August 1976

MFR PAPER 1194

Coho Salmon Farming in France

YVES HARACHE and ANTHONY J. NOVOTNY

ABSTRACT-The coast of Bretagne (Brittany) in France offers many suitablesites for salmon aquaculture. Seawater temperature varies from 8 to 18.5°C,but unusual climatic conditions may induce peak temperatures of 20°C. Cohosalmon research was induced in France in 1971 by a CNEXO-COB (CentreNational pour l'Exploration des Oceans/Centre Oceanologique de Bretagne)research team, in close relationship with NOAA-NMFS specialists. The resultsin freshwater-rearing were excellent, with high survival and good growth undernatural conditions, leading to a large percentage of young-of-the-year (O-age)

smolts. The first year of operation of an experimental saltwater, diked, tidalpond produced 7.6 metric tons of coho salmon in 1974 and 22 tons in 1975.Another pilot plant, built in June 1974, used net-pens in the Rade de Brest andproduced about 4 tons.

Late spring and summer adaptation of smolts to seawater showed heavymortality during the summer of 1974 and 1975, possibly due to high tempera­tures associated with high salinities. No evidence of bacterial infection wasfound in 1974, but Vibrio sp. was isolated from dying fish in 1975. However, thesurviving fish showed excellent growth. Part of the O-age 26 g smolts, adapted inJuly 1974, reverted to parr condition with a poor growth, while the other part ofthe population reached an average weight of 397 g by 31 December (1.58%daily weight increase) and 735 g by 10 April 1975. Large l-year smolts averaged522 g by 31 December (1.25% daily weight increase) and 1,050 g by 9 April1975. The salmon are reared in saltwater from October to May, when the seatemperature is below 13°C. The coho are marketed in France-fresh, whole,and in the size range of 0.3-0.8 kg. Market prices and acceptance are excellent.Total production should approach 100-120 tons in 1976 in three operating farms.

" "RESUME-Les cotes de Bretagne en France offrent un certain nombre desites favorables aI'aquaculture du saumon. Les temperatures de I'eau de mervarient de 8 a 18,5°C mais des conditions climatiques exceptionnelles peuvententratner des temperatures proches de 20°C en ete.

L 'equipe d'aquaculture du Centre Oceanologique de Bretagne debuta unprogramme de recherche sur I'elevage du saumon COHO en 1971.

Les resultats de I'elevage en eau douce furent excellents avec un fortpourcentage de survie et une bonne croissance dans les conditions naturelles,entratnant un pourcentage eleve de smolts d'age O.

La premiere annee de fonctionnement d'un etang a maree experimentalpermit de commercialiser 7,6 tonnes de saumon COHO en 1974 et 22 tonnes en1975. Une autre structure pilote utilisant des cages flottantes en rade de Brestfut achevee en juin 1974 et produisit environ 4 tonnes de saumon dont 2 furentcommercialisees.

Les adaptations de smolts a I'eau de mer a la fin du printemps et en ete setraduisirent par de fortes mortalites estivales en 1974 et 1975, pouvant ~tre

attribuees aux temperatures elevees associees a une forte salinite. Aucuneinfection bacterienne ne fut mise en evidence en 1974 mais Vibrio sp. fut isoleen 1975.

Cependant les poissons survivants presenterent une croissance excellente.Une partie des smolts d'age 0 (26 g) adaptes en juillet 1974 regresserent a I'etatde parr avec une faible croissance alors que Ie reste de la population atteignaitun poids de 397 g Ie 31 decembre 1974 (croissance journaliere: 1,58%) et 735g Ie 10 avril 1975.

1

Le smolts de 1 an (70 g) transferes en cages flottantes en juillet 1974atteignirent un poids de 522 g au 31 decembre 1974 (croissance journaliere:1,25%) et 1050 g Ie 9 avril 1975.

La production en eau de mer est actuellement programmee d'octobre amaiquand la temperature de I'eau est inferieure a 13°C.

Les saumons sont commercialises en France frais, en tiers dans la gamme depoids de 0,300 a0,800 kg.

Les prix obtenus et I'acceptation sont excellents.La production totale devarait approcher 100 a 120 tonnes en 1976 grace ade

nouvelles installations.

INTRODUCTION

Historically, the European consumerhas been accustomed to Atlantic salm­on, Salmo salar, as his first choice.However, due to the high cost ofobtaining wild Atlantic salmon (whichare in short supply), he has made somemovement toward the more plentiful(and economical) Pacific salmon, On­corhynchus spp., which is now anestablished consumer product.

Before the French Revolution, it isclaimed, the rivers of Bretagne (Brit­tany) were producing over 4,500 metrictons of Atlantic salmon a year. Theactual catch now is about 10 to 15 tons,and the additional high seas fisheriesoff Greenland of 2,500-3,000 tons isenough to endanger the species. Themain causes of this disastrous diminu­tion of Atlantic salmon are lack ofmanagement, overfishing, unadaptedlegislation, degradation of the environ­ment, and an almost total absence ofsmolt-rearing facilities for restockingthe rivers. This makes it impossible toobtain eggs from wild stocks ofAtlantic salmon in France.

The French coastline, particularlythat of Bretagne in the North, hasgeographical and climatic conditionsapparently favorable to salmon farm­ing. The Bretagne economy is partiallybased on exploitation of the sea, buttraditional fishermen are now interest­ed in developing aquacultural activity.Twelve rivers of Bretagne still supportsome small natural runs of Atlanticsalmon.

Sea surface temperatures fluctuatefrom 8 to 18°C, with optimum range of10 to 16°C, 9 months of the year. In1975, the highest atmospheric temper­atures recorded in Bretagne since thebeginning of the century led to surfacetemperatures of 20-22°C in deep baysand estuaries, while the open sea

2

surface temperatures approached 19°C.The salinity of most of the sites

deemed suitable for salmon farmingrange from 29-35%•. Tidal amplitudesrange from 5 to 12 meters, dependingon the area. This characteristic prvides good renewal of water but limitsthe number of suitable sites. Stormsoccur frequently during the fall andwinter months. Consequently, fishfarms have to be protected fromoceanic swell and, if possible, from thedominant southwesterly winds.

Studies of the seawater culture ofcoho salmon, O. kisutch, pioneered bythe National Marine Fisheries Service(NMFS) in Puget Sound, Wash., indi­cated that the Pacific coho might beadaptable to the environmental condi­tions in the region of Bretagne. NMFScooperative pilot farm studies provedthat the coho could be grown to amarketable size in less than 18 monthsfrom fertilization of the egg, at a finalproduction level of 250 tons per surfaceacre (Novotny, 1975). Thus, the Pacificcoho, which are much easier to rear infresh water than Atlantic salmon andless exigent about water quality, werechosen for the first French salmonfarming tests.

The first eyed coho eggs (60,000)were purchased in December 1971from the Washington State Depart­ment of Fisheries and were reared infresh water in Bretagne under contractwith a private fish farm. A secondshipment of 200,000 eggs was receivedat the end of 1971, partly from theOregon Department of Fish and Wild­life (Alsea River) and partly from theBureau of Sport Fisheries and Wildlife(Eagle Creek National Fish Hatchery).

In 1973, CNEXO-NOAA cooperationwas formally instituted for the develop­ment of coho salmon farming in France.NOAA furnished 250,000 eyed cohoeggs to CNEXO, and exchanges be-

Yves Harache is with the CentreNational pour l'Exploration desOceans. Centre Oceanologique deBretagne, Brest, France. AnthonyJ. Novotny is with the NorthwestFisheries Center, National MarineFisheries Service, NOAA, 2725Montlake Boulevard East, Seattle,WA98112.

This article is a contribution fromthe U. S. / France Cooperation inOceanology formally organized in1972 by Yves La Prairie, President-Directeur General, Centre Nation­al pour L 'Exploitation des Oceans(CNEXO), and Robert M. White,Administrator, NOAA. James E.Hanks, Middle Atlantic CoastalFisheries Center, National MarineFisheries Service, Milford Labora­tory (Conn.), is the NOAA Aquacul­ture Leader and Jacques Le Noan,Department Chief "Living Resour­ces", Paris, is CNEXO representa­tive for the aquaculture aspect ofthe Cooperation.

tween scientists of CNEXO's CenterOceanologique de Bretagne (COB) andNOAA's Northwest Fisheries Centerof the National Marine Fisheries Ser­vice were arranged. In late 1973, asurvey of possible net-pen culture sitesin Bretagne was conducted by Ameri­can and French scientists. In 1974, onemillion eyed coho eggs were obtainedby French salmon rearers from U.S.hatcheries.

At the same time, two ways ofrearing coho salmon to commercial sizewere planned: 1) Using old mill tidalponds which are quite frequent alongthe sea shore and the river estuaries ofBretagne; and 2) Selecting shelteredsea areas where salmon could bereared in floating net-pens.

A pilot company, the Societe pour IeDeveloppement de I'Aquaculture enBretagne (SODAB), was organized in1973 with CNEXO as the major owner.Two other farms using floating net­pens in open seawater were developedin 1974 and 1975 with fishermen'scooperatives.

Marine Fisheries Review

Figure 2.-Floating net-pens in the diked tidal pond at Moulin du Carpont. The Norwegiantype octagonal pens are 2.5 and 3 meters deep and have volumes ranging from 193 to 230 cubicmeters.

FRESHWATER CULTURE

The first 2 years of operation(1972-73) were tests of the ability ofoperators to produce good survival andearly growth of coho in the naturalenvironment of the freshwater experi­mental hatchery. At the same time,studies were conducted at the COBlaboratory concerning the size of fishand time of entry into seawater of cohosmolts.

The fish were raised in the hatcheryon a dry pelleted ration of Frenchformulation and manufacture. Theoverall survival of the first lot of cohowas only 50 percent at the end of thefirst year. However, the survival of thelots of the following year was 85 per­cent and 96 percent for one year'sgrowth, and average weight was 50 g(Harache ,11974). Eyed Atlantic salmoneggs were obtained from Scotland andcultured at the same hatchery at thesame time. By contrast, the survival ofAtlantic salmon at the end of the firstyear was only 4 percent, and theaverage size was less than 10 g. All fishwere reared in 10-11 DC reused springwater until the stream waters reachedlODC (April). In 1974, the survival wasabout 80 percent; in 1975, an upstreamdischarge of a pollutant destroyed400,000 O-age coho in early May.

Only a small number, approximately20 percent, of the 1971 brood progenyexhibited signs of smolting as O-agefish in July (15-20 g) and October (35 g)of 1972. The progeny of two lots of 1972brood eggs showed remarkable differ­ences. Over 50 percent of the progenyof the Alsea River Hatchery parentstock smolted before the end of thefirst year's growth (O-age). Virtually100 percent of the progeny from EagleCreek Hatchery parent stock, whichstarted feeding 3 weeks later, smoltedas yearlings. However, the averagesize of Eagle Creek yearlings was 70 gin May 1974, which is exceptionallylarge. The smallest fish of the EagleCreek stock, kept in fresh water untilOctober 1974, weighed 150 g. In July1974, 59 percent of the 1973 brood

I Harache. Y. 1974. Premiers resultats deJ'elevage experimental du saumon coho (Oncor­hyru;hus kisutch). In L. Laubier and D. Reyss,Colloque sur J'Aquaculture. 22-24 Oct. 1973,Brest. p. 343-356. Pub!. Cent. Nat!. Exploit.Oceans (CNEXO). (Fr.], Ser.: Actes CoUoq. 1.(Processed report.)

Eagle Creek stock were smolted asO-age fish.

The significance of high survival andexcellent growth of coho salmon inBretagne, which had no alterations ofthe natural freshwater environmentcannot be overlooked.

SEAWATER CULTURE

Rearing Facilities

SODAB developed a diked tidal pond(Moulin du Carpont) on the estuary ofthe river Jaudy for marine production(Fig. 1). The pond, which has a surfacearea of 6,000 m2

, is held at an averagedepth of 4 m, regardless of the tide.Water for the pond is produced by two600 mJ per hour (5.9 cubic feet persecond) pumps which can work from 9to 11 hours daily. A circulating pump inthe pond moves 3,600 m~ of water perhour (35 cubic feet per second) andinduces a continuous current. At thehigher tides, water can be partiallyrenewed by gravity. The salmon arecultured in 16 Norwegian-type floatingoctagonal pens (Fig. 2). Pen volumesrange from 193 to 230 cubic meterseach. In 1975, a submersible dike wasbuilt below the upper pond, creating anadditional pond with a surface area of2,000 m, suitable for rearing. Sub­merged at each high tide, the dikekeeps a 4-m water depth inside thelower pond which contains 12 octagonalnet-pens (Harache, 1974).

Theoretical loading capacities for theupper pond were calculated by theCNEXO-NOAA team for several sizeranges of coho. The studies were based

ATLANTIC

OCEAN

Figure l.-Bretagne region in France,showing the locations of the diked tidalpond at Moulin du Carpont. and L'Auber­lach Bay in the Rade de Brest (BrestSound). Brest is in the same latitude ascentral Puget Sound. where coho salmonhave been successfully cultured on acommercial scale.

on probable temperatures, oxygen sat­urations, oxygen consumption, andoxygen renewal. Surveys of the tidalponds are being conducted to determinethe possibilities of using this kind ofpond for intensive production.

Another pilot plant, much smaller,has been developed in a partiallysheltered bay of Rade de Brest. Asteel-pipe raft (Fig. 3), with four 60 m3

(3 m deep) pens made of knotted nylonmesh, was installed in early June 1974

August 1976 9

2000

19751974

RADE DE BREST (pensin open sea)

........ summer adaptation -good growth

0--0 summer adaptation - poor growth due to reversionto parr condition

-- tall adaptation

D---Q tall adaptation - brood stock

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Figure 3.-Floating rigid pen-frame system and net-pens in L'Auberlach Bay, Brest Sound.Note the polyethylene kegs for flotation. Wave height can reach 1.5 meters (4.9 feet) in thisbay.

First Marine Productionof Coho in France

The dike tidal pond at Carpont wascompletely equipped at the end of 1973.The first floating net-pens were instal­led during December 1973 and January1974 with coho from the 1971 and 1972parent brood stocks, ranging in sizefrom 180 to 500 g.

The average weight increases of thecoho transferred to the pond atCarpont (30-35%.salinity) ranged from0.4 to 1.1 percent per day (dependingon stock and sizes) from Januarythrough March. The advanced O-agesmolts grew slower (0.7 percent perday) in the marine environment thanyearlings of the same size at time ofentry (1.0 percent per day). In thesestages, the fish were fed the drypelleted ration, and mortality up tospring and early summer harvestingwas almost negligible.

(Virmaux,2 1974 and Danioux et aI.,1975). Water depth in this bay variesfrom 4.2 to 9 m depending on the tides.Current velocity does not exceed 0.3 mper second but wave amplitude canreach 1.5 during southwest storms inwinter.

This operation is conducted in closecooperation with a fishermen's cooper­ative, Cooperative Maritime Aquacoledu Tinduff (COMAT) that is in chargeof the operation. CNEXO-COB isresponsible for the technical and scien­tific advice and the cost of operation.After a I-year test of the structures,five commercial size rafts with 8.5x8.5x3.5 m deep net-pens were installedand stocked with coho in early Novem­ber 1975. This raft provides 2,200 m ofspace in which 30 to 35 tons of salmoncould be produced in the future.

A third experimental station usingtwo octagonal Norwegian-type pens isoperating in the estuary of the Jaudy,close to Carpont. The current velocityof 2 knots can be considered a limitingfactor in these conditions. These threeprojects are followed very closely byCNEXO biologists on a comparativegrowth and cost basis.

'Virmaux, J. F. 1974. Etude sur les cagesllottantes pour ['aquaculture. Mem .• Ec. Nat!.lng. Trav. Ruraux Tech. Sanit., Strasb., andCNEXO, Cent. Oceano\. Bretagne, Plouzane,Fr. 220 p. (Processed report.)

Figure 4.-Growth of zero age coho smolts in seawater. Values above the lines are thespecific growth rates in percent of weight increase per day between measurement periods.

Marine Fisheries Review

2000

Figure 5.-Subsampling of winter coho by the CNEXO-COB biological team justprior to harvest. Floating pens in L'Auberlach Bay. Brest Sound.

BroodStock

observed until early March 1975 whenthe average weight was 525 g (Fig. 6).The lower growth obtained in theclosed pond may possibly be attributedto low levels of dissolved oxygen.

0.96

1975

......... summer adaptation-Floating pens in Brest Sound

0-0 summer adaptation-

CARPONT pens in tidal pond

- fall adaptation-

Floating pens in Brest Sound

1974

500

1000

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Figure 6.-Growth of yearling coho in seawater. Values above the lines are the specific growthrates in percent of weight increase per day between measurement periods.

the same stock of fish was in excess of90 percent, and the average weightgain was 0.7 percent per day duringthe first period and 0.9 percent per dayduring the last period. These fish were

In 1974-75, we attempted to adaptO-age and yearling smolts during Juneand July, when the seawater tempera­ture was about 15°-17°C. In all thetests, mortality during the first 2-4weeks was high with some apparentdifferences in each environment. The30-day mortality of O-age smolts (20 g)in 1974 was 100 percent in the dikedtidal pond at Carpont, 95 percent at theCOB laboratory, and 40 percent in thenet-pens of the Rade de Brest. Noevidence of disease was found in spiteof alarming disease-like external symp­toms. The mortality increased withtime, reaching 100 percent at COB and78 percent in the net-pens. Ap­proximately 50 percent of the survivingfish grew well from September (1.6percent daily increase) until late Dec­ember and reached an average weightof 735 g by mid-April 1975 and 1,373 gby late October 1975 (Fig. 4). Themajority of the remaining 50 percentreverted to parr condition, and growthwas very poor. The fish were fed a drypelleted ration with a food conversionrate of 1.35:1 until December 1975 and1.7:1 in April 1975.

Yearling smolts (50 to 80 g) weretransferred to 34.5'/00 seawater in Mayand June 1974 (14° to 17°C) at the COBlaboratory for experimental purposesand into a reduced segment of theCarpont tidal pond. Growth was verypoor due to excessive handling andpoor environment, but mortality wasnot excessive until July when tempera­tures reached 18.5°-19°C in Carpontand 17.5°C at COB. Aeromonas salm­onicida was isolated at COB when 500fish (averaging 72 g) in stressed condi­tion were transferred from the COBlaboratory to the net-pens in Rade deBrest at the end of July when seawatertemperature was 17.2°C. (35.5'/00 salin­ity). The mortality of these stressedfish was 72 percent in the first 3 daysfollowing transfer. However, the sur­viving fish grew well, reaching anaverage weight of 262 g by lateOctober (1.3 percent weight increaseper day) with a 1.7:1 food conversionand 522 g weight by late December (1.1percent weight increase per day) witha 1.8:1 food conversion (Fig. 5). InApril 1975, the average weight was1,050 g with a 2.3:1 food conversion,and by late October the average was1,590 g. At Carpont, the mortality of

August 1976 5

Temperatures__ Diked tidal pond at Moulin du Car pont

0--0 L'Auberlach Bay in Brest Sound

Dissolved Oxygen Content

0----0 Treguier estuary below the Carpont pond

-- Inside the Carpont pond

• • L'Auberlach Bay

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1974 1975

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Figure 7.-Seawater temperatures and dissolved oxygen values in the diked tidal pond and in L'Auberlach Bay in Brest Sound.Dissolved oxygen values for the open estuary just outside the pond are also given. Note the differential in oxygen values whenthe production level reached 15 tons in late 1974.

Dissolved oxygen fell to 5-6 parts permillion when the pond density ap­proached 15 to 20 tons of fish (Fig. 7).

The results during the summer of1975 were even worse, with a mortalityin excess of 95 percent at all sites withunusually high temperatures. Vibriosp. were occasionally isolated fromdead or dying fish, but vibriosis couldnot be confirmed as the major cause ofmortality.

In the fall of 1974, fish were adaptedin the Rade de Brest and Carpont,either as O-age large fall smolts (70-100

6

g) or as 1-18 month smolts (150-200 g)..The growth of the larger fish wasexcellent with a 1.01 percent dailyweight increase in Rade de Brest fromNovember 1974 to February 1975.Brood stock isolated from this groupreached an average weight of 1,350 g inlate October.

The results with O·age smolts weredifferent. Coho smolts weighing 80·100g at the time of saltwater entry hadgood growth and survival. Fish smallerthan 70 g at saltwater entry had lowgrowth rates but no mortality (Fig. 8).

The first coho cultured in the sea inFrance were harvested in April 1974by SODAB and shipped to markets inParis. The fish were in excellentcondition- bright, silvery, good bodyshape, no blemishes, firm, and withgood flesh color. The fish were harves­ted once or twice each week; they werestunned and packed whole in ice instyrofoam cartons at a total cartonweight of about 10 kg. The individualweight range of marketed fish was 300­800 g, representing single portionmeals or enough for two persons.

Marine Fisheries Review

Figure B.-Market size French coho. Coho averaging 70 grams in late July (smaller fish) reachan average of 700 grams after just 6 months growth in seawater (large fish).

Figure 9.-Two-year-old maturing male coho in the net·pens in L'~uber.lach Bay. These fishare considerably smaller than the 3-year-old mature coho from the diked tidal pont at Carpont.

CONCLUSIONS

Although the growth and survival ofthe coho salmon in fresh water inBretagne is better than was anticipa­ted, there are some problems in marinerearing. When the coho are adapted toseawater in the fall or winter, there isalmost no mortality in the ensuing

genetic control to develop stocksadapted to the Bretagne environment.

In 1973, the first coho culturedentirely in the freshwater hatcheryreached maturity as 2-year-old fish,weighing from 0.3 to 0.8 kg. Approxi­mately 100,000 eggs were taken fromthe females, but the quality was ap­parently similar to the eggs of the firstbrood stock cultured in the sea byNOAA-NMFS at their Manchesterstation. The eggs were transparent,with poor yolk dispersion and extreme­ly fragile walls. The survival throughhatching was only 1-3 percent, which isidentical to the results of the NMFSfirst year brood.

The 2-year-old fish that did notmature were transferred to the dikedtidal pond at Carpont in January 1974.Only 3 percent of these fish reachedmaturity as 1-2.5 kg females in late1974 as 3 year olds. Approximately 17percent of the population matured asmales in a slightly smaller size range.Although a high proportion of thesematuring fish were bright and did notexhibit the usual sexual characteristicsof maturing coho cultured at Manches­ter, eggs could be extruded from thefemales, and ample quantities of semi­nal fluid from the males (Fig. 9). Un­fortunatley, the eggs were found to bein the same conditions as those of thefirst spawning from the freshwaterhatchery. In some cases, the femalegonads were atrophied.

In December 1974, at Yvias, eggswere taken in fresh water from 2-year­old fish with better results (Fig. 10).About 20 percent of the eggs survivedand the resulting progeny showed goodgrowth. These fry were 6 weeks laterin the development stage than thosefrom U.S. coho eggs fertilized in earlyNovember and reared in the sameFrench hatchery. But, by October1975, the French progeny had caughtup with the U.S. stock, reaching anaverage weight of 43 g (range 10-80 g).

this new product is bringing Frenchfarmers an average 16.6 percent of theU.S. prices. In addition, the farmers ofSODAB and COMAT do not have thelabor expense of dressing the fish, northe storage costs for freezing.

DEVELOPMENT OF FRENCHCOHO AND BROOD STOCK

Although the CNEXO project mustrely on the shipment of coho eggs fromthe United States for the present, theeventual goal is to develop self-sustain­ing French brood stocks. The excellentsuccess that NOAA-NMFS biologistshave had (at the Northwest FisheriesCenter's Aquaculture Experiment Sta­tion near Manchester, Wash., in cultur­ing 2-year-old brood parents in totalconfinement in floating net-pens inPuget Sound indicates that this shouldbe possible in France. This would giveFrench biologists the capability of

Marketing continued until July, when atotal of 6.2 metric tons had beenshipped. New stocks of coho wereintroduced to Carpont from the fresh­water hatchery in October 1974, andharvesting resumed in mid-Decemberto accommodate the demand for theholiday trade. The overall productionto market was 7.6 metric tons by 31December 1974. From January to Juneof 1975, about 25 tons were sent tomarket, both by SODAB (22.5 tons)and COMAT (2.5 tons), all from falladapted fish.

The prices paid to the salmon farmeraveraged 20 Francs (F) per kg (US$2.00per lb) for the whole fish on the Pariswholesale market, which is good. Theslightly smaller coho cultured and soldin the United States are now bringingPuget Sound farmers about 14 F per kg(US$1.44 per lb) dressed. The weightloss averages 18-20 percent on dressedfish. In the French wholesale market,

August 1976 7

Figure 10.-Length-frequency distributionof 2-year-old coho spawning stock from thefreshwater hatchery at Yvias (1972 brood).The weight range of these coho wasapproximately 300 to 800 grams.

months of culture. whereas normalsmolts placed in seawater during thesummer have high mortalities. It ispossible that the combinations of hightemperature and high salinity duringthe summer may induce an unaccept­able stress, but these are factors whichmust be studied to determine the exactcause of these problems. Nutritional

Fork lenQlh lcm)

'National Marine Fisheries Service, NorthwestFisheries Center, Seattle. Wash., MonthlyReport, Sept. 1974. p. 1-5.

survival considerably J (Novotny, 1975b).

Although the French production ofsea-farmed coho salmon is less than 40tons to date, it is nonetheless the firstFrench-farmed salmon to appear on themarket. Prices obtained by the SODABgrowers were excellent, the productwas of high quality, and the acceptanceon the market was high. Thesefavorable factors point to an estab­lished place for the coho salmon in thefuture of aquaculture in France.

LITERATURE CITED

Danioux, C., M. Girin, Y. Harache, and L.Laubier. 1975. L'Aquacu)ture Marine. (Inthree parts.) Grands Dossiers Alpha de laMer 16 (176): 301-320; 17 (177):321-340; 18(178):341-360. Grange Bateliere, Paris.

Harache, Y. 1974. L'aquaculture marine dessalmonides. Penn Bed (Brest) 9(77) :342-350.

Novotny, A. J. 1975a. Net-pen culture ofPacific salmon in marine waters. Mar. Fish.Rev. 37(1 ):36-47 .

. 1975b. Preventative medicine:status of the legal use of vaccines. In T. Y.Nosho and E. L. Brannon (editors), Salmoniddiseases: a workshop summary, April 17.1974, p. 18-20. Univ. Wash. Sea GrantProg., WSG-WO 75-2.

At present, a production cycle ofholding coho in a freshwater hatcheryuntil mid-fall and culturing in a sea forspring harvest appears to have thebest advantages. This is a somewhatlonger freshwater rearing period thanin the United States, but the survivalin the marine environment throughmarketing is high (95 percent). Thisslight disadvantage is almost negligi­ble. Most recently, the CNEXO-NOAAteam, working at the NMFS Manches­ter laboratory, found strong evidenceof a possible pathogenic French vibrio.If further tests prove that this is true,the introduction of a French vibriovaccination program similar to thatdeveloped by NMFS in Puget Soundmight improve the summer rearing

deficiency and bacterial infection can­not be overlooked as possible causes ofmortality.

It is not known if the combination ofhigh summer temperatures, high salin­ities and, in some cases, low dissolvedoxygen levels are responsible for thepoor results obtained with maturingfemales at Carpont in late 1974. Thepossible existence of nutritional defi­ciencies cannot, however, be excluded.

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MFR Paper 1194. From Marine Fisheries Review. Vol. 38, No.8, August1976. Copies of this paper, in limited numbers, are available from D825,Technical Information Division, Environmental Science InformationCenter, NOAA, Washington, DC 20235. Copies of Marine FisheriesReview are available from the Superintendent of Documents; U. S.Government Printing Office. Washington, DC 20402 for $1. 10 each.

8 Marine Fisheries Review