o 0. 1 2 3 4 5 6 7 8 9 11 1314 17 18 21 SAMPLE Fig. 21. Glandular oesophagus length of female Philonema. 9 4 30 20 10 0 4 t h Lv (2) (17) ( 6) cy o c o o (10) (6) (17) 59 mm e I 4 5 m m i (2) (5) ( 8 ) S 12 19 S 12 19 S 12 19 SAMPLE F i g . 22; T o t a l body l e n g t h o f f o u r t h - s t a g e l a r v a e and p r e a d u l t P h i l o n e m a . 88 400 _ 3 0 ? LLl > LU z 300. 200 . 12 19 SAMPLE F i g . 23. Nerve r i n g d i s t a n c e o f f o u r t h - s t a g e l a r v a e and p r e a d u l t P h i l o n e m a . 3 B O O I- -o UJ 600 _ j OO Z> O £ 400 CL G (7) Ix! O 200 or < 3 u 00 Z> 2 0 4th L v o c di c o o (2) (17). ^) (2) -(10) (17) (8) (5) S 12 19 S 12 19 S 12 19 SAMPLE F i g . 24. Muscular oesophagus lengths of fou r th-s tage l a rvae and p readu l t Phi lonema. 90 16C0 . 1200 _ 800 _ 400 _ 0 -S 12 19 S 12 19 S SAMPLE 12 19 Fig. 25 . Glandular oesophagus lengths of fourth-stage larvae and preadult Philonema. 91 _ 8 0 0 5 600 z: LU . _J LU ^ 400 y CL 00 Q < 200 . _ J < 0 . 4 t h Lv (17) (6) (2) (10) (17) (6) </> 3 C C 2 Ivclii o 1 1 1 1 (21 (8) G? Spicule (5) (10) (6) (17) ' ' ' S 12 19 S 12 19 S 12 19 S 12 19 SAMPLE F i g . 26. Tai 1 lengths of fourth stage larvae and preadult Phi lonema and also spicule lengths of male preadults . 

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