The Homing ofAtlantic Salmon (S a/rna seter)'t o a arlne Site

A. M. Sutterlin, R. L. Saunders,E. B. Henderson, and P. R. Harmon

Biological Station,St. Andr ew s, N.B., EOG 2XO

January 198 2

Canadian Technical Report ofFisheries and Aquatic Sciences

o. 1058

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Canadian Technical Report of

Fisheries and Aquatic Sciences l05R

January 1982

THF. HO II r. OF ATLA ITlC: SAL:1O (SALMO SALAR) TO A MARl F. SITE

by

Sutterlln l, R. r.. Sa und r-r a , r.. R. Hender Oil, .rnd P. R. lI"rmoll

FlsherleH and Environmental Scicnrps

Oepartment of Fisheries and Oceans

Biological Station

St . Andrews, ew Brunswick EOG 2XO

Iprescnt address: arine Sciences Research Laboratory,

emorlal Uni ve r s i t y o f ,'ewfo und l and , St. John's, ewf oundland Ale 557

This is the one hundred and forty-third Technical Report from

the IHological Station, St. Andrews, ' .B .

ii

~ Mi n i s t e r o f Supp l y and Services Can a d a 1982

Cat . '0 . 9 7- 6 /1 058 ISS 07 0 0-64 57

Co r rec t c i t a t i on f or this public a tio n :

Sutterl in , A. I . , R. L. Sa und e r s , E. B. Henderson , and P. R. Harmon . 198 2 . The homi ng of At l a n t i c salmon( Sa lmo sal a r ) t o a marine site . Can . Tec h . Re p . Fish . Aqua t , Sci. 1058 : ii i + 0 p ,

iii

ABSTRACT

Sutterl in , A. H. , R. L. Saund er s , E. B. Henderson, and P. R. Harmon. 1982 . The homing of Atlanti c salmon( Salm o sa l ar ) t o a ma r i ne si t e. Can. Tec h . Rep. Fi sh . Aqua t . Sci . 1058, ii i + 6 p.

Atlantic salon (Sal mo sa lar ) smol t s reared in a distant hatchery and released at a arine site 12 kmf rom t heir parent st ream return ed to the marine site after having spent fro 13-25 mo at sea . A g roup o fs mol t s c hemi ca l l y imprinted in sal t water wit h morpholine and re t a i ned 2-3 wk whil e being fed a high fat , highpr o t e in diet , had the highest retu rn rate . It i s suggested t ha t salmon smolts can be imprinted in t he marineenvironment t o natural and / or syn thetic cues , but da ta are insufficient to sepa rate effects due to i mp r in ting ,n ut r i t io n , smolt size , and delayed r e l ease on ocean surv iva l and homing .

Returning salmon remained wi t hi n 2 km of the re lease site for a peri od of 2 mo until many of them wer ec ap t ur ed . Returning grilse had cea sed feeding by August 1 and were periodically ca ptured near th e relea sesite t hroug hout t he s\mmer and fall , du ring whi c h time a progressive decrease in wei ght (0 . 26%/da y) , co nd i t io nfactor and flesh pala tability occur red .

~ words: Atlantic salmon , homing beha vior, marine envi ronmen t , sur v i va l , fi sh culture , marine aquac ulture

~S E

Sut ter lin , A. H. , R. L. Saunders , E. B. Hen der son , and P. R. Ha rmon . 1982 . The homing of Atlantic salmon( Sal mo salar) to a marine site . r~n . Tech . Rep. Fi sh . Aquat . Sci . 1058 , i i i + 6 p.

De s smolts de sa ons de l' Atl an tique (Salmo salar) eleves dans un etablis sement de pisciculature elo i gneet libere a un site en mer a 12 km de leur cou r s d ' eau natal retournent au sit e de libe ra tion ap r es vo i r passede 13 a 25 mois en mer . Le taux de retour Ie plus eleve est celui d 'un groupe de smolts chimiquementi pr egne s dans de l' eau de mer additionn ee de morpholine et main t enus pendan t 2-3 se a un regi e alimentai reriche en gr a i s se s e t en pro t e i ne s . I I est suggere que des signaux na turel s et (au) s ynthet i ques peuventimp r egn e r l es smolts de saumon dans un environn e ent mar in , ma i s nos donn ees ne nous permettent pas de sepa re rles effets de l 'impreg nation , de l a nut r ition , de la ta i l le des olts e t du retard a la ise en liber te surla su rvie en mer e t Ie homing .

Les sa umon s qui retournent au site de liberation de eurent en dedan s de 2 km de ce t end ro i t penda nt unepe r io de de 2 moi s , Ju squ ' i pl us i e ur s d'entre eux soient captures . Les gril se qui r ev i e nne nt on t ces s e de senou r r i r des Ie te r aout e t sont captur es per iod ique ent pr es du site de mise en liberte pendant tout l ' e t ee t l ' a utomne . II y a a l or s diminution progress ive du poids (0,26% par Jo ur) , du facte ur de cond i t ion et de l asaveur de la chair .

INTRODUCTION

For the purpose of salon enhancement, restora­~ion or for commercial appli~ations, the practice'o f sea ranching involves the release of hatchery­reared juveniles or olts fro a site, theirigr tion ·to sea where they feed and grow, and their

return to that site where they are spawned orharvested for food (Thorpe 1980). Co ercial enter­prises ploying a coastal or terminal harvest arebeing conducted with Pacific salon in J pan and theUnited States ( eil 1980).

Several techniques have been ployed in sear nching effort to reduce ortality rates due ton tural factors and over fishing (see review bySaunders 1977). These include stock election fordesired age and size at maturity or for particularoceanic igratory patterns ( ovotny 1980; Saunders

nd Bailey 1980); odifications in smolt quality,ize, ti e, and ethod of release (Mahnken and

Joyner 1973; Bilton 1980; Isaksson 1980; ovotny1980; Sakura oto and Yamada 1980; Wedemeyer et ale1980; M rtin et ale 1981); and artificial che icali printing to direct returning salon to specificsites for harvesting (Cooper and Hasler 1973;Madison et ale 1973).

It is well doc ented that ost salmonidsbeco e printed to naturally occurring che icals intheir nursery strea s, per itting subsequentrecognition and he ng (Hasler 1966; Carlin 1968).More recent studies with sal onids grating inlakes have shown that olts can be imprinted to anartificial che ical and induced to return to afreshwater source treated with that che ical (Cooperand Hasler 1973; Madison et ale 1973). The site andti e of imprinting appear more variable than wasoriginally suspected as Pacific salon can printto natural factors at rine release sites andreturn to such sites as adults (Mahnken and Joyner1973; Novotny 1975, 1980).

With the exception of so e prel inary infor-ation fro marine releases of postsmolt Atlantic

sal on ~n orway (Magnus Berg, personal co unica­tion), there re ains a degree of uncertaintyregarding several aspects of the imprinting processin Atlantic salmon. This study will attempt toexamine the homing ability of Atlantic salon asinfluenced by chemical imprinting and delayedrelease at a marine site.

MATERIALS AND METHODS

STOCK ORIGI AND SMOLT RELEASE

Atlantic salon spawners were collected fromthe a eig River, .B., using seines and divers inthe fall of 1973. !tie -Wa eig, a small strea ,~nter the St. Croix River estuary about 12 kmupriver fro the St. Andrews Biological Station(Fig. 1). The fish, a co bination of grilse andlarger salon, were permitted to ripen at theBiological Station in indoor tanks containing freshwater. After stripping, the eggs were fertilized,pooled, and transported to Cobequid Fish CultureStation, Oxford, .S., for hatching and rearing(Fig. 1). This resulted in the production of 22,4002-yr olts available for release in the spring of1976.

-1-

Fig. 1. Location of donor river (Waweig), smoltrearing hatchery (Cobequid), and release-recapturesite (Biological Station, Brandy Cove).

S 01ts produced in 1976 were divided into threegroups, coded by fin clips and tagging, and- receivedthe folIo ing treat ent (Table 1) after beingtrucked to the Biological Station: Group A - fresh-water imprinting (5 d) ' to orpholine and ediaterelease; Group B - .sa l t wa t e r imprinting (3 d) toorpholine and ediate release; and Group C -

saltwater impri ting to orpholine and retained for21 d with supplementary feeding in sea water beforerelease.

Solutions of morpholine were added to the tankstwice a day to provide fluctuating concentrations ofbetween 10-6 and 10-12 olar. Group A smolts wereheld outdoors in fiberglass tanks supplied withdechlorinated fresh water. These smolts were taggedbefore being transported from the hatchery by usingserially numbered Carlin tags with polyethyleneattachments (Saunders 1968). Group A smolts werereleased directly into the sea (salinity ca.30 0/00) after 5 d printing. Group B smolts wered ped fro the tank truck directly into a concretetide pool (10 x 20 x 5 ) equipped with a one-waytidal gate pe itting approxi ately 75% waterexchange during each tidal cycle. These olts weresimilarly i printed with orpholine for 3 d thenreleased. Group C smolts were held for 5 d in freshwater, then placed in the tide pool after the Bsmolts were released. They were retained for 21 d,during which time they were imprinted with morpho­line and fed a homemade oist pellet of dry weightco position: 56% protein, 19.4% fat, plus vita inpackage.

ADULT RECAPTURES

Return of grilse and larger salmon was antici­pated for two successive years, 1977 and 1978. Thetide pool was equipped with a trap-type entrancethrough which the salon could enter during hightide. Morpholine was added to the water in the tidepool twice a day at the concentrations used forimprinting. Some water continually leaked from thetide pool through cracks in the concrete, but most

Table 1. Treat ent of

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olt group pr i or to release in 1976.

Identificationo , s olts

F.W. i printingF.W: imprinting si teS.W. imprintingDate of re leaseMean si ze at release (g)

A

LV/T3612

May 5-10St. And r ews

May 1468.5

GroupsB

RV3094

May 6-9May 10

68.5

C

A15694

May 10-31June 1

76.2

ate: A - adipose clip; RV - right ventral; LV - left ventral;T - Carlin tag - polyethylene attachment.

of it left through t he trap e~trance as the tidereceded .

Sev er al addit i onal methods were used to capturethe fish . During t he s er of 1977. the run scomposed pr edo inantly of ale grilse. Fourfloating gillnets , 30 x 4 (10 -11 c stretchedesh), were arranged in Br andy Cove ( Fig . 2) . The

nets were checked twice dai l y and os t of t he f i shwere remov ed dead . They were ediately weig hedand measur ed . In th e s er of 1978 . atte pt weremade to cap tur e l a r ger sa l on alive, using a 40beach seine permanently oor ed in the intertidalzone in fron t of t he t ide pool (Fig . 2) . Apparentl ythe salmon en tered this area dur i ng .high tide andbecame trapped beh ind the se i ne as the tide receded.The salmon were r e oved f ro a all pool along t heedge of the seine and moved without weighing and

easuring to the tide pool for eventual us e as broodfish.

RESULTS

SAUiO BEHAVIOR

Gr i l s e and larger salmon fro the 1976 releaseswere first observed sw ing in schools and jumpingin id July of 1977 and 1978 near the arf (Fig .2). The fish tended t o stay in one to three schoolswhich remained within 2 km of the release siteduring the summer. As the summer progre ssed theyappeared to converge and spend more ti e nea r t~e

entrance to the tide pool. Only t hree gr ilseentered the tide pool which was accessible onlyduring high tide , and had only a Ii ited flow ofsalt water leaving t he entrance . Attempt s wer e madein the summer of 1978 to provide are "a t trac tionwater:" to induce the large salmon to enter the tidepool. Several fire hoses directed fresh waterthrough the entrance of the trap. Only two salonfrom a school of 25 fish entered the tide poolduring the three evenings in which the "attractionwater" was used. Had all the salmon not been caughtby beach seine, they ight have entered th e t i depool of their own accord as spawning ti e approached,or the return site may have been abandoned in favorof rivers 6-10 km farther up the estuary .

BrandyCove

Gill

Ie;. II :ud et2 0 IS Oftll i

Fig. 2. Saltwater release site and recapturefacilities at Brandy Cove, St . Andrews, N.B.Locations and type of recapture gear are shown .

t{ETURNS FRO 1976 RELEASES

Grilse captures during August through idOctober 1977 consisted of 97 males, six of Whichcould not be identified as belonging to any of thethree groups and were presumed wild (Table 2). In1978, 169 two-sea-winter salon were captured, 10 ofwhich re presu ed wild. The percentage returns ofboth grilse and larger salmon were higher in group Cthan B and higher in B than A (Table 2).

Grilse captured during early August wer eheavie r and had higher condition fac to rs than fishcaptured later in the summer (Fig . 3). Sto achsa pIing during early August revealed no food had

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Table 2. Adult returns to St. Andrews Biological Station as grUse andtwo- sea-winter salon.

1976 re leaseGroups

A B C

GrUse

No . released 3612 3094 15694Sex H F H F H FNo . recapt ured 2 0 10 0 79 0Hean weight ( kg) 1.58 1. 54 1.65Percent return 0.06 0. 32 0. 50

Two-sea-winter sa lmon

~ex H F H F H Fo . recapt ured 4 3 4 12 53 83

Hean weight (kg) 4.29 4.69 4.82 4.72 4.80 4.48Percent return 0.1 9 0.52 0. 87

Total grilse andtwo- sea -winte r sa l on

No. recapt ured 9 26 215Percent re t urn 0 . 25 0.84 1.37

1.40

1.30

1.20

01.10u

CI....t: 1.000

"" 0.90t:0

(.)

0.80

0.10

y=1.093 • 0.0037 Xr =0.65

. .-~....

.. ·--i.~.. . .. .-... .,.. ,. ..:- ....~..-.. .~.

0.60

o 14 21 28 3~ 42 49 ~6 63 10 11

Ti e ( Days)

Fig. 3. Condition fact or of salon at time ofcapture - CF = wt(g) x 100/L3 (em) .

been recently ingested . Ther e was no evidence thata ny of th e recaptur ed grilse had been feed ing duringt he period of capture ( Augus t - mi d Oc t ober) . Fishcapt ured l a t e r in t he season were noticeably thinner( lower co ndi t ion fac to r) and the instantaneousweight lo ss dur ing t he recapture period was esti­mated to be 0 .26%/d . Although flesh color, texture,and taste of salon were accept able dur ing ear l yAugust , fish captured in salt water short l y a fterwere not as "bright"; the fle sh was softer and therewas a subjective impression that th ey were not aspalatable .

Approximately 150 , 4 .6-kg salmon th at returnedduring the summer and fall of 1978 were held in t hesaltwater tide pool until October , when t he y weredistributed to va rious hatche ries fo r brood st oc k.During this ti e only one fish died as a resul t ofinjuries received in the seine . 0 problems we reencountered with fungus infections . All fi sh wer estripped between October 26 and ovember 6 ,producing viable eggs that hatched normally .

DISCUSSIO

Because of expected lo~ survival of Carlin­tagged smolts in compa rison with fin-cl ipped orunmarked smolts (Saunders and All en 1967) , it i s no tappropriate to compare the returns of group A with Bor C. The low r a t e of return of group A fis h is ,therefore, probably owing as much or mor e to e ff ectsof tagging as to the experimental t rea t ent, i . e .direct release in sea water . Group A was includ ed togain some fnformation on the cont rlhutlon of t histock t o distant ff hcries . One tag was returnedfr om a l ocal weir and one tag from ewfoundland . Ofthe nine previously tagged fish recap tu r ed (asindicated by LV fin clips) , only one had reta i nedthe tag .

An interesting result of this study was thatthe group C (delayed release) smolts gav e muchbetter returns as grilse and larger salon thangroup B smolts which were also morpholine-imprin tedbut re leased without delay . Unfortunately, th e setwo groups did not have comparable fin clips; groupB had right pelvic fins removed while group C smol t swere adipose-clipped . Saunders and Allen (1967)compared effects on survival and growth a ongfin-clipped, Carlin-tagged, and unmarked Atlanticsalmon smolts and report that tagging and finclipping often have adverse effects on sur vival andgrowth . We know of no studies comparing effec t s ofdifferential fin clipping on survival of Atlanticsalmon between smolt and adult stages . However,Isaksson and Bergman (1978) no ted th a t pe lv i c finclips resulted in a lower return r a t e in Atlanticsalmon smolts compared to fish marked wi th ic ro tags(Jefferts et al . 1963) . It is, therefor e, possiblethat loss of a pelvic fin iR ore da aging than lossof the adipose, and that this treat ent allowedgreater survival of our group C than of group Bs ol t s , In 1977, identical groups of s olts withalternate fin clips were released in an attempt toresolve this problem . Un for t una t e l y , adult re t ur nsin all groups during 1978 and 1979 were insufficientto warrant analysis.

Groups Band C, although possessing differentfin clips, should be are co parable with each otherthan with group A. Group C had a 60% gr eater returnrate than group B and t his applies to grilse as wellas t o two-sea-winter fish. The differen t return

- 4-rates a ong various groups ight be attrib uted todifferences in ho ing perfor ance, ocean survival,or ocean distribution. Group C s olts wereimprinted in salt water for a longer ti e than groupB smolts, and it is possible that, despite co ­parable survival, they could ve beco e oreeffectively i printed to the ite (Hasler et a l.1978 ; Mad i son et a1. 1973) . I t is not pos s ib le todeter i ne whet her t he i printing was owing to themorphol in e or to 80 e othe r odor as sociated ith themar i ne s i te, such as f r esh wate r runoff f ro m land oreffluent f r om fi sh ta nks at the Bio log ic al Station .It is i nteres t i ng to note t ha t Chamcook Lakesupplies wat er to the Biol og ical Station and to theorth Amer i can Salmo n Rese arc h Cent er whic h is loca­

ted approx i ately 10 km away ( Fi g . 1) . Only one fishfro t he 1976 releases at both s ites (22 , 00 atBio l ogic a l St ation and 19 ,000 a t ASRC) was known tohav e been recov ered in the opposite collectionfac ilit y. In fac t , one sa l on cap tu r ed at Br andyCove and re l eased fro ASRC a fter str i ppi ng re­t urned the nex t su er as a re pea t spawner to BrandyCove , t he orig in al olt release site ( Fig . 1) .

Our results are difficult to explain in l ighto f the pr oposed phero one hypot hesi s (White 1936;ordeng 1971 , 1977) . There were no sa lon of Waweig

parenta ge be i ng held at t he Biological Sta tion pasti d June , yet sa l on ho ed to this site du r ing mid

July and re ained in the vic i nity for 3 o , Based ont he pr oposed attractive inf luence o f phero ones , oneight have expected the Brand y Cove sa l mon to have

homed to the Wawei g Ri ver, a site 12 km dist an t fromt his cov e. Wawe ig River con t a in s a popu l a tion ofS l mo sa l dc , pr es umabl y emitting ra ce-specif i codors. If such phe ro ones a r e ope r a t i ve , it woul dappear that th e i r in fl uence ca n be overr i dden byother di r ective fac to rs .

The diffe r ence in s ize (Table 1) and nut ri ­tiona l state a ong the di f f e rent groups of s a l t s atr el ea se , as well as the ti e diffe rence at r e l ea se ,could have influenced subsequent na tural su rvivaland/or fishing mortality as a re sult of an alte reddistr i but i on in th e sea . The in fluenc e of smolts ize on the survi va l of hatche ry- r ea r ed Atl anticsa lon is well documented (Carlin 1968; Pete rson1971; R1 tte r 1972). This can be explained to somede gree by ocean mortality being si ze dependent(Mathews and Buckley 1976) . There i s ev idence thatthe ti e of s olt re l ease i s also i portant inPacific sa l on as mortality rate s a re initially veryhigh (Parker 196 ; Martin et al. 1981) . Larsson andEri ks son (197 9) have shown tha t r i ver temperatu re atti e of smol t r e lease was cor r elated wi t h adultreturn r a t e s dur ing many years in hatch ry-rearedAtlantic sa l mon in Sweden. The importance ofnu t r i tion and condition of hatc he ry- rea r ed Atlanticsalon had also been recognized ( Berg s t ro 1973;Peter son 1973; Wendt and Saunders 1973 ; Wed emeyer eta l , 1980) .

A further suggestion to ex pl a i n the differentre t ur n ra t es a ong the variou groups is thatde layed relea e may influence migr a to ry behavior .Mahnken and Joyne r (1 973) observed that coho thatescaped or were r elea se d in mid to l a te su er fromPuget Sound cages did not leave the general area . Alikely explana tion is t hat ig ra to ry behavio r is

odifi ed if smol ts are detained af te r entering seawater ( ovotny 1980) . Although our delayed releaseex per i ment s were done in recog ni t i on of the obser­va tions on Pacific sa l on , we do not know if the

ig rato ry behavio r of our fish was altered as acon sequence of delayed re l ea e .

Although t he echan is s res pons i ble f o r t hehomi ng behavio r ob se rved i n t his s t udy a re no tclearly under s tood , it would a ppear tha t Atlanticsa l mon can be re leased an d harvested at ar i ne sitesdistant f rom a j or r ivers . It has been suggestedthat t he imp r inting proc ess oc cur s dur ing or shor t l ya fte r s olt i f ic a t ion and ay be associated withdown st ream igra tion (Ca rlin 1968 ; J en sen and Duncan19 7 1 ) . The fi sh t r anspor ted f r om Cobeq u i d Fi shCul ture Station to t he Bio log i c a l St at ion a ppearedfully smolt if ied and wcre capa bl e o f to l era t inR thed ire c t trans fe r to full s a water in th e tide pool ;less than 1% mortality WA S ob e rved in g roup Csmo l S held 3 wk . ThI s ugge a t s that the imprintingstage might no t be r e s tr i c t e d to smoltifyi ngAtlantic salmon r e s i d i ng in f resh water . In an ye vent , so e effecti ve imprin t ing took pl ac e du ri ngthe smolt s ' delay in sea wat e r be fo r e eventualrelease . Homing t o mar ine si t e s by Pa c ific sa l monhas been desc ribe d fo r coho , O. k isutc h ( Ma hnke n an dJoyner 1973 ; l ovo t ny 1975 , 1980 ) and fo r pink salmon ,o. gorbuscha (R . Bake r , pe rsona l co uni c a tio n) .

Ta~ed and fln - clfpp d smolts an d ad u l t salmonf rom thts study nnd f rom the nea rby o rth Amer i canSalmon Re searc h Cen te r a rc occ as iona l ly r e por t e d asincidental byc a tch in t he e xten s i ve he r r i ng wei rfishe ry in Passamaquoddy Bay . It is vi r t ua llyimpossible t o se parate and re lease smolts f rom l a rgehe r ring ca tche s r emoved f rom weir s , and i t isp robable t hat many of t he smol ts released dur ingthi s study were captu red by weir fishe r en and no tr e po r t e d . This sou rce of smol t and ad ult morta lit ywo ul d appea r to be a se r ious i mpe d imen t t o se ar anc hi ng in Pas sa ma quoddy Bay .

The principal finding in ou r s tudy was t ha tAtlantic salmon r eared in a d i s tan t hat chery andreleased at a a rine s i t e 12 km f rom t heir pa r en tstream retu rned to the marine site aft er 1 or 2 y rat sea . The cond i tioning and di rect r e lease ofsmolts from mar ine impoundments such as he rringweirs or floating fish pens may be desirable inproducing and managing a selective commercialfishery separate f rom a f reshwate r r ecreat i o na lfishery . Homing to such site s would appea r spec i ficenough to enable simple harves ting techniques to beemployed . Also , brood fish co ul d be held inexcell ent co nd i t ion in ocean pens until shortlybefore egg take , thus eliminating ce rtaindifficultips encounte red in brood stock transport ,holding, and co nd i t i o n i ng .

However, to offset the high costs of sal onsmolts, any co ercial ranching venture undertakenin Passamaquoddy Bay would have to reali ze uchhigher adult escapement togethe r wi th a r ed uc t i o n inthe grilse :larger salmon ra t i o in compa r i son withthe r e s ul t s of this study . Al so, the re rema i n s somequestion conce rning the flesh quality of pre spawningsalmon harvested from a terminal fishery in la tesummer . Preliminary rearing trials conducted in thePassamquoddy area suggest that some of the problemsof survival, g rilse production , and flesh qualityencountered in ranched salon can be overcome byr ear i ng smolts in ocean pens fo r a pe riod of 18-20mo to obtain a ha rvest weight of 3.3-3 .5 kg(Sutte rlin et al . 1981) .

It hough the pr ospects for private secto rinvolvement in sea ranc hin~ with Atlantic salmon ineastern Canada are const rained by economic and legalconsiderations , advances in such r a nc hi ng techniquescould be useful in enhancing various publicfisheries .

- 5-

CK OWLEDGMENTS

We are gr a t eful t o Me s s r s . Ti Ca r ey andLeona r d MacIntosh who arranged for, and superVised,smolt produc tion a t Cobequid Fish Cul tu re Station .Dr s . A. W. White and • Waiwood made hel pf u ls ugge ti ons on he anus c ri pt . e s s rs . P . W. G.

cM ul l on and F. Cunningham pr epa red t he fiRu res andthe t echn i cal ed i t i ng pro v t ded hy 8 . R. Car ne t t didmuch to improve t he qua lity of this manus c r t pt ,

r s , J ean ine Hurl ey and MR . Rrenda c Cu11 o ug h typedthe mnnuac r t pt .

REFERE CES

Be r g s t rom , E. 1973 . The ro l e of nut rition ing rowth and su r vival of young hatchery rearedAt lan t i c salmon . Int . At l. Sa l m. Fo und , , Spec .Publ . 4 : 256- 28 4 .

Bilton , H. T. 1980 . F.xperi men t a l rel ea se s of co hosalmon in Rritish Col umbLa , p . 305-)2 • In J .Tho rpe (ed .) . Sa l mon Ranc hi ng. Ac a demic Pr s s ,Lo nd on .

Carlin , B. 1968 . The mig ration of salmon , p ,14-22 . In At lant i c Sa l mon Assoc . CentennialAwa rd Fund Se r i es of Lec tu res by Dr . BorJeCarlin . The Atlan t ic Salmon As soc . , . o n t r ea l ,Que , , Canada .

Coope r , J . C. , and A. D. Hasle r . 1973 . Anel ect rophysiologic a l approa c h t o salmon homing .Fi sh . Res . Board Can . Tec h . Rep . 415 , 44 p ,

Ha sler , A. D. 1966 . Unde r wat e r gu i deposts . n Iv ,o f Wiscon sin Pr es s , Wise . , 155 p .

Hasler , A. D., A. T. Scholz , and R•• Horrall .1978 . Olfactory imprinting and homing insalmon . Amer . Sci. 66: 347 -355 .

Isaksson , A. 1980 . Salmon ranching Iceland, p .383 -394 . In J . Thorpe (ed .) . Salmon Ranching .Academic Press, London .

Tsaksson , A. , and P. K. Bergman . 1978 . nevaluation of t wo t a gg Ing met hod s and survivalr at e s of diffe rent age and treatment grollJls ofhatche ry-rea red Atlantic salmon smolts • .I ,Ag r , Res . Icel. 10 : 74 -99 .

Jefferts, K. B., P. K. Bergman , and H. F. Fiscus .1963 . A coded wire identification system formac roo rganisms . ature 198 : 460-462 .

Jensen , A., and R. Duncan . 1971 . Homing oft ransplanted coho salmon . Prog . Fish-Cult . 33:216-218 .

Larsson , P.O. , and C. Eriksson . 1979. The i pactof water tempe ratu re at release on thesubsequent re t urn rates of hatche ry rearedAtlantic sa lmon smol ts , Salmo salar L. Set I .Res . In st , Rep . • 1 .

• adison, O. A. T. Scholz, .1. c. Cooper, R. n.Horrall , A. O. Hasler , and A. F. . 017:on . 1971 .I . Olfactory hypotheses and salmon igrati on: As yno ps i s of rec ent find Ings , Fish . Res . BoardCan . Tech . Rep . 414 , 35 p ,

Mahnken , C. , and T. Joyner . 1973 . Salon for ewEngland fi sherie s . III . Dev eloping a coa s t alfishe ry f or Pacif i c sa lmon . Ma r . Fi s h . Rev .35 : 9- 13 .

Ma r tin , R. M. , W. R. Heard , an d A. C. We r the i ere1981 . Shor t - te rm rearing of pink sa l on(Oncorhynchus go rbuscha) f ry : e f fec t onsurvival and biomass re t ur n i ng as ad ult s . Can .J . Fish . Aqua t , se i . 18: 554-558 .

athews , S. B. , and R. Buckley . 1976 . Marinemortality of Puget Sound coho salmon(Oncorhynchus kisutch) . J . Fish . Res . BoardCan . 33 : 1677-1684 .

Mc e I l , W. J . 1980 . Legal aspects of salmonranching in the Pacific , p . 325-369 . In J .Thorpe (Ed .) . Salmon Ranching . Academic Pr ess ,London .

o r deng , H. 1971 . Is the local orientation ofanadromous fishes determined by phe romones?

a t ure 231 : 411 -411 .

1977 . A phe r omone hypothesis for homewardmigration in anad rornous sa ImonId s , 01kos 28:155-179 .

- 6-Saunde rs , R. 1. , and J . K. Bailey . 1980 . The role

of genet i cs i n At l ant i c sa l on mana ge ment, p .182-200 . In A. E. J . Wen t (Ed .) Atlan ticsal mon: i t~fut u re . Proc . 2nd In t . At l . Sal onSympos., EdInb , , 1978 . Fi s hing News BooksLt d., Fa rnha , England .

Sutt e rlin , A. M. , E. B. Henderson , S. P. e r r t l l , R.L. Saunder s, and A. A. ac kay , 198 I . Sal monidrea r i ng t rials at Deer Island , w Bruns wick ,wi t h some projections on econom ic v ia h l l it y.Can . Tech . Re p . Fish . Aqua t , Sc 1. 1011 ,28 p ,

Thorpe , J . E. 1980 . The development of salmonculture towa rds ranching , p , 1-11 . In J .Thor pe (ed .) . Salmon Ranching . Academi c Press ,London .

Wedemeyer , G. A. , R. L. Saunders , and U. C. Clarke .1980 . Envi ronmental facto rs affectings mol tifica t ion and early marine sur v i val ofa nadromous salmonids . Mar . Fish . Rev. 42 :1-14 .

Wend t , C. A. C. , and R. L. Saunders . 1973 . Changesi n ca rhohyd rate metabolism in young Atlanticsa l mon in re s ponse to various fo r s of stress .Int . Atl. Sa Im, Found . Spec . Publ. 4: '>5 -82 .

ovotny , A. 1975 . l e t - pen cul tu re of Pacificsalmon in marine waters . Ma r . Fi sh . Rev. 37 :46-47 .

1980 . Del ayed release of salmon , p . 325­369 . In J . Thorpe (ed .) . Sal mon Ranc hi ng .AcademiC Press , London .

Parke r , R. R. 1964 . Estimation of sea mortalityrates for 1960 brood-yea r pink salmon of Hooko se Creek , British Co l um bf a , J . Fish . Res .

Board Can . 4: 757-794 .

Pe t er son , H. 1971. Small rearing met hods ,equipment , and te chni ques used successfully inSweden . Int . Atl. S..11 • Found , , Spec . Publ.Ser e 2 : 757-79 •

1973 . Adult ret urns to date fromhatchery-reared one -year-old smolts . Int . Atl .Sa Irn, Found . Spec . Publ. 4: 219-224 .

Ritter, J . A. 1972 . Preliminary observation on theinfluence of smolt size on tag re t urn rate andage at first maturity of Atlantic sa l mon (Salmosalar) . Inte r na t , Counc , Exp Lor , SeaC.H . 1972/M : 14.

Sakuramoto, K., and S. Yamada. 1980 . A study onthe planting effect of salmon - I . Bull . J ap .Soc . Sci . Fish . 46 : 663 -669 .

Saunders, R. L. 1968 . An evaluation o f two methodso f attac hing tags t o Atlanti c salmon smol t s ,Pr og , FiRh-Cult . 30: 104-1 09 .

1977 . Sea ranching - a promising way toenhance populations o f Atlantic salmon forangling and co ercial fisheries . Int . Atl .Sal . Fo und . Spec . Publ. 7: 17-24 .

Saunders, R. L., and K. R. Allen . 1967 . Effects oftagging and fin -clipping on t he su rvival andgrowth of Atlantic salmon between smolt andadult stages . J . Fish . Res . Board Can . 24 :2595 -2611 .

White , H. 1936 .Ri ver, . S.

The homing of sa I on in AppleJ . BioI. Board Can . 2: 391-400 .