Poststocking Movements of Large Coho Salmon ...

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Poststocking Movements of Large Coho Sa Oncorhynchus ntroduced in February into a Sma Stream Department sf Fisheries and Oceans, Biological Sciences Branch, West Vancouver Laboratory, 4 160 Marine Drive, West Vancouver, B.C. V7V 1 N6

Iwine, 1. R. 1988. Poststocking movements of large csko salmon (Oncsrhywchuskisutch) fingerlings introduced in February into a small coastal stream. Can. J.Fish. Aquat. Sci. 45: 1316-1 324 . Juvenilecoho salmon (Oweorhynchus kisuech), introduced into alternating 100-rn sections sf the lower kilometre of a steep-gradient stream in British Columbia, dispersed rapidly along the stream. After several days, fish sriginating from downstream of unstocked sections were almsst as numerous in the unstocked sections as fish originating from upstream. The largest coho (kk = 110 g), many of which had undergone smsltification, left the stream almost immediately after stocking. Six weeks after stocking, virtually no coho remained in the stream. Freshets apparently were responsible for displacing many of the fish out sf the system. Be jeunes saumons cskss (Bncorhynchus ks'sutch), intrsduits dans des tronqoms de 100 rn atternants du dernier kilsrnPtre d'un cours d'eau 3 forte pente en Colombie-Britannique, se sont disperses rapidement Je long du cours d'eau. AprGs plusieurs jours, Oes psisssns prsvenant de la partie situ6e en aval des trsncpns non ensernences 6taient presque aussi nsmbreux dans ces trsnqons que les psisssns provenant de la partie sitsree en arnsnt. Les plus gros saumons cohos (w= 4 10 $1, dont un grand nornbre avait subi la srnsltificatisn, ont quitte le csurs d'eau presque immkdiatement apr&s Ifensemencement. Six sernaines apr2s I'ensemencement, il ne restait pratiquement plus de sasrmons cohos dans le cours d'eau. Des crues nivales ont apparemrnent $t$ respsnsables de la sortie d'un grand nornbre des poisssns du reseau hydrsgraphique. Received September 4, ? 987 Accepted March 28, 1968 (J94H2)

T

he stocking of juvenile salmonids into streams, in pmticular coho salmon (Omsrhynchus kisutch), is a c o m o n enhancement strategy in the Pacific Northwest (Bilby and Bisson 1987; Nickelsopa et al. 1986). In British Columbia, underyeading coho less than 5 g me often introduced with the expectation that these fish will live md grow in the stream until the following spring (outplating, 8. B m s , Department sf Fisheries and Oceans, Pacific Biological Station, Nmaimo, B .C., p r s , comm.). In other cases, larger juvenile salmon classified as smolts are intmduced, but these are not expected to remain in freshwater for a significant period of time. Scdterplanting of underyearlings is usually reco point releases, as it is felt that by distributing fish over as much of a water course as possible, survival is improved (Fedorenko and Shepherd 1986). However, little work has been conducted on the effectiveness of different stwking techniques, or on the instream dispersal of fish following stocking (Reisenbichlerand McIntyre 1986). This note reports observations sf juvenile coho sdmon movements within a stream following their stocking as smolts. Cypress Creek, near the West Vancouver Laboratory in southwestern British Columbia (Fig. 11, is a steep-gradient 'Resent address: Department of Fisheries and Oceans, Biological Sciences Branch, Pacific Biological Station, Nanaims, B -83. V9W 5K6.

stream which varies in discharge from 8.05 mYs during dry summer periods to greater than 58 m3/sfollowing heavy winter storms. Historically, Cypress Creek had a significant run of coho salmon, but the run apparently became extinct in the 1978's. Various attempts to reestablish the run have Been made, a d in the autumn of 1986, at least 23 coho returned to the creek to spawn (M. Wddichuk, Department of Fisheries and Oceans, West Vancouver Laboratory, West Vancouver, B.C., pers. The lower creek was divided into ten 100-m long sections with the downstream section beginning at the confluence of the creek mouth and the wean at low tide and the upper section terminating wear a waterfall impassable to upstrem migrating fish (Fig. 1). A small dam in Section 7 is a barrier to the upstrem movement of juvenile sdrnonids, but adults can SUCcessfully pass. In the fall of 1985, eggs were obtained from fish at the Capilmo Hatchery on the nearby Capilano River. The eggs were incubated d the West Vancouver Laboratory in well water, and commencing in May 1986, the resulting fry were raised in water diverted from Cypress Creek. Growth of most fish during the summer and fall was rapid, and in November, coded wire tags were inserted in those fish longer than 10 cm. At 'this time, all fish Bowger than 19 cm were separated (Group I), and approximately the same number of fish between 10 and 19 cm were randomly selected (Group 2) as a csmphson (Table 1). M a y of the fish in Group 1 were silver and a few of the males were Can. J. Fish. Aquar. Sci., Val. 45, 1988


FIG. 1. Lower Cypress Creek illustrating the study sections. Inset shows Imaticsn of study area in southwestern British Columbia.

TABLE1. Mean fork lengths (em)a d weights (g) ( & 95% confidence intervals in parentheses) of the various groups (1-8)of coho in&ss%ucedto Cypress Creek, the numbers stocked, and the stream sections the groups were introduced to.

Weight Number stmked Section(s)

1

2

3

4

5

6

109.8 (35.2) 559

36.2 (36.4) 584

37.2 (38.7)

44.7 (44.2) 410

36.3 (29.4) 431

39.0 (30.1) 367

4

-

400

-

s

7

8

a

$ and lower portion sf 9

sexually mature- R o s e fish between 10 md 19 cm remaining after selection of Group 2 were randomly divided into six groups. Hn early December, all the fish were cold-brmded (Mighell 1969). Five different brads were u d , with fish branded differently from the following goups: I; 2; 3 md 4; 5

and 6; md '7 and 8. A minimum of 50 fish from each group were then weighed md measured. The fish were held until 2 February 1987 to monitor mortality due to handling, and on that date, they were intrduced into Sections 2,4, 6, 8, and the lower p a t of 9, as indicated in Table 1. No fish were stocked


in Section 1,3,5,7, or 10. Within the stocked sections, approximately four fish per linear metre were introduced dong each bank of the creek. The mean creek width at the time of stocking was 7.7 m and the stocking density in the sections stocked wags 1.02 fisWm2. Near the centre of each of Sections 2-8, one 28-m length of s b e m judged to be representative of its section was selected for population surveys. A 1-75-m-wide strip dong one or both sides sf these subsections was electrofished during 1&19 December (prestwking), 3-4 Feb stocking), and OW 16 Mach. Ow 3 F e b m q , Sections 2-5 were electrofished, but late in the afternoon a rainstom kgm which continued into the next day. Rain md a minor freshet on 4 kbmmy made electrsfishing the creek impossible but did enable a comp&son $0be made between pm- (3 Febmuy) and postfreshet (5 Febmzy) in sections that had k e n elecbofishd on 3 % b m q . Usually, three passes along each bank within each subsection were made, always in an upsfream direction with one person carrying m electrofishing mode a d two people carrying dipnets. Successive passes generally alternated between the two sides of the creek to give meaptwed fish the oppormnity to recover before electrsfishing there again and

thereby reduce the B&e%ihoodsf the probability of capture varying between runs. W i I e we were elecmfishing, we occasiondly observed fish moving from one side of the creek to the sther, but we never saw fish rnwing between stream sections. All coho were exmined for cold-brands and released along with other fish captured after dl elecwofishing was completed. Fish were released at the approximate location within the creek from where they were captured. Electxofishing results were andysed using the sequentid removal method of Zippen (1956) to obtain ppulation estimates with associated 95% confidence intervals. In some eases, additional elwtrofishing was carried out to increase the sample size of cold-brmded coho. A 15-rn beach seine was used to sample fish at the mouth of Cypress Creek (Section 1). At least eight sweeps were made on each of the following days: 18 December, 3 F e b m q md 5kbmq.

Juvenile coho sdmon were virtually absent from Cypress Creek during the December prerelease elecbofishing survey

TABLE2. Numkr of coho and trout per square metre ( & 95%confi"adence intends in parentheses) along h e left (E) a d right (R)banks of Cypress Creek. Coho densities on 2 F e b m q are the stocking densities which were calculated assuming uniform distribution across the stream; as fish appxed to be clumped along each bank, these densities are underestimates of the densities dong each bank. W e n no number is given, 1163 density estimate was made; min. is the minimum density (confidence intervals could not be estimated). IS Dec.

Section

Bank

Coho Trout

All

Both

90.8481 0.15

2 Feb.

3 kb.

Coho Trout Coho Trout

5 4 kb.

Coho

Trout

16 Mar.

Coho Trout

Can. J. Fish. Aqua. Sci., &Id. 45p1988


3 FEBRUARY

UPSTREAM

DOWNSTREAM

I

1

5 - 6 FEBRUARY

LIPSTREAM

DOWNSTREAM

DISTANCE AND DIRECTION OF MOVEMENT (m) FIG. 2. Composition of catches of stocked coho in each section before (left panel) and after (right panel) the 4 February freshet. The section electrofished md the number sf coho captured in it are given in the upper left corner of each g q h . The m m k m in or above the colums indicate the %&ion of stocking origin for the recaptured fish. The proportions of the total number of fish captured at each location md date originating from different stocking locations are given as percentages. Distances md direction of movement from the p i n t of release are indicated on the abscissa. Columns on the left-hand side of the central vertical line in each panel represent fish that swam upstream md columns on the right-hand side represent fish h t s w m downstream to their point of capture. Columns bisected by the vertical line represent fish that did not move out 0%the section in which hey were introduced. The proportions of the tb% paumber of recaptured fish originating in Sections 8 md 9 that were of the smaller (normal) size group are depicted by the shaded portion of the Sections 8 anad 9 columns.

(Table 2). The day after the release (3 Febmq), densities were high in the five sections that were sampled, higher thm the mean stocking density, indicating that few of the fish introduced to the lower creek had left the stream. Significant numbers of coho were caught on 3 F e b m q in unstocked sections (3 a d 51, which comffamd that considerable instream movement had wcumed shortly after the release. Coho densities at dl sites resampld were less after the fieshet on 4 k b m w than before, Can. J. Fish. Aqua%.Sei., &Poi.4Sp1988

significantly so d most sites (Table 21, indicating noticeable movement from the stream over a 3- to 4-d s p a . Coho densities in February were generally higher in stocked sections than adjacent unstmked sections and.were highest in those sections furthest downstrem. W e n the creek was next sampled on 16 March, virtually no coho were caught. Beach seining at the mouth sf the creek failed to capture my branded c%noalthough other fish were caught. 1319

TABLE3. Numbers of branded coho caught in each section of Cypress Creek elec$PofisBBdduring 3,5,md 6 F e b m q partitioned according to the section they were introduced to.

The freshet on 4 Feb placing some s f the fi


Section s f capture Seceisn stocked

2

3

4

5

6

7

8 9 9

mges in discharge were responsible movements sf coho fry stocked in

E

A significant and rapid redistribution sf coho

he Iswest section Trout ($airno gsirdpeeri) densities declined significantly

those of stocked sections within several days of the release. This ~ d i s t ~ b u t i oisncontrary to what so workers have reported. Egglishaw and Shackley (1988) md rtensen f 1977) reported

hat median dispersal

fish stocked, their aggressive behav sections, 3 coho (2%) had mo unstocked section, and 49 coho (25

from Sections 8 and

a technique as scatte~lmtingunder these circumstmces. Acknowledgments This short study was the result of a cmpmtive effort by numerous staff at the west &Imcouverkaboratoq. Andy L m b and Ian from the Fish Culture Research Section were responsible for in ing the eggs and raising the fish. Habitat C staff who assisted included S. Macdondd md E. ChsrommsK who beach seined at the mouth of Cypress Creek, equipment for branding and practical advice, and M. Waldichuk who Creek. Personnel

anonymous referee provided useful e s m e n t s om the manuscript.

Seetion 9 were eleetrofisked on 6 Febmxy, 57 coho were eapbred of which 52 (91%)were from the smaller size category. Discussion

Few of the stocked co appeared to leave Cypress Creek with the exception of the during their first 24 h in large size group of fish. Mmy of these larger fish were silver in colour, and therefore mably had undergone smsltifi1988); they probably migrated cation fFolmar md Dic coho were not captured at the directly to sea. Since mouth sf the creek when it was beac seined, the fish may have migrated away from the inmediate vicinity of Cypress Creek.

References BILBY,R. E., AND P. Aa.Bnso~.1987. Emigration and praducdsr~of coho sdmora (Bncor@ncbaaskisrstch) stocked in streams &zining an old-grow& and a clear-cut watershed Can. J. Fish. Aquat. Sci. 44: 1397-1487. LTQN, H.T., W. El. MOUY, A. S. COBURN, AND I. VAN TINE. 1984. The influerace of t h e and she at release of juvenile coho sdmm (O~ocorhyn&us kisutch) on returns at maturity; E S U ~of rekases fmm Q d n s m River Hatchery, B.C., in 8980. Can. Tech. Rep. Fish. Aquat. Sci. 1306: 98 p. CHAP MAN^ D. W. 1962. Aggressive behavim in juvenile coho salmon as a cause sf emigration. J. Fish. Res. Board Can. 19: 1M7-1080. EGGUSHAW, B.J., AND P.EE. SHACUY. 1980. Sumiv S ~ h ~(11ar o (L.), pl[mkdin a Scottish stream. 9. Can. J. Fish. Aquat. Sci., Vol. 45, 1888


~ N H ~ A. O ,Y., AND B. G . S m ~ m 1986. . Review of salmon transplant procedures and suggested transplant guidelines. Can. Tech. Rep. Fish. Aquat. Sci. 1479: 144 p. FQLMAW, L. C . , AW W. W. D I C ~ O1980. ~ . The pm-smelt transfornation (smoltificatisn)and seawater adaptation in sdmonids. A review of selected literature. Aquaculmre 21 : 1-37. H w , J. M. B., r n B. ~ A. P A R ~ S O 1987. N . Effects of stocking density on the. survival, growth, and dispersal of steelhead trout fry ( a l m o gairdneri). Can. I. Fish. Aquat. Sci. 44: 271-281. MKHELL,J. L. 1969. Rapid cold-branding of salmon and trout with liquid nitrogen. J. Fish. Res. Board Can. 26: 2765-2769.

MORTENSEN, E. 1977. The popuulation dynamics of young trout (Salms frutta L.) in a Danish brook. %.Fish Biol. 10: 23-33. N n c m ~ s oT. ~ ,E., M. F. S Q L ~ AWLB I , S. L. B O ~ S O N . 1986. Use of hatchery coho salmon (O~ucorhynchuskisutsh) presmolts to rebuild wild ppulations in Oregon coastal streams. Can. J. Fish. Aquat. Sci. 43: 243-2439. ~ I S E ~ I C H L E RW., R., AND J. D. MCINTYM.1986. Requirements for integrating natural anad artificial production s f mdromous sdmonids in the Pacific Northwest, p. 365-374. Bn R. H. Stmud [ed.] Proceedings sf a symposium sn the role sf fish culture in fisheries management. American Fisheries Society, Bethesda, MD. Z I P P ~@., 1956. An evaluation s f the removal method of estimating animal populations. Biometries 12: 163-189.

Structure of Sympatric and A Cutthroat Trout S a l m clarki c l a M ation to the M. A. Henderson1and T. 6. Northcote Resource Ecology, University of British CoBumbia, 2204 Main Mall, VancouverI B.C. V6T 7 W5

Henderson, M. A., and T. G. Northcote. 1988. Retinal structure of syrnpatric and allopatric populations sf cutthroat trout (Sa%moc%arkiclarki) and Dolly Varden char (Salve%inus rnalrna) in relation to their spatial distribution. Can. 1. Fish. Aquat. Sci. 1321-1 326. Retinal structures of cutthroat trout (Sa/moslarki clarki) and Dolly Varden char (Sa%ve%iwars m a h a ) were compared to determine if these features were consistent with the different light regimes in which the species live, depending on their sympatry or allopatry in lakes. Cone cell density in sympatric trout was over twice that of sympatric char and rod cell density was slightly less. The cross-sectional size of cone cells in syrnpatric trout was approximately 30% less than in sympatric char. The ratios of photoreceptor cells to ganglion cells in sympatric trout and char retinas were approximately 40:l and 80:1, respectively. There were no differences between sympatric and allspatric trout with respect to these structural features, Estimates of cone cell density, cone size, and number of photoreceptor cells per ganglion cell for allopatric char were significantly different and intermediate between those for sympatric trout and char. All four populations had similar cone cell mosaics with four paired cones surrounding each single cone. Results are considered in relation to differences in vertical distribution and feeding of sympatric and allopatric populations in three study lakes. On compare les structures retiniennes de la truite fard6e (Salmo elarki clarki) et de la Dolly Varden (Salvebinus malma) pour determiner si ces caract6ristiques correspondent aux differentes conditions de luminosit6 du milieu lacustre 0t1vivent ces espPees selon qu'elles soient sympatriques su allopatriques. La densit6 des cellules A canes chez la truite sympatrique est plus de deux fois supkrieure 2 celle de la Dolly Varden sympatrique tandis que la densite des cellules A batonnets est l6g6rement inferieure. La taille en coupe transversale des cellules 3 cbnes de la truite syrnpatrique est d'environ 30 % inf6rieure a celle observee chez la Dolly Varden sympatrique. Les rapports des cellules photorkceptrices aux cellutes ganglionnaires au niveau de la rktine de la truite et de la Dolly Varden syrnpatriques sowt d'environ 4011 et 8831 sespectivemepst. 11 n'y a aucune difference entre la truite sympatrique et allopatrique en ce qui concerne ces caracteristiques structurales. Les estimations de la densite des cellules 5 cdnes, de la taille des cdnes et du nombre de cellules photorkceptrices par cellule ganglionnaire pour la Dolly Varden allopatrique sont significativement diffkrentes et se situent A un niveau intermediaire de celles s'appliquant 3 la truite et a la Dolly Varden sympatriques, Les quatre populations possedent des mosa'iques de cellules 3 c8nes semblables, soit quatre c6nes appari6s entourant chaque c8ne individuel. On examine les rksultats obtenus en fonction des diffkrences obsew6es dans la rkpartition verticale et I'alimentatisn des populations sympatriques et allopatriques dans trsis lacs exp6rimentakex. Received luly 14, f 987 Accepted April 7, 7 988

(J935.5)

'Present address: Department of Fisheries and Ckems, Science Branch, 555 West Hastings S t . , Vancouver, B.C. V$B 5 6 3 . Can. J. Fish. aqua^. Sci., Vo(pE.45, 1988