NOAA Technical Report NMFS Circular 447

Proceedings of the Eighth
U.S.-Japan Meeting on
Aquaculture at
Bellingham, Washington,
October 17-18, 1979
William N. Shaw (Editor)
Under the Aquaculture Panel, U.S.-Japan
Cooperative Program in Natural Resources (UJNR)
November 1982

U.S. DEPARTMENT OF COMMERCE
Malcolm Baldridge, Secretary

National Oceanic and Atmospheric Administration
John V. Byrne, Administrator

National Marine Fisheries Service
William G. Gordon , Assistant Administrator for Fisheries

PREFACE
The United States and Japanese counterpart panels on aquaculture were formed in 1969 under the UnitedStates-Japan Cooperative Program in Natural Resources (UJNR). The panels currently include specialists drawn
from the federal departments most concerned with aquaculture. Charged with exploring and developing bilateral
cooperation, the panels have focused their efforts on exchanging information related to aquaculture which could
be of benefit to both countries.
The UJNR was started by a proposal made during the Third Cabinet-Level Meeting of the Joint United StatesJapan Committee on Trade and Economic Affairs in January 1964. In addition to aquaculture, current subjects inthe program are desalination of seawater, toxic microorganisms, air pollution , energy, forage crops, national park
management, mycoplasmosis, wind and seismic effects, protein resources, forestry, and several joint panels andcommittees in marine resources research, development, and utilization.
Accomplishments include: Increased communications and cooperation among technical specialists; exchanges
of information, data, and research fmdings; annual meetings of the panels, a policy coordinative body ; administration staff meetings; exchanges of equipment, materials, and samples; several major technical conferences; andbeneficial effects on international relations.

William N. Shaw-United States
Shigekatsu Sato-Japan

11

CONTENTS
SHAW, WILLIAM N., and SHIGEKATSU SATO. Joint statement of the UJNR Aquaculture Panel, October 18, 1979. Belhngham.
Washington ........................... .. ........................................ ............. .
ARAI, SHIGERU. Freshwater fInfish culture in Japan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
FOLMAR, LEROY C. , WALTON W DICKHOFF, WALDO S. ZAUGG , and CONRAD V W MAHNKEN. Freshwater develop7
ment and smoltifIcation ill coho salmon from the Columbia River . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
HARDY, RONALD W The use of soybean meal in trout and salmon diets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 15
GOULD, ROWAN W Freshwater aspects of anadromous salmonid enhancement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 21
DUPREE , HARRY K. CatfIsh aquaculture in the United States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. .. 23

NOTE: Some authors did not submit their papers for publication in the proceedings.

The National Marine Fisheries Service (NMFS) does not approve, recommend or endorse any proprietary product or proprietary material
mentioned in this publication. No reference shall be made to NMFS, or
to this publication furnished by NMFS , in any advertising or sales promotion which would indicate or imply that NMFS approves, recommends
or endorses any proprietary product or proprietary material mentioned
herein, or which has as its purpose an intent to cause directly or indirectly
the advertised product to be used or purchased because of this NMFS
publication.

Joint Statement of the UJNR Aquaculture Panel
October 18, 1979, Bellingham, Washington
The eighth Joint Meeting of the UJNR Aquaculture Panel was held October 17- 18, 1979 at Western
Washington University in Bellingham, Washington .
On the first day of the meeting five overview papers on the meeting theme, freshwater fish culture,
were presented by Japanese and US. scientists . In addition six scientific papers were presented reflecting recent research advances in freshwater fish culture in the two countries. This exchange of papers was
useful and informative to panel members and observers. The business meeting was held the second dayof the meeting. Dr. Sato and Mr. Shaw who were elected cochairmen presided over the businessmeeting .
Succe sful UJNR activitie during the la t year were reviewed. These included an exchange of scientists imolving extended tudy visit by 3 US. scientists and an industry representative to Japan andvi its by 5 Japane e scienti ts to the US. under spon orship of the UJNR.
It i anticipated that at lea t 2 US. cientists will visit Japan during the next year. A visit of intermediate length by Dr. Arai, a fi h nutritionist, to the US. is also planned a well as additional shorter visits.
ProviSion of information in advance of visits regarding opportunities for study and observation would
help make exchanges of cientists more useful.
The exchange of elected cientific information in the field of aquac ultu re has continued. A set of21
selected Japane e publications have been ubrnitted to the US. and ome of these are being translated.
Selected US. publication are al 0 being ub rnitted to Japan by the US. panel and lists of these are~ idel) dl tnbuted in Japan . Pos ibilitie for tran lation of several new Japanese books are being
explored
A cooperative re earch project presently in progre is a joint study of summer mortality of oysters
im'olnng field te ung of di ea e remtant US. strains in Japan . The joint study of oyster diseases which
ha been underway for 4 years IS continuing and plans for joint publication of results are being made.
An offiCial respon e regardIng Japane e input for the World Index of Fish Disease was requested by
the US. panel.
A plan wa pre ented for formalizIng future proposals for cooperative research projects and a draft
propo al for research on evaluation of abalone seeding was presented by the US. members. This propoal will be reviewed by the Japanese panel and modified as necessary after discussion of practicalaspect!> of the research.
The US. members have formed everal committees to improve and expand their activities. One of
the e, the publication committee, is working on publication of the papers presented at the 1977 meeting,and ha prepared a tatement of editorial policy for the Aquaculture panel. It was agreed that papers
presented at the UJ R meetings be published regularly in established journals and that the host country
take re ponsibility for publishing papers presented at UJNR meetings in their country. A suggested format for authors will be made available prior to each meeting .
Preliminary plans for the next joint meeting were made . Plans are to hold the meeting in conjunction
with the Indo-Pacific Fisheries Council (Symposium on Development and Management of Small Scale
Fisherie ) in Kyoto in May, 1980. Since the theme of the 1980 UJNR aquaculture joint meeting will be" Cru taceans" it i propo ed that a field trip to shrimp hatchery and production sites be made following
the meetings.
Respectfully submitted
William N. Shaw-United States
Shigekatsu Sato-Japan

Freshwater Finfish Culture in Japan
SIllGERU ARAJI

PRESENT STATUS OF FRESHWATERFINFISH CULTURE IN JAPAN80

Fish have been raised for hundreds of years in Japan not only forfood but also as a hobby. The culture of eel, carp, and rainbow trout
was established before World War II and in 1943 , 31,000 t of thesefish were produced . Due to the severe damage caused by the war, theproduction of cultured freshwater fmfish totaled only 4,300 t in 1950.
However, the industry was restored in the early 1960's and has
showed remmkable development; 82,000 t were produced in 1977
(Fig. 1) , an increase of 19 times in 28 yr. On the other hand , the catchof wild freshwater finfish was 40 ,000 t in 1950 and 67,000 t in 1977 ,an increase of only 1.7 times .
The catches and values of various types of marine and freshwater
fisheries are summarized in Table 1. As seen in the table, productionof cultured freshwater finfish accounted for a very small proportionof the total-only 0.8 % of production in 1977 . Howeve~ harvest
value of cultured freshwater finfish accounted for 3.7% of the total
value, indicating that cultured freshwater finfish are highly valued in
the market.
Principal species of freshwater fish being cultured in Japan arecarp, Cyprinus carpio; eel, Anguillajaponica; rainbow trout, Salmo
gairdneri ; and ayu, Plecogiossus altivelis. The average wholesale
prices of these fish during the past 10 yr are shown in Table 2. Amongthe cultured freshwater fish, eel and ayu are the most expensive . The
price of eel has always been 3-5 times higher than that of rainbow
trout and carp. The production and harvest values of the four major
species cultured in freshwater in 1977 are shown in Figure 2 with the
distribution ratios of each species. The produ.:tion of carp ranked
first, acounting for 36%; eel was second, accounting for 34 %. Howeve~ the harvest value of eel accounted for 61 % of the total and carp
only for 14 %. Thus, eel is very important in freshwater fmfish culture in Japan .
The production ratios of wild and cultured fmfish in 1977 areshown in Figure 3. The percentages of cultured eel and trout wereover 90%; carp was 81 %. The percentage of cultured ayu was only
30%; the remainderofayu production came from rivers . Due to theirimportance as game fish, ayu have been stocked in rivers every year
by fishery cooperatives. Ayu are herbivorous and in nature they eat
diatoms found on stones or rocks . Wild ayu are normally caught during the summer season in the southern part of Japan .
Culture methods for the four major species are shown in Table 3.
The running water pond system is a common method for rainbow
trout culture. There are 1,222 farms with urface area totaling 1,612
km2 using the running water pond system, which have produced
15 ,018 t of rainbow trout. The production rate is 9.3 kg/m2, inclicating that rainbow trout culture is intensive, and needs high quality andlarge quantities of water.
Ayu are mostly cultured in a running water system like rainbow
trout. There are 314 farms with surface area totaling 438 km 2, which

/

.

-

~

~

(/)

z

60

0

I-

0

a:

IW

50

::E

u..

0

40

(/)

0
Z

c(
(/)

30

:::>

0

:r
I-

20

10

0

'57 '59 '61 '63 '65 '67 '69 '71 '73 ' 75 ' 77

50

YEAR
Figure I.-Annual productio n of freshwat er finfi h culture.

Table I.-Distribution and value of the various types of marine and fresb" aterfish harvest in 1977 (Anonymous 1979).
HarvestHarvest val ueDistribution of harvest

I,OOOtMarine harvest
Sea culture
Inland freshwa ter harvest
Inland freshwater culture
Totals9,695 90.0
861
8.0
126
1.2
82
08
10,764 100.0%

100 million Yen%

20,513
3,522
486
930
25.451

806
138
I9
3.7
100 0

Table 2.-Average price of fresb"ater fi h(yen/kg) (Anon)mous 1979).

IFish Nutrition Division, National Research Institute of Aquaculture . Fisheries
Agency, Hiruta. Tamaki-cho. Watarai-gun, Mie-ken . Japan.

3

Year

Trout

1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977

197
199
195
236
373
373
470
517
492
535
611

Ayu

964
1.184
1.250
1,176
1,445

Carp

Eel

220
197
280
309
389
319
427
43

571
655
8 0
I 320
I 320
1 954
177
1 965
2020
1,960
2,05

425
405
444

HARVESTHARVEST
VALUE

Other

Other

Table 3.-Number und type, of farm s, ~urface area, and production (fourmajor frc\hwater fi.,h "pecie, cultured) in 1977 1 (Anonymou, 1979) .
Running

100 -

(

2.1
7.2

Ayu

21.4

Trout

J

~

Ayu
Trout
Carp

water

ro nd •

4.1
9.1

Trout'
Management,
Surface arca (kml)
Production (t)AyuManagcmcnh

11.6
14.0

1.2~2

Stili
water
pund,

1,612
15,OlH

9
15
10

114

4

Surrace area

43H

2

Production

4 ,'JOIi

114

Net
or

hrm
pond

5
10

"

cages

1<)",1

2
10
18

1,23k

1,647
15077
31k
440
4,990

arp

....Z

M,wilgcmcnts

35.7

Carp

~ 501a:w

Surface arCa
Producllon

KM2 1.087
1.279 -I.OH2
l,66k l,k2f>

H,IIiO
11.766

1f,8 2,507
374 24471
915 20821>

I
2
0

'J 'J

474
342
10,460

3.4322<),863
26.720[)2677
24,84921,741

Eel.'II1"nagemcnl

a.

urt KC area

Pnl\Jullion

Eel
Eel

61 .2

IFlgures un nnl In lude figure, 01 minor proJucllon prdcClure

33.6

havc produced 4.906 t. Thc production ratc i~ 11 2 kg/ml and ayu 1\
more intcn~I\l~ly cultured than rainbo'A tmut
in carp culture, there are scvcral types of cclture mcthod~. The
most productive method is net or cage culture; thi~ method can beused only in lakes or reo,ervoirs, The production r... te of net or cage
culture IS 30.6 kgfml, Further e.l(pansion of this production } tem
scems to be lImited. becau..,c the feceo, fmm fi hand f
re Idue arefactors in the eutmphicatlon of thesc closed bodle of water. The running 'Aater pond ,) It:m I al 0 a vel') intl.:n~ive mcth( . The highest
production rate, 220 kg m!, has been re ordcd b) K. Tanaka in
Gunma Prefecture, HO'Acver, the averagc production rate of the runrung 'Aater method was 2,9 kg/ml, The m~t exten\l\ e method IS thefarm pond }stem: thc production rate is onl) 0.4 kg/m~, This \) tem
is used principally for sced production
In eel culture, the still 'Aater pond syo,tem is most common: onl) a
small amount of cel 'Aere produced b) the running 'A ater pond, The
productJon rute IS 2.4 kg m In the running water pond and 0.9 kg in
the still water pond, ProductiVity of the running 'Aater y. tem ishigher than that of other method : however, thi method was adopted
by only 7"{ of the farms A a re ult of the e'<panslon of eel culture,
demand for eel ehers exceeded the pos ible productIon along thecoast of Japan Also, due to the large fluctuation in elver catch. Eur'Opean elvers are being Imported from France. Eel farmers have tried
to ral e them m the traditIonal till water pond. However. most of the
farmers failed to culture the European eels, becau e they are ensltive
to high water temperature and death often occcurs in the ummt::r eason. The eels are also hlghJ} usceptible to para itic disea es. At
present, several farmers have ucceeded cultunng European eel inrunning water pond . Succes has been attributable mostly to lower
water temperature and constant water conditions in the running water
system.
The types and amounts of feed used for freshwater fmfi h culture
are Ii ted in Table 4. At pre ent, formulated dry feed are u ed intensively for every species. U ually, more than half of the ingredients ofthe formulated feeds are composed of fish meal, especially whitefish
meal. The amount of fish meal used for freshwater finfish culture
was estimated to be about 70,0<Xl t, equivalent to 420,O<Xl t of raw
fish . A certain amount of fresh and frozen trash fish is still used asfood in eel culture, and the amount used in freshwater finfish culture
will decrease yea r by year. No fish meal other than whitefish meal isused as fish feed in Japan . The whitefish meal industry suffered fromoFigure 2.-Distribution ratios of ban est and hanest >alue of cultured fre'hwater finfish in 1977.

~

D

CULTURE

WILD

100

~

Z

W

~ 50

w

a..

a..

a:

<C
U

..J
W
W

0

..J

<C
~

o~

Figure 3.-Harvest ratios of wild and cultu red freshwater finfish in 1977.

4acid supplementation is needed in order to improve protein qual ity. A
method is proposed by the author in another paper (Arai 198 1).

Table 4.-Type and amounts (t) of feed used for freshwater fish culture in 1977
(Anonymous 1979).

Type of feed
Fresh and frozen fish
Fresh silk worm pupae
Dry silk worm pupae
Combined feed
Fish meal
OthersTotal

Rainbow
trout

Ayu

Carp

149
0
28
25 ,573134
475
26 ,359

30
0
0
8,313
3
133
8,479

120
13,437
7, 15533 ,234340
2 ,01356,299Eel

Pollution from Fish Culture

Total

6,590
6,889
2
13 ,43917
7,200
40,034 107 , 154
15
492
3,409
788
47 ,446

As mentioned above, most of the fresh water finfish cultu re 10
Japan is very intensive . With the expansion of production , pollution
problems occur in rivers close to culture ponds and in lakes. In Lake
Suwa and Lake Kasumigaura , cage culture of carp is claimed to be
responsible for eutrophication (Suzuki 1976). In Lake Kasumigaura,
the plankton blooms sometimes resulted in severe damage to cultured
fish as well as to wild fish during the summer season . In tho e clo ed
bodies of water, the scale of fish production must be regu lated
according to the water quality data .

the establishment of the U.S. 200-mi exclusive zone, and fish meal
production has decreased steadily, resulting in the rise of the price ofmeal as well as the cost of feed formation. An example of the production cost of rainbow trout culture in 1975 is shown in Table 5 (Brown
1977). Feed cost accounted for 57% of the total; this high cost is aserious problem in finfish culture in Japan at present.

Disease and Parasite Control
Disease and parasite control is one of the important problems forconsideration in finfish culture. In intensive cultu re of fish , di eases
cause serious damage; therefore, early diagnosis of diseases and suitable treatments are important. For bacterial diseases or parasitic diseases chemotherapy is effective. In the near fu tu re , moregovernmental control on the use of these chemicals, especially ofantibiotics, will be initiated . An epizootic prevention system must be
undertaken in fish culture.

Table 5.-Production costs, selling price, and net returns forrainbow trout, Fujinomiya Trout Cooperative, Shizuoka prefecture (1975) (Brown 1977).
Production costs(cents/kg)

Item
Fry
Feed
Wages, including bonu s
Pumping costs
Repairs and maintenance
Depreciation
Insurance and taxes
Office and transportation
Miscellaneous
Total costs
Selling priceNet returns

14 .7
69 .0
J6 .0
9.7
3.0
2.0
2.0
2.0
2.3
120.7
150.0
29 .3

%
12 .2
57 . 1
13 .2
8.0
2 .5

Stable Supply of Seed, Especially in Eel Culture
Eel culture is ve ry important, as mentioned above, but its production depends on the supply of elvers . The supply of elvers i determined by the catch of elvers under natural conditions. Before 1968,
elvers were imported from Taiwan, but since that year Taiwan began
its own eel culture and the industry has expanded rapidly. Now Taiwan exports annually about 20 ,000 t of food size eels to Japan . At
present, no elvers are supplied from Taiwan . Artificial spawning ofeels is carried out with silver eels. They are collected from rivers near
the sea and fertilization is carried out under artificially controlled
conditions. Hormone injection techniques are also used to assist theacceleration of maturation and spawning. At present, a good survival
rate is reported until hatching, after which it decrea es rapidly. Artificial larval production is a problem , but worth the challenge for the
stable development of eel culture .

1.7
1.7
1.7

1.9
100 .019 .5

PROBLEMS OF FRESHWATERFINFISH CULTURE

Shortage ofFish Meal for Formulated Feed
As mentioned above , the farming of freshwater finfish in Japandepends largely on formulated feeds , and the feeds rely on a stablesupply of fresh trash fish meal. With the increasing demand for formulated feeds as well as the serious effects of the u.s. 200-mi zone in
the northern Pacific Ocean, the fish culture industry is now sufferingfrom a shortage of whitefish meal . To cope with the shortage, brownfish meal from anchovy, mackerel , and saury has been considered as
an alternative to whitefish meal and research on the availability of themeal for fish feed has begun. Oil content of these fish is very high,thus elimination of the toxicity of oxidized oil is considered essential ,when large amounts of the meal are included in the feed.
On the other hand, it is necessary to intensively study the utilization of vegetable protein or single cell protein as fish feed . Amino

LITERATURE CITEDANONYMO US.
1979. Yearbook of Japanese fisheries and culture production (1977) Mini S!.
Agric., For. Fish. , Tokyo , Japan.
ARAI , S.
198 1. A puri fied test diet for coho salmon , Oncorhynchus kisurch , fry. Bull
Jpn . Soc. Sci. Fi sh. 47 :547-550 .
BROWN, E. E.
1977 . World fis h farming : Cultivation and economics AVI Pub!. Co., Westport , Conn. , 397 p.
SUZUKI , R.
1976 . The cul ture of common carp in Japan . FrR :AQ IConf. E.51 , FAO Technical Confere nce on Aquaculture , Kyoto, Japan .

5Freshwater Development and Smoltificationin Coho Salmon from the Columbia River
LEROY C. FOLMAR,' WALTON W. DICKHOFF, 2WALDO S. ZAUGG, 'and CONRAD V W. MAHNKEN 'ABSTRACT
Changes in gill Na +-K + ATPase activities and plasma concentrations of thyroxine (T 4), triiodothyronine(T3), Na +, K +, and C1 - were monitored during the period of smoltification in 10 groups of yearling and 1
group of zero-age hatchery-reared coho slamon, Oncorhynchus kisutch.
During this period, dramatic increases in ATPase activity and plasma T4 concentrations were observed in
the yearling groups but not in the zero-age group. Plasma T 3 concentrations increased in some, but not all , ofthe groups. Plasma T4 concentrations were significantly correlated with both gill Na +-K + ATPase and plasma
T3 concentrations. Plasma concentrations ofNa + and C1 - were found to be significantly related, but unrelated
to the other measured parameters.
Serial entry experiments with the zero-age fish have suggested that developmental stage was more important than size or age in successful adaptation to seawater. In the yearling fish, there was no relationshipbetween survival and the number of smolted fish, suggesting that smoltification and seawater adaptation are
not interdependent events.
A component of the T4 curve in freshwater fish was found to be significantly related to seawater survival.
The usefulness of this comparison in predicting hatchery releases is discussed.

INTRODUCTION

predict optimal hatchery release dates. Additionally, comparative
physiological profiles were established fo r fis h on an accelerated
growth regimen to enter seawater as zero-age animals and cohorts
reared under normal hatchery conditions to enter seawater as yearling
animals.

Due to the declining number of natural salmon runs on the Columbia River, it has become increasingly necessary to supplement these
populations with hatchery-reared fish. Releases from ColumbiaRiver hatcheries now average 110 million fish (2.5 million Ib) annually (Wahle et al. 1975). The success of these supplemental releases ,in terms of returns and contribution to the fishery, can vary from one
hatchery location to another and at the same location from year toyear. If oceanic conditions are considered to be relatively uniform,
the differential return rates among hatcheries are most likely due todifferences in the quality (ability of the fish to migrate successfully
and to survive and grow in s awater) of the smolts produced at thehatchery. Variation in the quality of the fish is probably due to different environmental conditions at the various hatcheries or annual environmental changes at a particular hatchery. However, before we canevaluate environmental factors such as temperature, photoperiod ,xenobiotic chemicals, feed , or effects of pathogenic organisms , it isessential that we have a thorough understanding of the normal physiological changes which occur during freshwater development,
migration, and entry into seawater.
The purpose of this study was to establish patterns of some basic
quantifiable physiological changes (i.e., gill sodium , potassiumactivated adenosine triphosphatase (Na +-K + ATPase) activities ,
plasma thyroxine (T.), triiodothyronine (T3) , sodium (Na +), potassium (K+), and chloride (CI - ) ion concentrations) which occur incoho salmon, Oncorhynchus kisutch, during the period of smoltification in freshwater. All of the physiological measurements accumulated during the course of this investigation were compared with thenumber of surviving and smolted fish through 6 mo of seawater residence to: 1) determine whether any statistically significant relationship existed and 2) if such relationships could be used as an index to

MATERIALS AND METHODSThe yearling coho salmon used in the first part of th is study wereobtained from hatcheries on tributaries to the Columbia River: Klickitat, Kalama Falls, Rocky Reach, Toutle (Washington Department of
Fisheries); Big Creek, Sandy (Oregon Department of Fish and Wildlife); and Willard (U.S. Fish and Wildlife Service).
Experimental fish used to determine developmental difference
between zero-age and yearling coho salmon were obtained as eggs
from the Toutle Hatchery. The eggs were transported to the National
Marine Fisheries Service (NMFS) Northwest and Alaska Fisheries
Center (NWAFC) in Seattle, Wash., and then divided into two test
groups. One group was placed on an accelerated growth regimen toenter seawater as zero-age animals, and the other group was reared
under normal hatchery conditions to enter seawater as yearlings.
Acceleration of growth was accomplished by raising the water temperature in 1°Cld increments, from 8° to l2°C at the swim-up tage.
and then maintaining the temperature at l2o-l3°C until transfer toseawater.
Samples of gill filaments and plasma were collected from random
samples offish in the freshwater raceways at the indivdual ColumbIa
River hatcheries, every 2 wk, from February through June 1978 In
the developmental study at NWAFC, random amples of gill tl ue
and plasma were collected biweekly from Apnl through Augu t
1978 .
Gill filaments were analyzed for Na--K ATPa e actiVIt) by themethod of Zaugg (1979). Pia ma T. and T, concentratIOns were
determined by radioimmunoas ay u ing the method of DICkhoff et
al . (1978). Plasma ions were mea ured with a flame photometer' Northwest and Alaska Fi sheries Center. Nati onal Marine Fisheries Service.
OAA . ~725 Montlake Bl vd . E .. Seattle, WA 98 112 .
' Department of Zoolog). Uni versity of Washington. Seattle, WA 98 195.

7

(Na+, K +) and chloridometer (Cl-). Samples for plasma ion determinations were prepared in accordance with the manufacturer's suggested methods for each instrument. Normal clinical control serumof known composition was prepared and analyzed in parallel withevery 20 samples.
Data resulting from these experiments were subjected to computerized statistical analysis. The statistical methods used to calculate
linear regressions, correlation coefficients, and analysis of variance(ANOVA) were those of Sokal and Rohlf (1969).

100

25

80

20

,

1

0

.t
15

60

- -

~

'" '"
..s.E

RESULTS

"0

E
3

..

f-f-

~ ~ 40

~

10

'"

0.

f-

0:0:

Although there were some variations in the magnitude and duration of the responses, Figures 1 and 2 represent typical changes in gill
Na +-K+ ATPase activities and plasma T4 and T) concentrations
which were observed for each of the Columbia River test groups.
Values for both gill Na +-K+ ATPase and plasma T. measurements
began to increase in March, peaked in April, and returned to startinglevels by the end of May.

E
0.-

~~
M

f

--i:

«

+

'"

+

20

5

Z

<:J

~
0

0
February

March

April

May

June

Oat e

100

25

Figure 2.-Changes in gill :-I a + - K + ATPase specific activities and plasma T4
and T J concentrations for coho salmon in fresh"ater reared at the Big Creek
Hatchery (N = 10) . (Hatchery release date sho",n b) arro",.)Typical patterns of plasma electrolyte (Na +, K +, Cl - ) fluctuations
during the same period are shown in Figure 3. Sodium and chloride
ion appear to be regulated by the same mechani m since their levels
fluctuated together (Fig . 4, P~O.OOI, r = 0.76, N = 286). However, potassium ions appeared to be independent of a+ and Cl - regulation. Although there wa a slight trend for plasma Na + and Cl - todecrea e with the increa e in gill Na +-K + ATPase activity during thearne time period (Figs. 1, 2). the decrea e wa not significant andthere was no statistical correlation between gill a+-K+ ATPase
activity and plasma Na + concentrations (Fig. 5, r = 0.09, N = 428).
This study was terminated on 1 November 1978. At that time,each vaccinated test group was evaluated to determine survival (Fig.
6) and the percentage of smolted animals among the survivors (Fig.
7) . Smolted animals were determined by visual characteristic which
included body and fin coloration as well a the pre ence or absence ofparr marks. Survival ranged from 27% (Kalama Falls) to 80%(Sandy 1). wherea the percentage of smolts ranged from 48 % (Willard
to 90% (Sa ndy
The results of these final seawater evaluations were compared with the physiological measurement~ taken

Figure I.-Changes in gill Na + - K + ATPase specific activities and plasma T J
and T. concentrations for coho sa lmon in fresh\\ater reared at the Sandy
Hatchery (hatchery release date shown by arrow).

m

m.

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Figure 3.-Plasma electrolyte (Na +, K +, CI- ) levels from coho salmon in freshwater at the Big
Creek Hatchery. (N= 10 except where parenthetically noted .)

8

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Figure 6.-Survivallevels for each of the Col umbi a River test stocks after 6 moin seawater.

~

Plasma sodium (meq/L)

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Figure 4.-A lin ear regression ana lysis of the relationship between plasma
sodium and plasma chloride in sea"ater for a ll of the Columbia River stocks
tested.

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Figure 7 .-Success of smoltification for each of the Columbia River test stocks
after 6 mo in sea" ater.

30

ATPase specific activity (I'moles Pi mg Prot" h,')percentage of the fish which survived until November in seawater(Fig. 6).
The significance of thi correlation has been illustrated in thescheme presented in Figure 11 . The numbers 1 to 5 indicate hypothetical successive seawater entry dates along a T. curve . As the linear regression in Figure 10 shows, the further along the curve (i.e ..
points 1 through 5, Fig. II) that the fish were tran ferred from thehatchery to seawater, the better was their survival . This suggest thatthe complete cycle of change in T. must occur in freshwater in orderto have maximal survival. There wa no relation hip between thecomponents of the T. curve and the number of successful smolt . The
number of smolted fish was found to be statistically unrelated to thenumber of surviving fish. The presence of nonsmolted. but urviving
fish has been previously reported for coho salmon reared 10 net-pen
culture systems (Bern 1978; Clarke and Nagahama 1977; Folmar
and Dickhoff 1981 ; Mahnken et a!. in press). Since seawater parrs
are not observed under natural conditons. this relationshIp may only
be valid for net-pen cultured coho salmon . The gill a - -K - ATPa ecurve was evaluated in a imilar manner; however. under our te t
condition there were no significant relationships between the components of that curve with either survival or number of succe ful

Figure S.-A lin ea r reg r essio n analysis of the relationship between gill
Na + - K + ATPase and plasma sodium co nce ntrations in seawater for all of theColumbi a River stocks tested.

during the period of freshwater residence.
While the fish were in freshwater, gill Na +-K+ ATPase activities
and plasma T~ concentrations appeared cyclical and related in time.
To evaluate this possible interrelationship statisticall y and compare
each of the indi vid ual curves with other events occurring in both
freshwater and seawater, it was necessary to separate the measurable
component in each curve (Figs. 8, 9). Figure 8 shows a hypotheticalrepresentation of plasma T. concentrations in the coho salmon groups
in fre hwater, indicating the peak height (A,), duration of the curve(B ,), and the integrated area beneath the curve (C ,). In Figure 9, A2
represents the proportion of the duration of the peak value at release,
B2 represents the proportion of the duration of the peak at seawatertransfer, and C 2 (shaded area) represents the proportion of the area
beneath the curve which had transpired at the time of release. A
shown in Figure 10, there was a sign ificant relationship (P::5 0.001, r= 0.92 , N = 10) between the proportion of the area of the T. curve
which had transpired at the time of release (C 2/C,) (Figs. 8,9) and the

9

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Fig ure JO .-A linea r regress ion a nal ~s i s of the relatiomhip bet .. ee n perce nt
surviva l a nd the perce nt of th e integ rated ar ea of th e T. cun e (Cl i , ) .. hi ch
had tra nspired at the tim e of release for eac h of th e 9 Columbi a Rh er test
stoc ks.

25

80

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Survival (percent)Fig ure 8.- A representative gra ph of plas ma T. co nce ntrati ons fro m Co lum bia
River coho salmon in fres hwater. Lett ers ind icate as pects (pa ra mete,,) of th e
curve "hich can be measured for a nal)sis.

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Figure 9.-A representati ve gra ph of plasma T. concent rations fro m Columbi a
Riv er coho salmon in freshwater. This gra ph shows the effect of the hatcheryrelease date on the measurements shown in Figure 8.

Figure II .- A representati ve gra ph of pl as ma T. concentrati ons in fr es hwat er
showing hypothetica l seri al release dates .

10

14

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t::. ComposIte of all Columbia River stocks... Montlake-Toutle stock (zero age)
Composite of all ColumbIa River stocks•

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Figure 12.-A comparison of gill Na + - K + ATPase and plasma T. concentrations in threegroups of co ho sal mon (Montlake-Toutle O-age, and a composite of 10 groups of Columbi a
River yearling fish).

smolts. There were no other significant relationships between any of
the other measurements (T), Na +, K+, CJ - ) obtained and the percentage of urviving or smolted fish.
Figure 12 represents a comparison of the developmental changes(gi ll Na +-K + ATPase activities and plasma T. concentrations)observed for the zero-age fi h versus a composite for all yearling fishfrom the Columbia River hatcheries . Peak values occurred during thefirst 2 wk of May in both groups; however, both the Na +-K + ATPaseand T. peaks were significantly lower in the zero-age fish than inyea rl ing fish.
Figure 13 presents the percentage of surviving fish from each of
the zero-age seawater serial entries compared with the seawater survival of the Toutle Hatchery yearling fish. The percentage of survival
was based upon the number offish remaining on I November 1978 .
The surv ival of the Toutle Hatchery yearling fish wa greater than allof the zero-age groups, which ranged from 13 to 49% . Survival was
greatest for those zero-age fish which entered seawater during July.
Figure 14 shows the percentage of smolted fish from each of thezero-age eawater serial entries compared with the percentage ofsmolts in yearling fish from the Toutle Hatchery. The percentage ofmolts was based on the number of fish surviving on I November
1978 . The percentage of smolted yearling fi h from the Toutle Hatchery was much greater than any of the zero-age groups which ranged
from 10 to 47 %. The groups with the highe t percentage of smolted
fish were those which entered seawater from late June through earlyAugust.

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Figure 14.-A comparison of smolt success beh,een the erial releases ofMontlake-Toutle O-age fish, and Toutle Hatcher) )earling fi sh. ( ea\\aterentr) dates are sho\\ n "ithin indh'idual bars.)

Figure J3.-A comparison of survival rates beh,een the serial releases ofMontlake-Toutle O-age fish, and Toutl e Hatcher) )earling fish. (Sea\\aterentry dates are shown \\ ithin indi vidua l bars.)

11

ter acclimation.
In addition to obtaining basic information relative to the parr-smolt
transformation, we were interested in any statistically significant
relationships between these basic physiological measurements andsurvival (Fig. 4) or smolt success (Fig. 5). Figures 6 and 7 demonstrated the method by which the freshwater curves for gill Na+-K +ATPase and plasma T. were evaluated. The curves were analyzed foreach of the test groups to determine maximum value, duration of thepeak, integrated area beneath the curve, and the proportion of each of
those values which existed at the time of release. These values werethen compared with the percentage of survival and smolts of eachgroup after 6 mo of seawater residence. As shown in Figure 8, there
was a significant relationship between the proportion of the area
beneath the T4 curves and the percentage of the fish wmch survived 6
mo in seawater (Fig. 4) . This relationship suggested that the survivalof our te t fish was related to their respective date of transfer to seawater. and that the further along the curve they were transferred, thegreater was their survival. This is depicted graphically in Figure 9,
where fish released at point number 5 should have greater survival
potential than tho e fish released at points I through 4. There was no
relation hip between the T. peaks in freshwater fish and the percentage of smolts in the population . There were no relationships between
any of the T4 measurements taken in seawater and urvival or smolt
success. There was no relationship between the T4 peaks in freshwater fish and the percentage of smolts in the population . There wereno relationsmps between any of the T. measurements taken in seawater and urvival or smolt success. Plasma levels of T. and T3 weresignificantly related in both freshwater and seawater. At the present
time, we cannot report whether this relationship is due to simultaneous hormone synthesis and relea e, or a uniform conversion rate of
T4 to T) in peripheral tis ue .
Treatment of the gill Na +-K ATPase data in a similar manner
showed no statistical relationship with either survival or smolt success after 6 mo of eawater residence. Survival and smolt uccesswere also unrelated to any gill Na +-K+ ATPase measurements taken
in seawater. Our results suggested that gill a +-K - ATPase is important as an integrated component of smoltification, but as a single discrete measurement did not predict the potential success of seawater
acclimation in net-pen culture of coho salmon.
There were no tatistically significant relationships between any ofthe plasma electrolyte measurements and 6-mo seawater survival or
smolt succes . The maintenance of a proper balance of body fluid
electrolyte is essential to seawater survival; however, as with gill
Na +-K+ ATPase, this is a process with many component and discrete measurements of Na +, K +, or Cl - are not adequate to predict
seawater succes .
The use of warmed water (12 D-13 DC) to accelerate the growth ofzero-age fish to yearling smolt length as 6-mo-old fish was quite successful. However, a comparison of the time course changes in gill
Na +-K + ATPase activities and plasma T. concentrations for the zeroage fish and the compo ite of all yearling Columbia River groups(Fig. 10) suggested that the length of the fish was not necessarily areflection of successful development. Although all of the fish wereapproximately the same length at seawater entry, the zero-age fish
had markedly lower gill Na +-K + ATPase activities and plasma T.
concentrations during their freshwater development than did yearling
fish. If the occurrence of a distinct thyroid hormone surge, as seen inyearling fish, is a requirement for successful seawater adaptation,
this may partially explain the poor performance of the zero-age fishin terms of survival (Fig. II) and smolt success (Fig. 12).
The relationship between gill Na +-K + ATPase and plasma T. in
the zero-age fish was similar to the yearling fish in that there was a

DISCUSSION
Representative time course changes in gill Na +-K + ATPase activities and plasma T4 concentrations for two groups of yearling coho
salmon in freshwater were presented in Figures 1 and 2. The
observed increases in gill Na +-K+ ATPase activity are comparablewith those reported by Adams et al. (1973) and Zaugg and McLain(1972) for coho salmon and steelhead trout, Salmo gairdneri, infreshwater. Also, gradual increases in circulating T4 levels have beenreported in brook trout, Salvelinus fontinalis, during the spring(White and Henderson 1977); however, prior to this study there had
been no previous reports of a surge in circulating T. levels associatedwith smoltification in anadromous salmonids (Dickhoff et al. 1978).
Both plasma T. and T3 were found to be significantly related(P<O.OI, r = 0.12, N = 483). In both Figures I and 2, the peaks ofenzyme activities and plasma T4 concentrations occurred withing 2
wk of one another. This relationship was observed in all 10 groups offish tested and was found to be statistically significant by correlation(P <0.01, r = 0 .17, N = 534). Plasma T3 concentrations were also
found to be statistically correlated with gill Na +-K+ ATPase activity(P<O .OI, r=0.29, N=523). There are several possible explanations for this relationship. Thyroid hormone has been reported to regulate Na +-K+ ATPase activity in a number of mammalian tissues(Ismail-Beigi and Edelman 1970, 1971, 1974; Valcana and Tirniras1969), amphibian epidermis (Kawada etal. 1969) , and in nurse shark
gill and kidney tissue (Honn and Chavin 1977). Also, there may be
involvment of other hormones acting synergistically with thyroid
hormone. Production of prolactin and cortisol is regulated by environmental salinity, and both have been demonstrated to affect kidney
Na +-K+ ATPase. Prolactin stimulates kidney Na +-K+ ATPase in
freshwater, while cortisol stimulates gill Na+-K+ ATPase activity inseawater (Epstein et al . 1971; Pickford et al. 1970). It is also possiblethat the simultaneous increase in gill Na+-K + ATPase activities andplasma T. concentrations are independent but responding to the same
stimulus, or that they are not causally related. The observed changes
in gill Na+-K+ ATPase activities and plasma T. concentrations at different hatchery locations appeared unique in both timing and pattern
for all the groups tested. This uniqueness may be attributable to thegenetic strain, environmental conditons, diet, or a combination ofthese factors .
Figure 3 represents the changes in three plasma monovalent ions
during the freshwater development of the coho salmon test groups.
The strong correlation between Na + and Cl - concentrations indicatesthat they may be regulated by the same mechanism. The slight depression in both Na + and Cl - concentrations corresponds with the time
period of gill Na +-K+ ATPase activity increase shown in Figures I
and 2; however, this relationship was not statistically significant.
These data suggest that monovalent plasma electrolyte levels may not
be directly regulated by gill Na +-K + ATPase , but rather by a complex
series of physiological events which may include gill Na +-K+
ATPase as a component. This evidence does not support the theory
that the migration and increased salinity preference are due tochanges in plasma ion balance in freshwater.
There were no correlations between gill Na +-K+ ATPase activities
and plasma T4and T3 concentrations during the seawater acclimation
phase, however, as in freshwater, plasma T4 and T3 concentrations
were significantly related. The fact that gill Na +-K + ATPase activities and plasma T. and T3 concentrations were significantly correlated in freshwater but not in seawater indicates that the hormone andenzyme relationship may be a freshwater developmental phenomenon which serves to prepare the fish for seawater entry rather than T4
acting as a regulatory mechanism of Na +-K+ ATPase during seawa12

Table 1.-A comparison of gill Na + - K + ATPase activities and plasma T 4 concentrations in O-age andyearling coho salmon after 8 d in seawater. All values expressed as X ±SE.
Yearling (ranges for
10 Columbia River stocks)

O-age
Seawaterentry date(I 978)Gill Na + - K + ATPase(I'molesP;fmg protein per h)

Plasma T4

5/ 16
5/3 1
6/ 14
6/27
7/11
7 /25
8/08
8122

8.9±2.3
14.0±2.2
14.3±1.1
9.1±0.9
14 . 1 ± 1.6
20.1 ±3.8
13 .8 ±2.5
no data

4.1 ±0.2
13 .5±1.l
23 .0±2 .5
15 .2 ± 1.9
23 .9±1.7
19 .9 ± 1.7
6 .6±1.0
no data(ng / ml)

Gill Na + - K + ATPase(I'molesP;fmg protein per h)

Plasma T4(ng/ ml)

14 .6± 1.7-27 .2 ±5.4

12 .5 ±2.2-38.2 ±2. 7

significant correlation in freshwater but not in seawater. Although gill
Na +-K + ATPase activities were lower in the zero-age fish than in the
yearling fish in freshwater, five of the seven zero-age serial seawater
entries had gill Na +-K + ATPase activities comparable with those ofyearl ing fish after the period of seawater acclimation (Table I) . Likewise, five of the zero-age serial seawater entries had plasma T4 concentrations comparable with those of the yearling fish after seawater
acclimation. These results suggest that there are qualitative differences between the increases in gill Na +-K + ATPase activities andplasma T. concentrations of fish in freshwater and those observed inseawater. The increased enzyme activities and hormonal concentrations in seawater adapted fish appear to be a reflection of the marine
environment, and it is possible to induce these changes in fish prematurely transferred to seawater. Our measurements in seawater acclimated fish indicated that the zero-age fish were as well developed as
normal yearling fish ; however, our measurements in freshwater
acclimated fish clearly indicated that the zero-age fish were not aswell developed as the yearling fish. Although we cannot make a valid
comparison without the data from the yearling cohorts of the zeroage fish , we have tentatively concluded that the poor seawater survival and the high incidence of seawater parr in the zero-age groupwere related to incomplete development in freshwater, rather than theinability of the fish to adapt to seawater.

HONN , K . V., and W CHAVIN .
1977 . M echani sm of T4 action upon nurse shark gill and kidney tissues[Abstr.] Am . Zool. 17 :857 .
ISMAIL-BEIGI , E , and I. S. EDELMAN.
1970. Mec hanism of thyroid calorigenesis: Role of active sodium transport . Proc. Natl. Acad . Sci. 67 : 107 1- 1078 .
1971 . The mechanism of the calorigenic ac tion of thyroid hormone. Stimulation of Na + + K + -activated adenosinetriphosphata e activity. 1. Gen . Physiol. 57 :7 10-722.
1974. Time-course of the effects of thyroid hormone on respiration andNa+ + K +-ATPase activity in rat liver. Proc. Soc. Exp. BioI. Med.
146 :983-988 .
KAWADA , J., R . E . TAYLOR , JR ., and S. B. BARKER .
1969 . M easu rement of Na-K-ATPase in the sepa rated epidermis of Ranacatesbeiana frogs and tadpoles. Compo Biochem. Phy siol 30:965-975
MAHNKEN , C. V. W , E. PRENTICE , W WAKNITZ , G. MONAN, C. SIMS, and
1. WILLIAMS .
In press. The application of recent smoltification research to public hatcheryreleases: An assessment of sizeltime requirements for Columbia River hatche ry coho salmon (Oncorhynchus kisutch). In C. V. W. Mahnken and H Bern(editors), Salmonid smoltification-Proceedings of a symposium ,ponsoredby the Pacific Sea Grant Advisory Program and the California Sea Grant College Program. Aquaculture.
PICKFORD, G. E., R. W GRIFFITH. 1. TORRETTI. E. HENDLEZ , and F H
EPSTEIN.
1970. Branchial reduction and renal stimulation of ( a +. K · )-ATPase byprolactin in hypohysectomized killifish in fresh water Nature (Lond)
228:378-379.
SOKAL . R . R ., and F. 1. ROHLF.
1969. Biometry. The principles and practi ces of statistics in biologicalresearch. W. H . Freeman and Co., San Franc, 776 p
VALCANA , T., and P. S. TIMIRAS.
1969. Effect of hypothyroidi sm on ionic metabolism and Na-K actl\ated ATP
phosphohydrolase activity in the developing rat bram J.
eurochem

LITERATURE CITEDADAMS , B. L ., W S. ZAUGG, and L. R . Mc LAIN .
1973. Temperature effect on parr-smolt transfo rmati on in steel head trout(Salm o gairdneri) as measured by gill sodi um-potassi um stimul ated adenosine triphospha ta se. Compo Biochem. Ph ysiol. 44A: 1333- 1339.
BERN , H . A .
1978. Endocrinol ogical studi es on no rmal and abnormal salm on smoltification . In P. 1. Gaillard and H . H . Boer (edito rs), Comparative endocrinology,
p. 97- 100 . Elsevier/North Holland Bi omedical Press, Amsterdam .
CLARKE , W C. , and Y. NAGAHAMA.
1977 . Effect of premature transfer to sea water on growth a nd morphology ofthe pituitary. th yro id , pa nc reas, a nd interrenal in j uve nile coho salm on(Oncorhynchus kislllch). Can. 1. Zoo l. 55: 1620- 1630.
DICKHOFF. W W., L. C. FOLMAR . and A. GORBMAN.
1978 . Changes in plasma th yro xine during smo ltification of coho salmo n,
On corhynchus kisutch. Ge n. Comp o Endocrinol. 36:229-232.
EPSTEIN , F. H ., M . CYNAMON, and W McKAY.
1971 . Endocrine control of Na-K-ATPase and seawate r adaptation in Anguilla
rastrata. Gen . Compo Endocrinol. 16 :323-328.
FOLMAR, L. C., and W W DICKHOFF.
1981 . Evaluatio n of some physiological parameters as predictive indices ofsmoltifi catio n. Aquaculture 23:309-324.

16:935-943.
WAHLE , R . 1., W D. PARENTE, P. 1. JURICH , and R R. VREELAND
1975. Releases of a nadromous salmon and trout from PaCific coa,t rearing
facilities, 1960 to 1973 . U.S. Dep. Commer., atl Mar Fish . Sen. Data
Rep . 101 ,443 p.
WHITE, B. A., a nd N. E. HENDERSON
1977 . Annual variations in the ci rculating levels of th} roid hormones m thebrook trout , Sa/l'e/inusjontinalis, as measured b} radiOimmunoassa} Can
1. Zool. 55:475-481.
ZAUGG. W S.
1979 . Freshwater Na +-K + ATPase acmilies at hatcheries and Jone, Beach{n A study to assess status of smoltification and fitness for ocean sun Ivai ofchinook. coho, and steelhead. Pacific North"e>r Regional Comm",ion ,ProJ . Rep . 817, Append. A, 46 p.
ZAUGG, W S., and L. R . McLAIN .
1972. Changes in gill adenosinetriphosphatase aem It) associated" ith parrsmolt transformation in steel head trout. coho. and ,pring lhlnt'ok
salmon. J. Fish. Res. Board Can. 29 . 167-171

13

The Use of Soybean Meal in Trout and Salmon Diets!
RONALD W. HARDY2
Worldwide demand for protein supplements used in animal feeds isincreasing and , as a result, the prices of these ingredients are rising.
Fish meal , either herring or anchovy meal, has traditionally been the
major protein supplement in trout and salmon diets . There has been aslight decrease in the worldwide production of fish meal during thelast few years. The production of high quality herring meal needed
for some salmon diets has decreased markedly as herring meal has
shifted from a primary product to a by-product of the herring roe
fishery.
There are some protein supplements that appear to be promising
candidates to replace part or all of the fish meal portion of trout andsalmon diets. From the perspective of worldwide supply, soybean
meal is the principal alternative. In recent years, its production has
increased approximately 9 %, with continued expansion of production predicted. Soybean meal is less expensive than fish meal and ,except for methionine and lysine, contains a higher level of all essential amino acids (on a percent of protein basis) than does herringmeal.
It has been known for over 50 yr that soybeans contain undersirable
compounds. When young rats or chickens are fed diets containing
raw soybeans, the following effects have been noted : decreased
growth, decreased absorption of fat, decreased metabol izable energy
value of the nonfat portion of the diet, increased pancreatic size,
increased gallbladder contraction, increased excretion of bile salts
lowered intestinal proteolytic activity, and altered methionine oxida~
tion (Scott el al. 1969) (Appendix 1) . Fortunately, these problems canbe corrected for most animals by proper heat treatment and supplementation of soybean meal , but trout and salmon may be more sensitive to the antinutritional effects of soybean meal.
The use of soybean meal as a feed ingredient lor trout and salmon
presents problems that reduce its value. These problems include deficiencies of amino acids, unavailability of phosphorous, presence ofantinutritional factors , alteration of trace mineral availability, andpossible palatability complications (Appendix 2) . These problems
have been researched by investigators throughout the world. However, the researchers have not reached unanimous agreement on theeffects of supplementation or processing on the nutritional value ofsoybean meal. Part of this may be due to differences in the sources ofsoybean meal, a variable commodity. Part is due to differences inexperimental design , in size and species of fish used, and in otherexperimental conditions. In other animals, the effects of antinutritional factors and deficiencies are greatest in the very young. Soybean meal diets that would be toxic to the young , however, can be
tolerated by older animals. There is no research to suggest that age
affects the nutritional value of de-fatted soybean meal in rainbow
trout or salmon.
Using a diet containing 80% commercial de-fatted soybean meal
(Table 1), Rumsey and Ketola (1975) investigated the effects ofamino acid supplementation on the growth of rainbow trout. The
experimental diets were supplemented with crystalline amino acids
to meet the reported requirement of chinook salmon for methionine

Table I.-Percent composition of the experimental diet (from Rumsey and Ketola 1975).
Ingredient

Percent

Soybean meal (49% protein)
Dextrin , tapioca
Herring oil
Carboxymethyl cellu lose }Vitamin premix
Mineral premix
NaCI
Amino acid supplement

80.0
6.5
10.0
1.0
0.5
0.3-3.8

and cysteine. There was no growth improvement over the unsupplemented control diet (Table 2). Other degrees of supplementation to
duplicate the amino acid levels in trout carcasses did not improve
growth . When combinations of amino acids were added that raised
the dietary levels to those found in trout egg protein or in isolated fishprotein , a growth response was seen. The fish were 9 g at the start ofthe experiment and gained about 50-70% of their starting weightafter 6 wk of feeding. Two problems with this work were the lack of astandard diet to compare fish growth during the experiment, and thelack of a supplemented control, whereby a nonessential crystalline
amino acid was added or removed to maintain constant protein andcrystalline amino acid levels in the diets.

Table 2.-Weight gain of rainbow trout fed the experimental dietsfor 6 wk (from Rumsey and Ketola 1975).
Dietary suppl ement
None
LYS
HIS
MET
HIS + LYS
HIS +LYS+MET
LEU
MET+LEU
MET+LEU +LYS+VAL+THR
MET+LEU+LYS+VAL+THR+HIS+TRP+TUR

Percent added
to dietWeightgain (g)1

0
0.7
0.3
0.3
1.0
0.7
1.0
2.0

4.2 a
3.4 a
4.2 a
4.6 a b4.5 a b4.4 a b4.4 a b4.8 a b6.0 bc

3.8

6.4

1.3

IValues not followed by the same letter are significantly different at
the 5% level.

Nearly the same experimental diet was used by Ketola (1975a) tostudy the effects of supplemental dicalcium phosphorus and ash on
fish growth. The ash supplement was prepared by burning fish meal
in a muffle furnace . The level of mineral supplement was adjusted toequal the level of mineral supplied by an appropriate dietary level ofherring meal . Soybean meal contains about one-third as much phosphorus as does herring meal , but much of that may be bound as phytate-phosphorus and thus may be biologically unavailable.
Supplementation of the basal diet with either 6% ash or dicalcium
phosphate resulted in a statistically significant (P<O.OI) growth
response in the 5-wk feeding trial (Table 3). None of the fish grew

IContribution No. 589 , School of Fisheries, University of Washington , Seattle.
2School of Fisheries, University of Washington , Seattle, WA 98195.

15

Table 5.-Percent weight gain of rainbow trout fed diets containing 80% soybeans for 8 wk (from Smith 1977).

Table 3.-Growth and food conversion of rainbow trout fed a soybean meal-based diet supplemented with dicalcium phosphate andash (from Ketola 1975a).

Processing

Food

DIetary supplement

Final weight(g)1conve rsion I

None
Ash
Dicalcium phosphate

3.50 a3.87 b
3.85 b

3 .33 a2.63 b
2.6 1 b

Percent gain

Full-fat dry roasted
Full-fat steam cooked
Extracted and reconsti tuted with soy oil (steam cooked)
Commercial meal , dehulled , solvent extracted,
reconstituted with soy oil , no additional heating

86
101
93
50

IValues followed by different lette rs are sigmficantly different at the( % level.

very well on any of the diets , however. Though the diets were supplemented with trace minerals, lysine, and methionine, the fish gained
only 30 % of their starting weight on the basal diet and 43 % on the
supplemental diets .
In a similar study conducted with Atlantic salmon, Ketola (1975b)
found that supplementation of a 70 % soybean meal diet with gradedlevels of inorganic phosphorus resulted in a stepwise increase inweight gain and a similar decrease in food conversion (Table 4) . Fishwere again fed for 5 wk . The basal diet contained 0 .7 % phosphorus,
all of plant origin . About one-third of the phosphorus in plants is generally considered to be available to young chickens. If trout canabsorb about the same amount of plant phosphorus as poultry, the dietary phosphorus requirement of 6.5 g Atlantic salmon would be about
0.8% . However, growth of fi sh on a commercial diet was significantly higher after 5 wk of feeding , indicating that the experimental
diet, supplemented with trace minerals , calcium, salt, andmethionine, was not nutritionally competitive with a commercial
nonsoybean-based diet, even when phosphorus was added.

found that relatively high roasting temperatures were needed toincrease digestibility and metabolizable energy (Table 6) and thatsome combinations of heating time and temperature resulted in promising values when the soybean meal was force-fed to trout held in
metabolizable energy chambers. When diets containing 80% full-fat
Table 6.-The effect of heat treatment of soybeans on the digestibility andmetabolized energy (ME) for rainbow trout (from Smith 1977) .
Heat treatment

Table 4.-Weight gain and food conversion of Atlantic
salmon fed a soybean meal diet supplemented with inorganic phosphorus (from Ketola 1975b).

Dietary supplement
None.15% P.30% P.45% P.60% P.75% P.90% P
Commercial diet

Weight gain
(g)1

Food
conversion I

2.0 a
2.6 b
2.7 b c
2.9 c
3.2 d
3.3 d
3.2 d
4.5 e

2.75 a2.49 a2.06 b
2.04 b
1. 84 b1.69 b
1. 80 b1.24 cpressure (lb)Time(m in)

Steam (S)or dry (D)Digestion coefficient
crude protein(%)

ME(Kcal /g)232
12321200
205
12041190
12041190
12041176
127
151b
10Ib
51b
51b

5
8
10
12
12
8
10
10
10
15
5

D
D
D
D
D
D
D
S
S
S
S

75.2
71.8
78.2
73.0
75 .5
71.8
45.4
61.6
80.1
71.1
39 .2

4.25
3.96
4 .21
3.93
4.22
3.96
3.08
3.22
4.. 16
3.55
2.28

o Cor

ISecond figure is approximate temperature of beans when removed from oven.

soybean meal were fed to small rainbow trout for 20 wk, excellent
growth was reported (Table 7) . Methionine and cystine supplementation improved weight gain over an aspartic acid-supplemented control . Heat treatment of the meal at 232°C improved weight gain overheat treatment at 204 °C. Smith (1977) speculated that the improved
growth was due to the destruction at higher temperatures of trypsin
inhibitors which interfere with protein digestion.

IValues not followed by the same letter are significantly different at the 5 % level.

Table 7.-Final 20-wk weights of rainbow trout fed diets
containing 80% full-fat soybean meal given three different
heat treatments and four amino acid supplements. Starting
weight 0.64 g (from Smith 1977).

Identification of the nutritional deficiencies of soybean meal anddiet supplementation to correct these deficiencies improved thegrowth of young rainbow trout and Atlantic salmon but did not bringgrowth up to the levels obtained with practical fish meal-based diets.
Obviously, there were other factors at work lowering the nutritional
value of soybean meal below its expected value. Researchers turned
to modified methods of processing in an attempt to make the soybean
meal more biologically valuable . They tried to destroy anti nutritional
factors or break disulfide linkages, thus improving digestibility.
Smith (1977) reported that, for rainbow trout, heating full-fat soybeans greatly improved their nutritional value over commercial
dehuJled, de-fatted soybean meal (Table 5) . Steam-cooking was
superior to dry roasting, and reconstituting commercial meal withoy oil did not improve growth. Smith heated raw soybeans for various lengths of time and at various temperatures using dry heat or
steam, and he measured the digestibility coefficient of the crude protein fraction and the metabolizable evergy level for rainbow trout. He

Heat treatment
Temp .

Time

Met +Cys

Met

Cys

Asp

232 0 C
204 0 C
204 0 C

8 min
12 min8 min

29.49
15 .97
11.30

18 .75
16.40
10 . 18

14 .55
13.13
7.56

12 .64
12 .381.50

PR-8 control (practical diet) 15 .66g (20-wk weight) .
H 440 control (purified diet) 20.58g (20-wk weight) .

Poston et aJ. (1978) autoclaved isolated soy protein at differentpressures and fed diets containing this material to rainbow trout. A
growth response was observed as autoclaving pressure of the isolated
soy protein increased (Table 8). Methionine supplementation greatly
improved growth at all levels of heat treatment.
16

Table 8.-Effect of autoclaving and methionine
supplementation of isolated soy protein on percent gain of rainbow trout (from Poston et al.
1978).
Autoclavepressure

bean meal had died , and this treatment was discontinued. Those fish
receiving diets in which 50% of the fish meal was replaced with soybean meal exhibited about 80% of the growth observed with no soybean meal in the diet (Table 11). When the phytin was enzymaticallyMethionine supplementation

(lbs)
0
8
16

None

0.9%

39
11 7
190

540
620
680

Table H.-Relative growth and relative feed conversion of rainbow
trout fed moist diets containing soybean meal substituted for 50% of
the fish meal (from Spinelli et al. 1979).

Diet
Control
Commercial soybean meal
(no treatment)
Steam heated
Steam heated and dephytinized

A long-term diet study using full-fat soybean meal as the major
protein source (Table 9) was conducted by Reinitz et al. (1978), who
fed these diets to rainbow trout for 35 wk. During that time, the fish

Table 9.-Percent composition of experimental soybean diets (from Reinitz et al.
1978).
Ingredient

Percent

Full-fat soybean meal
Anchovy meal
Blood flour
Brewer·s yeast
Dried whey (delactosed)
Vitamin concentrate
Durabond
Other variables

72.7
4.9
4 .9
4 .9
4.4
0.2
2.0
7.0-8.0

Relative
growth(%)

Relativefood conversion
(%)

100

100

80
82
87

77
77
84

removed from the soybean meal, a slight growth response was noted .
Blood samples of trout fed the 100% soybean meal diet were analyzed for calcium, copper, iron, and zinc. A significant reduction inserum zinc and iron levels was seen (Table 12) and an elevation ofserum copper was observed. Removal of the phytin in soybean meal
partially restored the mineral levels in the blood to control levels. The
authors suggested that materials other than phytin that interfere withmineral metabolism might be present in soybean meal.

Table 12.-Calcium, copper, iron , and zinc content (ppm)in the blood of rainbow trout fed diets in which 100% of the
fish meal was substituted with soybean meal and dephytinized soybean meal (from Spinelli et al. 1979).

grew from 26 g to about 175 g (Table 10) . Compared with fish fed apractical control diet, these fish gained more weight, had a lower
food conversion , and had similar cumulative mortality (5%). Additional supplementation of the test diets with dicalcium phosphorus,
lysine , or trace minerals did not improve weight gain .

DietControl
100 % soybean meal
100 % dephytinizedsoybean meal

Calcium

Copper

Iron

Zinc

71
73

1.5
2.2

213
141

14 .8
9.1

66

1.7

190

10. 1

Table 10.-Weight gain and food conversion of rainbow trout fed soybean diets for 35 wk (from Reinitz et al. 1978).

Dietary supplement
I. MET (l %)aCl (l %)Trace minerals (I %)Dicalcium phosphorus (I %)2. MET(I %)NaCI(I%)
Trace minerals (l %)Dicalcium phosphorus (2 %)3. MET (l %)aCl (l %)Trace minerals (I %)Dicalcium phosphorus (I %)Lysine ( I %)4 . MET(I %)NaCl (l %)Trace minerals (2 %)Dicalcium phosphorus (I %)5. Practical diet(control)

Weight gain
(g)l

Food
conversion I

149.7 a1.58 a b

147.0 a1.57 aResults of research on the use of soybean meal in salmon diets havebeen less promising than those with trout (Table 13). As soybean
meal levels increased in the diet, weight gain decreased (Fowler andBanks 1976). Supplementation with DL-methionine, phosphorus,

Table 13.-Final weight of chinook salmon
fed varying levels of soybean meal for 20
wk (from Fowler and Banks 1976).
148 .7 a1.60 a b

146.8 a1.61b129.5 b1.71 cPercent soybean
meal in diet

Final weight
(g)l

0
9 .5
14 .3
19 . 123.8

25.0 a22.6 b
21.2 c20.5 c21.0 clValues not followed by the same letter are
significantl y different at the 5 % level.

lValues not followed by the same letter are significantl y different at the
5 % level.

and trace minerals did not improve growth at the tested levels (Table14) for chinook salmon, but it seemed to improve weight gain at thelowest level of replacement. Full-fat soybean meal diets were notaccepted by chinook salmon and failed to support adequate growth incoho salmon.

Spinelli et al. (1979) replaced 50 or 100% of the fish meal in amoist diet with commercial soybean meal and fed these diets to rainbow trout for 210 d. After 90 d, 50% of the fish receiving 100% soy17

110

Table 14.-Growth of chinook and coho salmon fed diets with different
le,-els of soybean meal (-'8.5'< protein) (from Fowler 1980).

Diet
Control
Control + DL ~!ET+ trace minerals+sodium phosphate
12.7% SO) bean meal
25. % soybean meal
32.3 % soybean meal
80% full-fat SO) bean meal

Chinook
final weight
(gl

Coho
final weight
(g)

39.9
36.5

32 .3
32 .3

32.2
23.8

3 1.0
29.5
24 .7

213'
100

I:;-

..
~

1:

I A

~

>

..

~

213'

~
~

~

'"

Fowler (1980) attempted to duplicate the work of Smith (1977)
using different roasting temperatures for full-fat soybeans and feeding different levels of meal in the diet (Fig . 1). Final weight of chinook salmon decreased as the soybean meal level of the dietincreased . Higher heating temperatures did not improve the nutritional value of the meals. Although all diets were supplemented withdicalcium phosphorus, DL-methionine, and trace minerals, no groupof chinook salmon receiving a diet containing any amount of soybean
meal weighed as much as the control group. Cumulative mortality
increa ed as the percent of full-fat soy bean meal in the diet increased(Fig. 2).
Our understanding of the factors that affect the nutritional value ofsoybean meal for fish is clearly inadequate. Although the nutritional
deficiencies of soybean meal for poultry and rats have been elucidated, research with trout has indicated that more severe problems
exist that those which can be calculated from feed composition
tables. The antinutritional factors that have been identified may interfere with nutrient utilization in fish at a much lower dietary level thanoccurs in birds and mammals. It is likely that the growth benefits
observed by Smith (1977) and Poston et al . (1978) which resulted
from heat treatment of soybean meal were due to inacti ation of antinutritional factors present in soybeans rather than changes in protein
structure which resulted in increased accessibility to proteolytic
digestive enzymes and increased nutritional availability. Poston et al .
(1978) observed that trout fed autoclaved, isolated soy protein had
greater trypsin activity within the pyloric caeca than trout fed
untreated soy protein .

40

20

17 .5
Percent full-fat soybean meal in die t

Figure 2.-Cumulath·e mortality of chinook salmon fed full-fat soybean meal(from Fowler 1980).

Currently under investigation is the alteration of the bioavailabilityof trace minerals to rainbow trout when they are fed soybean meal asa dietary ingredient. An understanding of the causes ofthi phenomenon is necessary before a sensible solution to the problem can befound .
Salmon and trout have different life histories and are physioLogically different in some ways . Although they share a common freshwater existence during early life, it does not necessarily follow thatdiets which are successful for trout will be suitable for almon. Chinook salmon must migrate to the ocean within 3-4 mo after they
begin to feed . Size at hatchery release affects survival, to someextent, so diets must be used which allow maximum growth to occur.
Dietary ingredients like soybean meal, which lower the growth rate
and alter the physiological state of salmon, cannot be used in practical diets until the underlying nutritional problems are identified andsolved. These problems seem to be more severe for chinook salmon
than for coho salmon. Fish culturists have more flexibility with coho
salmon as far as growth in hatcheries is concerned since coho spend
ll/z yr in freshwater before migrating to the ocean. Usually it is notnecessary to obtain maximum growth from coho during their freshwater residence in order to ha e large smolts at hatchery reJea e.
Nevertheless, until the extent and effect of physiological alterationsof salmon fed diets containing soybean meal are known, it is unwise
to use soybean meal in practical salmon diets. When these problems
are resolved, soybean meal will be a valuable feed ingredient forsalmon diets and a practical alternative to fish meal.

25

20

15

60

~

discontinued

«

~

BO

190'

~

'"
~

.=

LITERATURE CITED

1'.5

FOWLER. 1. G.
1980. Substitution of oybean and cottonseed products for fish meal in diets
fed to chinook and coho salmon . Prog . Fi h-Cult. -I2 :87-9l.
FOWLER. L. G .. and J. 1. BA KS.
1976. Animal and vegetable substitutes for fish meal in the Abernathy diet.
1973 . Prog . Fish-Cult. 38 : 123- 126 .
KETOLA . H . G.
1975a . fineral supplememaljon of diets containing soybean meal as a sourceof protein for rainbow (JOut. Prog . Fish-Cult. 37 :73-75.
1975b . Requirement of t1antic salmon for dielary phosphorus . Trans. Am .
Fish. Soc . 104:548-551.

33.2

Percent: full-fat soybean 'Ileal in diet

Figure J .-Influence of dietan Ie' el a nd heat treatment of full-fat SO) bean
meal on gro" th of chinook salmon (from Fowler 1980).

18

POSTON, H. A" J. L. WALLACE, R. C. RIIS, and G. F. COMBS, JR .
1978. Cataractous and digestive protease responses of rainbow trout fed autoc1aved isolated soybean protein and added methionine . [Abstr.] Fed . Proc .
37 :839.
REINITZ, G. L., L. E. ORNE, C. A. LEMM, and F. N. HITZEL.
1978 . Full -fat soybean meal in rainbow trout data . Feedstuffs 50(3) :23-24 .
RUMSEY, G. L., and H . G . KETOLA .
1975 . Amino acid supplementation of casein in diets of Atlantic salmon(Salmo solar) fry and of soybean meal for rainbow trout (Salmo gairdneri)
fingerlings . J. Fish . Res . Board Can . 32 :422-426 .

SCOTT, M . L. , M. C. NESHEIM, and R. J. YOUNG .
1969 . Nutrition of the chicken. M . L. Scott and Associates , Ithaca , N.Y. ,511 p.
SMITH, R. R.
1977. Recent research involving full -fat soy bea n meal in salmonid
diets . Salmonid 1(4):8- 11 , 18 .
SPINELLI , J. , C . MAHNKEN , and M . STEINBERG .
1979 . Alternate sources of proteins for fi sh meal in salmonid diets . Proceedings of the World Symposium on Finfish Nutrition and Fishfeed Technology,
Hamburg , Germany, June 20-23 , 1978 , p. 13 1- 142 .

APPENDIX I.-EFFECTS OF FEEDING RAW SOYBEANS TO YOUNG CmCKENS OR RATS
l. Decreased growth .
2. Increased pancreatic size .
3. Decreased absorption of fat.
4. Decreased metabolizable energy of nonfat portion of diet.
5. Gallbladder contraction .

6. Increased excretion ofbile salts .
7 . Lowered intestinal proteolytic activity.
8. Altered methionine oxidation.
9 . Cataracts (trout fed untreated isolated soy protein) .

APPENDIX 2.-NUTRITIONAL PROBLEMS WITH SOYBEAN MEAL
Solutions

Problems
A. Deficiencies

1. Supplement with MET and CYS or blend with otherfeedstuffs
2 . Supplement with phosphorus

1. Methionine and cystine
2. Unavailable phosphorus (bound with phytin)
B. Antinutritional factors
1. Trypsin inhibitors
2. Chymotrypsin inhibitors
3. Hemagglutinin
4. Other unidentified factors causing decreased
protein or fat digestibility
C. Trace mineral availability alteration

1. Heat treatment
2 . Heat treatment
3. Inactivated by acid in stomach
4 . Unknown
Supplement with chelated trace minerals or
dephytinize
Mask with olfactants or other feeds

D. Palatablity
19

Freshwater Aspects of Anadromous
Salmonid Enhancement
ROWAN W. GOULD I

ABSTRACT
Freshwater enhancement of anadromous salmonid populations has been practiced in tbe United States andCanada since tbe late 1800's. Reduction of natural spawning habitat and increasing fishing pressure make artificial enhancement a possible alternative to declining populations .
Enhancement of anadromous salmonids involves improvement of the natural environment and reducing
natural mortality. Methods of enhancement include fisbways , spawning and rearing channels. stream rehabili tation, lake fertilization, environmental management, and artificial propagation techniques.
Five Pacific salmon species and steel head trout are commonly enhanced, primarily in watersheds entering
the Pacific Ocean and Great Lakes . Enhancement efforts contribute heavily to a commerical and sport industry realizing over $1.5 billion.

Artificial propagation of anadromous salmonids has been practiced
n the United States and Canada since the late 1800's. Newly formed:tate and federal fish commissions believed that artificial propagation",ould eliminate declines caused by industrial development. The first
tnadromous fish hatchery was built in New Castle, Canada , in 1866
tnd was designed to take Atlantic salmon, Sa/rna safar, eggs forntroduction into local streams (Wahle and Smith 1979) . Most early>acific salmon hatcheries were constructed to provide eyed eggs forntroduction into east coast waters. These programs proved unsuc;essful because east coast streams were generally too turbid or warm
'or good Pacific salmon reproduction. Eventually, west coast faciliies turned to enhancement of runs on the Pacific coast.
Six species of anadromous salmonids are extensively enhanced :;hinook salmon, Oncharhynchus tshawytscha; coho salmon, 0.
,isutch; sockeye salmon, 0. nerka; chum salmon, 0. keta; pink;almon, 0. garbuscha; and steelhead trout, Sa/rna gairdneri. All(lnge naturally from Alaska southward to Oregon Chinook, coho,:hum , and steelhead extend further south into California . Over 3 ,000
;treams support salmonid runs along the Pacific coast. Enhancement:fforts occur predominantly in these streams with some chinook,:oho, and steelhead enhancement along the Great Lakes, as a result)f artificial transplants in 1964. Presently, there are in excess of 200'ish hatcheries , including newly developing private hatcheries ,:ngaged in artificial rearing of anadromous salmonids. These facili.ies directly affect an extremely important commercial and recrealonal fishery valued in excess of$1.5 billion (E. Sald) . From 1960
01976, a total of2.4 billion chinook, 723 million coho, 177 million;teelhead, 111 million chum, 18 million sockeye, and 11 million
Jink salmon have been released from Pacific coast hatcheries (Wahle
md Smith 1979). To date, in the case of coho salmon, these releases~ave resulted in juvenile to adult returns (commercial/sport catch
plus escapement) of 5 to 20 %, depending on the location.
Freshwater culture of anadromous salmonids is made possible byGoming instincts which cause adults to reproduce in freshwatertream of their origin . Spawning for most species generally occurs
from August to December. Exceptions include some chinook andsockeye stocks which begin to spawn earlier in the ummer. and \tcelhead which are spring spawners. Fish migrate from the sea to dcpma
and fertilize eggs in gravel spawning redds. The eggs filter do\\ namong the rocks and are covered by the female. After a fe ..... \\cek ,they emerge as fry. At this point, most chum and pmk ~Imon mlgratc
directly to the sea. Chinook, coho, sockeye. and steelhead develop in
freshwater (time depending on the species) until a Pfl)(C\S ~alled"smoltification" occurs. Smolts, as they are called at thiS stage, areready to migrate to the ocean, Further development occurs in ~ea ..... ater. If anadromous salmonid reproduction proceeded natural I}. < 17cof the fish would survive from egg to returmng adult At each IIfc
stage, the natural and man-induced losses are tremendom . Fresh water aspects of the salmonid life cycle are the most logical ch()lCe~
for effective, positive manipulation. Loss of habitat. Increasing
exploitation, and reduced water qualIty are ever increaSIng prohlems.
Artificial culture procedures and effective enhancement of c I,tingnatural conditions reduce or eliminate bamers to survival c\eml
techniques have been devised ,The fishway is one successful enhancement tool to artifiCiallyrestore, stabilize, or initiate salmon runs. Fi hways either Clfl'umvcnt
man-made blocks to fish migration. such as dams or di\'erslon , Ir
serve to increase access to previously unaccessible \pa\\ lllng habitats. Many states, especially Alaska. are makmg cxteflSI\ cue of
artificial fishways. Three types are popular I) a ,enes llf conse~utJ\ c
open bottom weirs down the length of a channel or artifiCial flume(weir and orifice fishway), 2) a series of slotted ..... elrs do ..... n thelength of a channel or artificial flume (vcrtlcal-slot baffle II<,h'Way),or 3) baffles attached to the sides and floor of a channel or :H1lfi I I
flume (De nil fishway) (Bell 1973), All dissipatc flo ..... encrgy In turbulence and provide dead spots for migrating fish to rest.
Another enhancement techmque u. ed to maea e the a\all bllIt) of
natural spawning habitat IS stream channcl rehahIillatl nand lcarance. Compacted gravel can be cleaned, dchn removed and re lingpools created, along with other manipulations de Igned t In rca!
stream spa\\ ning or rearing (Xltennal The llpcmng of nc..... pa .... mn
habitat is u uall) coupled \\ ith fie h tran plant procedure
fforts rc
being made to reduce the impact oftran. plant on eXlSlln g n po< 1while ensuring optimum tI':lmplant Urvl\ abllH)
Enhancement offood-cham orgalll m 1 am thod used t In
SUDI>al of naturall) pa\\ nmg popul lJ nddln
r han Inbank vegetation can mcrea>e food pct nnal for tream reannn

I ational Fisheries Research Center. U.S. Fish and Wildlife Sef\ice. Department,fthe Interior. Bldg. 204. ayal Base. Seattle. \VA 98115~E. Salo. Professor. Fishenes Research In'litute. lJnl\erslt) of\\ashmgron, SealIe . WA 98105. pers. commun. Jul) 1979,21

enhancement technique to increase food potential currently being
tested is nursery lake fertilization . Sockeye salmon require lakes forjuvenile life-stage rearing. British Columbia and Alaska embarked
on extensive programs to enrich nursery lakes with phosphate fertil izer. The result is increased primary production of phytoplankton ,thus increasing zooplankton, the main food for young sockeye
salmon. Lake enrichment experiments on Vancouver Island , B.C.,
have resulted in substantial increases in numbers of adults, both in
retuJ;ns to commercial and sport catches, as well as escapement to thespawning streams (Stockner 1977). In Alaska's Little Togiak Lake,site of another lake enrichment program, smolt size was increased but
juvenile to adult survival has not been eval uated .
Not all lake fertilizations have been successfuJ. Lakes respond differently to fertilization , so extrapolation of results from one lake toanother is unwise. More understanding of applicable physical andbiological processes is required before the technique can be
employed effectively.
Spawning and rearing channels, which constitute additional techniques, are not manipulations of existing spawning habitat, but are
created entirely by man. Spawning channels are artificial streams
possessing ideal gravel and flow characteristics for optimum spawning. Rearing channels are also artificial streams but designed for optimum rearing characteristics. An advantage of spawning and rearing
channels is minimum human intervention once they are constructed.
Generally, spawning channels are used to enhance chum, pink, orsockeye salmon . For sockeye salmon, channels are built in conjunction with nursery lakes. Rearing channels are u ed to culture chinook, coho, and steelhead. The U.S. Fish and Wildlife Service hadeveloped a spawning/rearing channel combination for propagatingchinook salmon.
Physical modification of holding, rearing, and migration environments can be used to increase survival of natural or artificiallyenhanced populations. In limited cases, water temperature is being
manipulated where barriers allow controlled mixing of impoundedwarm surface water with cool subsurface water. Controlled temperature makes possible optimum growth while minimizing diseases andphysiological stresses characteristic of high water temperatures.
Flows can also be manipulated . Several Pacific coast spawning
streams have dams which produce hydroelectric power. Controlled
discharge of impounded water with consideration for migrating fish
softens the negative effects of excessively low or high natural streamflow.
The best-known technique for fishery enhancement is hatcherypropagation. Hatcheries rely on the homing instinct to return adults
to the hatchery or egg-taking facility. Fish culturists then artificiallyspawn, fertilize, and rear the fish. In the natural condition, most mortality occurs before the free-swimming stage. The [trst few days after
fertilization eggs are extremely sensitive to mechanical shock.
Changing environmental conditions or displacement by other spawn-

ing pairs can result in significant mortality. Disease and predation are
also prevalent. Artificial rearing from the egg avoids many of these
conditions, thus resulting in many more juveniles for seaward
migration.
In the hatcheries, adult fish are held in ponds until physiologicallyready for spawning . Eggs are generally removed from the female byincision and fertilized artificially with sperm from the male. With the
exception of steelhead , adult fi sh are sacrificed . For salmon species,
spawning naturally result in death . Some steelhead survive to returnand spawn again, requiring nonlethal egg-take for artificial fertil ization . After hatching, the flSh are reared in incubators or troughs untillarge enough for transfer to holding ponds. They are fed from wimup (a tage where they become free-swimming versus bottom dweIJing) until released as smolts . Release times are determined bybehavioral characteristics, normal wild stock migrations, and variou
tests to ascertain capability to with tand exposure to saltwater. Rearing ponds may be located on many streams allowing transfer andrelease to many watersheds (satellite concept). After the life cycle iscomplete, eggs can be collected from returning adults for subsequent
incubation m a centralized hatchery.
Two general schools of thought prevail concerning fre hwatel1
aspects of anadromous salmorud culture. The first, production strategy, emphasizes maximum total output from each rearing facility.
The second, a qualIty fish strategy, emphasize smolt output designed
to maXlmlZe survival after release to the '" ild thus increasmg return toeither the fi hery o r the hatchery escapement. All artificial enhancement techniques, with the exception of hatcheries, accomplish theirgoal by improving or imulatlng natural habitat. In the past, hatcheryoperations have generally emphasized productIOn of large numbersof released fish. The trend, however, ha recently switched t.o fi hsurvivabillty. The goal of all aspects of anadromou salmonid
enhancement is to provide the maximum numbers of harve table andreturning adult fish. Ultimately, it is our hope that natural and artificial enhancement will aid in maintaining this valuable and fragile
resource.

LITERATURE CITED
BELL.M C
1973 Flshenes handbook of engineering requirements and bIologIcal cnteria SpecIal publicatIon . Fisheries Englneenng Research Program . orthPacific DIviSIOn, Army Corps of Engineers. Portland . Oreg .. var. pag .
STOCKNER, J. G.
1977 . Lake fenilizatlon as a means of enhancing sockeye salmon populations:the tate of the an 10 the Pacific orthwesl. Can . Fish . Mar. Servo Tech .
Rep. 740. 14 p.
WAHLE , R. J., and R. Z. SMITH .
1979. A historical and de criptive account of Pacific coast anadromous
salmonid rearing facilities and a summary of their releases by region, 196076. U.S. Dep. Commer.. NOAA Tech . Rep . NMFS SSRF-736, 40 p.

22

CatfISh Aquaculture in the United States
HARRY K. DUPREE I

ABSTRACTOne of the most recent success stories in aquaculture is the development of the catfish industry in the
United States. Situated primarily in the southeastern and south central states, the food fish industry has
expanded from $100,000 in farm level sales in 1960 to an estimated $70 million in 1979. Commercial catfish
sales for food at the retail level now exceed several hundred million dollars annually. Recreational gross income
to pay lake owners, live fi sh distributors, and the ancilliary industries and ser vices will approach $1 billion
annually. Most sales come from the production of channel catfish, but modest returns are reported from salesof blue, white, and bullhead catfishes. Most production continues in earthen ponds, with some yield from cage,net pen , and raceway facilities. Pond areas in intensive catfish culture are estimated to be 36,400 ha in 1979,and production levels have increased from less than 1,500 kg/ha in 1960 to 4,000-7,000 kg/ha today. Feeds ,disease prevention , harvesting, and marketing have improved remarkably, but water quality deterioration due
to maximizing production continues to be the principal limiting factor.

One of the most recent success stories in aquaCUlture is the develpment of the catfish industry in the United States. Situated primarily
in the southeastern and south central states, catfIsh production has
moved into the west coast states, and into unlikely areas such as theeated artesian waters of Idaho. Commercial catfish sales for food at
e retail level now exceed several hundred million dollars annually.
Recreational gross income to pay lake owners, live fish distributors,
and to the ancilliary industries and services will approach $1 billion
annually.
Catfishes have been cultured for over 50 yr in the United States.
Most of the early programs were state and federally supported andinvolved production of seed stocks for supplemental stocking in farm
ponds . Commercial aquacultural production was limiteu to 200-400
kgfha annually which was approximately the standing crop attainablein natural fertilized ponds. In the late 1950's Auburn University produced a signifIcant breakthrough, determining that the feeding of pelleted formulations would increase production levels to > 1,500
kgfha. Thus, commercial catfish aquaculture was born.
A number of catfish species are adaptable in varying degrees tointensive aquaculture. The most widely used is the channel catfish,
Ictalurns punctatus. This species readily adapts to the crowded conditions in ponds , raceways , and cages; eats a wide variety of prepared
feeds; and converts these ingredients efficiently into flesh. It is tolerant to handling and hipping, and possesses excellent table qualities
and human acceptance. This fish is also widely used in commercial
fish-out enterprises and in public recreational programs.
The blue catfIsh, lctalurns furcatus, is somewhat similar morphologically to the channel catfish. This species attains a larger size, and'i higher dressing percentage (60-62 % for the blue catfish comparedwith 56-58 % for the channel catfish). However, at sizes up to 1 kg,
the blue catfIsh grows slower and converts food less efficiently thanthe channel catfish. The blue catfish is also more difficult to spawn
due to the large size of the brood fish, 10-30 kg, and the fry and fIngerlings are more susceptable to infectious diseases and handlinginjuries. This species appears to have only limited value in commercial aquaculture, but it does have value as a large predator in lake andriver management.

White catfish, Ictalurns catus, was studied in the 1960's and foundto be inferior to the channel catfish in most aquaculture programs.
Few, if any, fish producers are now culturing tills species. Extensive
testing and commercial production activities during that period
showed that the fish initially grew rapidly, but growth rate and feed
efficiency decreased rapidly when the size exceeded 0.25 kg. Dressing percentage was < 55 % due to the large head size but the flesh
quality was comparable with the channel and blue catfishes. The
white catfish is the most hardy of the catfishes and tolerates thecrowding, adverse water conditions, and high water temperaturescommon in intensive aquaculture in the southern United States. This
species is desirable in combination stockings with channel catfish forrecreational fishing.
Bullhead catfishes have received attention in aquaculture with thebrown bullhead, Ictalurns nebulosus, the most promising. Generally,
the brown bullhead, yellow bullhead, lctalurns natalis, and thesmaller black bullhead , lctalurns melas, are more susceptable to disease, but more tolerant to adverse water conditions than the channel
catfish. Prices paid for bullhead catfishes are generally quite low, andconsumer demand is limited. Economics of the production of bullhead catfishes are identical to those of the channel catfIsh, and no
economic advantage exists for their production. Some production forrecreational purposes may be warranted in those areas where water
quality and other environmental constraints limit the production ofchannel, blue, or white catfishes.
The remaining catfish having aquacultural potential is the flatheadcatfish, Pylodictis olivaris. This fish is highly prized for human consumption, but due to its habit of eating only living animal food, culture of tills fish is labor intensive and expensive. Culture of the fry
and smaller fIngerlings of this species has aquacultural potential since
it is very desirable as a large predator in management of rivers andlarge reservoirs.
Growth of the catfish industry has been rapid (Tables 1, 2). Starting in 1960, 130,000 kg of marketable fish were produced on 160 ha .
By 1975 , an estimated 50 million kg of fish were produced on 30,000
ha , and production has increased to 54 million kg on 36,000 ha ofwater in 1979. Growth of the industry is projected to be 10-15% peryear for the next 10-15 yr. In states where catfish production isalready a major industry, e.g., Mississippi, annual expansion rates> 30% are common. Additionally, in states that are new to catfish

IU.S. Fish and Wildlife Service, Fish Farming Experimental Station, P.O. Box860, Stuttgart, AR 72160.

23

Table 2. - "ectare~ devoted to catfi~h farming

Table I.-Estimated hectares devoted to catfish farm ing, kilograms produced, and value of production .

Year

Hectares

Millionkilograms(undressed)

1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1975
1979

200
200
400
1.000
1.600
2.800
4.000
6.100
12.10016.20018.20030.40036.400

01
0.2
0.5
1.1
1.8
3.2
50
75
15.0
20.0
24.5
51.0
54.4

Approximate
value(mdhon $)
01
02
04
10
1.6
2.8
4.4
6.6
13.2
17.6
189
40.0
70.0

by ~tate\.

ApproXimate
number of hectares

Updated from Madewell . C E 1971 HIStorical development of catfish farmmg. producing and marketing catfish
in the Tennessee Valley. Tennessee Valley Authonty Bull
Y-38. Muscle Shoals. Ala .

State

1972

, 1978MISSi\\lppl
Arkan\a,Texas
Alabama
LOUISiana
Georgia
MIS,ounOklahoma
Tenne, cc
California
Kan,.\South CamllOa
OthersTotal

5,tiOO
4,200
1.600
1.400
1.200
800
300
300
200
200
100
100
300
16.30010,1004 , 100
4 .000

6.100' ReVised on basIS of e IImate Recent data notavailable 10 all catfi~h prodUCing states
Source . Office ofTechOical A SI tance, EconomiC
Development Admlnl>lratlOn, U.S Depanmenlof
Commerce. 1972 .

farming, e.g., Califorrua. the production area has increa ed from240 ha in 1972 to an estimated 600 ha in 1979.
Production of catfish for direct human consumption i now influenced primarily by economic factors. wherea everal years ago biological limitations were more prevalent. Acquisition of land andconstruction expenditures for pond and essential facIlities minimall}cost $3,OOO/ha. Production units must usually exceed 40 ha in water
surface area to be economically sound, and larger sIZes are moredesirable. Capital requirements of $500,000 to over $1 million arecommon. Annual expenditures for feed, chemicals. nets. vehIcle ..
other equipment and supplies, and labor will normally exceed$500,OOO/farrn to produce 0.5-1.0 millton kg of fish annually. Additionally, a processing plant is usually nece ary for the sale of fish
produced within 100-200 km of the plant. In these plants the fish areprocessed for human consumption and are old to the public directly,
or indirectly through restaurants and food store . These plants now
cost $1-2 million. Feeds and equipment must also be made available
to the fish producer by specialized industries .
As previously stated, feeding of pelleted formulations established
the basis for commercial catfish aquaculture. The next major breakthrough was development of reliable, economical techniques for production of seed fish. Early production techniques for seed fish werelabor and equipment intensive, and so unreliable that most fisheryscientists and fish producers predicted little industry potential. Howeve!; this limitation in seed stocks proved not to be a problem since by
the mid-1960's techniques had been developed for brood fish care,dependable spawning and hatching, and husbandry of the fry and fingerling fishes. Limitations in the availability of seed stocks are now
economic rather than biological, and are due to hesitancy of seedstock producers to maintain brood fish populations and to spawn andculture seed stocks for more than their known sales.
Broodfish may be obtained from reservoirs and rivers as "wild"
fish, or puchased from a catfish producer. Many of the producers in
the 1960's had to rely on "wild" stock which, after several generations in the commercial hatcheries, became the basis for the industry
in that area. The fish, when captured from the "wild," possessed diseases and parasites of unkown significance, but the fish either"cleaned up" in captivity, or died. The survivors thus imparted somedisease resistance and other cultural characteristics to the domesticating strain. Cultured broodfish and their offspring in production sys-

tern are often better able to tolerate low m(ygen levels and other poo
water qualities. Presently. there are numerous domesticated strain
and broodfish are seldom obtamed fmm the """ild" e1(cept fo
genetic and other research program~.
Good broodfi h are e~sential to good fingerling production. Prope
care throughout the year is neces ry to insure healthy broodfi
when the spa ..... rung p<!riod amve Mmimum age for sexually matu
broodfish IS 3 to .. yr. For spawnmg. females mu t be gravid. and th
male must po sess secondaryexual characten tics. Mature an
grand females will pawn approximately 5.000 eggs!kg of bodweight. and ..... hen paJred ..... ith a good male the re ultmg hatch ..... i1l
near 100%. Fry from uch a mating will be large and health). and a
80% Urvlval of the e ff} to the 10 cm ize is commonl} obtamed.
Fmgerling producers m the early 1960's u ed gonadotropIC hormone to mduce spawning. but ..... lth the development of gbroodfl h maintenance technique . thi gave way to natural spa ..... nin
in pond. In thi production y tern. cans or other type of cover a
provided for the fi h to pair and pa ..... n. The egg masses can be recov
ered and hatched in mechanical device, or left for the male to hatch.
To increase the predictability of hatching and survival of the fry. mostegg are hatched in troughs using mechanical stirrers and the fry arestocked in known numbers m peciall} prepared pond for rearing tosalable ize. Currently. fingerlings produced for food fish seed tocks
and recreational stockings are estimated to exceed one-fourth billion
artnually with a value of $20 million.
Catfishes are now generally produced in earthen ponds. but raceways and cages, and more recently net pen , have been used. Earthen
ponds have varied from < 1 ha to > 100 ha in surface area, and from
1 to 3 m deep. Generally, pond surface area has decreased to 5-10 hasince management and harvest problem are greater in the larger
units. Management and operations have changed from a system ofsingle spring stocking-single fall harvest to that of continuous
stocking-monthly harvesting with draining occurring only every 2 or
3 yr. The monthly harvesting is accomplished using seines with meshsizes which retain larger fish and allow the smaller fish to escape andgrow to harvestable size. In the single stocking-single harvest program, usually 3,000-6,000 fingerling fish 10-20 cm in length arestocked, and are fed during the warm weather months at an estimated24

2.5-4.0% of their body weight daily. Harve table fl5h are usuallyobtained in 180-220 d . In contrast, the continuou ~toclung-monthly
harvesting program maintain a standing crop of IS ,-20,000 fish
ha. The feeding cherne is similar for the two programs, and results In
annual harve ts of nearly 1,800 kg/ha for the single harvest program
to 4,000-7,000 kg /ha for the continuous harve t program .
In cage and net pen culture, the fish are confined to only a small
area of a tream or lake . The technique has potential since fish can beproduced in areas not uitable for draining , seining, or intensive management. These areas could include very large lakes, strip mining
pits, gravel pits and quarries, irrigation reservoirs, and even streams .
Production in cage and net pens generally will not exceed the production potential of open pond culture or a given body of water, andthu the use of cages and net pens in ponds su itable for intensive management is not beneficial.
Advantages and disadvantages of cage and net pen are many, andopinions differ among scientists and producers . Obviously, fish canbe produced and harvested from cages and net pen in unmanagable
waters, and this is the strongest point in favor of this technique. Incidence of disease and disease control,losse to predation , losses fromoxygen deflciencie and poor water quality, and behaviorial losses(fighting) vary with quality of management. However, little question
remains that better and more expensive feeds are required comparedwith open pond culture, and that more time and labor are required .
Cages and net pens are expensive but in turn the expense of pond
construction is avoided. Obviously, there is a potential , though limited, for the production of catfish in these systems.
Raceway culture of catfish essentially parallels that of trout culture. However, with wannwater culture, large quantities of goodquality water at temperatures of 24°-30°C usually do not exist.
Ground waters are usually cooler, and surface waters (streams andrivers) often contain agricultural chemical toxica nts, and parasites
and disease organisms. Some studies are underway or being planned
which, if successful, will enable the fish producer to re-use water
economically, or to utilize surface water by removIng the waste
metabolites and environmental contaminants. Techniques for raceway production and suitable feeds exist, but becau e of limited water
the production is now estimated to be < 5,000 Ice, all produced inwarm artesian water in Idaho.
At the pre ent time, good information exists on nutritional requirements and feed formulation, infectious diseases and their control.
harvesting and processing, and to some extent marketing. However,very little useful information on fish genetics and selective breeding
has been made available to the catfish producers. Most stocks are
essentially hatchery domesticated but un elected . Water quality andwater re-use studies coupled with better feeds, di ease control, andmanagement have reduced mortalities and increa ed production .
However the farmers till continue to maximize their output, so continuing research and development are necessary in all problem areas
to maintain the pace of the growing industry.
An inadequate program in technical a sistance to the catfish producers has hindered development of the industry. In area whereextcn ion and diagnostic service are available large aquaCUlture program have developed . EAperienced producers have been able tomove into areas \\here no assistan e wa available. Howeve[ peciflc problems in disea~e, water qualit), and other cultural aspect\usuall) require the assistance of professionall) tramed biologiSts For
thc most part. thc catfish producers havc onl) a few federal and tatesupportcd group. or pn\,ate indi\ IduaL a\31lable for assistance In
some fi~h pmducIng state. there IS e. scnllall) no a. ,}tance. andfarmci must trawl 100 k.m or further for 31d and ad\ Ice

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