NOAA Technical Report NMFS 102

Marine Ranching
Proceedings oj the Seventeenth
Us. -Japan Meeting on Aquaculture!se, Mie Prefecture, Japan
October 16, 17, and 18, 1988
Ralph S. Svrjcek (editor)

u. S. Department of Commerce

May 1991

NOAA Techncial Report NMFS
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NOAA Technical Report NMFS 102

Marine Ranching
Proceedings of the Seventeenth
U. S. -Japan Meeting on AquacultureIse) Mie Prefecture) Japan
October 16) 17) and 18) 1988
Satellite Symposium: October 20
Ralph S. Svrjcek (editor)
Publications Unit
Northwest and Alaska Fisheries Science Centers

Panel Chairmen:

Conrad Mahnken, United States
Hisashi Kan-no, Japan

Under the U. S. -Japan Cooperative Programin Natural Resources (UJNR)

May 1991

U.S. DEPARTMENT OF COMMERCE
Robert Mosbacher, Secretary

National Oceanic and Atmospheric Administration
John A. Knauss, Under Secretary for Oceans and Atmosphere

National Marine Fisheries Service
William W. Fox Jr., Assistant Administrator for Fisheries

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

Conrad Mahnken - United States
Hisashi Kan-no - JapanThe National Marine Fisheries Servil:(", (NMFS) does not approve, recomffiend 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
indlcat~ 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 productte' be used 01 purchasod ,ecause of this NMFS publication. The U.S.Japan subs«i.. of NOAA Techmcal Reports on aquaculture is used (0communicate prr:liminar:' results, interim reports, and similar timely
information. It is not :subject to tormal p('cr review.

Text printed on recycled paper

CONTENTS
Efficient techniques for producing masu salmon smolt and improving adult returns from
outplantings

1

Recent advances in halibut (Hippoglossus spp.) culture

9

T. NOMA

Control of hydraulic environment and development of an artificial pocket beach In
sandy coastal areas

15

C.W. HOPLEY Jr.

Temporal and geographic variability in survival of sea-ranched coho and chinook salmon
in North America

21

Y. KOSHIISHI
H. ITANO
Y. HIROTA

Artificial stock-size improvement of the flounder Paralichthys olivaceus: Present status oftechnological achievement

33

S.K. ALLEN Jr.
S.L. DOW ING

Reproductive sterility in triploid Pacific oysters

45

K. TANIGUCHI

Marine afforestation of Eisenia bicyclis (Laminariaceae: Phaeophyta)

47

J.F. KITCHELL

Salmonid carrying capacity: Estimates and experiences in the Great Lakes of North
America59

K. TANAKA

Farming techniques for bay scallop, Pecten (Notovola) albicans, in the western regions of
the Japan Sea

67

Release of hormonally sterilized coho salmon from a Puget Sound hatchery

77

Large-scale culture system for attaching microalgae

83

The importance of smolt development to successful marine ranching of Pacific salmon

89

Control of skin ulcers in young bluefin tuna in fish farming

99

H. ITO

Successful HOTAC methods for developing scallop sowing culture in the Nemuro districtof east Hokkaido, northern Japan

107

J.L. PITTS

The use of aquaculture for enhancement of the common property fishery in Oregon,
Washington, and Alaska

117

T. KIMURA
M. YOSHIMIZU
T. NOMURA
T. AWAKURA

Incidence of fish pathogenic viruses among anadromous salmonids in the northern partof Japan, 1976-1987

123

H. MATSUNAGA

Ecology and production of fish in a man-made Sargassum forest

129

H. MAYAMA

R.R. STICKNEY
H.W. LIU
S.D. SMITH

W.W. DICKHOFF
C.W. HOPLEY
C.V.W. MAHNKEN
N.TANAKA
W.S. ZAUGG
C.V.W. MAHNKEN
H. SAKOY.INUlS. MIWAIII

O. HIROI

Masu salmon production studies of the Marine Ranching Program

133

H.OGATAT. MURAl

Nutritional approach to the production of masu salmon (Oncorhynchus masou) smolt

145

K. OHKUMA
T. NOMURA

An approach to the efficient enhancement of masu salmon through the release ofjuveniles
into streams

151

Present status and future of the Marine Ranching Program

161

A.C. FOX
C.K. ARAKAWA
j.R. WINTON

The application of current techniques in molecular biology for detection and control
of infectious diseases in salmonid aquaculture

165

S. KAWAMATA

Physical considerations for the design of algal drift traps

171

A. KOGANEZAWA

IV

Efficient Techniques for Producing Masu Salmon Smolt
and Improving Adult Returns from Outplantings
HIROSHI MAYAMA
Hokkaido Salmon Hatchery, Fisheries Agency ofJapan
2-2 Nakanoshima, Toyohira-ku
Sapporo 062, Japan

ABSTRACTThe goal of enhancing chum salmon (Oncorhynchus keta) levels through the introduction of hatcheryreared juveniles was reached in the early 1980's. Thus, scientific study became more focusedon accomplishing similar progress with the masu salmon (Oncorhynchus masou). This paper dis·cusses critical areas of concern for the development of a comprehensive and effective program
to improve this important fishery resource. In addition, significant research achievements arereviewed and a basic framework of techniques for smolt production are outlined specificly to theneeds of masu salmon.

Introduction_

Masu salmon (Oncorhynchus masou) usually spend one, sometimes two, years in freshwater after fry emergence fromthe redds. Young masu salmon which reach the smolt stage
migrate down stream to the sea the following spring (Kubo
1980). Environmental devastations in rivers, such as manmade obstructions to fish migration and decreases in waterflow resulting from intensive water utilization projects,
have resulted in serious decreases in masu salmon resources(Sano 1964; Kobayashi 1980).
In the propagation of masu salmon in Japan, fry havebeen released from April to June either unfed or after ashort-term feeding lasting from 1 to 3 months. This technique is similar to those used in the propagation of chum
(Oncorhynchus keta) and pink (0. gorbuscha) salmon fry that
migrate to the sea in early spring soon after their release(Kobayashi 1980). However, the release at the fry-stage
has not been an effective method in areas where the environment has been devastated (Kato 1982). In order to augment the decreased masu salmon stocks in these areas, theproduction of large numbers of smolts in hatchery facilities was considered to be the most promising method, andthus was chosen for further study.

Smolt Production_

Masu salmon smolts are normally released as yearlings (age1 + ) in the spring after a rearing procedure mimicking the

growth pattern of fish in the natural state (Mayama et al.
1986). Therefore, new technological developments such as
underyearling (age 0 + ) smolt production (Konno et al.
1983; Sato et al. 1986) are not necessary to produce them.
However, in order to achieve high smoltification rates withthis method, masu salmon should be reared using strategies closely regulating their growth. Inhibiting growth at
the proper time can prevent the early maturation of young
males. Conversely, growth acceleration is used to increase
the number of fish reaching the minimum size for smoltification by release time.
Males growing to 70 mm or more in fork length by theend of July become sexually mature (Utoh 1976). Thus,
techniques used on males to delay egg and sac fry development, with water temperature control and reduced
feeding under low water temperature conditions, are considered to be effective for inhibiting the maturation of maleduring this period. Throughout the winter, from lateNovember through late March, no growth occurs in thenatural state under the low water temperatures which are
below 5°C. Pond-reared fish, however, tend to grow alittle because the water is slightly warmer, and consequently development of the testis often starts (Mayama
et al. 1985a). Therefore, growth control during the winterseason is also required to achieve a high smoltification
rate.
From the results of experimental releases of smolts andfingerlings, it is clear that growth up to 9 em or more infork length before overwintering is necessary for smoltification the next spring (Mayama et al. 1988). The ideal

2

NOAA Technical Report NMFS 102: Marine Ranching

30

··

25

--

_

Okhotsk Sea

J t:

?Cl

Japan Sea
Precocious
Male

,o

\

o

ISmoltPacific Ocean

o

100

km

-"'-----',,-'

Figure 2

5

Map showing the locations of the Shari River (A), Shibetsu River(B), Shizunai River (C), and Shiribetsu River (D) where experimental smolt releases were carried out.

MJ J ASONDJ FMAM
Con. ! Accelerate! Control ! Accel.
Figure 1

Diagram showing the controlled growth pattern for efficient masu
salmon smolt (age 1 + ) production in southwestern Hokkaido.
Body weight of 5 g in July and 10 g in November are criticalpoints to prevent the early maturation of young males and to reachthe minimum size for smoltification by release time, respectively.
Ideal growth range (open part between the two critical borderlines) with the average body weight (solid dots) indicates anoptimal standard for hatchery-rearing. (Mayama et al. 1986.)
M = May; J = June, etc.

growth pattern for efficient smolt production based on thefactors described above is shown in Figure I. The regulated
growth curve is divided into four periods:
1. Initial growth control from emergence to early summer (less than 7 cm in fork length, or 5 g in body weight,
at a point in late July);
2. Growth acceleration during summer to fall (morethan 9 cm in fork length, or 19 g in body weight, by
November);
3. Inhibition of growth in the winter season;
4. Growth acceleration prior to smoltification (morethan 12 cm in fork length, or 20 g in body weight).
An increase of approximately 20 to 30% in the smoltification rate is obtained by applying this method (Yagisawa
and Watanabe 1985; Mayama et al. 1986) resulting in 80%
or more conversion to yearling smolts in a large-scale rearing. The diagram applies specifically to masu salmon rearing in south-western Hokkaido. The most effective growth

curve will vary by area because of differences in living
condition.

Smolt Release_

Most of the technological development studies for releasing masu salmon smolts have been carried out in the
Shiribetsu River (Fig. 2) on the Japan Sea coast of Hokkaido since 1981. Much information and knowledge on
their migration and growth were obtained from theseexperiments.

Preliminary Experimental Release
The first experimental smolt release was done in 1981. The
results of this experiment were reported previously by
Mayama ct al. (1985b). The text is summarized here.
About 70,000 hatchery produced smolts, averaging 28 g
in body weight and 13.8 cm in fork length, were marked
by clipping the adipose-fin and released into the Shiribetsu
River from late April to early May. About 60,000 fish(except resident parr) migrated to the sea as smolt.
A total of 481 marked fish were recovered in the coastal
waters around the home river's mouth from mid-February
to late June. The number of marked adults recovered increased in mid-April in accordance with the overall risein coastal commercial catches.
From the body-weight analysis of the recovered fish it
is obvious that the marked salmon were rather small earlier
in the study, less than 2 kg until mid-April (Fig. 3). In late
April, the average body weight exceeded 2 kg, reaching

_ _ _ _ _ _ _ _ _ _ _ _ _ Mayama: Techniques for Producing Masu Salmon Smolt and Improving Returns:3

NO. OF FISH

6
3. . . .

~5----J-lE

M
MARCH

L

E

M
APRIL

L

E

M
MAY

L

2.7 kg by late May. From this trend of increases it is clearthat masu salmon show significant growth from active
feeding just before their upstream migration. The fork
lengths of marked fish recovered throughout the season incoastal waters ranged from a minimum of 29 cm to a maximum of 70 cm, while body weights varied from 0.2 to
6.1 kgReturning adults showed a great variation in body size.
The accepted hypothesis that all masu salmon originatingin Japan spend one winter in the ocean had been doubted
because of the wide variation in body size of adult masu
salmon (Machidori and Kato 1984). From the results ofusing marked salmon belonging to the same brood-yearclass, a remarkable variation was seen in the adult bodysize. Only one marked fish returned to the river the next
year as a 4-year-old fish that had spent two winters infreshwater and one winter in the ocean; thus it became clearthat all masu salmon produced in the Shiribetsu River
spent one year, or one winter, in the ocean returning afterwards to its natal waters for spawning.
An examination of the scale patterns of marked adults
did not show any significant correlation between adult sizes
and estimated smolt sizes at the beginning of the seaward
migration (Ohkuma and Mayama 1985).
Adult trapping for artificial hatchery work in the Shiribetsu River was carried out from late August to midOctober with peak captures occurring in mid-September.
A total of 361 marked masu spawners were recaptured in
the river.
The estimated rate of return was 0.7% in the natal river,
5.8% in the coastal waters within 50 km from the rivermouth: a total of 6.5% of the 60,000 smolt originallyreleased (Table 1). The migration range of masu salmon
in the ocean is extremely limited compared to that of other

E

M
JUNE

L

Figure :3
Seasonal change in body weight distribution of marked masu salmon recovered
during 10-day periods in coastal waters
adjacent to mouth of the Shiribetsu
River, 1982. E, M, and L in frame ofmonth indicate early, middle, and latemonth, respectively. (Mayama et al.
1985b.)

Table 1
Estimated numbers of marked masu salmon returned in
the natal river and coastal waters around the natal river,1982. (Modified after Mayama et al. 1986b.)
Area

Estimated no. offish returned% of returnto each area

404

0.7

River
Coast within 50 km
from the mouth ofnatal river

3,564

5.8

Total

3,968

6.5

salmon (Machidori and Kato 1984). Masu salmon migratealong the coastal waters of Japan for 8 to 9 months outside the summer season when they stay in the Okhotsk Sea.
During the summer period before the spawning return,fishing mortality is considered to be very high. It is also
likely that a large number of young masu salmon encounterfishing nets during their northward migration.

Body Size of Returned
Adults from the Smolt Release
The size of spawning adults from the same release groupvaries extensively as mentioned above. Their fork length
distribution is shown in Figure 4. The average male fork
length was larger, and variance greater, than that offemales in every river. There were obvious differences infish size by area. The average fork length of fish caught
in the Shari River on the Okhotsk Sea side was small, about
40 cm, which is 10-15 cm less than fish on the Japan Sea

4

NOAA Technical Report NMFS 102: Marine Ranching

Female

_

Male

20

A

~ o~

B

c: 20

1 -Ar------.0

It ~

c

Figure 4

D

20

o I
30

40

70

Length

30

(em)

40

50

60

Fork length distribution of marked
masu salmon recaptured in various rivers. (A) Shari River (Okhotsk Sea coast); (B) Shibetsu
River (Nemuro Strait); (C) Shizunai River (Pacific Ocean); and(D) Shiribetsu River (JapanSea).

side, which are on average the largest. Masu salmon in
the Nemuro Strait and the Pacific Ocean sides were between these values.
According to past studies (Machidori and Kato 1984),
the size of upstream migrating adults varies extensively by
area in far-east Asia. The size of masu salmon caught in
the Primore and northeastern Sakhalin areas are larger
than those in the Okhotsk Sea side in Hokkaido. Thus,
the relationship between latitude and adult size is not clear.
Within the limits of these results, we do not have sufficientknowledge to explain the differences in fish size by area.

small at times, but usually there were significant differences. On the other hand, fingerlings, released in the fall
before their overwintering, returned as equal to or larger
than the wild fish (Mayama et al. 1988). These results
indicate that smolts released after long-term rearing havedifficulty acclimating to new environments. It is necessary
to determine either the best time or the optimum smolt
condition, to increase both the survival of masu salmon
smolt and their adult size.

Growth of Hatchery-reared
Fish after the Release\Ve confirmed that smolt releasing was an efficient method
to establish an original stock rapidly. However, it is very
difficult to take a large number of eggs on a regular basis
from ascending native spawners. Salmon eggs have beentransplanted frequently to various areas. In particular,
almost all the chum salmon resource in Japan has been
supported by artificial propagation so that a great number of eggs are transplanted among many rivers. But, inthe genetic study of the chum salmon population structure
by Okazaki (1982), the author suggested that it was nearly
impossible to expect good results from a transplantation
between latitudinally distant rivers. He also reported thathigh genetic divergence occurred among masu salmon river
populations and that significant differences in the frequencies of alleles were observed even among the proximal river populations (Okazaki 1986).

In order to clarify the influence of hatchery rearing upon
growth and survival after release, the body size of returned
adults and rate of return is useful information. However,as mentioned before, it is difficult to estimate the returnrate, because the total catch of masu salmon during theirfeeding migration is not yet clear.
The relationship between average fork length of adults
from fish released into rivers on the Japan Sea coast andof adults from wild smolts of the same bood-year-class isshown in Figure 5. These released fish were produced fromthe native stocks of the rivers used in these experiments.
As shown in this figure, adults from the released smolts
were always smaller than the wild fish. The differences were

Effect of Transplantation on Adult Return

_ _ _ _ _ _ _ _ _ _ _ _ _ _ Mayama: Techniques for Producing Masu Salmon Smolt and Improving Returns

Female

j
~55
E

0**
Male

-e

a**0**

~

:I

~
'0 50

.**
**

..J

u..

•**•**

t

I
50

55

60

Avg. Fork Length of Wild Adult (em)IJ'~-----

Figure 5
Relationship between the average fork length of adult masu
salmon from hatchery-reared smolts (circles), or fall-releasing fish
(triangles), and that of adults from wild smolts of the same broodyear-class. Shaded symbols indicate comparison of males, open
symbols females. Asterisks indicate significant difference(*P<O.05; **P<O.Ol). (Data: Mayamaetal. 1985b, 1986, 1987,
1988, 1989.)

As previously discussed (Fig. 4), there was obvious difference in fish size among various rivers. The Shari Riverstock in the Okhotsk Sea belongs to the minimum fish sizegroup. In contrast, the Shiribetsu River stock in the Japan
Sea belongs to the maximum size category. Those rivers
are located a great distance from each other (Fig. 2). Exchange transplantation experiments between these rivers
were carried out to clarify the ability of nonnative adults
to return to the site of outplanting as adults.
Two groups of smolts, one from the native stocks andanother from the introduced stocks were released at thesame time into each river (Table 2; Mayama et al. 1989).
Unfortunately, we cannot compare the differences in
returning fish size between strains in each river because
the number of adults recaptured in the rivers from theintroduced stocks was very small. The recapture rate of
the introduced group was significantly lower than the native
group in both rivers. Differences in the seaward migration
time were thought to be causing the low survival rate of
the introduced stocks.
The smolts were collected repeatedly during their seaward migration (nine times at intervals of 1 to 4 weeks)at an area about 10 km downstream from the release site
in the Shiribetsu River from April to July (Fig. 6). Captured fish were classified into smolt and parr by morphological features.
The seaward migration period of the hatchery-reared
smolts originating from the native stock corresponded withthat of the wild stocks. On the other ~and, smolts fromthe introduced stock originating from the Shari Rivermigrated downstream in June, or about one month later
than the natives.

Table 2
Summary of experimental data for fish stocks exchanged between the Shiribetsu and Shari rivers and for native river stocks(modified after Mayama et al. 1989.
Release
Brood
year

Original
flver

5

No. of adults recaptured

Date

No. ofsmoltsAvg. fork
length (cm)

In
coast

riVer

Total

Recapture
rate (%)"

In

Shiribetsu River
1984

NativeShari

22-23 Apr. 1986
23-24 Apr. 1986

25,00037,000

12.4
9.9

86
13

58
4

144
17

058(023)0.05(0.01)

1985

NativeShari

21-22 Apr. 1987
20 Apr. 1987

37,00045,000

11.2
10.1

31
9

49
2

80
II

0.22(0.13)
0.02 (0.00)

Shari River
1984

NativeShiribetsu

13 May 1986
13 May 1986

39,00035,000

11.9
14.4

182
29

195
8

377
37

0.97 (0.50)
0.11 (0.02)

1985

NativeShiribetsu

20 May 1987
20 May 1987

42,00044,000

12.4
15.5

36
13

345
25

392
38

0.93 (0.82)
0.09(0.06)'Recapture rate: smolts-to-total adults. Value in Parentheses: smolts-to-adults in river.

6

NOAA Technical Report NMFS 102: Marine Ranching

_

20
()

-

0

...:::J 15

..
Q)

l!

8- 10

E

~

..~...
Q)

50
Shari Strain

20

.' .'

Release..
~ l~t -

~

.t:.

..

0

~

fI)

~-_

'

~

Shiribetsu Strain~--P--U---rl-i-"-"~":"-.I!!!.....
!!!!!I.._-~------

i! 100

'0

...
! 50

Wild Fish

E
:::J

Z

o~-t--J'---'f---J'--l--'--f.......J.-+--I
April

In the coastal waters of the Japan Sea off sou th-western
Hokkaido, it is known that the density of chum salmon
fry decreases rapidly from late May to early June, disappearing in mid-June (Mayama 1985; Mayama et al.
1982, 1983). The seaward migration ofmasu salmon smolts
is usually two or four weeks behind that of chum salmon
fry. Masu salmon smolts reach the coastal waters when thesurface water temperature is approximately 8 to 100 C.
Both species of salmon disappear from the coastal waten
in early June when the water temperature reaches from12 to 13 a C. The same migration pattern was observed off
the Pacific coast of Hokkaido (Sana and Abe 1967).
It is not yet clear what triggers the mechanism that
stimulates young salmon to disappear from the coastal areaadjacent to the natal river. However, offshore migration
may be induced by a simultaneous change in the marine
environment which produces inadequate conditions for
growth (Mayama 1985). The effect of the Tsushima Warm
Current also increases at this time (Hata 1962). Somehatcheries raising chum salmon on the Japan Sea side have

Figure 6
Seasonal changes in seaward migration of different
stocks of masu salmon smolts released into the Shiribetsu
River in 1986 and the surface water temperature in theadjacent coastal waters at the mouth of the Shiribetsu
River (solid circle) and the Shari River (open circle),
Optimum migration period (8-13°C) of each stock in
its natal waters is shown as the range. Fish were caught
in the lower reaches of the river and classified into smolt(open part of histogram) and parr (shaded part). (Modified from Mayama et al. 1989.)

used low temperature (instead of warmer spring water) forrearing. The colder water retards development and leads
to a longer rearing time and a later release date. The
occasional absence of any returns under these conditions
indicates high mortality as a result of delayed release(Mayama, unpub!. data).
Therefore, from the observations made on chum salmon,
it is suggested that the low returns of introduced stock into
the Shiribetsu River indicates high mortality as a resultof a late seaward migration. The Shiribetsu River stock
which was introduced into the Shari River smolted at thesame time as the native stock; however, the introduced
stock migrated to sea about one month earlier than thenatives.
Along the Okhotsk Sea coast, drifting ice comes close
to shore until mid-April. After the ice disappears, watertemperatures increase reaching only 4 or 5°C by mid-May(Fig. 6) when the early smolt oftheShiribetsu River stock
migrate to sea. The temperature may be too low for thesmolt. but this is not considered as the critical factor in

_______________ Mayama: Techniques for Producing Masu Salmon Smolt and Improving Returns

their mortality. The smoltification peak of native ShariRiver smolts coincides with the occurrence of a temperature of lOoe in the Okhotsk Sea. Similarly, the same peakoccurs with the native Shiribetsu stock as waters in theJapan Sea reach lOoe.
We do not have sufficient knowledge to explain why theearly seaward migration of the Shiribetsu strain in the
Okhotsk Sea side resulted in low survival. Many factors
have yet to be considered, all of which influence the genetic
adaptation of the stock to a new environment.

Conclusion_

The effects of masu salmon transplantation from proximal rivers have been evaluated. The results indicatethat preservation of the native stocks is the most important factor in their rehabilitation, and that a donor river
must be selected using definite but yet undefined criterion
for more effectiv~ transpiantation. This theory is supported
by results with coho salmon (0. kisutch) (Reisenbichler1988).

CitationsHata, K.
1962. Seasonal variation uf the volume transport in the nurthernpart uf the Japan Sea. J. Oceanogr. Soc. J pn., 20th Anniversary Vol. 168-179. (In Japanese; English abstr.;
Kato, T.
1982. Necessity of smolt release In masu salmon propagation.
Marine Ranching Program Prog. Rep. on Masu Salmon Project
2:1-3, Hokkaido Salmon Hatchery. (In Japanese.)
Kobayashi, T.
1980. Salmon propagation in Japan. In Salmon ranching
Thorpe, ed.), p. 91-107
Acad. Press, London.
Konno, S., S. Nakae, and S. Takahashi.
1983. Observations on the affect of artificially controlled light on
the smoltification of masu salmon, Oncorhynchus masou - III.
Marine Ranching Program Prog. Rep. on Masu Salmon Project
3:26-50, Hokkaido Salmon Hatchery.
Kubo, T.
1980. Studies on the life history of "Masu" salmon (Oncorhynchus
masou) in Hokkaido. Sci. Rep. Hokkaido Salmon Hatchery 34:
1-95. (In Japanese; English abstr.)
Machidori, S., and F. Kato.
1984. Spawning populations and marine life of masu salmon(Oncorhynchus masou). Int. North Pac. Fish. Cumm. Bull. 43:
1-138.
Mayama, H.
1985. Technical innovation in chum salmon enhancement withspecial reference to fry condition and timing of release. In Proceedings of the eleventh U.S.-Japanese meeting on aquaculture,salmon enhancement; 19-20 October 1982, Tokyo, Japan (CJ.
Sindermann, ed.), p. 83-86. Dep. Commer., NOAA Tech. Rep.
NMFS 27.
Mayama, H., M. Kato, J. Seki, and I. Shimizu.
1982. Studies on the chum salmon released in the Ishikari River
System - I. On the seaward migration and inshore distributions

a.E.

7

ofliberated fry in 1979. Sci. Rep. Hokkaido Salmon Hatchery36: 1-17. (In Japanese; English abstr.)
Mayama, H., J. Seki, and I. Shimizu.
1983. Studies on the chum salmon released in the Ishikari River
System - II. On the seaward migration and inshore distributionof liberated fry in 1980 and 1981. Sci. Rep. Hokkaido Salmon
Hatchery 37'1-22. (In Japanese; English abstr.)
Mayama, H., T. Nomura, and K. Ohkuma.
1985a. Experimental release of masu salmon (Oncorhynchus masou)smolts. Results of adult returns in 1984. Marine Ranching Program Prog. Rep. on Masu Salmon Project 5:109-120, Hokkaido
Salmon Hatchery. (In Japanese.)
1988. Seaward migration and adult return of the marked masu
salmon, On,orhynchus masou, released in late fall before wintering.
Sci. Rep. Hokkaido Salmon Hatchery 42:21-36. (In Japanese;
English abstr.)
1989. Reciprocal transplantation experiment of masu salmon(Onccrkvnchus masou) population. 2: Comparison of seaward migrations and adult returns of local stock and transplanted stock of masu
salmon. Sci. Rep. Hokkaido Salmon Hatchery 43:99-113. (InJapanese; English abstr.)
Mayama, H., K. Ohkuma, T. Nomura, and K. Matsumura.
1985b. Experimentai release of masu salmon, Oncorhynchus masou,smolts into the Shiribetsu River. Adult returns of marked fish'.·e!eased in the spring of 1981. Sci. Rep. Hokkaido Salmon
Hatchery 39:1-16. (In Japanese; English abstr.)
Mayama, H., K. Ohkuma, and T. Nomura.
1986. Experimental reiease of masu salmon (Oncorhynchus masou)smolts. Results of adult returns in 1985. Marine Ranching Program Prog. Rep. on Masu Salmon Project 6:82-91, Hokkaido
3aimon Hatchery. (In Japanese.)
1987. Experimental release of masu salmon (Oncorhynchus masou)smolts. Results of adult returns in i 986. Marine Ranching ProiSram Prog. Rep. on Masu Salmon Project 7:19-30, Hokkaido
Salmon Hatchery. (In Japanese.)
Ohkuma, K., and H. Mayama.
1985. On the studies of scale pattern and growth of masu salmon(Oncorhynchus masou). 2: Growth and scale pattern of hatchery rearedmasu salmon returned in 1982. Sci. Rep. Hokkaido Salmon
Hatchery 39: 17-25. (In Japanese; English abstr.)
Okazaki, T.
1982. Genetic study on population structure in chum salmon(Oncorhynchus ketal. Bull. Far Seas Fish. Res. Lab., 19:25-116.
1986. Genetic variation and population structure in masu salmon
Oncorhynchus masou of Japan. Bull. Jpn. Soc. Sci. Fish. 52(8):1365-1376.
Reisenbichler, R.R.
1988. Relation between distance transferred from natal stream andrecovery rate for hatchery coho salmon. North Am. J. Fisheries
Management 8:172-174.
Sano, S.
1964. Ecology of masu salmon and the resource conservation.
Fish and Eggs 104:1-7, Hokkaido Salmon Hatchery. (InJapanese.)
Sana, S., and S. Abe.
1967. Ecological studies of masu salmon (Oncorhynchus masou(Brevoort». The observation on smolts in the coastal waters.
Sci. Rep. Hokkaido Salmon Hatchery 21:1-10. (In Japanese;
English abstr.)
Sato, R., T. Shibuya, and U. Akutsu.
1986. Smoltification of underyearling masu salmon (Oncorhynchus
masou) at different temperature. Bull. Natl. Res. Inst. Aquaculture 9:21-27. (In Japanese; English abstr.)
Utoh, H.
1976. Study of the mechanism of differentiation between the stream

8

NOAA Technical Report NMFS 102: Marine Ranching
resident form and the seaward migratory form in masu salmon,
Oncorhynchus masou Brevoort. I: Growth and sexual maturity of
precocious masu salmon parr. Bull. Fac. Fish., Hokkaido Univ.
26(4):321-331. (In Japanese; English abstr.)_
Yagisawa, I., and S. Watanabe.
1985. Smolt production of the 1983-brood masu salmon in Kushiro
Hatchery Fish and Eggs 155:1-10, Hokkaido Salmon Hatchery.
(In Japanese.)Recent Advances in Halibut (Hippoglossus spp.) Culture

ROBERT R. STICKNEY and HAN WU LIU
School of Fisheries WH-10
University of Washington
Seattle, Washington 98195

STANLEY D. SMITHu.

S. Fish and Wildlife Service
National Fisheries Research Center
Building 204, NAVSTA
Seattle, Washington 98115

ABSTRACTThe Atlantic halibut (Hippoglossus hippoglossus) is currently receiving a significant amount ofresearch attention in Norway, Iceland, and Scotland and interest in the culture of that species
is developing in North America (particularly Nova Scotia and Newfoundland, Canada). Successin spawning and larval rearing has been achieved by Norwegian scientists though the numbersof postlarvae produced to date are small. On the west coast of the United States, our researchin conjunction with the International Pacific Halibut Commission, the United States Fish andWildlife Service, and the National Marine Fisheries Service has led to the captive spawning ofPacific halibut (H. stenolepis). We have also investigated seasonal patterns in circulating hormone
levels. Future work with Pacific halibut will be aimed at production ofpostlarvae and determination of nutritional and environmental requirements of larvae and juveniles.

Introduction_

Atlantic halibut (Hippoglossus hippoglossus) and Pacific halibut (H. stenolepis) have long been fished by various nations.
Atlantic halibut are found in the boreal and subarctic
Atlantic Ocean. Along the North American coast they havebeen occasionally reported as far south as New Jersey and
New York, and in the eastern Atlantic they have beenreported from the Bay of Biscay and the English Channel.
The fish are abundant in the North Sea, near Iceland,along the Norwegian coast, and in the Barents Sea (Bigelow
and Schroeder 1953). Pacific hailibut also have a broad
distribution, occurring from California northward along
the coast of North America into the Bering Sea. Along theeastern Pacific coast, H. stenolepis occur as far south as
northeastern Japan (Hart 1973).
Management of Pacific halibut has a long history. The
International Fisheries Commission (currently the International Pacific Halibut Commission or IPHC) was organized in 1924 and began its work early in 1925 (Thomp-

son 1950). Today, the IPHC manages the commercial
halibut fishery off the west coast of the United States andCanada, where yearly quotas in some areas are taken in
48 hours or less of fishing!
A great deal of information has been collected on thebasic biology of halibut, but the interest of aquaculturists
is largely a phenomenon of the present decade. While there
are some differences between the Atlantic and Pacificspecies, they have many characteristics in common and it
is assumed that much of the information generated byaquaculturists interested in one species can be applied tothe other.

Biology of Halibut_

Halibut are laterally compressed, assymetrical fishes withcolor occurring only on the right side. In postlarval andlarger individuals the eyes both occur on the right side
as is typical of members of the family Pleuronectidae.
9

10

NOAA Technical Report NMFS 102: Marine Ranching

Individuals may exceed 300 kg in weight (Bell and St.
Pierre 1970). Halibut are strict carnivores which preyprimarily on other fishes. Crabs, lobsters, squid, clams,
and mussels are also frequently recovered from halibut
stomachs (Bigelow and Schroeder 1953; Hart 1973).
The spawning season of Pacific halibut extends from
November to late March, with peak spawning occurringin December and January (St. Pierre 1984). Spawning occurs near the continental shelf edge at depths ranging from100 to 550 m. Pacific halibut males generally mature ateight years of age, while females typically mature at 12
years (St. Pierre 1984). Maturity in males generally occurs
when the fish are between 70 and 110 cm, while females
mature at lengths of90-140 cm (Novikov 1964). Atlantic
halibut spawn in the winter and spring at depths from180-1000 m (Thompson and Van Cleve 1936). Water
temperature for spawning of both species is within therange 3-8°C (Thompson and Van Cleve 1936).
Halibut have large eggs relative to other flatfishes. Forrester and Alderdice (1973) indicated that the mean unfertilized egg diameter for Pacific halibut is 3.1 mm. Atlantic halibut eggs average 2.9 mm (L¢mning et al. 1982).
Fertilized eggs expand over a period of a few hours to
3.2-3.3 mm for Pacific halibut (Forrester and Alderdice1973) and 3.1 mm for Atlantic halibut (Blaxter et al. 1983).
Egg development of both the Pacific and Atlantic species
appears to be identical (Forrester and Alderdice 1973;
Rollefsen 1935).
Larval development of Pacific halibut appears to be
typical for the genus. Two to three weeks following fertilization, the drifting eggs hatch into pelagic larvae 8-15
mm in length (Thompson and Van Cleve 1936). Time tohatching is dependent upon temperature (Van Cleve andSeymour 1953). As larval development progresses, the fish
move upward in the water column and over a period of
three to five months are carried shoreward by surface currents. Following metamorphosis, postlarvae settle to thebottom in about Mayor June (Thompson and Van Cleve
1936).

Halibut Culture_

Atlantic halibut have been spawned in captivity for many
years in Europe (Meggs 1988). Spawning of Pacific halibutin the laboratory has also occurred in Canada (Forresterand Alderdice 1973). Adult Atlantic halibut are currently
being held in Iceland, but spawning has not yet been accomplished (Ami Isaksson, Institute of Freshwater Fisheries, Reykjavik, Iceland, pers. commun., January 1990).
After several attempts to produce postlarval Atlantic
halibut, researchers at the Norwegian government laboratory at Austevoll, near Bergen, were successful in 1986.
From two postlarvae produced that year, about 200 survived in 1987, and that number was expected to increase_

to 1,000 in 1988 (Meggs 1988). In 1987, the Sea Fish
Industry Authority Marine Farming Unit in Scotland
reportedly produced about 22,000 larval Atlantic halibut
from 700,000 eggs and was able to carry 18 fish to a stage
approaching metamorphosis (Anonymous 1988).
While the number of surviving postlarval halibut produced in captivity remains small, interest in aquacultureof Hippoglossus sp. is growing rapidly. Research or development of aquaculture enterprises centered around halibut
is occurring in Norway, Iceland, Scotland, Canada, andthe United States. We have spoken with investigators in
Newfoundland, Nova Scotia, and British Columbia, Canada who are interested in halibut as an aquaculture species.
Discussions with Ingvar Huse (Institute of Marine
Research, Austevoll Marine Aquaculture Station, Storeb~,
Norway, pers. commun.) both in Austevoll, Norway (September, 1987) and during a visit he made to Seattle,
Washington (November, 1987) revealed that larval Atlantic
halibut are maintained in total darkness. Exposure to lightis related to increased mortality. The eggs and larvae aresuspended in the water column and are easily damaged
if they strike the walls of rearing containers. Buoyancy canbe maintained if the proper combination of salinity andtemperature is provided.
In 1980, spawning adults were captured by gill net at
sea and stripped aboard ship (Blaxter et al. 1983). In recent years, captive brood stock have been maintained atAustevoll and are the primary source of gametes. The eggs,
which are incubated in the dark, are neutrally buoyant at
37%0 salinity at 5 and 7°C. Hatching occurred after 18days at 5°C and 13 days at 7°C. The presence of antibiotics in the culture water led to improved percentage of
hatch.
In their first attempts at halibut rearing, Austevoll
researchers had little success in getting fry to feed after yolksac absorption. However, that situation has improved.
First-feeding larvae are offered wild zooplankton in Norway (Ingvar Huse, pers. commun.) and cultured copepods(Trigriopus sp.) in Scotland (Anonymous 1988). Postlarval
Atlantic halibut can be trained to accept pelleted feed
(Ingvar Huse, pers. commun.).
Our work in Washington is centered around determination of some of the basic biology of larval and juvenile
halibut, but the results of that research clearly haveaquaculture implications. Our research is supported by theInternational Pacific Halibut Commission and is being conducted cooperatively with the National Marine FisheriesService and the U.S. Fish and Wildlife Service. The latterhas facilities at their Marrowstone Island facility on northern Puget Sound (Fig. 1).
Limited success has been achieved in spawning and larval rearing of Pacific halibut. The techniques employed
are similar to those developed in Norway for Atlantic
halibut. Brood stock are collected at sea and transported
in live tanks to the Marrowstone laboratory where they are

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Stickney et al.: Advances in Halibut Culture

11

Figure 1
U.S. Fish and Wildlife Service laboratory on Marrowstone Island, Washington, a location for halibut research by.the authors.

placed in a circular rubber lined tank about 5 m in diameterand 1.2 m deep. Pacific halibut rapidly adapt to the holdingtank. They begin feeding actively within a few days. The
broodfish tank can easily accommodate 20 broodfish of
60-100 cm length.
A black plastic cover is kept over the brood stock tankto drastically reduce incident light levels. The fish are provided with fresh or frozen Pacific herring (Clupea harengus)
two or three times a week.
During the past two years we have had only one mature
male available. The duration of the spawning season was
shortened because that fish became ripe before the females
and ceased the production of viable sperm before some of
the females had become ripe. Short-term storage of sperm
in the refrigerator was accomplished, and a recently published report indicates that it is possible to use cryopreservation on the sperm of Atlantic halibut (Bolla et al. 1987).
If problems with males occur in the future, we will attempt
to freeze sperm for later use, using the cryopreservation
technique.
For the 1988-89 spawning season, additional males were
to be obtained. There has been no problem getting adults

to mature in captivity, though Liu (1988) collected data
indicating that females may not spawn each year after
reaching maturity.
During the 1986-87 spawning season, spontaneous egg
release in the brood stock tank occurred, but eggs were also
obtained by stripping. No fertilization was achieved. However, in the 1987-88 spawning season, several groups of
eggs were obtained from five females, and sperm was
obtained from the single available male. Approximately
tO,OOO eggs were fertilized, from which a total of eightlarvae were produced. This appears to have been the firsttime that intentional captive spawning of Pacific halibut
was achieved in the United States. Spontaneous spawning, subsequent stripping and fertilization, followed bylarval hatching was accomplished in British Columbia,
Canada (Forrester and Alderdice 1973), but no long-term
larval rearing was attempted.
None of the larvae hatched in 1988 were retained past
five days because the numbers were so small. Hatching wasachieved in chambers which allowed the eggs to rest on
the surface of 150-micron mesh plankton netting that had
been attached to one end of a short piece of plastic pipe

12

NOAA Technical Report NMFS 102: Marine Ranching

4000

_

T
0.

o

3000

Hormoneconcentration(pg/ml)•• Androgen
2000·0- Estradiol

1000

0+----+---+--.... -_":~::;;-~-+-----11
Mar

Coo

Apr

h.g

Nov

Date (Dec. 1987 - Nov. 1988)

Figure 2
Mean seasonal patterns in plasma androgen and estradiol levels in mature female Pacific halibut.

8000

T

7000.

6000

5000

Hormoneconcentration(pg/ml).•- Androgen
4000·0- Estradiol
3000

2000

1000

o

. ,

•

Jal

Mar

•

~

~-----9......x~Q_~-~0S..=~=:::!e~..::::..---:::::~~
Coo

Apr

h.g

~

Nov

Date (Dec. 1987 - Nov. 1988)

Figure 3
Seasonal patterns in plasma androgen and estradiol levels in a mature male Pacific halibut.

about 10 cm in diameter and placed within water baths
that received a slow exchange of sea water. A variety of
incubator designs were to be tested during the coming
spawning ~eason.

Initially our plans were to feed Pacific halibut fry on therotifer Brachionus plicatilis. Brine shrimp nauplii (Artemia sp.)were to be substituted once the halibut larvae were too large
to feed on rotifers. Prepared diets were to be used subse-

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Stickney e~ al.: Advances in Halibut Culture

quently, the formulation being similar to salmon rations
but with a reduced lipid content.
Blood samples 'Nere collected from captive Pacific halibut(4-6 females, 1 male) at intervals of several weeks from
December 1986 through November 1987. From thosesamples, annual patterns in plasma androgen and estradiol
levels were examined usmg radioimmunoassay (Sower andSchreck 1982). In mature temales, steroid concentrations
began to rise in September and peaked in December andJanuary (Fig. 2). Stercid levels dropped dramatically amonth before the fish spawned (each point in the figure
represents the mean of samples obtained from four to sixfish).
In the mature male, the androgen level began to increasein August and peaked in D-:cember, after whIch the concentration of that steroid declined precipitously about amonth before matur'.: sperm were obtained (Fig. 3). Estradiol was found in the male blood plasma, but little change
in the level present occurred during the year, a pattern thatwas seen for both steroids in samples obtained from Immature fish (Liu 1988).
In conclusion, our results have demonstrated that Pacifichalibut broodstock can be held in captivity for extended
periods, and that captive spawning can be achieved during the normal spawning season of the species. Viable larvae are difficult to obtain in large numbers, but modifications in the hatchery aimed at providing a more conducive
environment for the fragile young fish are being made. The
challenge of carrying larval Pacific halibut through tometamorphosis is currently being addressed.

Citations_

Anonymous.
1988. First glimmers of success with halibut. Fish Farmer,
January/February: 16-18.
Bell, F.H., and G. St. Pierre.
1970. The Pacific halibut. Int. Pac. Halibut Comm. Tech. Rep.
No.6. (IPHC, Seattle, Washington), 24 p.
Bigelow, H.B., and W.C. Schroeder.
1953. Fishes of the Gulf of Maine. Fish. Bull., U.S. 74:1-577.

13

Blaxter, j.HS., D. ;)anielssen, E. Moksness, and V. <l>iestad.
1983. Description and early development of the halibut Hippoglossus
hippogiossus and attempts to rear the larvae past first feeding. Mar.
3iol. 73:99-107
Boila, 3., !. Holmefjord, and T. Refstie.
1987. Cryogenic preservation of Atlantic halibut sperm. Aquaculture 65:371-374.
Forrester, C.R., and D.F. Alderdice.
1973
Laboratory observations of early development of the Pacifichalibut. Int. Pac. Halibut Comm. Tech. Rep. 9 (IPHC, Seattle,
Washington), 13 p.
Hart, ].L.
1973. Pacific fishes of Canada. Fish. Res. Board Can. Bull. 180,
740 p.
Liu, H.W.
1988. Seasonal changes In sex steroids of Pacific halibut Hippoglossus
Itenoiepis. M.S. thesis, Univ. Washington, Seattle, 33 p.
Llinning, S., E. Kjorsvik, T Haug, and B. Gullisen.
1982. Early development of the halibut, Hippoglossus hippoglossus(L. I, ~ompared with other marine teleosts. Sarsia 67:85-91.
Meggs, G.
1988. Journey to tne future. Supplement to The Fisherman, May
25, 1988, B p.
NOVlkov, N.P.
1964. Basic elements of the biology of the Pacific halibut (Hip/Joglossus .7ippoglossus stenolepis, Schmidt) in the 3ering Sea. In')ovlet fisheries investigations in the northeast Pacific (P .A.
Moiseev, ed.), p. 175-~19. U.S. Dep. Commer.iFSTI, Washington, D.C.
Rollefsen, G.
1935. The eggs and ;he larvae of the halIbut (Hippoglossus vulgaris).
Kgl. Norske Vidensk. Selsk., Forh. 1934, 7:20-23.
Sower, S.A., and C.B. Schreck.
1982. Steroid and thyroid hormones during sexual maturation ofcoho salmon (Oncorhynchus kisutch) in seawater or fresh water. Gen.
Compo Endocnn. 47:42-53.
St. Pierre, G.
1984. Spawning locations and season for Pacific halibut. Int. Pac.
Halibut Comm. Sci. Rep. 70 (IPHC, Seattle, Washington), 16 p.
Thompson, W.F.
1950. The effect of fishing on stocks of halibut in the Pacific. Univ.
Washington Press, Seattle, 60 p.
Thompson, W.F., and R. Van Cleve.
1936. Life history of the Pacific halibut (2). Distribution and iife
history. Int. Fish. Comm., Rep. 9 (IFC, Seattle, Washington),
184 p.
Van Cleve, R., and A.H. Seymour.
1953. The production of halibut eggs on the Cape St. James spawning bank off the coast of British Columbia, 1935-1946. Int. Pish.
Comm. Rep. 19 (IFC, Seattle, Washington), 44 p.

Control of Hydraulic Environment and Development of an
Artificial Pocket Beach in Sandy Coastal Areas

TOSHIFUMI NOMA
National Research Institute of Fisheries Engineering
Ebidai, Hasaki
Ibaraki 314-04, Japan

ABSTRACTThe control of shellfish larva dispersion is important for the establishment of shellfish enhancing grounds. The larva should stay within a planned area of the sea. The retention effect of pocket
beach formation was studied with wave basin experiments and numerical simulation. A circulation in the pocket, created by wave shoaling, is important for water quality conservation. To
intensify the circulation a wide entrance is needed, although for the retention effect the entrance
should be narrow.

Introduction_

Japanese fisheries are keenly interested in the developmentof the sandy coastal areas that comprise one third of theJapanese coastline of about 10 thousand kilometers.
A sandy coast confronting an open sea is an area where
waves, coastal currents, and sand drifts are the prevailingforces which result in the creation of severe conditions forthe survival ofjuvenile fish and shellfish. The natural areais therefore not left useful for fisheries purposes. Nevertheless, it happens that we found the enhancement ofbivalves in harbors constructed in such a sandy coast (e.g.,
Japanese surf clam, Pseudocardium sybillae, in Hachinohe
Port, Aomori Prefecture and Meretrix lamarkii in Kashima
Port, Ibaraki Prefecture) while these ports were under construction. This suggests that we can enhance the marine
resources on sandy coasts by controlling the flow of waterand the drifting of sand.
In the Marine Ranching Program, we have accomplished the following types of environmental control formariculture:• development of a wave-induced circulation method(Toda and Nakamura 1981),• diffusion control behind a wall (Toda 1983),• fundamental study on internal hydraulic bore (Noma1986),• bed materials control in a sandy beach (Uekita and
Akeda 1985),• analysis of bottom flow pattern on a reef (Akeda andUekita 1987),• environment control of underwater forest,• development of a "pocket beach" method (present
paper), and• design criteria for underwater structures (Takeuchi1987).
This paper introduces the artificial "pocket beach",especially its retention effect on floating matter and current dispersed substances.

Control of the Hydraulic Environment
in Sandy Coastal Areas_

On sandy coasts, we sometimes find topography such thata small inlet is formed with sides composed of headlandsof rock or reef (called a "pocket beach") whose sandy
bottom is stable under severe conditions. One of the purposes of the study was to develop a method of creating an
artificial pocket beach, where the controlled diffusion ofsubstances and removal of bed materials occurs. Marineorganisms spend their early larval stage floating and aretransferred soley by the motion of seawater. This may resultin a wider distribution of the species. On the other hand,
it may result in a critically high mortality rate at that stage.
Dispersion control aims to limit the motion of seawater,
and thus, the larvae of target species, within a planned
area.
Since the shallow water of sandy coasts is a severe dispersion field caused by wave and water flo~, it is possible forthe larvae to be transported to other waters or offshore.
15

16

NOAA Technical Report NMFS 102: Marine Ranching~___:":'""1,..J.-~

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TRAJECTORY OF PARTICLESTRAJECTORY OF PARTICLESSo as not to be transported, the larvae must in some way
be enclosed. A simple enclosure with four walls, for example, causes the seawater movement inside to cease andbecome stagnant, thereby causing mortality of the larvae.
A protected enclosure is needed, which results in the formation of a circulation. An eddy or circulation can be independent of a general flow such as coastal current andcan prevent dispersion.
Offshore breakwaters are one of the coastal structures
used to attenuate wave energy and to control the move-

Figure 1
Simulated current distribution and trajectory ofimaginary particle. Waveheight is 1 m; wave period is 6 seconds.

ment of bed materials. In mariculture, offshore breakwaters
are adopted for the purposes of• attenuating wave action,• allowing for continued seawater exchange,• providing dispersion control (i.e., suppression of longshore current and rip currents), and• controling drifting sand.
Figure 1 shows a simulated flow pattern III the pocket
beach on the bottom with slope 1: 100, the water depth at

___________________________ Noma: Development of an Artificial Pocket BeachrJwavec:::>longshoT'ecurrent, : / '"' ~ ....: :;..

;.'~:' •off,,,,,,, breakwater: fine sand(larva deposit),-:.. ,~.:: ~.':,:.: :.... :.~.;':: C'-Zn~

,..

17

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'01./.)"':

silt\(habitat)1

' ,
.. -.
tombalo , ... - "' :'......

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'" :'

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coarse sand(habitat)<'~ .

... ~:: .'l.,:~ *."; ""':,'":1''':"":'' .,.<:-,' 0"

the entrance is 6 m. The simulation principally consistedof a calculation of the wave field, a calculation of flow field,
and consideration of the movement of the sand bed. In thesimulation, the last factor was omitted.
A circulation can be intensified with submerged dikes,
because the breaking of a wave beyond the dike induces
a large flow velocity in the direction of the propagatedwave. If the circulation control method is performed in anarea enclosed by three sides, the suppression of the dispersion is greater than that of simple arrangement of an
offshore breakwater. This area may be used as a nursery
ground in sandy coastal areas. The mechanisms by whichbivalve establishment are enhanced in a pocket shaped
beach as shown in Figure 2 is interpreted as follows:• suppression of the dispersion of larvae,• supply of proper habitats for newly settled shellfishes
because of segregated bed materials by wave action into
coarse, fine, and silty sands.
• calmness (i.e., reduced turbulence),• wave-induced circulation to prevent stagnation of water,and• accumulation of larvae from outer waters owing to masstransportation by waves and currents.
Ragino (1987) investigated the ability of structures tosuppress the dispersion of retention of free swimmingorganisms by wave basin experimentation and numericalsimulation. Figure 1 is a simulation example.

Outline of the Experimentation

Figure 2

Schematic presentation of pocket
beach.

length and width of approximately 6 x 3 m, with entrancesof either 1- or 2-m diameter. Incident waves of 1 and 3
cm high with periods of 0.6 and 1.0 sec, respectively, were
made. Wave height was measured by a conductance wave
gauge, flow velocity by an ultra-sonic flow meter, and dye
concentration change (dye was injected and fully mixed
inside the pocket before wave test) by a photo-electriccolorimeter.
Six wave gauges were equipped on an observation truck,and measurements were done in planned points using a
100 x 100 cm mesh. Three flow meters and three colorimeters were set on the bottom of the basin; planned meshpoints were also measured. That is, Figure 4 represents
the compound results of repeated tests under the same experimental conditions. Station number (St.) in the figure
were points whe're dye concentration was measured.
The dispersion characteristics were mainly analyzed bydye concentration change. In the numerical simulation, themotion of an imaginary particle was determined and compared with the basin experiment.

Results_

Figure 4 shows the results of the basin tests with entrancesof width 1 and 2 m, the arrows representing the flow
velocity vector, and broken lines representing wave height
distribution. "Case" represents experimental conditions,and the difference between Cases 6 and 8 was entrance
width of the pocket. In both cases_

In an experimental wave basin as shown in Figure 3, themodel pocket was settled on a bottom with slope 1: 100,incident wave height R o

3.8 cm,wave period T

1.3 sec.

and18

NOAA Technical Report NMFS 102: Marine Ranching_

Coastal current generator( flow out)

i............
U..,_ .. II...,U~.=~ wall
,

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Figure 3 (left)Experimental basin and apparatus. Units are in
millimeters.

Model

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Figure 4 (below)
Current vectors and wave height. Case 6 entrance
is I m wide; Case 8 entrance is 2 m wide.

10, 000

CASE 6

CASES
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-./ I

1)XU il'(WAVE HEIGHT (em)

VELOCITY (em/sec)
3 ---2 -1 -.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Noma: Development of an Artificial Pocket Beach,.DE=:
Entrance

1 m wide

19

2 m

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Figure 5 (left)
Time change of dye concentration.

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Measured exchange rate
at each measuring point.
H o: incident wave height(em); T: wave period (sec).

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20

NOAA Technical Report NMFS 102: Marine Ranching

Flow velocity with the 2-m wide entrance was about
twice as fast as that with a l-m wide opening.
Figure 5 shows the changes in dye concentration. The
concentration decreases gradually at each measuring pointby mixing with noncolored water outside the pocket.
Assuming that perfect mixing occurs inside the pocket, thedye concentration can be estimated by Equation 1:

C = Co e -CIt

(1)

where, c is the dye concentration at time t, Co is the initialconcentration, and a is the coefficient of seawater exchange
rate. Coefficient a is determined by the rate at which dyeconcentration decreases according to the formula:a

The value R t is obtained experimentally as shown in Figure 6. If the retention time of the dye, R t is defined as thetime elapsed until the initial concentration, Co decreases toco/e.

Conclusions
In a pocket beach, waves produce circulation, the intensity of which relates to entrance width, wave height, andwave period. The wider the entrance, the stronger thecirculation.

_

For the retention time ofa unit volume of water, narrowing the entrance improved dispersion control.
Deployment of this method was planned for enhancement of Meretrix lamarkii in Aomori Prefecture but it has
not yet been done owing to problems with the cost/benefit
ratio.

Citations_Akeda, S., and Y. Uekita.
1987. Studies on reduction effect of velocity on the shape and arrangement of artificial reef. Tech. Rep. Nat!. Res. Institute ofFisheries Engineering, Aquaculture and Fishing Port Engineering 7:101-109.
Hagino, S.
1987. Residual effect of floating matter in the artificial pocket beach.
Tech. Rep. Nat!. Res. Institute of Fisheries Engineering, Aquaculture and Fishing Port Engineering 8: 1-11.
Noma, T.
1986. Fundamental study on interfacial wave. Bull. Nat!. Res.
Institute of Fisheries Engineering 7: 1-12.
Takeuchi, T.
1987. On the characteristics of bottom layer flow off Ibaraki Pref.
in Japan. Bull. Nat!. Res. Institute of Fisheries Engineering
8:59-80.
Toda, S.
1983. On the characteristics of water exchange in the wake (II) Non dimensional expression of the coefficient of exchange. Bull.
Nat!. Res. Institute of Fisheries Engineering 4:43-57.
Toda, S., and M. Nakamura.
1981. Experimental study on wave induced circulation related tooffshore structure. Bull. Nat!. Res. Institute of Fisheries
Engineering 2: 1-11.
Uekita, Y., and S. Akeda.
1985. An experimental study on stability of block in surfzone. Tech. Rep. Nat!. Res. Institute of Fisheries Engineering,
Aquaculture and Fishing Port Engineering 6: 141-149.

Temporal and Geographic Variability in Survival of Sea-Ranched
Coho and Chinook Salmon in North America
CHARLES W. HOPLEY Jr.
Washington Department oj Fisheries
115 General Administration Bldg.
Olympia, Washington 98504

ABSTRACT
Public, private, and cooperative ranchers released about 1.9 billion salmonid fingerlings from
North American hatcheries into the eastern Pacific Ocean in 1987. This number has increased
from a level of approximately 700 million since 1982, largely owing to major increases in pink
(Oncorhynchus gorbuscha) and chum (0. keta) production in Alaska. Chinook (0. tshawytscha) andcoho (0. kisutch) salmon continue to represent the majority of production on a weight basis becauseof their relatively large size at release, often exceeding 40 g. Chinook and coho salmon havehistorically been emphasized in public sea ranching because of their importance to North American
recreational and commercial fishermen. As a result, relatively more is known about culture techniques, ocean survival, and the contribution to fisheries of these species. Over 25 million of these
salmon are marked each year before release to increase our knowledge of survival and contribution rates. Results from marking programs have shown that survival rates after release to theocean are highly variable, ranging from near zero to over 30% for coho salmon. Research has
shown that survival and contribution rates vary for a number of reasons including geographic
and temporal influences. Research has also detected significant variability in survival and contribution rates within production from a single hatchery and even within a single production
lot. The paper will describe the variability found in contribution and survival rates of oceanranched chinook and coho salmon. Proposed sources of variability will include geographic andtemporal causes as well as variability resulting from other sources.

Introduction_

Along the Pacific Coast of North America, the use ofhatcheries to produce juvenile salmon that feed and maturein the North Pacific Ocean is a traditional method of
salmon enhancement (Allee 1988). Salmon ranching in the
Pacific Ocean began at the McCloud River Hatchery,
California in 1872 (McNeil 1980). By the late nineteenth
and early twentieth centuries salmon hatcheries wereoperating throughout the eastern Pacific range of salmon.
Early hatcheries focused most often on chinook salmon(Oncorhynchus tshawytscha) , coho salmon (0. kisutch), andsockeye salmon (0. nerka), all of which normally require
extended rearing in fresh water before migrating to sea(McNeil 1980). By 1987, releases of chinook and coho
salmon on the Pacific Coast of North America had reached154.4 million and 373.2 million, respectively (Allee 1988).
Coho and chinook salmon are exploited in the common
property fishery by commercial and recreational fishermen

and are most often taken in high seas and mixed-stock
fisheries remote from their place of origin. Managementof these fisheries is extremely complex. The fisheries must
be regulated to assure adequate spawning escapement andto meet various harvest expectations. A good deal must
be known about the performance of these species after they
are released from the hatchery to migrate to the ocean. The
salmon culturist must also have a means to evaluate various
fish culture techniques and determine their effects on performance once the salmon are released from the hatchery.
An estimate of total survival is a parameter often used
to describe the performance of ocean-ranched chinook andcoho salmon. The estimate is usually stated as the percent
of juveniles released to the ocean that are subsequently
recovered in the fisheries and spawning escapement
combined.
Survival rates are determined from salmon marking programs that have been conducted throughout the historyof ocean ranching. Marks of various types have been
21

22

NOAA Technical Report NMFS 102: Marine Ranching

_

20

c--

18
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c--

16

c--

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r

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n

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f---

12

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20Rouge River
California

E

Columbia River
Oregon Production
Index

I-f---

Quinsam British
Columbia

Rosewall Creek
British Columbia

Release location

Figure 1

Survival of coho released at four locations betweer: 38 0 and 51 0 N latitude. Sources: Pacific Fishery Management
Council 1987 for Rouge River, California, and Columbia River, Oregon Production Index; Bilton et al. 1984
for Quinsam, British Columbia; and Bilton 1980 for Rosewall Creek, British Columbia.

recovered in the coast-wide fisheries and at the hatcheries
as adult salmon return to spawn. Because chinook and coho
salmon have historically been emphasized in ocean ranching, a large amount of survival data has been collected andrelatively more is known about the performance of these
species compared to other ranched salmonids. About 25
million salmon are marked each year. The primary tool
used for marking salmon for evaluation is the implanted
coded-wire tag (Bergman et al. 1968).
Upon examination of survival data, one fact becomes
obvious. There is a wide range of variability in the postrelease survival rates of ocean-ranched chinook and coho
salmon. Survival rates vary with some consistency overgeographic distances. Survival rates also vary temporally
within geographic zones. There is also variability in survival rates within single production units and even withinsingle experimental lots.

Geographic Variability_

The range of chinook and coho salmon in North America
extends from central California in the south to Kotzebue
Sound, Alaska in the north, a distance of well over 3500

km (Wahle and Pearson 1987). Ocean ranching is practiced throughout this range with varying success. Thereis sufficient biological data on chinook and coho salmon
to suggest that average smolt-to-adult survival can vary
widely and in a consistent manner over geographic distances. For example, Bilton (1982) and Bilton, et al. (1984)
report average smolt-to-adult survival rates of 25 % for cohoin the Georgia Strait region of British Columbia, Canada.
Hilton and Jenkenson (1980) reported a survival rate of
47.5% for a group of coho released from Rosewall Creek
Hatchery on Vancouver Island, B.C. Bilton (1980)
reported survival rates for 72 groups of 1975-brood coho
released from Rosewall Creek. The average survival rate
for all groups combined was 19.99% (Fig. 1). In anotherstudy of coho smolts released from Quinsam Hatchery,
B.C. in 1980, the average survival rate for 36 groups was
6.24% (Bilton, et al. 1984) and a maximum survival rateof 11.2 % was predicted under optimum release conditions.
In contrast, survival rates for California and southern
Oregon hatchery coho salmon were estimated over a 17
year period (PFMC 1987). The average rate for the period
was 0.78%, ranging from 0.03% to 1.83% (Fig. 1). The
average survival rate for Columbia River-origin coho
salmon was estimated at 4.07 % for the same period of time.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Hopley: Survival of Sea-Ranched Coho and Chinook Salmon

23

10
9

8

P

e
r

c
e

In
I

?

6

t

s

5

u

r
v

4

i
v

3

a
I

2
1

0

8-10GRMS

5-7GRMS

11-13GRMS

Release size and location

Figure 2

Survival of chinook salmon of three size categories released at 38 0 and 51 0 N latitude. Lighter shading represents
three California hatcheries on the Sacramento River; darker shading represents the Big Qualicum Hatchery, B.C
Data for the 11-13 gram range represent only one point. Sources: Reisenbichler et al. 1982 and Pacific Fishery
Management Council 1987 for California data; Bilton 1984 for Quinsam, B.C. data.

The specific causes for clinal differences in survival rates
an: not clear. One major factor, however, deserves speculation. The British Columbia, Canada hatcheries are locatednear the center of the range for coho salmon at approximately 51 0 N latitude. Coho salmon from California andsouthern Oregon hatcheries are produced near the southern
extreme of the range, at about 38 0 N latitude. Coho salmon
from the Columbia River are between the two at 46° N
latitude. One might speculate that performance and productivity decline as a species nears the limits of its range.
This factor might explain, in part, the progressive increasein survival rates of coho salmon between the southern limit
and center of their range. If in fact there is a geographic
cline affecting survival rates, as the data suggest, the needremains to explain the causitive mechanisms. For example, environmental and climatic factors are often implicatedin the advance or decline of a species' range (Krebs 1972).
Alternatively, the differences in survival rates occurring
over the range of coho salmon might simply be an artifactof poor hatchery practices, improper stock selection, localized climatic events, unique geographical features, or otherdirect causes. Those effects are less persistent than would
be expected in the range-limited theory above.

Although less dramatic, there is evidence that the postrelease survival of chinook salmon varies along a similar
geographic dine as coho salmon (Fig. 2). The data are not
as abundant but results of two studies might serve to suggest this trend.
Reisenbichler et al. (1982) compiled survival data forchinook salmon released from three Sacramento River(California) hatcheries at various sizes over several years.
These data when compared to survival data for chinook
salmon released at equivalent sizes and dates from Big
Qualicum Hatchery (B.C.) (Bilton 1984) indicate a four
to five fold difference in average survival rate. Again,chinook salmon produced from a British Columbia hatchery tended to have higher average survival than chinook
salmon produced nearly 1500 km to the south.
It seems reasonable to speculate that these results are
consistent with a theory of declining performance of a
species near the end of its range. We must also note in thiscase, that the environment that chinook salmon experience
after release from British Columbia hatcheries is relatively
undamaged compared to the Sacramento River system in
California. Hydroelectric projects, irrigation and domestic
diversions, low flows, high temperatures, and toxic residues

24

NOAA Technical Report NMFS 102: Marine Ranching_,-------------------------------------------------,
9

8

P

7

e
r

c

6

e
n
t

5

s
u

4

r
v

i
v

3

a
1 2

1

o
1967

1969

1971

1973

1975

1977

1979

1981

1983

Brood year

Figure :3

Estimated survival rates for public hatchery coho from the Oregon Production Index. Source: Pacific Fishery
Management Council 1987.

all are present to a much greater extent in the Sacramento
system. The Columbia River system is also affected-toa lesser degree than the Sacramento-but to a greater extent than in British Columbia. If there is truth to the
speculation that survival decreases near the extreme of therange, then a low quality in-river environment might
simply worsen an already tenuous existence.

Temporal Variability_

Temporal fluctuations within many animal populations arewell documented phenomena (Krebs 1972) and can bedemonstrated for several populations of chinook and coho
salmon. For example, the Chinook Technical Committt"eof the Pacific Salmon Council recently developed trend information for ten populations of ocean-ranched chinook
salmon from British Columbia, Washington, and Oregon
using a continuous series of coded-wire tag recovery data
(Mike Fraidenburg, Wash. Dep. Fish., Olympia WA,
pers. commun., Sept. 1988; see Appendix Figures). These
trend lines represent the surviving cohort of 2- and 3-yrold chinook salmon for a series of brood years. In general,the highest survival rates for chinook salmon are below the
maximum rates for coho salmon. Even so, the survival rates

within these populations of chinook salmon vary by a factor of eight to ten times over a ten year period, demonstrating that significant temporal variation is a common
trait of salmon populations.
Continuous mark or tag data of this nature have historically been difficult to develop from marking or tagging
studies because, by design, marking studies are often shortterm and discontinuous. However, adequate representation of long-term trends can be developed using historical
records of landings coupled with escapement data, andwhen appropriate, stock composition data. One such dataset (Fig. 3) provides a recent and notorious example oftemporal variability in a coho salmon production unit. The
Oregon Production Index (OPI) is a coho salmon production and harvest area where hatchery coho salmon of
Columbia River origin predominate in the harvest fromMonterey Bay, California to Leadbetter Point, Washington(Gunsolus 1978). A controversy erupted when the 1977
ocean commercial harvest in the OPI fell to the lowest pointin 15 years. Ocean sport harvest dropped to a historicallow. This collapse followed a record high production year
in 1976. The controversy was compounded by the fact that
adult production in the OPI was becoming increasingly
erratic as hatchery production releases increased fromfewer than 1 million coho smolts in 1960 to over 30 million

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Hopley: Survival of Sea-Ranched Coho and Chinook Salmon

by 1970. By 1981, smolt releases totalled 61.9 million. During the period after 1970 the abundance of coho salmon
appeared to fluctuate independently of the number ofsmolts released (Nickelson 1986).
The fisheries that exploit coho salmon in the OPI wereseverely impacted during years oflow abundance, resulting
in a flurry of activity among scientists attempting to explain the wildly fluctuating survival rates. Two primary
hypotheses have been advanced in explanation. Several
researchers, among them McGie (1981) and McCarl andRettig (1983), hypothesized that abundance of coho salmon
in the OPI was density dependent and that marine survival has been reduced by the release of excessive numbersof hatchery smolts. Peterman and Routledge (1983) and
McGie (1984) suggested density dependent relationships
in years of low coastal upwelling. In contrast, Clark and
McCarl (1983) did not find evidence of density dependelKe. Nickelson (1986) concluded that survival in the OPI
was density independent and proposed the second primarytheory; that survival was correlated mainly with thestrength of ocean upwelling in the spring and summer ofsmolt outmigration. He also presented evidence that ocean
temperatures had an effect on survival but only in yearsof high upwelling.

At this time there is no final agreement on what hascaused survival rates for coho salmon to vary so drastically in the OPI. We can be assured that new theories will
be advanced and existing theories will be re-evaluated. It
is probable that the complete explanation is complex andnumerous factors are involved. It is also probable that themost influential factors, such as ocean upwelling, arebeyond our control and any improvements we can makein hatchery practices will do little to dampen the magnitudeof temporal variability over the long term.

Conclusion_

Survival data for Alaskan chinook and coho salmon havenot been included because it is difficult at this time to obtain compiled general survival data. These data, whenavailable, will be important to the interpretation of clinal
effects in geographic variability by addressing the northern
extreme of the range for chinook and coho salmon.
It has proven difficult in general to find and use complete and comparable data for geographic or temporalcomparisons. Marking and tagging projects often addressa unique experimental situation over a short time period.

0.4
mean=0.259

-

0.35
p

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c
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n
t
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8.D.=0.070

0.311111IC.V.=27.02%

0.25

-

0.2

-

-

0.15

-

-

I--

0.1

-

-

+-

-

-

-

-

-

r--

I--

-

-

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-

-

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41

2

25

3

44

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Replicate number

Figure 4
Observed variability in survival rates among replicates of a single experimental treatment group of Washington
coho salmon at the Washougal Hatchery (A. Appleby 1984).

26

NOAA Technical Report NMFS 102: Marine Ranching

The results are not generally applicable on a broad geographic basis and are discontinuous so they do not support long-term temporal analyses. However, the resultsfrom unique short-term experiments do demonstrate thatthe level of variability even within statistical replicates ofa single experimental treatment can be significant (Fig. 4).
If researchers are to achieve better resolution of the extent
and causes of variation in survival of ocean-ranched salmon
a more extensive survival record must be developed. An
effective tagging program would include annual application of tags to ocean-ranched salmon throughout thegeographic range of interest and under similar rearing andrelease conditions. Only when variability in survival isshown to be persistent in magnitude and direction on aclinal basis or consistently related to causitive factors on
a temporal basis and greater than the background variability within a single production group can the speculations
made here be demonstrated in fact.

Citations
Allee, Brian J.
1988. Status of salmonid ocean ranching on the Pacific Coast of
North America. Alaska Dep. Fish Game., P.O. Box 3-2000,
Juneau, Alaska 99802. Unpubl. manuscr., 25 p.
Appleby, A.
1984. Quality improvement studies at Columbia River hatcheries.
Annual Report to the National Marine Fisheries Service (Contract No. 83-ABH-0002), Washington Dep. Fisheries, Salmon
Culture Division, Olympia, WA 98504, 21 p.
Bergman, P.K., K. B. Jefferts, H.F. Fiscus, and R.C. Hager.
1968. A preliminary evaluation of an implanted, coded-wire fish
tag. Wash. Dep. Fish., Fish. Res. Pap. Vol. 3, No.1, p. 63-84.
Bilton, H.T.
1980. Returns of adult coho salmon in relation to mean size andtime at release ofjuveniles to the catch and the escapement. Can.
Tech. Rep. Fish. Aquat. Sci. No. 941, Dep. Fish and Oceans,
Nanaimo, 41 p.
1982. Returns of adult coho salmon from releases of accelerat~dand normally reared juveniles. Can. Tech. Rep. Fish. Aquat.
Sci. No. 1054, Dep. Fish and Oceans, Nanaimo, 22 p.
1984. Returns of chinook salmon in relation to juvenile size-at·
release. Can. Tech. Rep. Fish. Aquat. Sci. No. 1245, Dep. Fish
and Oceans, Nanaimo, 33 p.
Bilton, H.T., and D.W. Jenkenson
1980. Returns to the fishery and escapement of adult coho salmon
from accelerated and normally reared juveniles. Can. Tech. Rep.
Fish. Aquat. Sci. No. 925, Dep. Fish and Oceans, Nanaimo, 11 p.
Bilton, H.T., R.B. Morley, A.S. Coburn, and J. VanTyne.
1984. The influence of time and size at release of juvenile coho_

salmon (Oncorhynchus kisutch) on returns at maturity; results ofreleases from Quinsam River Hatchery, B.C., in 1980. Can.
Tech. Rep. Fish. Aquat. Sci. No. 1306, Dep. Fish and Oceans,
Nanaimo, 98 p.
Clark, J., and B. McCarl.
1983. An investigation of relationship between Oregon coho salmon(Oncorhynchus kisutch) hatchery releases and adult production utilizing law of minimum regression. Can. J. Fish. Aquat. Sci. 40:
516-523.
Gunsolus, R.T.
1978. The status of Oregon coho and recommendations for managing the production, harvest, and escapement of wild and hatcheryreared stocks. Oregon Dep. Fish Wildlife, Metro Center, 2000
S.W. First, Portland, Oregon 97201. Unpubl. manuscr., 59 p.
Krebs, C.].
1972. Ecology: the experimental analysis of distribution and abundance. Harper and Row, New York, NY, 694 p.
McCarl, B.A. and R.B. Rettig.
1983. Influence of hatchery smolt releases on adult salmon production and its variability. Can. J. Fish. Aquat. Sci. 40:1880-1886.
McGie, A.M.
1981. Trends in escapement and production of fall chinook andcoho salmon in Oregon. Oregon Dep. Fish Wildlife, Fish. Div.
Info. Rep. 81-7, Portland, OR, 44 p.
1984. Commentary: evidence for density dependence among coho
salmon stocks in the Oregon Production Index area. In The influence of ocean conditions on the production of salmonids in the
North Pacific: A workshop (W.G. Pearcy, ed.), p. 37-49. Oregon
State U niv. Press, Corvallis.
McNeil, W.J1980. Salmon ranching in Alaska. In Salmon ranching (JThorpe, ed.), p. D-28. Academic Press, London, 441 p.
Nickelson, T.C.
1986. Influences of upwelling, ocean temperature, and smolt abundance on marine survival of coho salmon (Oncorhynchus kisutch) in
the Oregon Production Area. Can. J. Fish. Aquat. Sci. 43:
527-535.
Pacific Fishel"\' Management Council.
1987. Oregon Production Index (OPI) area coho salmon methodology review of data-methods-predictors-processes. The OPI
methodology technical team, Draft Report. Pacific Fisheries
Management Council, Metro Center, 2000 SW First, Portland,
OR 97201.
Peterman, R.M., '!nd R.D. Routledge.
1983. Experimental management of Oregon coho salmon (Oncorhynchus kisutch): designing for yield of information. Can. J. Fish.
Aquat. Sci. 40:1212-1223.
ReisenbicWer, R.R., J.D. McIntyre, and R.]. Hallak.
1982. Relation between size of chinook salmon (Oncorhynchus
tshawytsr.ha) released at three hatcheries and returns to hatcheries
and ocean fisheries. Calif. Fish Game. 68(1):57-59.
waWt:, R.]., and R.E. Pearson.
1987. A listing of Pacific Coast spawning streams and hatcheries
producing chinook and coho salmon. NOAA Tech. Memorandum NMFS F/NWC-122, 109 p.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Hopley: Survival of Sea-Ranched Coho and Chinook Salmon

Appendix Figures_

TOTAL FISHING MORTALITY AND ESCAPEMENTAS A PERCENTAGE OF RELEASEBIG QUALICUM
10.0%.----------------------...,
8.0%
6.0%
4.0%
2.0%

O.O%l-c!-4---l--+--1-+~~ ....~~~~'t__+_J~Rn~~~Mn~~OOffi~~~~ffi

BROOD YEAR-

2 ~ar Old SUrvival-

3 ~ar Old SUrvIval

TOTAL FISHING MORTALITY AND ESCAPEMENTAS A PERCENTAGE OF RELEASE

CAPlLANO
3.5%.-----------------------~

3.0%
2.5%
2.0%

1.5%
1.0%
0.5%
0.0% ~+--+--t-_f____+-+___+__+__+__+~~~~_1_~
70 71 72 73 ~ 76 77 78 79 80 81 82 ~ ~ ~ ffi

BROOD YEAR-'---------

2 ~ar Old SurvIval-

3 ~ar Old SUrVival

I

J

Survival rates for 2- and 3-yrs post-release for ten populations of hatchery salmon. Source:
Exploitation rate analysis, Chinook Technical Committee 1987 annual report to the PacificSalmon Commission, Vancouver, British Columbia, Canada.

27

28

NOAA Technical Report NMFS 102: Marine Ranching_

TOTAL FISHING MORTALITY AND ESCAPEMENT
IS A PERCENTAGE OF RELEASEQUIN~M

3.0%

A

2.5%
2.0%
1.5%
1.0%

/

0.5%

/\
/ \
/\
\ /
\

V

0.0% t-----t--t-----t--t-----t--t-----t--..,t-----t--t-----t--t----f~~~~n ~ ~ 00 ffi ~ ~ ~ ~ ~BFOJD YEAR-

2 'rear Old Survival-

3 'rear Old SUrvival

TOTAL FISHING MORTALITY AND ESCAPEMENT
IS A PERCENTAGE OF RELEASEROBERTSON CREEK
3 . 5 % , . . . . - - - - - - - - >------------...,
3.0%
2.5%
2.0%
1.5%
1.0%

"-..

/

0.5%

0.0% t--+--+---;--t---t--t-+--+--+-t---t-~=----1f_+----4
71

72 73 74 75 76 77 78 79 80

81

82 83 84 85 86

BROOD YEAR-

2 'tear Old Survival-

3 'rear Old Survival

Appendix Figures (continued)

_ _ _ _ _ _ _ _ _ _ _ _ _ Hopley: Survival of Sea-Ranched Coho and Chinook Salmon

TOTAL FISHING MORTALITY AND ESCAPEMENTAS A PEfCENTAGE OF RELEASECOLUMBIA UPRIVER BRIGHT
1.0%.----------------------,
0.8%
0.6%

0.4%

/' "\
0.2%

"-

--

/

\

0.0% r----+-+---i--+--+--t--+--I---+--+---+---i
~

~

~

n

~

~

00

~

W

~

~

ffi

~

BROOD YEAR-

2 ~ar Old SUrvival-

3 )ear Old SUrvival

TOTAL FISHING MORTALITY AND ESCAPEMENTAS A PEFCENTAGE OF RELEASEWILLAMETTE HATCHERY SPRING
2 . 0 % r - - - - - - - - - - - - - - - - - - - -......

1.5%

1.0%

0.5%

0.0% t----f~-+--__+_-t__t-_t_-_t_---=1___lf___+-_f
~

~

~

n

~

~

00

W

~

~

BROOD YEAR-

3 )ear Old Survival-

4 ~ar Old Survival

Appendix Figures (continued)

~

ffi

29

30

NOAA Technical Report NMFS 102: Marine Ranching_

TOTAL FISHING MORTALITY AND ESCAPEMENT/JS A PEPCENTAGE OF RELEASESPRING CREEK TUlE
2.5% . . . - - - - - - - - - - - - - - - - - - - - - - - . ,
2.0%

1.5%
1.0%

0.5%
0.0% t---t--t---t-+---t--t-+---+--+--It---t--t-=:alIIII---t---t

71

72 73 74 75 76

n

78 79 8081

82 83 84 B5 86

BFDOD YEAR-

2 'rear Old Survival-

3 'mar Old SUrvival

TOTAL FISHING MORTALITY AND ESCAPEMENT/JS A PEPCENTAGE OF RELEASE

COI'JLITZ TUlE

0.6%.-----------------------.
0.5%
0.4%
0.3%

0.2%
0.1%

-

0.0% t - - - - I t - - - - t - - ; - - t - - t - - - + - - + - - + - - - t - - - - i
~

n

m

~

00

m

~

~

~

BROOD YEAR-

2 'rear Old Survival-

3 'rear Old SUrvival

Appendix Figures (continued)~ffi

_ _ _ _ _ _ _ _ _ _ _ _ _ Hopley: Survival of Sea-Ranched Coho and Chinook Salmon

TOTAL FISHING MORTALITY AND ESCAPEMENT/IS A PEFCENTAGE OF RELE/ISE

BONNEVillE TUlE
3.0%
2.5%
2.0%
1.5%
1.0%
0.5%
0.0%
75

76

77

78

79

80

81

82

83

84

85

BROOD YEAR-

2 'lear Old Survival-

3 'lear Old Survival

Total Fishing Mortality and Escapement/IS A PERCENTAGE OF RELEASESTAYTON POND TUlE
2.5%r------------------------.
2.0%
1.5%
1.0%
0.5%

--- --

0.0% ~_.L.-_...L__...l..__

75

76

n

78

_ L ___ l . ____I_.__1._-_.::...L_

79

80

81

82

83

BROOD YEAR-

2 ~ar Old SUrvival-

3 ~ar Old Survival

Appendix Figures (continued)__l.._

84

__..J

85

31

Artificial Stock-Size Improvement of the Flounder Paralichthys olivaceus:
Present Status of Technological Achievement

YUICHI KOSHIISHI*
Japan Sea National Fisheries Research InstituteSuido-Cho, Niigata 951, JapanHIDEAKIITANO**
Niigata Prefectural Fisheries Experimental Station
Bandaijima, Niigata 950, Japan

YUICHI HIROTA
Japan Sea National Fisheries Research InstituteSuido-cho, Niigata 951, Japan

ABSTRACTIn Japan, the number of hirame (Paralichthys olivaceus) seed released has increased rapidly inthe last decade. In 1986, about six million hirame seeds were released. The early life historyof hirame and some of the technology for the release of small seeds (30-80 mm in total length)were studied in order to raise stock levels of released hirame. It was assumed that the presenceof mysids as prey in the area of seed release was more critical for the survival of the seeds thanfor the wild hirame of the same size. Therefore, the time and area of release should be determined with reference to the seasonal change of the prey density. Acclimatization of seed to theconditions of the natural environment is one of the most important areas of study as we seek
to raise stock levels of released hirame. The survival rate of reared hirame during the days
immediately following their release was shown to be lower than that of wild hirame of the same
size. The time off the bottom for feeding was demonstrated to be a criterion for acclimatization.
Melanism, which inevitably occurs on the blind side of mass produced seeds, can be profitably
noted to discriminate the released hirame from wild ones. The percentage of the commercial
catch attributable to the released seed was estimated by checking the anomalies in the body colorof landed hirame at the market.

Introduction_

Hirame (Paralichthys olivaceus (Temminck et Schlegel)), a
carnivorous flat fish with a maximum total length of about
one meter, is one of the most important species of theJapanese coastal fishery. Male hirame usually mature in
their third spring, whereas females mature in their fourth• Present address: Seikai National Fisheries Research Institute, Kokubumachi, Nagasaki 850, Japan.
•• Present address: Niigata Prefectural Freshwater Experimental Station,
Ohkawara, Nagaoka 940-11, Japan.

spring. The mature hirame is considered to be situated at
the higher niche among the coastal demersal fishes. The
production of hirame is about 7,000 metric tons a year inJapan. However, indications of overfishing in the hirame
fishery have been revealed in recent years.
Mass production of hirame seeds was accomplished forthe first time in 1965 (Harada et al. 1966). Then, in thelate 1970's, natural spawning from brood stocks reared intanks was achieved, and fertilized eggs of good quality
became available regularly on a large scale (Hiramoto andKobayashi 1979; Ohthuka et al. 1980). Consequently, thenumer of the seeds produced for release increased rapidly,
33

34

NOAA Technical Report NMFS 102: Marine Ranching_

Table 1

Number of seeds released in Japan (thousand seeds). (Fisheries Agency and Japan Sea-Farming Association 1980-1988.
Year

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

Number
297
898
260
2,370
1,156
'------------------------------

2,923

3,278

4,581

4,621

5,860

p:

exceeding twelve million in 1986 (Fisheries Agency andJapan Sea-Farming Association 1988). The number ofseeds released also increased, but this is a phenomenon thathas occurred only in recent years as shown in Table 1.
Studies for artificial stock size improvement ofhirame are
centered on the technology used for the release of the seeds.
We have been carrying out the ecological studies of
a-group (i.e., juveniles less than I-year old) hirame andtheir prey in the Marine Ranching Project since 1982. In
this same project we also have been working to improve
the technology for the release of seeds. It should be notedthat prefectural fish farming centers and fisheries experimental stations supported by the Fisheries Agency havebeen studying technology for the release of seeds since 1980.
This report discusses the early life history of a-grouphirame and some of the technological achievements relating
to the release of seeds.

Early Life History of Hirame

,~

11

'1111

~

,/

'Ilil III
,

/

//
/

_

Hirame is a multiple spawner. The spawning season occurs
when the water temperature rises to about 11 0 C, and it
continues for 2 months (Kobayashi 1974; Odagiri 1985a).
They spawn from January through August along theJapanese archipelago (Minami 1983; Odagiri 1985a).
Hatched larvae live a planktonic life for a month or more
(Minami 1984). In the latter half of this time period they
met'lmorphose and immigrate into the nursery ground, thearea shallower than 10m (Koshiishi et al. 1985) or 20 m
(Kiyono and Hamanaka 1974). a-group hirame immigrate
periodically into the nursery (Imabayashi 1980a; Tanaka1988). After settling on the nursery ground, they live forabout 2 months in their nursery. During their nursery life,
a-group hirame grow from 15 mm to 100-120 mm in total
length. The distribution of O-group hirame, which havegrown to this size, gradually expands offshore (Kato 1985;
Koshiishi et al. 1985). Afterwards, as the seasons change,
they exhibit depth migration. Usually their recruitment
occurs one or two years after hatching.
The food habit of a-group hirame in the nursery is rather
simple. Mysids are very important prey for them, especially in the first half of their nursery life (Imabayashi
1980b; Kato 1985; Koshiishi et al. 1985). The food composition of the O-group hirame caught in the nursery off
Igarashi-Hama (Fig. 1) is shown in Figure 2 (Koshiishi

Shinkawa R.

o

500

1000m

Figure 1

Research area of a nursery of the O-group hirame off IgarashiHama, Niigata, Japan.

1988). Fast growth, linear with respect to the body length,
was observed in this nursery. In 1987, three groups ofO-group hirame that immigrated periodically into thisnursery were recognized by tracing the change in their bodylength (Fig. 3). The growth of the first immigrated group
before the expansion of their distribution was estimatedat 1.64 mm/day (Koshiishi et al. 1988). A tendency forearlier immigrating fish to grow faster was shown. Thistendency was also observed in Yuya Bay (Kojima et al.
1986).
The estimated change in the hirame stock in the coastal
area is shown in Figure 4. The size of hirame just after
the steep decline in the stock number (Fig. 4, wild fish,time 2) may be a theoretical one for release (i.e., minimum
size that can expect a relatively high survival rate after
release). Takahashi (1974) estimated this size as being 50

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Koshiishi et al.: Stock-Size Improvement of Flounder

~

r::l

~

....··
D

My

Pi

Mo

140

•m
Go

mm in total length, taking the changes in body proportion
associated with growth into consideration. Thirty and fifty
millimeters may also be the minimum sizes that correspondto the changes in feeding habit (Koshiishi, unpubl. data),
and the mortality due to predation (Miniami 1986;
Koshiishi 1984), respectively. The survival rate of artificially reared seeds during the early days following theirrelease (Fig. 4, reared fish, time 2 to 3), was shown to belower than that of wild hirame of the same size, even if
their size was larger than 50 mm (Doi 1985). Therefore,raising the survival rate during the acclimatization period
is one of the most important areas for raising stock levelsof released hirame.

Ce

120

E 100
E
.c

80

CJ'

c

Q)

>.
-0

35

60

o

m

Technology for
the Release of Seeds

40

20

Recently, the number of seeds released has markedly increased, reflecting technological improvements for mass
production (Table 1). The size of the seeds can be divided
broadly into two categories, small seeds of about 30 to 80
mm in total length, and large ones which are over 100 mm.
Principally, the latter are produced to bear tags. Here we
discuss the small ones.

a
o

20

Food

40

composition

60

100

80

_

in weight (%)

Figure 2
Food compOSItion of the O-group hirame of each size class(1981-1986, off Igarashi-Hama, Koshiishi 1988). My: Mysidacea;
Pi: Pisces; Ma: Macrura; Ga: Gammaridea; Ce: Cephalopoda.

180

0
0
0
0

150

0

0
0

E
E

~~ to ~

120..c...<::
C)

>""C

c

90

o

60

CO

11 .1' ~030

Figure 3
Change in the body length of the hirame
caught in a nursery off Igarashi-Hama in
1987.

I '8
0

CJ)

•8
160

~
8
0

8

Cb

9

go

0
8>80

180

0

§

0

t
8 f

8
0

0

0
0

0°

0

0

0

00

8

8

0

0

0
0

1

~

0

0

0

200

220

J u I i an

day

24-0

260

36

NOAA Technical Report NMFS 102: Marine Ranchingl/HotCh

I
i

z
c

'

/ Settlement'. .

Recruitment.....................
'.' .'' .... ~.~.-r-:-~"':"'":"":-:-:~~/~.,....,....,~-:'.'
W. . . . . ..
.
.
. . . . . .. . . . ..
.

.......................

_ _.·········~:·.···········.······R

a

12

3

4
Time

Figure 4
Schematic view of the change in hirame stock 0N: Wild hirame;
R: Reared hirame). Time 0 to 1 corresponds to planktonic phase(ca. 1 month). Time 2 to 3 corresponds to the acclimatization
period of released seeds (ca 2-4 weeks in the case of small size
seeds 30-80 mm in total length). The survival rate of released
hirame during this period is lower than that of wild ones. Usually
recruitment (Time 4) occurs 1 to 2 years after hatching when their
total length exceeds 25 cm or more.

_

Release Timing and Release Area
Our studies were carried out in the nursery off IgarashiHama. Basically, we focused on the relationship between
O-group hirame and their prey (mysids) distribution(Yasunaga and Koshiishi 1981).
Regarding mysids, new species are still being discovered
and noted (Murano 1979), while little has been established
about their ecological behavior. To catch the mysids andthe other food organisms, a tow net with a rigid frame anda sledge was designed (Hirota et aL 1986, 1988). From 1984
through 1987, about five hundred tows were carried out
in an area shallower than 10 m. Mysids, the most dominant group caught, separated into twenty-one species with
Acanthomysis robusta Murano the most dominant (Hirota
et al. 1988). Each species was further characterized by theirseasonal and vertical abundance. Although the dominant
species were most abundant at distinct depths, their abundance changed seasonally in a consistent pattern. Consequently, the number of mysids per unit area increased
rapidly in spring followed by a sharp reduction in latesummer (Fig. 5).
five groups of the small size seeds (Table 2) were released from 1984 to 1987 (Koshiishi et al. 1986, 1988).
They were released along a 200 m line at 4 m (1986, 1987)
or 4- and 8-m (1984, 1985) depths. Flag poles with line
and sinker were set up previously at both ends of these lines
as a guide. The seeds were recaptured by a small beam
trawl (functional mouth width: 1.7 m; mesh aperture: 2.1

1984--.-- 1985-...-- 1986

300
N

-0-

E

'2

-0-

1987

Oct

Nov. Dec.

Q)

.0

E
:::J

200

C

a.

0
:::J

,

"0

>
"0

c

...

··
·.
,
,

100

a.._. ___ . _. __.........:

..
.

a
Jon

Feb

MGr.

Apr.

May

Jun,

Jui

Aug.

Sep,

Month

Figure 5
Seasonal change in the abundance rof th", mysids in a nursery of hirame off Igarashi-Hama. Mysids
were caught in a depth of 2 to 10 m. (Hirota et al. 1988.)

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Koshiishi et al.: Stock-Size Improvement of Flounder

Table 2
Date of the release, number, and total length of the seeds
released in the nursery off Igarashi-Hama. (Modified from
Koshiishi et al. 1986, 1988.)
Total length
(mm)
Year
(group)0ate

Number

Mean

SD

1984
1985
1986
1987N
1987M

28 Aug.
30 Jul.
01 Aug.
30 Jun.
03 Aug.

26,40062,10050,800150,000
52,000

57.6
32.5
37.7
27.0
30.5

10.8
6.3

--_._---

3.9
3.1

37

or 3.6 mm), which was towed by a boat at the speed ofabout 0.75 m/sec. Within a month after each release, 6
to 9 days of sampling (4 to 12 hauls/day) were carried out
over an area of 1 km 2, the area shallower than 10m
around the release line. The numbers of the recaptured
seeds of the 1984,1985,1986, 1987N, and 1987M groups
during this period were 30,202,323,347, and 30, respectively. After weighing the whole body and measuring thetotal length and body length, the stomach contents of therecaptured seeds were dissected out and weighed. The
feeding rate of the recaptured seeds on each sampling day
was expressed as LSCW/LBW (sum of stomach contents
weight/sum of body weight, %). The incidence of feeding(i.e., percentage of fish that were found with food in theirstomach) and the feeding rate of the recaptured seeds in1984 and 1985 were lower than those of 1986 and 1987
(Fig. 6). Almost all the organisms ingested by the seeds......

_.... ........".:.:::.-.:.:.:.~::.-..:::...-.:::::.-.;.,.:.

100

A
~

80

,

0>
C

~

60

Q.l
'+-

,

o

~

c

40

Q.l

'0
U
C

~,

,
,
,,,
,,
,,,
,
,,

'+-

20

,

\
,,
,

!

,,
,
,

.-.

,

o

•
I

B
10 [ \

8

\
I

o~

I

\

"

W,' \ ....
I

.

I

..

1985

---.Jl,----

1986

---0-

. i

\.-- /~·-·-.
'~----*--"'-'.1.
~.
I
I~

\

I

.

-0-

_........ - 1987,N

i
"
I.'
"'
\ ! f\i... '.

4

..

\

i
I

6

......- !984

~
i\

,/

1987,M

•

"

2

o
o

10

20
Days after release

J

- - -

I

Figure 6(A) Incidence offeeding (expressed as thepercentage of fish found with food in theirstomach) of seeds recaptured during tne
first month after release otT Igarashi-Hama(Koshiishi 1988, modified); (B) feeding
rate (expressed as the sum of stomach rontents weight/sum ufbody weight, ISCW/
IBW).

38

NOAA Technical Report NMFS 102: Marine Ranching

Table 3
Change in the body length, incidence offeeding (INF), andfeeding rate of recaptured hirame seeds during early days
after release. Five groups of hirame seeds (Table 2) werereleased in the nursery off Igarashi-Hama. (Supplemented
to Koshiishi and Akamine 1987 )

100
0~

E

80

0Cl>
~

c

_

60

c

0

Group

V>

(Days
Body
after
Fish
lengthDate release) no. (mean, mm)

INF'

Feeding
rateb

0

a. 40
E

1984

28 Aug. (0.21)
29 Aug. (1)31 Aug. (3)05 Sep. (8)

19
17
1
2

52.3
47.5
47.2
44.3

5.3
5.9
100.0
50.0

0.01
0.04
0.22
0.22

1985

30 Jul. (0.25)
31 jul. (1 )02 Aug. (3)05 Aug. (6)08 Aug. (9)

40
42
9
12
2

29.6
286
32.6
29.8
33.3

62.5
52.4
55.5
91.7
100.0

1.61
0.83
1.49
2.61
3.04

1986

01 Aug. (0.25)
02 Aug. (1)04 Aug. (3)08 Aug. (7)09 Aug. (8)

31
63
55
18
9

32.1
32.5
33.9
39.5
41.7

100.0
93.7
92.7
100.0
100.0

9.87
4.30
3.74
4.37
1.90

1987N

30 jun. (0.29)
01 jul. (1 )03 jul. (3)06Jul. (6)08 jul. (81

22
25
23
32
23

24.4
22.3
23.5
26.3
30.3

95.5
76.0
100.0
100.0
100.0

4.82
3.76
9.07
3.07
4.53

1987M 03 Aug. (0.25)
04 Aug. (1)06 Aug. (3)11 Aug. (8)

23
20
1
2

25.5
27.4
28.4
36.6

91.3
100.0
100.0
100.0

5.23
4.42
5.71
2.03

0

u
"0
0
0
i..L

20

0
0(6hr)

3

7

14"
Days after release

Figure 7
Food !:ompOSttlOn of the recaptured seeds during the earlydays after the release in 1986 (Koshiishi 1988, modified). My:
Mysidacea; Pi: Pisces.

recaptured during the early days after release ill 1986 ",,'ere
mysids (Fig. 7). This ingestion of mysids occurred during
a period when high prey density existed. The feeding rate
corresponded closely to the abundance of the mysids in thearea where the seeds were released. In 1984, the seeds werereleased on 28 August, when their prey density decreased
to a level near zero (see Fig. 5), thus the feeding rate wasvery low. The prey density after the release in 1985 wasslightly higher but lower than that in 1986 and 1987 (seeTable 2 and Fig. 5). No growth was observed when thefeeding rate of the seeds was much lower than that of wild
hirame of the same size (Table 3 and 4).
The prey densities in the research area were also reflected
III the apparent survival rate during one to two months

I'Percentage of fish that were found with food in their stomach.
b~SCW/~BW(%).

after release (Koshiishii et al. 1986; Koshiishi and Akamine
1987). Real survival rate is difficult to estimate because
dispersion from the research area is immeasurable. However, from information given by fishermen concerning

Table 4
Incidence of feeding (INF) and feeding rate of wild O-group hirame in each size class. O-group hirame were caught from 1981
through 1987 in the shallow area off Igarashi-Hama.
Body length (mm)

10-15

-20

-25

-30

-35

-40

-45

-50

-55

-60

Fish number

40

3b

35

5?

52

61

57

85

63

83

INF'

98

100

100

10(l

98

97

95

92

94

92

Feeding rate b

3.8

5.0

3.8

3.4

2.9

2.4

2.2

4.2

4.6

'Percentage of fish that were found with food in their stomach.
b~SCW/~BW(%).

4.6

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Koshiishi et al.: Stock-Size Improvement of Flounder

the catch of the released hirame, it seems that real survival
rate also corresponds to prey density in the released area
during early days after release.
Mysids were observed by SCUBA divers to be living inschools within a 5 cm layer off the bottom. Considering
the feeding behavior of hirame, the availability of themysids is estimated to be substantially high compared withother prey such as fish and shrimp. It is assumed that thepresence of the mysids is more critical for the survival of
released seeds than for wild hirame. This is because theirability to feed during the early days after release may beinferior to that of wild ones.
The results of the studies carried out in the nursery off
Igarashi-Hama clearly indicate that the presence of a certain level of prey is necessary for good growth and thus
affects the survival of the released seeds. However, the mere
presence of the prey itself may not be adequate because
both biotic and abiotic circumstances in the field where theseeds are released vary significantly with each t:ase. If many
predators are distributed in the release field, the prevention of predation becomes more important.

Measurement of Acclimatization
Usually the intermediate rearing of hirame is carried out
in tanks on land. The rearing of demersal hirame in floating net cages at sea, as with yellowtail (Seriola quinqueradiata)
or red sea bream (Pagrus major), often causes abrasion which
is followed by high mortality. Therefore, rearing for mass
production of seeds has been confined to tanks that areof limited capacity. SCUBA diving observations revealed
that the abilities of the seeds to feed and to escape frompredation were inferior to that of the wild ones (S. Furuta,
Tottori Prefectural Fisheries Experimental Station,
Tomari-mura Ishiwaki, Tohaku-gun, Tottori, pel's.
commun., May 1988). This inferiority may be caused byintensive rearing. Thus, the improvement of intermediate{'earing techniques to acclimatize the seeds to their naturalenvironment is an immediate necessity.
The establishment of a criterion to measure acclimatization is essential for the improvement of rearing methods.
Physiological and biochemical measurements are useful inevaluating the activity of the seeds (Nakano and Shirahata
1988; Maruyama et al. 1986); however, in this case acriterion relating to the ecological behavior of the seeds isnecessary.
Furuta (1988) estimated that the mortality of the seeds
during the early days after release was caused principallyby predation. Predation occurred as the seeds were swimming off the bottom to feed on live mysid. Therefore, hemeasured the time off the bottom of the wild and rearedhirame as they fed, and established this time as a criterion
for acclimatization. Furuta reared the seeds under low density condition (3 ind.lm 2 ) and reported that the effect of
this rearing on the time off the bottom was manifested after

39

a relatively short time period (3 to 7 days). Using a net
enclosure which was set on a beach to prevent the invasion of predators and which covered an area of 28,000 m 2 ,he also reported that rearing in the field under low density
conditions was effective in raising the survival rate after
release (Furuta 1988).
Thus, for acclimatizing seeds to the conditions in thefield, rearing in a net enclosure can be useful and effective. However, maintenance of the net enclosure without
dispersion of the seeds is fairly difficult owing to wave forces
and sand drift. An effective and inexpensive facility forintermediate rearing should be planned in the near future.

Discrimination Between the
Released Hirame and Wild Ones_

To estimate the effect of releasing hirame, the ability todiscriminate between the released and the wild ones isfundamentally important. Marking or tagging the mass
produced small seeds is delicate and laborious work, andmany methods have been used. For example, clipping
various fins and inserting dart tags with an automatic tag
applicator has been used frequently for small and large size
seeds respectively. Both of these methods have shortcomings. If we clip the fin with a part of the trunk, themark can be identified for a long time, although few arerecognized by the public. Dart tags can be easily recognized, but the drop off rate is relatively high and varies
with handling when inserted. Moreover, the fact that therate of recapture was fairly low when the tags were inserted
into seeds smaller than 13 cm in total length implies thatthe tagging is a severe encumbrance (ltano 1985).
A high percentage of anomalies in the body color has
been observed in mass produced hirame seeds. These
anomalies are classified into two groups: partial or fullalbinism on the ocular side and partial or full melanismon the blind side (Nakatani 1984). Though the causesof these anomalies are still obscure (Seikai 1985; Fukusho et al. 1986), the occurrence of the albinism on theocular side has abated in recent years. However, theoccurrence of melanism on the blind side is still high
(100% in some cases). The albinic seeds are not suitable for release owing to a high mortality which seems
to be caused by predation. Higher mortality of the albinic seeds than normal ones can be recognized by the
steep decline in the proportion of albinic seeds recaptured
after release (Fig. 8). No ecological or physiological shortcomings have been reported on melanism on the blind sideyet, and the patterns of the blackish part have not changed
for at least two years (ltano 1987). Melanism on the blindside has been observed among wild hirame, too, but theoccurrence rate is very low, 0 to 1.0 % for O-group hirame(Odagiri 1985b), and the patterns of the blackish part seems
to be different from those of mass produced seeds (Yama-

40

NOAA Technical Report NMFS 102: Marine Ranching

~

'"

"0

_

Before release

40

OJ
OJ

'"

"0

~
::J

30

co
<.>

OJ
~

20

0

(;
I-

........
'"
"0
OJ
OJ

10

'"
<.>
Soda Is.

.!':

.c

<{

0
0

2

4

10

8

6

Days after re lease

Figure 8

Change in the proportion of the albinic seeds recaptured (1985,
offIgarashi-Hama). Albinic seeds: the seeds presented the symptom of albinism on more than 30 % of the area of their ocular side.

Table 5a-group (juvenile)

Date of the release, number, and total length of the seedf:
released into Mano Bay from 1980 through 1984. (Modified from Itano 1988.)
Total length(mm)_-----Year(group)Date

Number"

Mean

SD

1980
1981
1982
1983
1984-

02 Jul.
31 Jul.
16 Jul.
13 Jun.
16 Aug.

35,000
4-7,000
16,50069,00022,20025.0
38.44-0.8
33.1
75.4-

7.
4-9
6.0
12.;

.•.

"Number of the seeds without albinism on the ocular side.

moto 1985). Thus, melanism on the blind side can be
profitably noted in order to discriminate the released
hirame from the wild ones.

Distribution and Impact of Released
Hirame Seeds Around Mano Bay_

In the area around Sado Island, Niigata Prefecture, about
70 metric tons of hirame are landed every year (Itano
1982). These hirame are netted mainly in and around
Mano Bay where the Niigata Prefectural Fish Farming

a-group

0

10

20km

........_ - - ''----'---'-_

1-3-group
Figure 9

Recapture area of the seeds released into Mano Bay from 1980
through 1984. About 190,000 seeds were released from 1980
through 1984.

Center is located. The hirame population distributed
around Sado Island is thought to be isolated from that of
Honshu. About 190,000 seeds without albinism on theocular side were released from 1980 through 1984 (Table5) by the Niigata Prefectural Fish Farming Center (Itano
1988). The occurrence rate of melanism on the blind sideof these seeds was high, from 80 to 100 %. Before release,
we asked all members of the Fisheries Cooperative Association on Sado Island to inform us of the capture of hiramewith melanism on the blind side. The points of recapture
extended across an area of over half way around the island(Fig. 9). More than 90% of these points were located inand around Mano Bay. The hirame with melanism on theblind side were checked out at four markets near the mainfishing ground. Landed hirame were measured for their
total length and their body color checked on the blind sideat the markets before auction. The checkup was carriedout year round, almost every day at the main market, andthus about 20% of the yearly catch was checked. The per-__________________________ Koshiishi et al.: Stock-Size Improvement of Flounder

41

Table 6

Table 7

Percentage of the catch of hirame with anomalies in theirbody color on the blind side. Landed hirame that werecaught by fishermen in and around Mana Bay werechecked for body color at four markets.

Estimated number of O-group hirame 10 the nursenes.
(Supplemented to Koshiishi and Akamine 1987.)

Year

1984

1985

Total catch in weight (kg)20,166

16,428

Total catch in number

42,69039,030Percentage of the fish with anomalies
in their body color"

11.9

11.8

Year

Number/km 2

Taisha Bay

1983

500,000

Off Shichirinaga-Hama

1984
1985

77,5008,750

Off Igarashi-Hama

1984
1985
1986

320,000
320,000
49,000

Nursery'90% + of this figure may be attributable to the released hirame.

Acknowledgments
centages of the catch with anomalies in the body color were~1.9 and 11.8% in 1984 and 1985, respectively (Table 6).
Ninety percent or more of these hirame with anomalies
were estimated to be attributable to the release from their
proportion or pattern of the blackish part on the blind side.
The other hirame, which numbered less than 10 %, developed only slight anomalies (e.g., those with small blackish
part at their caudal fin on the blind side), and thus a discrimination between the released and the wild fish could
not be made. In 1985, the age of the recaptured hirame
ranged from 1 to 4 years, and the 2-year-old group accounted for nearly 70 % of the recapture (Itano 1986). The
large number of seeds released in 1983 (Table 5) may bereflected in the latter age composition.

Beneficial Effectsof Releasing Hirame Seed_

The effect of releasing hirame has been dearly demonstrated in some districts where fishermen have started therelease program by themselves. However, in order to improve the stock size, many problems need to be overcomein the near future. Among these problems the following
ones are fundamentally important.
The abundance of the O-group hirame in nurseries haveJ1uctuated markedly (Koshiishi and Akamine 1987) asshown in Table 7, and the average density has been estimated at about 100,000 ind./km 2 (Takahashi 1974).
Compared with the number of the wild O-group hirame,
the number of released seeds is still too small. Therefore,
the releases must continue on a regular basis in order toimprove the hirame stock size.
The high market price of hirame has caused overfishing in recent years. However, little economic effect can be
expected when the seeds are recaptured before they are
given a chance to grow up. Therefore, management of thehirame fishery will be required in order to improve its
profitability.

_

We would like to thank the fishermen of Igarashi-Hamaand Mano Fisheries Cooperative Association; without theirsupport and cooperation, our research could not have beenaccom plished.

Citations
Doi, S.
1985. Effect of releasing the flounder (Paralichthys olivaceus) seeds.
Comprehensive Report on the Technology for the Release of
Hirame Seeds. Tottori Prefectural Fisheries Experimental Station, Tottori, 55 p. (In Japanese.)
Fisheries Agency and Japan Sea-Farming Association
1980-1988. Materials on production, supply and release of fingerlings for enhancement of fisheries resources injapan. japall SeaFarming Assoc., Tokyo, Yearbook of Data and Statistics. (Injapanese.)
Fukusho, K., T. Yamamoto, and T. Seikai.
1986. Influence of various amount of aeration during larval development of hatchery-reared flouncer Paralich/hys olivaceus :)0 the
appearance of abnormal coloration. Bull. Nat!. Res. lnst. Aquaculture 10:53-56. (In japanese; English summary.)
Furuta, S.
1988. An investigation on the effect of short periGd acclimatization of artificially produced seeds of a flounder Paralich/hys otivaceus. Contributions to the Fisheries Re,earches in the japan Sea
Block 13:61-72. japan Sea Natl. Fish. Res. lnst., Niigata. (Ir.
japanese. )Harada, T., S. Umeda, O. Murata, H. Kumai, and K. Mizuno.
1966. On the growth and rearing methods of the fry of hirame(Paralichthys olivaceus) obtained by artificial fertilization. BulL Fish.
Lab. Kinki Univ. 1:289-303. (In japanese.)
Hiramoto, Y .. and K. Kobayashi.
1979. Studie, on the artificial reproduction of the plaice, ParallChthys olivaceus (Temrmnck et Schlegel) - I. Spawning of the pla:cecultured in an aquarium. The Aquiculture 26:152-158. (Injapanese.)
Hirota, Y., M. Noguchi, and Y. Koshiishi.
1986. Ecologicai studies of food orgaOisms and a competitor (Tar·phops oligo!£pis) for a flounder (Paralichihys olivaceus) in a littoral region
off Niigata, the Sea of japan. Marine Ranching Program Progress Reports on Flounder Production 2:75-85. Sekai Nat!. Fish.
Res. Inst., Nagasaki. (In japanese.)

42

NOAA Technical Report NMFS 102: Marine Ranching

1988. Assessment of carrying capacity of ground fishes based on
the ecology of their food organisms. Marine Ranching Program
Progress Reports on Flounder Production 3:203-215. Seikai Nat!.
Fish. Res. Inst., Nagasaki. (In Japanese.)
Imabayashi, H.
1980a. Settling mechanism oflarvae of bastard halibut, Paral.chthys
olivaceus, in the nursery ground, estimated from the size distribution. Bull. Jpn. Soc. Sci. Fish. 46:419-426. (In Japanese; English
abstr. )1980b. Feeding activities of juvenile and young bastard halibut,
Paralichthys olivaceus, in the biotic community - 1. Intraspecificrelationships in the population. Bull. Jpn. Soc. Sci. Fish.
46:427-435. (In Japanese; English abstr.)!tano, H.
1982. Research on the fisheries of the flounder (Paralichthys olivaceus)
around Sado Island. Annual Report on the Technology for theRelease of Hirame Seeds. Toyama Prefectural Fisheries Experimental Station, Namerikawa, 118 p. (In Japanese.)
1985. On the tagging experiment of the flounder (Paralichthys olivaceus). Comprehensive Report on the Technology for the Releaseof Hirame Seeds. Tottori Prefectural Fisheries Experimental Station, Tottori, 55 p. (In Japanese.)
1986. Release experiment of the flounder (Paralichthys olivaceus) in
Niigata Prefecture. Annual Report on the Technology for theRelease of Hirame Seeds - The Japan Sea Block. Yamagata
Prefectural Fisheries Experimental Station, Tsuruoka, 204 p. (InJapanese.)
1987. Release experiment of the flounder (Paralichthys olwaceus) in
Niigata Prefecture. Annual Report on the Technology for theRelease of Hirame Seeds - The Japan Sea Block. Shimane
Prefectural Fish Farming Center, Oki-gun, 204 p. (In Japanese.)
1988. Release of artificial seedling plaice Paralichthys olivaceus in sandy
beach. Fisheries Engineering 24(2):53-58. (In Japanese.)
Kato, K.
1985. Distribution and food habit of juvenile flounders (Paralichthys olivaceus) in the northern coast of Niigata. Marine Ranching Program Progress Reports on Flounder Production
1:93-105. Seikai Nat!. Fish. Res. Inst., Nagasaki. (In Japanese.)
Kiyono, S., and Y. Hamanaka.
1974. Change in distribution of hirame Paralichthys olivaceus withgrowth. Comprehensive Reports on the Preliminary Survey for
Sea Farming in the Japan Sea. Jpn. Sea Nat!. Fish. Res. Inst.,
Niigata, 108 p. (In Japanese.)
Kobayashi, K.
1974. Spawning season and spawning ground of hirame Paraliththys olivaceus. Comprehensive Reports on the Preliminary Survey
for Sea Farming in the Japan Sea. Jpn. Sea Nat!. Fish. Res. Inst.,
Niigata, 108 p. (In Japanese.)
Kojima, K., T. Domon, Y. Hanabuchi, and T. Kinoshita.
1986. Acclimatization of the released seeds of a flounder (Paralichthys olivaceus) in Yuya Bay. Marine Ranching Program Progress
Reports on Flounder Production 2:47-55. Seikai Nat!. Fish. Res.
Inst., Nagasaki. (In Japanese.)
Koshiishi, Y.
1984. Ecology ofO-group flounder (Paralichthys olivaceus) related to
the release of the seeds. In Present status of seedling production
technique of hirame, Paralichthys olivaceus, in the northern part of
the Japan Sea (Research Group for Seed Production in the Northern Part of the Japan Sea, eds.), p. 97-100. Nihon Suisan Shigen
Hogo Kyokai, Tokyo. (In Japanese.)
1988. Some characteristics on the feeding habit of small size seedsof the flounder Paralichthys olivaceus during early days after release.
Contributions to the Fisheries Researches in the Japan Sea :Block
13:73-77. Jpn. Sea Nat!. Fish. Res. Inst., Niigata. (InJapanese.)_

Koshiishi, Y., and T. Akamine.
1987. Technology for the release and estimation of its effect of aflounder (Paralichthys olivaceus). Proceedings of the annual meeting on aquaculture and propagation of fishery resources. Tohoku
Nat!' Fish. Res. Inst., Shiogama, 74 p. (In Japanese.)
Koshiishi, Y., M. Noguchi, and K. Tanaka.
1985. Distribution and growth of O-group flounder (Paralichthys
olivaceus) in a nursery off Igarashi-Hama, Niigata. Marine Ranching Program Progress Reports on Flounder Production 1: 11-23.
Seikai Nat!. Fish. Res. Inst., Nagasaki. (In Japanese.)
Koshiishi, Y., M. Noguchi, Y. Hirota, and No' Naganuma.
1986. Ecological characteristics of the flounder (Paralichthys olivaceus)
seeds during early days after release and the conditions for the
successful release. Marine Ranching Program Progress Reports
on Flounder Production 2: 11-24. Seikai Nat!' Fish. Res. Inst.,
Nagasaki. (In Japanese.)
Koshiishi. Y., T. Fujii, M. Noguchi, and Y. Hirota.
1988. Estimated amount of feeding by released O-group flounder(Paralichthys olivaceus) and other demersal fishes on mysids in shallow
area off Igarashi-Hama, Niigata. Marine Ranching Program
Progress Reports on Flounder Production 3:263-267. Seikai Nat!.
Fish. Res. Inst., Nagasaki. (In Japanese.
Maruyama, K., S. Tsumura, and T. Morioka.
1986. Experiments on the vigorousness of the seeds of red sea bream- 1. Comparisons between the seeds produced intensively andextensively. Saibai Giken. 15:157-167. (In Japanese.)
Minami, T.
1983. Early life history of flatfishes - II. Spawning season. Aquabiology 5:450-453. (In Japanese; English abstr.)
1984. Early life history of flatfishes - V. Duration of pelagic phase.
Aquabiology 5:450-453. (In Japanese; Eng!. abstr.)
1986. Predations on the young flatfishes in the Japan Sea. Bull.
Jpn. Sea Reg. Fish. Res. Lab. 36:39-47. (In Japanese; English
abstr.)
Murano, M.
1979. A guide to mysidology. Systematics, distribution and ecology.
Aquabiology 1: 2-10. (In Japanese.)
Nakano, H., and S. Shirahata.
1988. An evaluation of the physiological quality of hatchery rearedchum salmon fry Oncorhynchus keta. Nippon Suisan Gakkaishi
54: 1263-1269. (In Japanese; English summary.)
Nakatani, S.
1984. Diseases and anomalies of mass produced flounder (Paralichthys olivaceus). In Present status of seedling production techniquesof hirame, Paralichthys olivaceus, in the northern part of the Japan
Sea (Research Group for Seed Productior. in the Northern Partof the Japan Sea, eds.), p. 84-92. Nihon Suisan Shigen Hogo
Kyokai, Tokyo. (In Japanese.)
Odagiri, J.
1985a. Ecological characteristics of the flounder (Paralichthys olivaceus). Comprehensive Report on the Technology for the Releaseof Hirame Seeds. Tottori Prefectural Fisheries Experimental Station, Tottori, 55 p. (In Japanese.)
1985b. Release experiment of the flounder (Paralichthys olivaceus) in
Aomori Prfecture. Annual Report on the Technology for theRelease of Hirame Seeds. Tottori Prefectural Fisheries Experimental Station, Tottori, 273 p. (In Japanese.)
Ohthuka, 0., K. Maruyama, and M. Hirano.
1980. Studies on the mass production of the flounder (Paralichthys
olivaceus) - 1. Brood stock rearing and natural spawning in a concrete tank of 100 m' capacity. Bull. Niigata Prefectural Sea
Farming Center 3:67-72. (In Japanese.)
Seikai, T.
1985. Influence of feeding periods of Brazilian Artemia during

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Koshiishi et al.: Stock-Size Improvement of Flounderlarval development of hatchery-reared flounder Paraliehthys olivaeeus
on the appearance of albinism. Bull. Jpn. Soc. Sci. Fish. 51:
521-527.
Takahashi, 1.
1974. Technology for the release of hirame Paratiehthys olivaeeus.
Comprehensive Reports on the Preliminary Survey for Sea Farming in the Japan Sea. Jpn. Sea Nat!' Fish. Res. Inst., Niigata,
108 p. (In Japanese.)
Tanaka, M.
1988. Occurrence, recruitment, settlement and mort:llity ofJapanese flounder larvae and juveniles in Shijiki Bay. Fisheries

43

Engineering 24(2):33-43. (In Japanese; English abstr.)
Yamamoto, K.
1985. On the anomalies in the body color of the flounder (Paraliehthvs
olivaeeus). Comprehensive Report on the Technology for theRelease of Hirame Seeds. Tottori Prefectural Fisheries Experimental Station, Tottori, 55 p. (In Japanese.)
Yasunaga, Y., and Y. Koshiishi.
1981. Basic studies of problems on the propagation of plaice,Paralighthys otivaeeus - II. A consideration of relation between
density of juvenile plaice and of mysids. Bull. Jpn. Sea. Reg.
Fish. Res. Lab. 32:9-26. (In Japanese; English summary.)Reproductive Sterility in Triploid Pacific Oysters
STANDISH K. ALLEN Jr. *Center of Marine Biotechnology
Maryland Biotechnology Institute600 E. Lombard Street
Baltimore, Maryland 21202

SANDRA L. DOWNING
School of Fisheries, WH-10
University of Washington
Seattle, Washington 98195

ABSTRACTTriploid Pacific oysters (Crassostrca gigas) were produced as part of a research program at the
University of Washington to alleviate problems of low marketability of oysters in the summer.
The immediate aims of this investigation were to evaluate the feasibility of producing triploidoysters reliably, to determine the extent of sterility, and to scale the procedure up to commercial
levels for use by the industry.
Results of experiments to induce triploidy with cytochalasin B were successful. Gametogenesisin triploids was investigated and triploidy was found to retard gametogenesis in oysters. Gonad
production in triploids was reduced by 50 and 75% in males and females, respectively, as measured
by the proportion of cross-sectional area of the body occupied by gonadal tissue. Histologically,females produced some eggs, but there was a wide variation among individuals in the extent
of egg production. Males underwent spermatogenesis and produced spermatozoa, but this process
was delayed compared with that of diploid controls. Carbohydrate reserves remained high intriploids because of their reduced reproductive effort.
Triploidy improved the marketability of oysters. Consumer taste panels and trial marketingin the Pacific Northwest area have demonstrated that triploids are marketable during the summer when the fecundity of normal diploid oysters makes them unpalatable. In contrast, productquality is maintained in the triploids because the reduced reproductive effort helps retain theirsolid meat texture and the higher carbohydrate levels retain their sweet taste.
Triploids have been embraced by the industry. Commercial hatcheries in the Pacific Northwest
are currently producing them for both the half-shell and shucked meat trade. Triploid oysters
represent about 10% of the production for two major companies in Washington. Production at
one company supplied approximately 80,000 gallons of shucked triploid oysters in 1988 and,at the other, approximately 10,000 dozen were produced for the half-shell trade. Both hatcheries
project that a greater proportion of their production will be triploids in the future.
Two outstanding and unexpected features of gametogenesis in triploids are described below,
but future investigations will need to be done to determine the "whys." First, there are a highproportion of hermaphrodites among triploids. Analysis of gametogenesis was performed on three
populations. One population of triploids was produced by mass spawning and, after setting, weregrown out in Humboldt Bay, California. Two other populations of triploids were produced as
half-sib families (one male fertilized the eggs from two female~ to produce families 306 and 251)
Both of these families vvere planted in Mud, Oakland, and Rocky Bays, all located in southern
Puget Sound .

• Present location: Rutgers Shellfish Research Laboratory, P.O. Box 687, Port Norris, NJ 08349.
45

46

NOAA Technical Report NMFS 102: Marine Ranching
In the diploid control oysters from Humboldt Bay, I of 78 was hermaphroditic, while among
the triploids (siblings of the diploids), 29 of 101 were hermaphroditic. Similarly, summing over
all three bays in Puget Sound, families 306 and 251 had no hermaphrodites among the diploid
controls sampled (sample size: 15 and 36, respectively) and among the triploids, families 306
and 251 had 24 hermaphrodites of 49 sampled and 12 hermaphrodites of 27 sampled, respectively. In Mud, Oakland, and Rocky Hays the respective incidence of hermaphrodites wasa) 44, 35, and 69% for Family 306 and b) 27, 50, and 50% for Family 251. The incidence ofhermaphrodites in triploids may have a genetic basis.
The second unexpected feature was the production of haploid sperm by triploid male Pacificoysters. Most of the spermatozoa that are produced by triploids are 1.5N or aneuploid as judged
by flow cytometric analysis of gametes. However, many males also produce IN or true haploid
gametes in higher proportions than would be expected from a binomial distribution based on
random segregation of the third chromosome set. Production of haploid sperm within an individual
was not uniform throughout the gonad: different regions of the gonad of one individual produced IN or 1.5N sperm or both. Families were produced from backcrossing five triploid males
to diploid females and resulted in metamorphosis and setting in four of the five families. All of
the surviving offspring were diploid. The cytogenetic mechanism for the production of In sperm
in triploid males is unknown.

_

Marine Afforestation of Eisenia bicyclis(Laminariaceae; Phaeophyta)

KAZUYA TANIGUCHI
Tohoku National Fisheries Research Institute27-5 Shinhama-cho 3 chome, Shiogama-shi
Miyagi 985, Japan

ABSTRACTThe structural variations within communities of sublittoral marine algae were investigated in
the Pacific coast of northeastern Honshu, Japan. Fundamental data were obtained to support
the creation of a marine afforestation of Eisenia bicyclis in an area presently covered by crustosecoralline red algae considered a "sea desert." The algal community was usually segregated bydepth into three zones populated predominantly by either E. bicyclis (0-7 m), Dilophus okamurai(7-8 m), or crustose corallines (8-9 m). Variation in seawater temperature in the months fromJanuary to July affected the population dynamics of these and other species in waters 2-7 m indepth. When the average water temperature was low, the zones occupied by both E. bicyclis andD. okamurai changed as increased numbers of juvenile E. bicyclis appeared. Similarly, the quick
growing Undaria pinnatifida became established in the zone predominanted by D. okamurai. The
following year, a dominant population of E. bicyclis res,ulted as the previous year's juveniles
developed. When the average water temperature was high, densities of the large brown algaeof both E. bicyclis and U. pinnatifida decreased, and a population of D. okamurai became dominant. Feeding by herbivorous predators were abundant in the crustose corallines and E. bicyclis
subzones, but few in the D. okamurai subzone. The thallus of D. okamurai was found to have spatanetype diterpenes which may have deterred predation by herbivorous animals. Afforestations ofseveral algae were established in a sea desert area for two years in order to create an environment
suitable for culture of the abalone Haliotis discus hannai. Concrete blocks fitted with three kindsof seeded string having approximately O.l-mm-long young sporophytes of either E. bicyclis, U. pinnatifida, or Laminaria japonica were placed in 3- to 7om-deep water over a 1,000 m 2 wide area,
to form a forest dominated by E. bicyclis. The following year, 8,000 juvenile abalone, approximately 5.3 em in shell length, were released into the artificially created forest. Two years later,
up to 62.4% of the abalone were recaptured and well grown (approx. 9.1-cm shell length).

Introduction.......

_

Communities dominated by the large perennial brown
alga, Eisenia bicyclis, with stipe as long as 1 m or more, arethe most typical marine forests along the Pacific coast of
Honshu, Japan. Annual net production of the E. bicyclis
population was estimated to be 20 kg wet weight/m 2/year(Yoshida 1970), equivalent to the highest level of annual
net production of the terrestrial forests in the temperatezone (Yokohama et al. 1987). In some areas off the Pacificcoast of northeastern Honshu, E. bicyclis populations often
disappear, and dense growth of crustose coralline red algae
becomes established covering all rock surfaces. Such a phenomenon, called "Isoyake" in Japanese or "sea desert"
in English, are supposed to occur because of the following

factors: 1) competltlOn for substratum with other algae(Iwahashi et al. 1979); 2) overgrazing by herbivorous
animals (Nakahisa 1980); 3) hydrographic changes (Kawajiri et al. 1981); 4) decline of transparency and increase
in sediments by polluted sea water (Yokohama 1982).
However, it can be said that the conclusive factor responsible for the formation of the sea desert has yet to be clearly
established.
The need to develop the technology to create artificial
marine forests of E. bicyclis has become pressing becauseof its use as a feed for commercially valuable abalones andsea urchins.
In this study the structural variations in the algal communities inhabited by E. bicyclis were observed along the
Pacific coast of northeastern Honshu. After collecting
47

48

NOAA Technical Report NMFS 102: Marine Ranching_r-----------------.-.--.--------------------------,_Sargasswn yezoense

fig .

:'

---------------] 87.5%
Pterocladia capiilacea
Ge/idium amansii~:mA¥mfE'»i!i!@il\···,lilli%m%t§.··i§1i.;[tlHr:-------------;:==

Chondrus oceilatus
!....

.

'-$ ..

Ge/idium vagum~----------

Gigartina intermedialiW"ik"f1.c ...

Colpomenia sinuosa<· .. A9g··---E---@iiii%£,.

Bossiera cretacea
Pachymeni opsi s ell i pt i ca .
Aii!k¥th##¥#iM¥t4MW'&4%¥£!4W_J~Caltiarthron yessoense
Acrosorium POlyneU~

w

I-

e·'

2

a:::
0«
3;

k·h+&§

4

LL

a

::r:

I0.
W

D;/,phu,6______________

a

.$

13

..,

!

'kamu,~­~r~s.!.o~e_ c~r~1I0e.: __~

8

20

40

100

80

60

120

140

180

DISTANCE (m)Figure 1
Distributional pattern of major benthi,: algae coverage with the bottom topography of the coast of Oshika Peninsula, June 1987.

fundamental data on this area of the sublittoral zone,
marine afforestation of E. bicyclis began on a sea desert area
at Matsushima Bay, Miyagi Prefecture. In this experimental area, many juvenile abalone, some tagged, were released and their growth observed after two years.

Structural Variation in
the Eisenia bicyclis Population_

Off the coast of the Oshika Peninsula, in Miyagi Prefecture, algal communities on the sublittoral rock slope canusually be classifed into three groups according to the domi-

nanl species (Fig. 1). The large perennial brown alga,
E. bicyclis, is predominantly located in the shallow subzone
between 0 and 7 m in depth, along with small perennial
red algae, such as Pterocladia capillacea, Gelidium amansii, G.
vagum, and Pachymeniopsis elliptica. The small annual brown
alga, Dilophus okamurai, occurs in the middle subzone between 7 and 8 m and crostose coralline red algae in thearea below 8 m. This structure of algal communities is very
common along the Pacific coast of northeastern Honshu.
Figure 2 shows the proportions of herbivorous animals
in the three algal communities. In the E. bicyclis community, several species of herbivorous predators were found.
The sea urchin, Strongylocentrotus nudus, occupies 84.4% of

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Taniguchi: Marine Afforestation

49

OH

600

H

Activecompound

1

400

~
.....

OH

C)

lI
C)

w
~

....
....
....
....
. ...

I-

w
~
....,
CJ'J
CJ'J

<:

200

~

....

0

CXl

....

o

:jfj~ ~:...
...
.......
...
... .

E

D

....
...
... ..

....

cFigure 2
Mean standing crop (g/m2 ) of herbivorous animal communities
dominated by Eisenia bicyclis (E), Dilophus okamurai (D), andcrustose coralline red algae (C) off the coast of Oshika Peninsula,
sampled June 1987. Values were obatined by six quadrats (2 x 2m) settled in each community. Tp = Tegula pfeiiferi; Hd = Haliotis
discus hannai; Sn = Strongylocentrotus nudus; blank = others.

the D. okamurai zone and 97.1 % of the crustose coralline
community.
During the present survey, we found that the D. okamurai
community contained few predators. This suggested thatperhaps the thallus of D. okamurai contains toxins which
deter predation. A bioassay of the neutral fraction of amethanol extract from the thallus induced abnormal behavior, mutation, and death of the veliger of the abalone,
Haliotis discus hannai (Taniguchi et al. 1989), as well as anti-

H
H

ActiveH_/)-compound2

Figure .'3
Structures of two active spatane-type diterpene alcohols isolated
from the thallus of Dilophus okamurai.

feeding activities for juvenile H. discus hannai and S. nudus .
Two active spatane-type diterpene alcohols (Fig. 3) wereisolated with repeated bioassays and purifications of theneutral fraction (Kurata et al. 1988).
Observations on the structural variations of the algal
communities were first made off the Joban coast, in Fukushima Prefecture from 1980 through 1982 (Fig. 4, Taniguchi et al. 1986). During these three years, E. bicyclis
remained dominant and stable in the area less than 2 m
in depth. In the deeper area of2-6 m, the dominant species
varied by year (i.e., the donimant species was D. okamurai
in 1980, Undan'a pinnatijida in 1981, and E. bicyclis in 1982).
The E. bicyclis population included plants of various ages
(Fig. 5). High recruitment of E. bicyclis in 1981 and adominant population of one-year-old plants in 1982 wasobserved. In 1981, seawater temperatures during thegermination period of E. bicyclis from January to July,which were caused by the First Oyashio Branch, were conspicuously low (Fig. 6).
The close relationship between seawater temperatureand the occurrence of the various algal species was also
observed off the coast of Oshika Peninsula (Fig. 7, Taniguchi et al. 1987). In 1983, E. bicyclis showed low recruit-

50

NOAA Technical Report NMFS 102: Marine Ranching

SPECIES NAME

DEPTH OF WATER
0.1- 2.0m

ABOVE O.Om

Eisenia_

2.1-4.0m

bicyclis

S argassum yamadae

Phyllospadix iwatensis

Untlaria

pinnatifida

Pachymeni ops i sCalliarthron

elliPti~yessoensei

Gelidium amansii~

AcrosQlium spp.

i

Dilophus~

okamurai8~

pi ocam ium telfairiae

1980
1981
1982

'1

Colpomenia

sinuosaI
LI....L.......L.......L....L1.....J..1-...L.1-'--'-....L1-,I

Ll....!-'-J...-...L.'....L1--,-I....L-'-....J1L...,J1

50

50

o

1000

RELATIVE BIOMASS

IL....L.....l--'-....L...L1.....J..I-'--'-.......
1 .....1

1000

50

100

(%)

Figure 4
Yearly changes of major benthic algae biomass (%) in the three depth ranges in Joban coast, from 1981 through 1982.

ment and the population decreased. In this year, large
annual brown algae, such as U. pinnatifida, Lamir<aria
Japonica, and Costaria costata, decreased and D. okamurai increased, conspicuously.
Thus far the results suggested that E. hi~yclis remains
dominant in shallower areas, stabilized by varously agedplants and by its high density. However, the populationin the lower limit area of 6-8 m is unstable and sensitive
to high temperatures experienced during the germination
period.
It is suggested that the phenomenon known as sea desert,
may be a result of the crustose coralline community be-

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Taniguchi: Marine Afforestation

Age Composition of
Eisenia bicyclis Population

-

,..-

51

_

1 980
200 f-

N = 750

Eisenia bicyclis populations are composed of 0- to 6-yearold plants (Taniguchi and Kato 1984). The composition
was examined in the populations located within two permanent quadrats off the coast of Oshika Peninsula, from
August 1983 through December 1986 (Fig. 8, Taniguchi
and Kito 1988). Variations in the relationship between
recruitment and extinction by grazing, withering, or detachment were examined. The population density of newly
germinated plants was largely governed by seawater temperature from January toJuly; the rate ofrecruitmem wasconspicuously high during periods of low seawater temperature but low at high temperatures. In general, theplants which germinated at low water temperatures maintained the dominant population. The annual rate of mortality for existing plants was estimated to be 70 % in thefirst year, 60 % in the second year, 40 to 50 % for plants
2-4 year old, and 80% for the 5-6 year old population.
The newly germinated plants decrease rapidly in areas
with a higher density of adult plants probably on accountof low light intensities caused by the canopy of the adultplants. If the older adult plants in the population are low
in density, the young plants survive well. The E. bicyclis
community includes individuals from each age group thatserve to adequately maintain the populations over time.

f-

0
6PO

r

,.--

'--

400

1 981
N = 999f-

200 I-(J)-.....J

«
:::>

n

0

>
0

z

0
1,000

u.

..-

0

0::

UJ
CO
~

800 I--

:::>

z

f-

Establishment of Artificial Reefs
600 I--1 982
N = 1,599

400

..-

200

-

-

-

o

o

I

n
AGE

III

nn
IV

v

IN YEAR

Figure 5
Age distribu tion of EisliTlia bicyclis population along the J ohan coast,from 1980 through 1982.

coming dominant during changes in the algal communities'
structure and maintained by the high grazing pressure of
herbivorous animals.

_

The experimental establishment of artificial reefs was
carried out for five years in a sea desert area between 1
and 8 m in depth off Funairi-jima Island at the mouth of
Matsuchima Bay (Fig. 9). The area is rocky, composedof boulders and cobblestones. Seawater temperatures
ranged from 23.3°C in August to 5.0°C in February
during the years from 1984 to 1988.
During preliminary investigations in July 1983, 35
species of algae were recorded. At a depth more than 1 m,large algae had low standing crops below 100 g/m 2 .
The sea urchin S. nudus was the most dominant herbivorous
animal, with an average standing crop of 144 g/m 2 . In
August 1982, 10 reefs were artificially constructed for themarine afforestation of E. bicyclis at a depth of 3 m at an
inlet to Funairi-jima Island. Seeded strings with approximately O.l-mm-Iong young sporophytes of this alga weretransplanted to the reef in December 1982. However, thejuveniles of this alga disappeared completely in September
1983, because they were devoured by herbivourous
animals.
Seventy-three more artificial reefs, fastened by ropes toeach other were set at 3-7 m in depth in an approximately 1,000-m 2-wide area in August 1983. The threekinds of seeded string of either E. bicyclis, U. pinnatijida,

52

NOAA Technical Report NMFS 102: Marine Ranching

_

25

2
w
0::
:J
t-

20

~

0::

W
0..

~

w 15
t-

o::

W
t~

3

w

<.'J
~

0::

W

>

~

5

ot!
4

2

2

0

w -2

<.'J
~

1981

0::

w 2

>
~
~

0

0::

I.J...

0

-2

z -4
o

i=

2

:>

-:t

~

w
o

f~.c:J

1982
C"J

/\

.

M

A

.~

F

M

A

s

~

,

o

N

A

D
MONTH

Figure 6
Seasonal variation of the sea surface temperature along the Joban coast, obtained from ten-day mean values
during the period from 1941 through 1970 (upper panel), and ten-day mean surface temperatures (deviations from the value in the upper p:mel) for 1980 through 1982 (lower panels).

or L. japonica were attached to the artificial reffs in December 1983. The seeded string of L. japonica was transplanted to the ropes.
Undaria pinnatifida grew rapidly and occupied the surface of the artificial reefs three months after seeded stringtransplantation. Laminaria japonica occupied the surface

after six months. From December 1983 to September 1984
the total production of U. pinnatifida and L. japonica wasestimated at approximately 6.7 tons from each 438 m ofseeded string on the artificial reefs. The L. japonica biomass was approximately 2 tons from 60 m of cultureline.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Taniguchi: Marine Afforestation

SPECIES NAME
Juvenile ofEisenia bicyclis
Adult ofE,
bicyclish••••••••••••••r

Laminaria japonicoh

Costaria costota-,.....---~

Undaria pinnatifida

1-----'Sargassum yezoensebIm1WIlRi!ll!l!llllllIlllll"ilIIIIIIIII1~

S.

confusum,lS.

horneri

LIl_.mi.h_mler------I

Codium hubbsii
Gelidium amansii

G.

vagum

53

I

1982
1983

6;-,--~

IIi

1\• • • •Bossiera cretacea
Calpopeltis fIIaberatuml• •iIlimlt• • • •r . . .

••••••I-I

Pachymeniopsis elliptica /.~g
Chondrus ocel/atus
Cladophorc sakaiik="""'"'------'

Dilophus okamurai~• • • . •
I',

o

20

40

60

80

100

FREQUENCY (%)
Figure 7
Number of quadrats (%) in which major benthic algae appeared in the survey area off the coast of the
Oshika Peninsula in July 1982 and August 19!B.

Eleven months later, from December 1983, E. bicyclis
occupied the surface of the artificial reefs. By that time U.
pinnatifida and L. japonica had decreased. The population
densities of the transplanted E. bicyclis and the newly
regenerated populations after 1986 are shown in Figure 10.
The newly regenerated populations were also observed on
the sea bottom. The combined E. bicyclis biomass fromplants on the artificial reef and the sea bottom for the years
1984 through 1987 were 1-9, 1.1, 3.0, and 2.3 tons, respectively. However, the population densities were low compared with average density of 10-20 plants/m 2 in natural
populations (Taniguchi et al. 1987). This may be due tothe fact that 1) seawater temperatures were high during

the years from 1986 to 1988; 2) the biomass of herbivorous
animals gradually increased reaching high levels before
transplantation of seaweeds; and 3) approximately 8,000
abalone were released in July 1986, further increasing theeffects of predation (discussed below).

Production of
Abalone in the Artificial Reefs_

In order to assess the productivity of abalone in an afforestation area, juvenile abalone, H. discus hannai, measuring
53.5 ± 4.8 mm in shelllellgth and 24.4 ± 2.2 g in body

54

NOAA Technical Report NMFS 102: Marine Ranching

_

10
5

N

E 30

1984

"-en
~

Z

25
«
--J
0U.

0

20

a::
w

CO

~

15

::)

Z

10
>~
en
Z
w
0

5
0

II

]

II

I

I

~

......

I

•

I

I

I

I

I

I

I

I

I

I

I

I

I

I

I

!

It!

I

!

I

I

I I

I

o

5~

1986
/

/~'0-0

o ._.

~./

l-

ot

I

It

I

i

I

I

i

!

..-----·if
I

•

I

!

!

I

!

I

"-.-.-.-.
!

!

,

I

'0

I I

»
o~ ASONDJFMAMJJASONDJFMAMJJASONDJFMAMJJASOND
1987

II

I

I

r- 1983

I

I

1984

I

I

1985

I

I

I

I

I

I

/0-0

I

I

I

1986

I

I

I

'1

I

Figure 8
Seasonal variation of density (number of plants/m 2 ) of various year classes of Eisenia bicyr.lis at station 1 (open circles)
and station 2 (solid circles) along the coast of Oshika Peninsula from Augus[ 1983 through December 1986.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Taniguchi: Marine Afforestation

55

Figure 9
Artificial reefs
that were fastened
to each other byropes, designed formarine afforestation of Eisenia
bicyclis.

Figure 10(below)
Seasonal variationof Eisenia bicyclis
density (numberof plants/m 2 ) at
the experimental
marine afforestation station in
Matsushima Bay
from July 1984
through July 1988.

40

•

-.-

1984 YEAR CLASS

-0-

1986

"'E

.-.- .-._-

1987

"

----0----

1988

30

U)

IZ

<{

..J

c..

u..
0
CC
W

co
::2

20

•

\
\

\

:;)

z

i 1O~ \\\~.,.,.
~>-"oI I I

i

I

I

I

I

!

I:

r\

I
.-.
'\
•,
I!

t

°'0\
'-."
0-0',
\
~,
0-0_
'.
0-0-0-0- 0 " 0-0

0
.-.
I

!

!

1

!

i

'

I

I

I

I

I

I

j

I

I

I

.-.-.-e-.-

r'\

.•

·0

'1---.'1::1::o-o~ - ,. -i
. - -

~~'
'-(
O
.' .

- . - - -•.•-.-.-.-•..•-•.•-

I

I

j

I

I

I

I

•

_•• ~hJASONDJ FMAMJJASONDJFMAMJJASONDJFMAMJJASONDJFMAMJJ

f-- 1984 - t - - - - 1985

I

1986

I . - - 1987

I

1988 ----j

56

NOAA Technical Report NMFS 102: Marine Ranching_

Table 1
Recapture record of reared abalone two years after release and estimation of the standing stock (Taniguchi
and Yamada 1987).
Afforested area

Natural field-I

Natural field-II

Square of cultured field (ha)Number of released abalone
Total number of abalone caught (T)Shell length (mm)'Body weight (g)'

ca. I
8000
2579
93.3 ± 9.7
111.9±39.0

ca. 1
8000
3879
100.6 ± 8.9
152.7 ± 43.6

ca. 0.4
3000
1841
74.7 ± 10.2
67.9 ± 31.7

Recapture number of released abalone (I:'
Shell length (cm)'Body weight (g)'r/T (%)

2379
91.6 ± 9.3
11.9 ± 33.7
94.3

2334
97.3±79134.8 ± 31.8
83.0

916
67.3 ± 7.9
48.2 ± 17.9
55.2

Estimation of standing stock size
Number of tagged abalone
Recapture rate of tagged abalone (%)
Standing stock size estimated

100
45.0
5344-

100
55.0
5713

117
62.4
2863

Survival rate of released abalone (%)

82.0

76.1

72.8

'The values were obtained from a 10% sampler.

weight were transplanted into three experimental areas: 1)
an afforestation area; 2) a high primary production areawith E. bicyclis and Sargassum horneri (natural field I), and
3) 3000 into a sea desert area (natural field II) in Matsushima Bay (Taniguchi and Yamada 1988). Recapture data
after two years is shown in Table 1. In an afforestationarea, 2579 abalone totalling 357 kg in weight were caught
by fishing. The standing stock size at the start of the fishing was estimated at 5344 individuals totally 771 kg in
weight by Petersen's method. Released abalone accounted
for 94.3 % of the catch, measuring 91. 6 ± 9.3 mm in shelllength and 111.9 ± 33.7 g in body weight. The rates ofgrowth in the released abalone were approximately 19.9
± 7.1 mm/year and 43.8 ± 17.8 g/year with 82.0% survival in an afforestation area, 23.5 ± 6.3 mm/year and55.2 ± 22.5 g/year with 76.1 % survival in Natural fieldI, and 6.8 ± 1.1 mm/year and 12.9 ± 12.8 g/year with
72.8% survival in Natural field II. The growth rate compares favorably with the values obtained under excellent
natural field conditions, and the survival rate was muchhigher than that in most natural fields.
As ofJuly 1988, only three adult plants/m 2 of E. bicyclis
were found. It is believed that these plants survived because U. pinnatifida or L. japonica were grazed by predators
instead of E. bicyclis.
The results of this marine afforestation experiment suggest that change from a crustose coralline community toan E. bicyclis community can be achieved artificially under
the proper environmental conditions. Predation and seawater temperatures during the E. bicyclis germination
period are major biological factors influencing the successof such a venture. It was further verified that this manmade control over the sea desert environment is an effective technology for the practical management of abalone
and sea urchin production.

Citations_

Iwahashi, Y., s. Inaba, H. Fushimi, T. Sasaki, and H. Osuga.
1979. Ecological studies on Eisenia and Ecklonia in the coast of Izu
Peninsula - IV. The distribution and characteristics of kelp stand.
Bull. Shizuoka Pre£. Fish. Exp. Stn. 13:75-82. (In Japanese.:'
Kawajiri, M., T. Sasaki, and Y. Kageyama.
1981. Extensive deterioration of the Ecklonia kelp stands and deathof the plants, and fluctuations in abundance of the abalone offToji,
southern Izu Peninsula. Bull. Shizuoka Pre£. Fish. Stn. Stn.
15: 19-30. (In Japanese.)
Kurata, K., M. Suzuki, K. Shiraishi, and K. Taniguchi.
1988. Spatane-type diterpenes with biological activity from thebrown alga Dilophus okamurai. Phytochemistry 27(5): 1321-1324.
Nakahisa, Y.
1980. Marine afforestation experiment in the sea desert area.
Saibai-Gi-Ken. (Magazine on Technical Development for Artificial Enhancement of Fisheries Resources) 9(1):25-30. tIn
Japanese.)
Taniguchi, K., and F. Kato.
1984. On age and growth of EiJenia bic,J'clis (Kjellman) Setchell(Phaeophyceae, Laminarialesj. Bull. Tohoku Reg. Fish. Re•.
Lab. 46:15-19. (In Japanese; English abstr.)
Taniguchi, K., and H. Kito.
1988. Age composition in the population of Eisenia bicyclis (Lam;·nariaceae; Phaeophyta). Bull. Jpn. Soc. Sci. Fish. 54(9):1583-1588. (In Japanese; English abstr.)
Taniguchi, K., and Y. Yamada.
1988. Annual variation and productivity of the Sargassum horneri
population in the Matsushima Bay on the Pacific coast of Japan.

____________________________________ Taniguchi: Marine Afforestation
Bull. Tohoku Reg. Fish. Res. Lab. 50:59-65. (In Japanese; English
abstr. )Taniguchi, K., M. Sato, and K. Owada.
1986. On the characteristics of the survival variation in the Eisenia
bicyclis population on the Joban coast, Japan. Bull. Tohoku Reg.
Fish. Res. Lab. 48:49-57. (In Japanese; English abstr.)
Taniguchi, K., Y. Sato, Y. Osada, and H. Suenaga.
j 987.
On the structure of the Eisenia bicyclis population on the coastof Oshika Peninsula in northeastern Honsyu, Japan. Bull.
Tohoku Reg. Fish. Res. Lab. 49:103-109. (In Japanese; English
abstr.)
Taniguchi, K., K. Shiraishi, K. Kurata, and M. Suzuki.
1989. Inhibitory effects of the settlement and the metamorphosis of the abalone Ralio/is discus hannai veligers by the57

methanol extracts from the brown alga Dilophus okamurai.
Bull. Jpn. Soc. Sci. Fish. 55(7):1133-1137. (in Japanese; English
abstr. )Yokohama, Y.
1982. The riddle of the seaweed. Sanseido Co., Tokyo. (InJapanese.)
Yokohama, Y., J. Tanaka, and M. Chihara.
1987. Productivity of the Eck/onia caoa community in a bay of Izu
Peninsula on the Pacific coast of Japan. Bot. Mag. Tokyo
100(1058): 129-141.
Yoshida, T.
1970. On the productivity of the Eisenia bicyclis community. Bull.
Tohoku Reg. Fish. Res. Lab. 30: 107-112. (In Japanese; English
abstr.)

Salmonid Carrying Capacity: Estimates andExperiences in the Great Lakes of North America

JAMES F. KITCHELL
Center Jor Limnology
University oj Wisconsin
Madison, Wisconsin 53706

ABSTRACTDuring the first half of this century, a long and complicated history of overexploitation of fisheries
and invasion by exotic species left the Laurentian Great Lakes with depauperate and low-value
fish communities. Beginning in the 1960's, introduction of hatchery-reared exotic salmonids createda recreational fishery estimated to have an economic return of $3-4 billion per year. Ten years
ago we used energetics models and expected stocking rates to estimate the total predatory demand. We forecast a predator-induced decline in the dominant forage species. More recently,
primary prey species have declined in Lakes Michigan, Huron, and Superior. Maintenance andallocation of the forage base is now a major concern for management agencies. Effective management of all the Great Lakes fisheries now requires the consideration of salmonid stocking effects
on the food web in each lake. Principles 3.nd practices derived from the Great Lakes may be
useful in developing management policies for other systems where predator populations areenhanced by stocking.

Introduction_

Enhancement of desirable fish stocks through hatchery production and stocking has a long and somewhat checkered
history. Stocking is widely practised in the managementof inland waters and is, in many cases, the major if notsole support of fish populations. This paper reviews theexperiences derived from large scale salmonid stocking asa management practice employed in developing fisheriesof the Laurentian Great Lakes of North America. Althoughthese systems are smaller and less complex than the marine
environments where salmon enhancement programs arepractised, some guidance may be derived from the lessons
and tools employed in developing management strategies
for large lakes.
Fish communities and fisheries of the Great Lakes(Superior, Michigan, Huron, Erie, and Ontario) have beenin c:onstant flux since the early part of ~his century (Kitcheli
and Crowder 1986). Invasions by exotic species, notably
sea lamprey (Petromyzon marinus) and alewite (Aloo'a pseudo
harengus) , coupled with an intense fishery explvitation
resulted in the declin~ of most native piscivores. Local
extinctions were common. With few piscivores present,
alewife became the dominant planktiv0re, replacing a suiteof native species-including several endemic ciscoes (Core-gonus spp. )-that had served as the forage base for native
piscivores and that had supported major commercial
fisheries. Alewife populations burgeoned to the extent thatmassive die-offs were common and resulted in major
economic costs because of clogged water intakes and fouled
beaches (Eck and Wells 1987).
Sea lamprey control measures, first implemented in the
1950's, allowed reintroduction of top predators such as thenative lake trout (Salvelinus namaycush) (Kitchell andCrowder 1986). During the 1960's, management agencies
began stocking Pacific salmonids such as coho (Oncorhynchus kisutch) and chinook salmon (0. tshawytscha), rainbow
trout (0. mykiss) and the European brown trout (Salmo trulla)
in an attempt to create a biological control for the overly
abundant alewife (Scavia et al. 1986). In addition, pinksalmon (0. gorbuscha) were accidently introduced to Lake
Superior and subsequently invaded each of the lakes.
Unlike the other salmonids that are maintained largely or
only by annual stocking, pink salmon have established selfsustainmg populations through natural reproduction.
While management through salmonid stocking was firstand most intensively developed for Lake Michigan, similar
practices have since evolved in each of the five lakes. The
assemblage of stocked salmonids has been very effective
in controlling alewife abundance and now supports a sport
59

60

NOAA Technical Report NMFS 102: Marine Ranching

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Figure 1

Estimated biomass of adult alewife and numbers of juvenile sil.lmonines stocked in Lake Michigan forthe period of 1962-87. Alewife data are extrapolations from bottom trawl surveys reported by Wells etal. (1987). Estimates of alewife abundance during the period of 1962-72 are based on a composite ofsources presented by Hatch et aI. (1981) and Wells (1985).

fishery estimated to yield economic benefits approaching
U.S. $3-4 billion per year in the Great Lakes region (Talhelm 1987).

Estimating Carrying Capacity_

In the early stages, salmonid stocking was limited only byhatchery production capacity which grew rapidly in response to public demand. Fishing was excellent, alewife
was the predominant prey and the frequency and intensity of alewife die-oft's decreased. As stocking rates increasedin Lake Michigan, it became evident that introduced
salmonids might act as keystone predators and begin to
restructure the forage community through increased predation on alewife. Given the tremendous effect of the alewife
invasion on the other components of Lake Michigan's foodweb, a complex series of events might transpire if alewife
were to decline (Kitchell and Crowder 1986).
While traditional fisheries research is based on waitingfor data, the importance of the Lake Michigan fisherycalled for alternative approaches that might help anticipate
effects and offer some guidance to research and management activities. We (Stewart et aI. 1981) attempted toevaluate the nature and magnitude of potential predatorinduced changes using bioenergetics modeling to estimate
total predatory demand on alewife in Lake Michigan.

Estimates of alewife biomass were derived from the trawl
surveys reported by Hatch et al. (1981), Wells (1985) andWells et al. (1987). Based on extrapolations of the intended stocking policy and estimates of alewife production
capacity, we predicted a dedine in alewife stocks (Stewart
et al. 1981). Shortly thereafter, alewife stocks declined
precipitously and have remained at a fraction of their abundance during the period 1966-80 (Fig. 1).
Based on ecological reasoning, other predictions regarding responses to alewife decline included reduced growth
rates and increased diet breadth of salmonids, increased
abundance of large zooplankton owing to the reduction inzooplanktivory, and a resurgence of the native planktivores
that were suppressed by competition-predation interactions
during the alewife population explosion of the 1960's(Stewart et al. 1981). These forecasts have been tested anddocumented (Kitchell and Crowder 1986: Scavia et al.
1986) although there are credible alternative explanations
that may have contributed to the decline of alewife (Eckand Wells 1987).
It appears that predation pressure by piscivores stockedin Lake Michigan may be approaching the capacity of thesystem. This view is evident in the current stocking policies
of both the Wisconsin and Michigan Department of
Natural Resources. Their procedures derive, in part, froman energetics modeling approach which is used to determine stocking rates and species mixes that will keep total

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Kitchell: Salmonid Carry Capacity

61

Lake Michigan Estimated Biomass
320.....--------------------.,

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predation pressure at levels evident in 1982 (Krueger andDehring 1986). This equates to a stocking rate of about
15 million salmon and trout "equivalents" per year.
As alewives have declined, populations of many planktivores and benthivores in Lake Michigan have increased,
most notably yellow perch (Percaflavescens), bloater chubor deepwater cisco (Coregonus hOYI), rainbow smelt (Osmerus
mordax), and deepwater sculpin (Myoxocephalus thompsoni)(Wells et al. 1987). Both sport and commercial fisheries,
which declined during the period of alewife dominance,
are again developing for perch, chub, and smelt. Theirrelative abundance is notably different between inshore andoffshore areas. Offshore, alewives have been replaced
primarily by bloater chub and rainbow smelt (Fig. 1),
whereas yellow perch now predominate inshore ude andTesar 1985; Wells et al. 1987). Quantitative estimates ofabundance for these resurgent species are not available,
but it appears that total fish biomass has increased (Fig.
2). Difficulties in estimating abundances are due, in part,to differences in the distribution of these species and theselectivity of bottom trawls used for assessment (Eck andWells 19R7; Wells et al. 1987). Alewives are more pelagic
whereas bloater chubs and yellow perch are primarily
demersal and thus may be more available to bottom trawls.
As the alewife has declined, resource partitioning among
the native species (Crowder 1980) may have allowed
development of a greater total fish biomass than thatobserved in the early 1960's when alewife comprised 90%of the total (Wells et al. 1987).
Changes in the species composition of the planktivore
and benthivore communities and their effects as predatorsin the Lake Michigan food web have had profound effects
on the plankton community. Using paleoecological evidence' Kitchell and Carpenter (1987) reconstructed theaFigure 2
Estimated biomass of forage species In
Lake Michigan. Data from Wells et al.
(1987). Yellow perch are not included inthese data but have generally increased inparallel with populations of the bloaterchub (Eck and Wells 1987).

historical food web which changed dramatically as alewife
expanded in the 1960's. More recently, as alewife havedeclined, yellow perch populations have increased the levelof zooplanktivory resulting in a 10-fold decrease of inshore
zooplankton biomass since 1978. However, there was nochange in species composition, as a small cladoceran,Bosmina longirostris, continues to dominate (Evans 1986).
Offshore, the switch to bloater chubs, with their hypolimnetic distribution and benthic food habits, has directedpredation pressure away from the epilimnetic zooplankton.
This produced an abrupt shift in the offshore zooplankton
community. Between 1982 and 1983, dominance switchedfrom calanoid copepods (Diaptomus spp.) to large Daphnia
spp., although total zooplankton biomass remained similar(Evans and]ude 1986; Scavia et al. 1986). Daphnids aremuch less selective and more efficient grazers than arecalanoids thus, total phytoplankton grazing rates have increased dramatically since 1982 (Scavia et al. 1986). A shift
occurred in species composition of offshore phytoplankton
parallel with that seen in the zooplankton. Prior to 1983,
summer epilimnetic phytoplankton was dominated by filamentous and colonial blue-green and green algae. Since
1983, dominance has switched to small cryptophytes(Fahnenstiel and Scavia 1987a). Total phytoplankton carbon concentration has remained stable over this period,
although subthermocline phytoplankton communities haveincreased (Fahnenstiel and Scavia 1987b). The result of
these changes in the offshore plankton community is increased water clarity. Maximum summer secchi disk readings have increased from 4 to 5 meters in the mid-1960's(Lesht and Rockwell 1985) to 15 meters or more in recent
years (Scavia et al. 1986).
Thus, the story of Lake Michigan is one of dramaticchange in community composition and species abundance

62

NOAA Technical Report NMFS 102: Marine Ranchingat different trophic levels resulting from strong interactions
among food web linkages. These changes were initiated,both in the early part of the century and recently, by
dramatic changes in the abundance of top predators andthe predation pressure they exerted down through the foodweb. While the decline in predators in the early part ofthe century was a relatively inevitable event, the recent increase in predator abundance has been directly controlled
by man. Changes in water quality over time have resulted
from a synergism of nutrient abatement and food webinteractions.

Management of
Dynamic Systems_

Within the dynamic ecological framework described above,
the Great Lakes Fishery Commission provides an institutional opportunity for development of a management policythat can include consideration of the species interactions
represented in a complex food web. The Great Lakes
Fishery Commission coordinates management and research
activities involving the agencies of 11 Great Lakes states,
the Province of Ontario, and the federal governments ofboth the U.S. and Canada. In addition, the Sea Grant
Programs in each of several states offer the benefit ofuniversity-based research programs focussed on Great
Lakes resources. One example of policy that derived fromthe collaboration of research and management interests isrepresented by the planning document produced by the
Wisconsin Department of Natural Resources (1986). It
defines a series of objectives for managing Lake Michigan
fisheries that include• reestablishing a self-sustaining lake trout population
through continued stocking and reductions in sport andcommercial fishing mortality;• limiting commercial harvests of bloater chub to 4 million
pounds and of yellow perch to 200,000 pounds;• increasing sport harvests to 400,000 yellow perch and
650,000 trout and salmon per year;• placing more emphasis on rainbow trout enhancement
and a trophy fishery (fish> 22 kg) for sterile chinook
salmon.
The states of Michigan, Illinois, and Indiana have
similar policies with some amendments for local interests.
Meeting these objective~ will require changes in stocking policies to produce changes in the relative abundancesof salmonid predators and the distribution of predationpressure over space and time. Bioenergetics models havebeen developed to aid the planning process as represented
in recent work on the role of sterile salmon. Sterile chinook
salmon, which were first stocked in 1986, will live up to
10 years, attain trophy weights of 45 kg by 1994, and_consume about 1.5 times as much forage as a cohort ofnormal chinook salmon (Kitchell and Hewett 1987).
Similar analyses are underway in the current evaluationof the stocking policy for anadromous rainbow trout (steelhead). The Wisconsin Department of Natural Resources(1986) will seek to enhance shore and stream fishing opportunities through the use of three different seasonal-run
strains: a spring run (Ganarasha), summer run (Skamania), and fall run (Chambers Creek) strain. These fish are
all expected to be epilimnetic, but differences in summer
temperature preferences and distributions are not known.
The three strains will be stocked at different ages (12-16
months) and will have different residence times in the lake(from 2 to 3 years). As demonstrated by Stewart et al.
(1981), differences in thermal preferences and life histories
have very large effects on total predation patterns.
Changes will also occur in mortality patterns of Lake
Michigan salmonines. Lake trout have been specificallytargeted for reductions in harvest mortality through adecrease in the sport bag limit, a shortened season, a closed
area in the western part of the lake, and numerous changes
in the commercial fishing regulations. These reductions inharvest will very probably result in larger lake trout populations and in compensatory increases in sport harvest ofother salmonines. Some salmonines, particularly coho andchinook salmon, have already experienced a shift in seasonal patterns of mortality. In the 1970's, sport harvestof salmonines occurred mostly in nearshore areas during
the fall spawning run (Stewart et al. 1981). In contrast,
Kitchell and Hewett (1987) recalculated mortality schedules
based on reports by Bleser and Hansen (1985). They foundthat harvest was occurring earlier in the season and in
deeper, offshore areas. In effect, fish are being harvested
at a younger age. thus their total predatory impact is lessened by an initial estimate of 30-40 % per year Thi5change contributes to the recent increase in alewife observed since 1985 (Fig. 1).
Successful natural reproduction by salmonines could act
as a destabilizing influence on the fish community. Reproduction by rainbow trout, plus coho, chinook, and pinksalmon, has occurred in some tributary streams of northern
Lake Michigan. This coupled with possible lake trout
reproduction represents a new, variable input to the total
predator biomass and thus reduces our ability to control
predator biomass (and predation pressure) through manipulating stocking rates and fishing regulations.
Changes in the relative abundances, life histories, andmortality patterns of lake trout and other salmonines will
impose new temporal and spatial patterns of predation on
the forage base. Shifts in predation pressure away fromalewives and toward alternate prey species (e.g., smelt,
chubs, and perch) could impinge upon commercial andsport harvest objectives for those species. Obviously, thereverse is also true if commercial fisheries compete withsalmonine predators for prey resources.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Kitchell: Salmonid Carry Capacity

Prospects for the Future_

The resiliency of alewife, the primary prey, in these systems
is unknown. The dynamics and potential of this exotic
species are a key to effective management for the future.
Like many clupeid fishes, its population dynamics arevolatile and defy prediction based on traditional fisheriesmodels. There is no doubt that hard winters can cause
higher alewife mortalities (Eck and Wells 1987). However,
the magnitude of that factor remains confounded bydensity-dependent intraspecific competition and the depensatory effect of a highly efficient predators (salmonines)
whose populations are dictated more by management
policy than the ecological principles of typical predatorprey systems. Alewives were 90% or more of salmon andtrout diets in the 1960's and still constituted a major portion (70-80 %) of the diet in the mid 80's aftertheir populations declined (Hagar 1984) indicating an apparent preference for alewives over other forage species. Given thispreference along with current levels of salmonid stocking
and intensified competitive interactions among forage
species (Fig. 2), it seems unlikely that alewives will return
to former levels of abundance. They may exist at low levelsin the system or may exhibit recurrent outbreaks associatedwith strong year classes.
Salmonid stocking also resulted in responses higher inthe trophic system. Sizes of spawning-run adult sea lampreys approximately doubled over the two decades of continuous growth in the salmonid stocking program. While
the sea lamprey population is controlled by the lampricide
treatment program and remains low, the parasitic or predatory effect of an individual sea lamprey has increased
nonlinearly and by about sixfold (Kitchell 1990).
Thus, it appears that Lake Michigan is entering a newphase of management. The goal is no longer simple expansion of the predator complex to control alewife populations and produce more fish for sport anglers. Managers
must now regulate the top predator levels, considering not
only the lotal predation pressure within the system, but
how that pressure is distributed over different predatorsand forage species. Manipulating top predator communities provides an effective means of managing not only
those species of direct interest to fisheries, but also ofeffecting changes in lower trophic levels through directedpredator-prey interactions that can ameliorate competitionpredation effects, facilitate recovery of native species, andenhance water clarity (Kitchell et al. 1988).
Among the tools available to management and researchscientists, bioenergetics modeling (Hewett and Johnson
1987) can be used to quantitatively address questions ofpredation rates and production by an individual predatory
species or a suite of predators within a single trophic level(e.g., Kitchell et al. 1977; Kitchell and Breck 1980; Stewart
et al. 1981; Stewart et al. 1983; Rice and Cochran 1984;
Bartell et al. 1986; Olson and Boggs 1986; Stewart and63

Binkowski 1986; Kitchell and Hewett 1987; Kitchell 1990).
It differs from other modeling techniques in that it does
not depend upon the a posteriori assessments of traditional
fisheries models, has a firm quantitative basis, and can beused to test and strengthen the assumptions of simulation
modeling. We must now expand this approach to consider
how changes in management policy are expressed throughout the food web (i.e., in piscivores, planktivores, benthivores, and plankton). Development of an ecological rationale for managing Lake Michigan fisheries will require
improved understanding of seasonal and long-term production dynamics of the major forage fishes as well as quantification of fluxes between trophic levels. As indicatedabove, this approach can also yield benefits in water quality. The larger goal for long-term management is to develop
the research perspective, analytical tools, and practicalguidelines that will allow managers to put strategic planning into tactical practice.
Bioenergetics modeling can provide valuable insight into
predator-prey interactions under different community
structures. But, which of the possible structures is most
likely to represent a stable configuration within the productive capacity of Lake Michigan? We can begin to address this question by examining indicators of past community structure in the lake. Zooplankton community
dynamics are widely recognized as highly responsive to
predator etTects and have been successfully used as indirect
and integrative sources of insights for the entire ecosystem(Kitchell and Kitchell 1980; Kerfoot 1981; Mills et al. 1987;
Carpenter and Kitchell 1988). Our recent paleoecologicalwork on Lake Michigan sediment cores showed that thesesediments contain zooplankton remains which provide
archival evidence of past predator-prey states and dynamics(Kitchell and Carpenter 1987). The mean length of the
mucron (the posterior spine) on Bosmina longirostris carapaces decreased dramatically in the sediment core at a
depth representing sediments deposited around 1960, thetime of rapid increase in alewife abundance. Prior to 1960,
zooplanktivory in Lake Michigan was relatively low andabundance of predatory copepods was high. The mucronserves as a defense against predation by copepods, thus during this period, long spined morphs dominated. The increase in alewife abundance after 1960 reduced abundanceof predatory copepods through size-selective predation andthe short spined morph of Bosmina became abundant. The
most recent analysis of open-water plankton samples from
Lake Michigan indicates that as abundance of alewife has
declined and predatory copepods have increased, Bosmina
mucron lengths have increased and are currently about
twice as long compared to the 1950's (Kitchell, unpubl.
data). This indicates that current levels of zooplanktivory
in Lake Michigan are likely lower than those under any
ancestral condition. Thus, Bosmina morphology over time,
as reconstructed from sediments and open-water samples,
documents the advent, dominance, and recent decline of

64

NOAA Technical Report NMFS 102: Marine Ranching

the impact of alewife on the Lake Michigan zooplankton
community. It also appears that Bosmina morphology is anindicator of alternate steady-state behavior of the predatJrprey system. The morphological response exhibited in Lake
Michigan was neither gradational nor linearly related toalewife effects and suggests a combination of switching anddepensatory mechanisms often observed as systems change
state (Holling 1978; Walters et al. 1980).
Events similar to those in Lake Michigan have also occurred, to varying degrees, in each of the Laurentian Great
Lakes. For example, there have been sharp declines in thealewife population of Lake Huron (Argyle 1984), and in
Lake Superior, smelt declined while lake herring (Coregonus
artedil) increased (Selgeby 1985). A decline in body condition oflake trout in western Lake Superior may have been
due in part to the smelt decline. In both Lake Superiorand Lake Huron, declines in the forage fishes occurred assalmonid stocking rates reached high levels (Selgeby 1985).
In Lake Ontario, salmonid stocking rates increased rapidly
in the late 1970's and yet another highly successful sport
fishery developed (Hartig et al. 1991). Density-dependent
effects appeared to be the primary regulator of alewife
dynamics (O'Gorman et al. 1987). However, concern for
the forage base (primarily alewife) and the lessons learned
elsewhere have caused the fisheries agencies involved toadopt a "hold-the-line" policy since 1985 while large
cohorts of recently stocked salmon come to maturity andhave their maximum predatory impact (Hartig et al. 1991).
Each of the Great Lakes have different levels and stagesof predator-prey interactions, but all within the same basic
ecological framework. Comparisons between systems canhelp determine Lake Michigan's status relative to the otherlakes. Principles derived from Lake Michigan can then be
modified for application to other systems. While the lessons
from Lake Michigan's history may be readily appliedamong the Great Lakes, their application to different
systems will require an astute combination of experience,
insight, logic, and modeling.
The dimensions, complexities, and compensatory potential of large marine systems make it difficult to imagine
that stocking policies might have a readily apparent impact on marine food webs. However, we should not ignore
the many examples of predator effects demonstrated in thescores of over-exploited marine fish stocks and the compensatory responses of communities selectively altered byfishing. In my opinion, effects of selective and intensive
fishing on marine food webs must have occurred but remain poorly documented. It follows that extensive stockenhancements, such as those due to the salmon enhancement programs, should receive the attention of the researchcommunity.
Perhaps a very important lesson to be learned from thehistory of the Great Lakes can be conveyed by anecdote.
A recent discussion with one of the most experienced ofGreat Lakes fisheries biologists (LaRue Wells, now retired_

from U.S. Fish and Wildlife Service) turned to the question of which of the many change~ observed in Lake
Michigan were fully antic:ipated by researchers andmanagers? His answer can be paraphrased as: "Only
one-that was the effect of sea lamprey on lake trout. We
knew that was coming because we'd seen it in the otherlakes." Since then we have developed a greater understanding of basic ecological principles as they apply to large
pelagic systems and can use those.as a basis for testable
forecasts (Kitchell and Crowder 1986; Carpenter andKitchell 1988). Some of those forecasts are wrong. That,
however, is the essence of science and the essential requisite
if we are to learn how ecosystems work and how the lessons
from one place may be generalized in applications to others.
The Great Lakes now offer us the opportunity to learn
from history as we consider the cascade of effects that may
descend through food webs enhanced by the continuous
addition of large predators. The salmon enhancement
programs currently underway along the North Pacific rim
offer the chance to observe ecological analogues in a large
pelagic marine environment. Logically, we should attend
to that prospect in planning for research and management
programs.

Acknowledgments_

I thank the organizers of this symposium for offeringme the opportunity to share the experience of many fisheries biologists in the Great Lakes region. I thank Steve
Hewett (Great Lakes Environmental Researsh Laboratory, Ann Arbor, MI) for help in preparing the figures andBarry Johnson (Center for Limnology, Univ. WisconsinMadison) for help with the text. Support for my participation in this effort was derived from the University of
Wisconsin Sea Grant Program; the National Sea Grant
Program Office, NOAA, Department of Commerce,
Washington, DC; and from the Graduate School, University of Wisconsin-Madison. This paper was preparedwhile I was a Visiting Scientist at the NOAA Great Lakes
Environmental Research Lababoratory in Ann Arbor,
Michigan.

Citations_

Argyle, R.L.
1984. Status of forage fish stocks in Lake Huron, 1983. Rep. to
the Great Lakes FIshery Comm., Lake Huron Comm. Meeting,March 1984. Great Lakes FishelY Commission, Ann Arbor, MI
48105.
Bartell, S.M., J.E. Breck, R.H. Gardner, and A.L. Brenkert.
1986. Individual parameter perturbation and error analysis of fishbioenergetics models. Can. J. Fish. Aquat. Sci. 43: 160-168.
Bleser, C.A., and M.J. Hansen.
1985. WisconSin's 1984 Lake Michigan charter fishery. Wise.
Dep. Nat. Resour., Madison, WI.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Kitchell: Salmonid Carry Capacity
Carpenter, S.R., and J.F. Kitchell.
1988. Consumer control of lake productivity. BioScience 38:764-769.
Crowder, L.B.
1.980. Alewife, rainbow smelt and native fishes in Lake Michigan:
competition or predation? Environ. BioI. Fishes 5:225-233.
Eck, G.W., and L. Wells.
1987. Recent changes in Lake Michigan's fish community and theirprobable causes, with emphasis on the role of the alewife (Alosapseudoharengus). Can. J. Fish. Aquat. Sci. 44 (Suppl 2):53-60.
Evans, M.S.
1986. Recent major declines in zooplankton populations in the inshore region of Lake Michigan: probable causes and implications. Can. J. Fish. Aquat. Sci. 43:154-159.
Evans, M.S., and D.J. Jude.
1986. Recent shifts in Daphnia community structure in southeastern
Lake Michigan: a comparison of inshore and offshore. Limnol.
Oceanogr. 31 :56-67.
Fahnenstiel, G. L., and D. Scavia.
1987a. Dynamics of Lake Michigan phytoplankton: recent changes
in surface and deep communities. Can. J. Fish. Aquat. Sci.
44:509-514.
!987b. Dynamics of Lake Michigan phytoplankton: the deep
chlorophyll layer. J. Great Lakes Res. 13:285-295.
Hagar, J.
1984. Diets of Lake Michigan salmonids: an assessment of the
dynamics of predator-prey interaction. M.S. thesis (Zoology),
Univ. Wisconsin-Madison, 97 p.
Hartig, J.H., J.F. Kitchell, D. Scaviam and S.B. Brandt.
1991. Rehabilitation of Lake Ontario: The role of nutrient reduction and food web dynamics. Can. J. Fish. Aquat. Sci. In press.
Hatch, R.W., P.M. Haack, and E. H. Brown Jr.
1981. Estimation of alewife biomass in Lake Michigan, 1967-1978.
Trans Am. Fish. Soc. 110:575-584.
Hewett, S.W., and B.L. Johnson.
1987. A generalized bioenergetics model of fish growth for microcomputers. UW Sea Grant Tech. Rep. WIS-SG-87-245, Madi·
son, WI.
Hollin1<;, C.S.
1978. Adaptive environmental assessment and management. John
Wiley & Sons, New York, NY, 377 p.
Jude, D.J., and F.J. Tesar.
1985. Recent changes in the inshore forage fish of Lake Michigan.
Can. J. Fish. Aquat. Sci. 42:1154-1157.
Kerfoot, C.A.
1981. Long-term replacement cycles in cladoceran communities:
a history of predation. Ecology 62:216-233.
Kitchell, J .A., and J .1'. Kitchell.
1980. Size-selective predation, light transmission and oxygen stratification: evidence from the recent sediments of manipulated lakes.
Limnol. Oceanogr. 25:389-402.
Kitchell, J.F.
1990. The scope for mortality caused by sea lamprey. Trans. Am.
Fish. Soc. Vol. i19, p. 642-648.
Kitchell, J.F., and J.E. Breck.
1980. Bioenergetics model and foraging hypothesis for sea lamprey(Petromyzon marinus). Can. J. Fish. Aquat. Sci. 37:2159-2168.
Kitchell, J .1'., and S.R. Carpenter.
1987. Piscivores, planktivores, fossils and phorbins. In Predation:
direct and indirect impacts on aquatic communities (W.C. Kerfoot and A. Sih, eds.), p. 132-146. Univ. New England Press.
Kitchell, J.F., and L.B. Crowder.
1986. Predator-prey interactions in Lake Michigan: model predictions and recent dynamics. Environ. BioI. Fishes 16:205-211.
Kitchell, J.F., and S.W. Hewett.
1987. Forecasting forage demand and yield of stcrile chinook salmon

65(Oncorhynchus tshawytscha) in Lake Michigan. Can. J. Fish. Aquat.
Sci. 44:384-389.
Kitchell, J.F., D.J. Stewart, and D. Weininger.
1977. Application of a bioenergctics model to yellow perch (Perea
flavescens) and walleye (Stizostedion vitreum vitreum). ]. Fish. Res.
Board Can. 34:1922-1935.
Kitchell, J.F., M.S. Evans, D. Scavia, and L.B. Crowder.
1988. Food web regulation of water quality in Lake Michigan:
Report of a workshop. J. Great Lakes Res. 14:109-114.
Krueger, C.C., and T.R. Dehring.
1986. A procedure to allocate the annual stocking of salmonids inthe Wisconsin waters of Lake Michigan. Wisc. Dep. Nat.
Resour. Fish Manage. Rep. 127.
Lesht, B.M., and D.C. Rockwell.
1985. The state of the middle Great Lakes: results of the 1983 water
quality survey of Lakes Erie, Huron, and Michigan. Rep.
ANLlER-85-2, Argonne Natl. Lab., Argonne, IL.
Mills, E.L., D.M. Green, and A. Schiavone.
1987. Use of zooplankton size to assess the community struclllreof fish populations in freshwater lakes. N. Am. J. Fish. Manage.
7:369-378.
O'Gorman, R., R.A. Bergstedt, and T.H. Eckert.
1987. Prey fish dynamics and salmonine predator growth in Lake
Ontario, 1978-1984. Can. J. Fish. Aquat. Sci. 44 (Supp!. 2):
390-403.
Olson, R.J., and C.H. Boggs.
1986. Apex predation by yellowiin tuna (Thunnus albacares): independent estimates from gastric evacuation and stomach contents.
bioenergetics, and cesium concentrations. Can. J. Fish. Aquat.
Sci. 43:1760-1775.
Rice, J.A., and P.A. Cochran.
1984. Independent evaluation of a bioenergetics model for largemouth bass. Ecology 65:732-739.
Scavia, D., G.L. Fabnenstiel, M.S. Evans, D.J. Jude, andJ.T. Lehman.
1986. Influence ofsalmonine predation and weather on long-termwater quality trends in Lake Michigan. Can.]. Fish. Aquat.
Sci. 43:435-443.
Selgeby, J.H.
1985. Population trends of lake herring (Curegonus ar/edit) and rainbow smelt (Osmerus mordax) in U.S. waters of Lake Superior,
1968-84. In Presented papers from the Council of Lake Com"mittees Plenary Session on Great Lakes predator-prey issue,,; 20March 20 1985 (R.L. Eshenroder, cd.), p. 1-12. Great Lakes
Fish. Comm. Spec. Publ. 85-3.
Stewart, D.J., and F.P. Binkowski.
1986. Dynamics of consumption and food conversion !)y Lake
Michigan alewives; an energetics modeling synthesIs. Trans. Am.
Fish. Sor. 115:643-661.
Stewart, D.J., J.F. Kitchell, and L.B. Crcwder.
1981. Forage fishes and their salmonid predators in Lake Michigan.
Trans. Am. Fish. Soc. 110:751-763.
Stew,,-rt, D.J., D. Weininger, D.V. Rottiers, and T.A. Edsall.
1983. An energetics model for lake trout, Salvelinus namaycush: application to the Lake Michigan population. Can. J. Fish. Aquat.
Sci. 40:681-698.
Talhclm, D.R.
1987. Economics of Great Lakes fisheries: a 1985 assessment.
Special Economic Rep., Great Lal<es Fishery Comm., Ann Arbor,
MI.
Walters, C.J., G. Steer, and G. Spangler.
1980. Responses otlake trout (Salvelinus namaycush) to harvesting,stocking, and lamprey reductions. Can. J. Fish. Aquat. Sci.
37:2133-2145.
Wells, L.
1985. Changes in Lake Michigan's prey fish populations with increasing salmonid abundance, 1962 to 1984. In Presented papers

66

NOAA Technical Report NMFS 102: Marine Ranchingfrom the Council of Lake Committees Plenary Session on Great
Lakes predator-prey issues (R.L. Eshenroder, ed.), p. 15-25.
Great Lakes Fish. Comm. Tech. Rep. 85-3.
Wells, L., R.W. Hatch, and E.H. Brown.
1987. Status of bloater chubs, alewives, rainbow smelt, slimy
sculpins, deepwater sculpins, and yellow perch in Lake Michigan,_

1986. Rep. to the Great Lakes Fish. Comm., Lake Michigan
Comm. Meeting, March 1987. Great Lakes Fishery Commission, Ann Arbor, MI 48105.
Wisconsin Department of Natural Resources.
1986. Lake Michigan fisheries management plan. Wise. Dep.
Nat. Resour. Admin. Rep. 25.

Farming Techniques for Bay Scallop, Pecten (Notovola) albicans,in the Western Regions of the Japan Sea

KUNIZOH TANAKA*
Nansei Regional Fisheries Research Laboratory
Ohno-cho
Hiroshima 739-04, Japan

ABSTRACTThe bay scallop, Pecten (Notovola) albicans, is an important resource in the coastal waters ofJapan.
Scientists with the Marine Ranching Research Program are studying bay scallop ecology anddeveloping new methods to improve its survival, growth, and harvest. This paper discusses thenatural mechanisms controlling these outcomes and also introduces a new bottom-type spat collector that greatly improves the collection of settling larvae. It is suggested that the number ofhanging cultured shells be increased in order to increase bay scallop seed resources for their higher
fecundity.

Introduction_

The bay scallop, Pecten (Notovola) albicans, is distributed fromthe southern coast of the Aomori Prefecture to the Tsushima coast on the japan Sea. The annual catch of thisspecies fluctuates remarkably. In the Marine Ranching
Research Program, we have developed new techniques
useful in bay scallop farming.
The purpose of this research is to improve bay scallop
production by increasing our knowledge of 1) the natural
mechanism controlling the concentration, deposition, andsurvival of swimming bay scallop larvae in the sea and 2)
the relationship between spat deposit-site conditions andtheir corresponding survival rates.

Materials and Methods_

Research was conducted in the coastal areas of Tottori and
Shimane Prefectures from 1980 to 1988. The project teamconsisted of four laboratories: The japan Sea Regional
Fisheries Research Laboratory, N ansei Regional Fisheries
Research Laboratory, and the Tottori and Shimane Prefectural Fisheries Experimental Stations.
A total of 65 research stations were established for collecting samples.

• Present Address: Hokkaido National Fisheries Research Institute, 116
Katsurakoi, Kushiro, Hokkaido 085, Japan.

Swimming Larvae Collection
Each laboratory collected swimming larva using a NXX
13 nylon cloth NORPAC net (diameter 45 cm, side length
180 cm), which was hauled vertically from 30 or 50 m tothe surface. Nets were retrieved at the rate of 10 cm/sec
and weighted with 5 kg of ballast.
All of the 540 samples were collected over an 8 year
period from December through May. Samples were treatedwith 5 % formalin and examined microscopically in thelaboratory.

Establishment of Sea Currents
Generally, the number one branch of the Tsushima Warm
Current in the japan Sea flows by the northern coast of
Honshu. The surface water temperatures, which range
from 11.00 to 15.18°C from December to May, are generally stable to a depth of 50 m during the collection period.
The NOAA satellite images (AVHRR, Advanced VeryHigh Resolution Radiometer) of surface water temperatures in the range of 6.85 to 15.69°C were almost equal
to the layer in which the swimming bay scallop larvae were
found.
The upwelling of cold water masses and sea bottom
topography combine with the currents of the first branchof the Tsushima Warm Current to make several eddy
zones. In the upwelling cold water in the japan Sea at
Hashizu in Tottori Prefecture, phosphate (P0 4 ) is stable
at about 0.40-0.60 ppm (Tanaka et al. 1981).
67

68

NOAA Technical Report NMFS 102: Marine Ranching

_

,...
8

tf

><
<Il

"tl

c:

6 f-

H

I<II

4 f-

c:

• • • • • ••

f-

0

Cl

• ++,

+

"tl

2 lfI

0

Feb. Mar.

• • • •

I

I

I

I

Apr.

May

June

July

I

Aug.

Oct.

Sept.

•
I

I

Nov.

Dec.

Figure 1
Seasonal change of gonad index of bay scallop (Moriwaki et al. 1981).

1l,1l1J,>c.,.,.

KJIKJIJ,urIlIlIll .

Q)

::J
CT
Q)

'-

lL.

f

E

I~HF

Jon.

I

I ,-

,1lIlmI_.DUll tL~L'---~--'-----'-----""---'-----J
v

Feb.

Mar.

Ill] ._--'-_..L.---JL---l_--'-_-'Apr.

May JuneJuly

Aug. Sept. Oct.

Nov.

Dec.

Figure 2
Seasonal change of gonad development of bay scallop (Moriwaki et al.
1981). A: premature stage; B: follicular stage; C: growth stage; D: mature
stage; E: spawning stage; F: spawned stage; I: ovary, and 0: testis.

In the warm current, it is only 0.10-0.20 ppm. Ammonia
levels (NH.j.) are stable at 1.0-2.0 ppm in the cold watermass.
The difference in phosphate-P concentration dissipates
as one moves from the cold water mass.

1981; Tanaka et al. 1985, 1986a). Gonadal development
was determined using microsectioning methods after which
specimens were classifed into six ranks by Yamamoto's
method.

Deposited Larvae Collection
Gonadal Indices
Natural and cultured bay scallop gonadal indices have beendeveloped using either dredged or purchased samples taken
on a monthly basis from the coasts of the Oki Isles, Shimane Peninsula and Tottori Prefecture (Moriwaki et al.
(

The new larval collector was constructed of an onion bag,mesh size 2-4 mm, fJ..ltered with a collection material madeof hard nylon fibers from a 50-70 mm mesh size fishingnet. Each collector was set on the sea bottom using a basketlike crab pot (3 x 4 x 2 m) and a long line approximately

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Tanaka: Farming Techniques for Bay Scallop

69

Table 1Development and growth of bay scallop. (Hotta 1977.)
Development

Diameter size or shell length

Characteristics

Fertilization of egg
2 days after
10 days after
14 days after
20 days after
25 days after
28 days after
1 month after
2 months after
3 months after
6 months after
1 year later
1.5 years later2 years later
2.5 years later78.81Jm
104IJm120"-'160 IJm
190"-'210 IJm
154"-'270 IJm
154"-'270 IJm
230"-'250 IJm
315"-'356 IJm
1.5"-'3.6 mm
10 mm
5 em
8 em
10 em
11 em
12 em

submerged globular form
D-shaped swimming larva
Umbo stage growth, 4.0-5.2 IJm/day
Umbo stage growth, 7.3-8.3 IJm/day
Eye spot, velum appears
Deposited by byssus
Marginal shell formed
8.6-16 IJm/day growth20-140 IJm/day growth
Benthic life, 2.0-3.0 mm/day growth
Adult shell form, 14 g BW
Adult shell form, 60 g BW
Adult shell form, 100 g BW
Adult shell form, 150 g BW
Adult shell form, 200 g BW

Table 2
Relation between bay scallop and other bivalve larvae (individuals/m 3 ). (Tanaka et al. 1982,
1983. )

Range

Average

Range

Average

Appearanceof bay scallop
(% )

1980
1980

0"-'9
0"-'201
40"-'1178"-'338

29
68

3.4
5.8

April
1981
1981
May
December 1981

0"-'5
0"-'3
0

1
1
0

0"'1450"-'235
10"-'394

45
136

2.2
1.4
0

March
April
May

0"-'130"-'122
0"-'2

2
11
0

2"-'2183"-'1415
10"-'274

23
157
68

8.7
7.0
0

Other bivalve larvae

Bay scallop larvae
Date
March
April

1982
1982
1982

50-80 m in length. The level of the total organic carbon(TOC) of muddy settling substrates was measured using
a TOC meter; ignition losses of mud were measured at
550 0 C for one hour using an electric muffle hearth.

Results and Discussion_

Spawning Season
and Swimming Larvae Stages
Off the coast of the San-in district, the bay scallop's spawning season is from November to March (Figs. 1,2; Moriwaki et al. 1981). The swimming-larvae stages follow fertilization by several days, last 3 or 4 weeks, and occur
primarily in shallow water less than 50 m in depth (Table
1; Hotta 1977). Larvae accumulate in the Tsushima Warm

72

Current as their growth continues. Bay scallop larvae range
from 0.4 to 8.1 % of the total bivalve larvae population,
averaging 4.2% (Table 2; Tanakaetal. 1982, 1983). The
peak ofveliger larvae distribution was found in December
and February (Fig. 3; Yuki et al. 1985).
The mechanism of spawning larvae accumulation canbe explained as follows. The swimming larvae distributein the middle layer of the first branch of the Tsushima
Warm Current (Fig. 4; Kasahara and Itoh 1985) whichflows to the east of this experimental district. Along the
Honshu coast around the Oki Isles, a sea valley exists fromthe Tottori city to the eastern coast of the Nishinoshima
Oki Isles. Here an upwelling cold water mass was observed
which controlled the first branch of the Tsushima Warm
Current flowing eastward (Fig. 5). The formation of an
eddy was observed in this zone (Fig. 6) wherein the bay
scallop swimming larvae concentrated (Fig. 7).

70

NOAA Technical Report NMFS 102: Marine Ranching

l.<
Q)
.j.l

St.

0.3

be displayed with a 3.1-km mesh, enabling us to detect the
distribution area of the swimming larvae. The maximum
density of the swimming larvae was 122 individuals per
cubic meter of sea water. This density is very low compared to the Japanese scallop (PacinopectenyessoensisJay) in
Mitsu Bay. The supply may be affected by the swift currents involved.

A (Norpac Net)

ro

~

ro

Q)

rtJ

.,

0-26m/haul
0.2

~

0.1

\'

a

.........

""""ro

::l

~

\

'0-1

>

'0-1

'e'

I

Deposition of Bay Scallop Larvae
As the swimming larvae increase to 0.3-0.5 mm in shelllength, they settle to the bottom. Before reaching the sea
bottom, the larvae attach to suitable materials by attachment of the byssus. If suitable materials are not present,
they settle down on the sandy or muddy bottom characteristic of the slow current areas of eddy zones. Larvae
deposited in the muddy conditions usually cannot survive(Tables 3, 4; Fig. 10). We have forecasted that larvae of
23.25 ± 1.80 to 3.50 ± 0.60 mm in shell length might beunable to survive in the mud more than 2 or 3 weeks. It
is not surprising therefore that the 0.3 to 0.5 mm shelllarvae deposited on the mud also could not survive. It issuggested that the bottom materials in the deposition zone
are an important survival factor, and environments highin organic matter and silt content are unsuitable for larval
development.

~......~

0.0
Dec.2l Jan.30 Feb. 13 Mar.8 Apr. 13

Figure 3
Distribution of swimming larvae for each month at Stn. A (Yukiet aI. 1985). ----- = 0-26 m a haul; - - = 0-13 m a haul.

We also estimated the areas of concentrated swimminglarvae (Fig. 8, 9; Tanaka et al. 1986b) using NOAA
satellite images of surface water temperatures when thecollection of larvae was difficult owing to stormy conditions. Presently, satellite imaging using infrared rays can

130·

_

135"

140·

Water front-:;::'.;:.

45"%

Current direction
Current axis
Warm water area
Cold water area

45"

40·

40"

35"

35"

Figure 4
130"

135"

140"

Sea current of the Sea of Japan by Nagamuma's current pattern. (Kasahara and ltoh 1985.)

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Tanaka: Farming Techniques for Bay Scallop

St.6

7

8

9

9

11

10

10

O~.~.. ;O·~!~~6·········o·I·::>·(;;~·32..........

MARCH

~,8

.................

0.4~:0.40100.............. ::•11

O~- ................--'----r---~::-::""""T"""---;:--::--'

o r-lr-~O"":.3:'1'0"":0:-.734-:----r---::-0-:.3:"""4--;;:0"":.3:;-;;0:---~0. 30

100

.

-

-1.00 200

St.6 7 8
0.20 0.30.r."··:·:··::::{:.'S::~::::·::::.·......:..; .
0.30

10

9

° '--.: :.··rr..O 34::); ....

St.6

11

o.36.....?~~::.~~~oo·~......:.~

100~.:~.C------~
0.2'

'.

"\O.

:~0.8

100

1.0
·.... ·.. ·..·1.2

.

APRIL

..... ; 1. 2
1.0". 0.80 ·200

St.6
7 8
9
10
11
0 ....- - - . - - . - - - - - - . - - - - - - . - - - - - - ,0.4~=~4~3 0.2

~1/

.• '

':";/,0.50/

1011
0.6 0.8 1.0

9•":"':::.<::\

200

.

8

~'·:~(···············~····;·.:~~~,~o.:28... :::.:;' 307

o 0 80.60.4

00.30 ..:.. :~0.40

APRIL

O~=--"""T"""_.,__::__---r--_;::_::_--.-------(:0.1--'----...:'0.3

.1.4

100

MAY

I.

7

8

9

O:.L~~:.~~.

10:'1. 0"1.3
11• ..... ",,:::::0.12.. 0.8
200

o

100

JUNE

Ph 0 S p hat e- P (p pm)

/0.50
/0.60

St,6

7

9

8

-..l:~.•. 0.6•'"

0.6 O.~·

11

10';"'4":::" :c.;~:~).-:.::.::.::::.::>,
0........ ,'. ':"::':.:·"'::::;:;":'.'i·"';'·'·'~::::,r;:o.40

1.2

MAY-:::::::: 0•4

200
St.6

11

0.4 .. :.~0.8

~O,2

100

200

.

MARCH

··~'O.50

200

o

71

:

........

...

; 0.4

.~:

0.6
0 4

0: 2

........ 0.4

100

zoo

.

. "
,

JUNE

Anmonia-N (ppm)

Figure 5
Vertical distribution of P0 4-P (left) and NH 4-N (right) offshore of Hashizu, Tottori Prefecture in 1980 (Tanaka et al. 1981).

Natural Mechanics of Shellfish Survival
The period of swimming-larvae blooming is about thesame as plankton blooming. A shortage offood materials,
however, does not seem to be the main reason for bay
scallop mortality. Significant factors in shellfish survival

may include: 1) number of spawned eggs and the fluctuation of spawning term; 2) changes in eddy zone location
dependent on the strength of the first branch of the
Tsushima Warm Current and of the upwelling of thecold water mass in the Japan Sea by the coast; 3) volumeof organic and muddy material in the sea bed deposition

72

NOAA Technical Report NMFS 102: Marine Ranching_

Japan Sea

36°N

Figure 6
Horizontal distribution of Phosphate-P at the depth of 10 m; arrows indicate current direction as determined by current meter SD-2; phosphate concentration isobars shown in parts
per million; - . - indicated 100 m isobath (Tanaka et al. 1981).

(

133 ° ~ 1

134° E

'v'.

,

i

!

..... \. ...-....-,. . . . . . .;:. . . . . . /0';:"..\ . . "'-'"
.

:

I

:. )

Oki

:,-

;.

(;'

i;les

/

I

) :'"

Japan Sea~·:l.. ··

r;..j";?, 1;1./

\~

\ ~

\

\.~~D-0 /---'20.
.:

20/~·:
__
\::
:

\:

(~>.

.......

.

r,...............

".

\.... 20

.....

\

50

36° N

/,

'';'

50-; 2O%~\"" "': -:-":" ,'-·~·:----··--- . _.
/

/

./

\

\\

100~."::"'-'~~O.::::>

'\

/

50

- 200..

-l--.... ,

100

. -'
100 .
,r'

L _ _........

......... ' -\'--"-'-'-100"

50
C1.....L_-'-_~--L.

---JL__ ' __ _..1

Figure 7
Distribution of bivalve swimming larvae off the eatern coast of Shimane Prefecture aroundthe Oki Islands in the Japan Sea; - .. - indicates 200 m iscbath; _. - indicates 100 m
isobath; ..... indicates 20 larvae/m 3 isobar; ----- indicates 50 larvae/m 3 isobar;
indicates isobars for larval concentra;ions > 100 larvae/m 3 as shown in figure.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Tanaka: Farming Techniques for Bay Scallop

73

Pecten larvae: ",Bivalve larvae

Figure 8
Distribution of bay scallop and bivalve swimminglarvae off the eastern coast of Shimane Prefecture around the Oki Islands in the Japan Sea;..... indicates 20 larvae/m3 isobar; ----- indicates 50 larvae/m 3 isobar; - - indicatesisobars for larval concentrations> 100 larvae/m 3 as shown in figure.

_'---_I~I=========~I
14.80
13.90 13.24
11.24°C

15.47

Figure 9Distribution of surface water temperature by NOAA
6 Polar Orbiting Satellite (Satellite Data Serv. Div.
of NESDIS [Nat\. Environ. Sat., Data and Info. Service] 5627 Allentown Rd., Camp Springs, MD
20746) in 0.3 0 C intervals; Dashed lines show theapproxImate location of isodensity lines seen in
Figure 7 (survey conducted on 27 May 1980, 1840
to 1852 hours by NOAA 6).

74

NOAA Technical Report NMFS 102: Marine Ranching

132'

133'

_

134'E

N
36"-t-----+--+----'-P'-1:J,/--'-------'(---tT---..,

,300m

/

MARCH
132'
I

J{
N
36

-

-

-

133'

i

;:::::--1'----.

l

? /:

I /'

~

134'S

,fO)

)
~

C

\

\

~

/

I

35

I

1"-..
'-f-

I-~

-

't

APRIL
134':;:

133'(

5t.2526f-~-~,~ f~ p-

l7

r-;.

1"
tV-

\

) ( .~~~
y
'\
D

N

'

36'----f--I----4{"" --I----~-t____h
""

/300m

34

35'

MAY 1982

ll:ii
o 12

zone of sWlmmmg larvae; and 4) concentration of
predators, In other words, the bay scallop quantity
is influenced by the survival rate during the early

Figure 10
Number of dead demersal bay scallop shells undervarious conditions off the eastern coast of Shimane
Prefecture around the Oki Islands for March throughMay 1982. The zero point of each bar graph indicatesthe location of the sampling station location. For each
set of bars, top left bar indicates ignition loss of mud(%); top right bar indicates total organic carbon (TOemg/g dry wt.); lower left bar indicates the total numberof dead bay scallops; and lower right bar indicates bay·scallop numbers per kg of mud. Scales for each are
shown in the lower right hand corner of the figure;for May 1982, bay·scallop numbers are set off to theleft owing to lack of space in the figure.

stages of life. Table 5 shows that both large quantities
and high densities of bay scallop occur off the San-incoast.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Tanaka: Farming Techniques for Bay Scallop

75

Table :3
Bottom environment characteristics of areas of high juvenile
bay scallop mortality in the year 1982. Inds.: individuals;
SL: shell length; IL: ignition loss; TOC: total organiccarbon.

Table 4
Bottom environment characteristics of areas of low juvenile
bay scallop mortality in the year 1982. Inds.: individuals;
SL: shell length; IL: ignition loss; TOC: total organiccarbon.

Dead bay scallop
shell

Dead bay scallop
shell

Date

Sea
depth
(m)

March
April
April
April
April
April
April

77
74
79
72
38
50
86

20
22
18
12

Average

68.0

18.1

Bottomenvironment

Date

Sea
depth
(m)

Inds.lmud
(kg)

14.9
21.1
9.8
7.9
6.1
15.7
30.0

March
March
March
March
April
April
April

46
40
69
59
59
37
60

0
0
1
3
1
0
3

15.1

Average

52.9

1.1

Inds.lmud
(kg)

SL
(mm)

IL
(%)

TOC
(mg/g)

2.6
2.4
2.5
2.3
4.2
2.8
2.6

2.4
3.7
2.5
2.1
1.5
3.0
t.6
2.82

11

10
25

Table 5The maximum outbreak of bay scallop density on the San-in coast.

Bottomenvironment

SL
(mm)

IL
(%)

TOC
(mg/g)

3.5
4.4
2.8

1.1
1.7
1.6
1.5
1.4
1.9
1.7

3.4
7.4
5.5
6.6
5.1
5.1
6.3

1.56

5.60

4.7

t: metric tons.
Density

Individuals(10 6 )

Area
(km')

(t/km' )(Ind.lm')

District

Year

Catch
(1000 t)Tottori
ShimaneIshikawa

1924-251965
1966-67

28
18
39

350
225
487

453
988
1108

61.8
18.2
35.2

0.77
0.23
O.H

85

1062

2549

33.52

0.42

Total

Table 6Comparison of bay scallop spat collection between bottom and hanging method in 1982.
Avg. SL: Average shell length (Matsuyama and Takeuchi 1983).
Bottom collector (A)Hanging collector (B)Collector
setting
date

Recoverydate

Deposits(ind.)

Avg. SL(mm)

Deposits(ind.)

Avg. SL
(mm)

Ratio
(A/B)

February
February
February
March
March
April

March
April
June
April
June
June

24,932
8,787
2,920
873
849
138

1.0
2.2
14.3
1.9
6.2
12.0

185
876
1,035
21
19
17

1.0
5.9
14.9
1.9
5.5
11.0

134.8
10.0
2.8
41.6
H.7
8.1

Total

Research to Increase Bay Scallop Seed Resources
The deposition of swimming larvae in eddy zones withmuddy bottoms combined with heavy predation predicts
an area oflow survival. Therefore, to increase the production of the bay scallop in its natural environment, it is mostimportant to develop effective techniques for the collectionof shelled larvae to support a program of marine farming.

13.7

The new, bottom collecting method was developed andtested for this purpose.
Each collection bag in the new method had a total capacity of at least ten thousand larvae. A comparison of the
new and the traditional hanging method of larval collection was performed (Table 6). The new method proved
superior in all cases, collecting from 3 to 134 times theamount taken by the hanging method.

76

NOAA Technical Report NMFS 102: Marine Ranching

In order to increase the density of swimming bay scallop
larvae in the field, we must increase the number of adultbay scallop shells. The fecundity of natural shell (90-100
mm shell length) is about 7,290,000 eggs per shell while
shells from hanging cultures yield 27,529,000 eggs. Thus,
the latter produces 3.78 times more eggs. To increase thenumber of spawned eggs in the field, we should therefore
increase the numbers of hanging cultures. Thus, we canobtain the necessary numbers of swimming larvae from thecultured shells while using only one quarter to one third
the number of natural shells that would otherwise beneeded.

Conclusion_

Increasing the deposited larvae does not always result inincreased numbers of adult shell. The number of depositedlarvae are affected by many factors. In order to obtain highsurvival rates when we release larvae collected from~henatural environment, larval shell lengths should be greaterthan 30-50 m, and spat deposition sites should be low inorganic matter and silt content and provide good substrates
for byssus attachment.
Future research needs to focus on developing more
effective methods for collecting juvenile shells and improving techniques to mark and track shells used in research.

Citations_

Hotta, K.
1977. Swimming larvae and juvenile shell breeding of bay scallop,
Pecten (Notouota) albicans (Shroter). Hiroshima Pre£. Fish. Exper.

_

Stn. Rep. 9, p. 37-45.
Kasahara, S., and S. Itoh.
1985. Tsushima warm current-its oceanic structure and fisheries.
Suisan-gaku series 5, Koseihsa kouseikaku, Tokyo, 158 p.
Matsuyama, Y., and S. Takeuchi.
1983. Growth of bay scallop and its bottom environment. Jpn.
Sea Reg. Fish. Res. Lab., MRP Progress Rep. Bay Scallop and
Arkshell 3:47-53. (In Japanese.)
Moriwaki, S.. H. Semura, and S. Takeuchi.
1981. Growth of bay scallop and its bottom environment. Jpn.
Sea Reg. Fish. Res. Lab., MRP Progress Rep. Bay Scallop
1:44-57. (In Japanese.)
Tanaka. K. M. Nagahara, T. Akamine, and K. Ikehara.
1981. Swarm of bay scallop and its bed materials. Jpn. Sea Reg.
Fish. Res. Lab., MRP Progress Rep. Bay Scallop 1:86-121. (InJapanese.)
Tanaka, K., M. Nagahara, T. Akamine, T. Nakanishi, and K. Ikehara.
1982. Swarm of bay scallop and its bed materials. Jpn. Sea Reg.
Fish. Res. Lab. Marine Ranching Res. Prog., Progress Rep.
Bay Scallop 2:47:66. (In Japanese.)
Tanaka, K .. M. Nagahara, T. Akamine, T. Nakanishi, Y. Koshiishi,
R. Shibata, T. Nagasawa, and N. Naganuma.
1983. Swarm of bay scallop and its bed materials. Jpn. Sea Reg.
Fish. Res. Lab., MRP Progress Rep. Bay Scallop and Arkshell
3:15-33. (In Japanese.)T«naka, K .. R. Shibata, N. Naganuma, T. Akamine, and T. Nakanishi.
1985. On the gonad formation and spawning of bay scallop at thecoast of San-in area. Jpn. Sea Reg. Fish. Res. Lab., MRP Progress Rep. Bay Scallop and Arkshell 5:15-21. (In Japanese.)
1986a. On the gonad formation and spawning of bay scallop at thecoast of San-in area. Jpn. Sea Reg. Fish. Res. Lab., MRPProgress Rep. Bay Scallop and Arkshell 6:21-28. (In Japanese.)
Tanaka, K., K. Kitani, T. Akamine, and M. Tanaka.
1~36b. Anticipation for the aggregation of bay scallop larvae basedon infrared images. Jpn. Sea Reg. Fish. Res. Lab., MRP Progress Rep. Bay Scallop and Arshell 6:47-55. (In Japanese.)
Yuki, Y., K. Ishida, H. Semura, and S. Takeuchi.
1985. On the development of reasonable bay scallop collectors. Jpn. Sea Reg. Fish. Res. Lab., MRP Progress Rep. Bay
Scallop 5:44-57. (In Japanese.)Release of Hormonally Sterilized Coho Salmon
from a Puget Sound Hatchery
WALTON W. DICKHOFF
School oj Fisheries HF-15
University oj Washington
Seattle, Washington 98195
Northwest Fisheries Science Center
National Marine Fisheries Service2725 Montlake Blvd. East
Seattle, Washington 98112

CHARLES W. HOPLEY
Washington Department oj Fisheries
Olympia, Washington 98504

CONRAD V.W. MAHNKEN
Northwest Fisheries Science Center
National Marine Fisheries Service2725 Montlake Blvd. East
Seattle, Washington 98112

ABSTRACTThe purpose of the study was to evaluate the use of hormonally sterilized fish in a fisheriesenhancement project. Coho salmon (Oncorhynchus kisutch) at embryonic and fry stages were treatedwith 17a-methyltestosterone to prevent gonadal differentiation. The majority of the fish werereared at the Puyallup Salmon Hatchery, marked with coded wire tags and released as yearlings.
For physiological studies, subgroups of the fish were transferred from the hatchery to the freshwater
experimental hatchery in Seattle (NMFS), maintained for one year, and then transferred toseawater net pens. Gross examination of yearling fish in the treated group indicated 94% with
undifferentiated gonads. Growth, development, and seawater survival of the sterile and control
fish were generally equivalent. Analysis of data obtained from recoveries of released tagged fishin the fisheries revealed significant differences in the catch and distribution of control and sterile
fish. As expected, control fish were caught in 1986 only, whereas sterile fish were caught in both1986 and 1987. For 1986 and 1987 combined, the total catch offish from the sterile groups was
33 % lower than that for the control groups of fish. It is not clear from these data whether the
reduced catch of sterile fish could be due to decreased marine survival or to reduced efficiency
of catching the sterile fish. It can be concluded from these studies that the release of hormonallyneutered fish from hatcheries results in an extended time for harvest of fish and slightly larger
fish during the second year of harvest. However, the reduced numbers of sterile fish caught may
not justify these benefits.

Introduction_

Although sex of salmonids is normally determined by thegenetics of the individual fish, steroid treatment of fish earlyin development can reverse or eliminate sex determination(see review by Hunter and Donaldson 1983). Treatmentof salmon with appropriate doses of androgens during thetime of normal sex differentiation can block this process
and produce sterile fish. Since sterile salmon cannot reproduce, they will continue to live and grow beyond their normal age at reproduction.
77

78

NOAA Technical Report NMFS 102: Marine Ranching

There are many potential applications of sterile salmon
to fisheries enhancement and aquaculture (Donaldson andHunter 1982a). The elimination of sexual maturation andassociated deterioration of flesh allows year-round marketing of adult salmon. Eliminating precocious maturation ofmales should increase the number of fish which reachharvestable size. Extending the age of the fish may allow
the fish to grow to trophy-size. Since nonmaturing fish
should not return to the hatchery, a portion of the smolts
produced at the hatchery could, therefore, be specificallytargeted for the fisheries.
Large numbers of hormonally sterilized coho salmon(Oncorhynchus kisutch) were first released from a Canadianhatchery in 1980 as part of a study by Donaldson andHunter (1982b; Solar et al. 1986). The sterile fish did not
return to the hatchery as did the normal control fish, but
remained in the fishery for at least two additional years.
Overall, the control fish contributed to the fishery at approximately twice the rate of the sterile fish. Althoughinitial studies indicate that survival of hormonally sterilized salmonids in fresh water or in seawater net pens is
not compromised, the question remains regarding thefishery contribution of such fish after their release into theenvironment. The present study was designed to evaluate
the performance of hormonally sterilized coho salmon
before and after release from a hatchery in the Puget Soundbasin of Washington.

Methods and Materials_

Coho salmon used in this study were from the normal
production stock that returned to Puyallup Hatcherv(Washington Department of Fisheries). Eggs were collected from the 1983 brood, fertilized, and maintained inincubation trays (Heath-Techna) which were supplied withwater from Voight Creek (a tributary of the Puyallup
River) at ambient temperature. Fish were subjected tosteroid hormone treatment for sterilization similar to themethod of Hunter et al. (1982). On 10 and 17 January
1984 when the embryos were well-eyed and on 8 and 15
March 1984 when the alevins were at approximately 50%
yolk absorption, they were treated by immersion in a solution of 17a-methyltestosterone (MT; 300 ~g/L) for twohours on each date. Approximately 90,000 fish in total
received steroid treatment. When the fish were ponded,
the control groups were placed in Burrough's raceways,
and treated groups were placed in two rectangular fiberglass raceways (1 m x 1 m x 10 m). Starting with initial
feeding and extending for 90 days, the experimental fish
were fed a diet containing 20 mg MT per kg of diet.
BioDiet (Bio Products, Warrenton, OR) was used as thestarting feed; Oregon Moist Pellet (LaConner, WA) wasused as the production feed. After termination of feedingwith the treated diets, the experimental fish were placed_

Controls

2420-_-_-_-_-_-_-_-_-_-_-_~~OJ: : 16
.<:

:-.

OJ

'iii

3:

12

.

Steriles

-i) 8
o
CD

4

Dec

Jan

Feb

Mar

Apr

May

Jun

Date

Figure 1

Average body weight of fish in control and hormone-treatedgroups maintained at the freshwater hatchery in Seattle from
December 1984 to June 1985.

in Burrough's raceways. The fish were maintained outdoors under natural photoperiod and temperature (approximate range 4° to 14°C).
Both control and experimental fish (approximately
120,000 total fish) were marked with coded wire nose-tags;
tagged fish were identified by clipping the adipose fin. Bothcontrol and treated groups of fish were released as yearlings at the traditionai release time (4 May 1985) and, in
addition, at a delayed release time (30 June 1985). Eachof the four release groups were replicated once, so that there
was a total of eight tagging codes. All groups were released
into Voight Creek.
In December 1984, 1,500 fish from both the experimental and control groups were transferred from Puyallup
Hatchery to the freshwater hatchery facilities at the Northwest Fisheries Science Center (National Marine FisheriesService) in Seattle. The fish were maintained outdoors infour cylindrical fiberglass tanks (1.3 m diameter x 1 m
depth) supplied with dechlorinated municipal water at ambient temperature (5° to 16°C); the fish were fed Oregon
Moist Pellets. The groups of fish (20 fish per group) in
Seattle were weighed and sampled for blood at two-weekintervals to determine thyroid and androgenic hormone
levels during the parr to smolt transformation. On 15 May
and on 18 July 1985, times which corresponded approximately to release times at the Puyallup Hatchery, groupsof 150 fish from each group were transferred to floating
net pens in seawater (27°/00) at the National Marine Fisheries Service field station near Manchester, VI/A. The survival of the fish in seawater was determined for fourmonths.
Blood plasma concentrations of thyroxine (T4) were
determined according to Dickhoff et al. (1978); plasma
levels of total androgens were measured according to Sowerand Schreck (1982).

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Dickhoff et al.: Release of Hormonally Sterilized Coho Salmon

:§

30

1.2

E

Ol

.s
Q)

c

0,

... Males.. Females.... Steriles

1.0.s 0.8

20

c

x

Q)

e>-

Ol

e 0.6

.s::

I-

79

"0

c

10

<ll

0.4

<ll

E

<ll

E

l/l

11l

c:::

0.2

l/l

<ll

0

Mar

Apr

May

Jun

c:::

Ju I

0.0

Mar

Apr

May

Jun

J uI

Figure 2

Figure 3

Blood plasma concentrations of thyroxine during the parr to smolt
transformation (1985) of control and sterile fish maintained in
the freshwater hatchery at Seattle. Symbols indicate means;brackets indicate plus or minus one standard error.

Blood plasma concentrations of total androgen during the parrto smolt transformation (1985) of control and sterile fish maintained in the freshwater hatchery at Seattle. Symbols indicate
means; brackets indicate plus or minus one standard error.

Results

and lowest in the sterile fish. Plasma androgen levels were
below the limit of detection in 25 % of the sterile fish
assayed. Androgen levels appeared to increase near the endof May and beginning ofJune in the male and female fish,
but not in the sterile fish.
The survival of groups of fish transferred from the
freshwater hatchery in Seattle to seawater net pens showedsome slight differences between sterile and control groups(Fig. 4). In all groups initial mortality was low but mortality began to increase after one month in seawater. The
sterile groups however, showed higher mortality compared
to controls for both the May and July entries.
The fishery contribution of the control and experimental groups indicated that fish from both groups were caught
in 1986, but only fish from the sterile groups were caught
in significant numbers in 1987 (Fig. 5). However, the total
recovery of released sterile fish was 15% in 1986, but only
0.3% in 1987. In both 1986 and 1987 the percent of fishcaught from the May release groups was higher comparedto the June release groups. In 1986 sterile fish contributed
approximately 30 % less than the controls. These data indicate that regardless of release time, the contribution of
the sterile fish for both years was less than that of controls
for one year.
The 1986 c.ontribution of the four release groups to specific fisheries indicates that there were no major differencesin the distribution of control and sterile fish (Fig. 6). As
expected from previous information on the migrationroutes of this stock of fish, there was little contribution to
the Oregon fisheries. The largest contribution was to the
Puget Sound net fishery, followed by the British Columbia
troll, British Columbia net, and Puget Sound sport fisheries There was a slightly greater contribution of the sterile
fish to the British Columbian troll and net fishery at theexpense of the Puget Sound net fishery (Fig. 6).

_

The body weights of fish sampled from the experimental
and control groups are shown in Figure 1. The average
body weight of the experimental group (steriles) was lessthan that of the control fish at the time the fish were obtained from the hatchery. The difference in average bodyweight between the two groups developed when the fish
were maintained in the fiberglass raceways during the hormone treatment. During the sampling period, the steriles
grew slightly faster than the controls so that their average
body weight at the end of June was about 20 % smaller.
The ration of the fish at Puyallup Hatchery was controlled
to produce equivalent-sized fish at the times of release. For
the 4 May release, the average body weight of the control
groups was 25.2 g and that of the steriles groups was 24.8 g.
For the 30 June release both groups had average bodyweights of 37.8 g. Macroscopic analysis of the gonads of
160 yearling fish examined from the groups maintainedin Seattle indicated 94% of the experimental group had
no distinguishable gor.ads.
The plasma concentrations of thyroxine (T4) during theparr to smolt transformation showed similar patterns forboth the sterile and control fish held at the hatchery in
Seattle (Fig. 2). During the early period of sampling, themean level of T 4 was lower in the sterile compared to thecontrol fish. However, both groups showed a peak inplasma T 4 in mid-May followed by a decline by the beginning ofJune. These data suggest that the timing of smoltification was equivalent in both groups, and that smoltification was completed by early June.
The blood plasma concentrations of total androgens
showed variable patterns among the groups and throughout
the sampling period (Fig. 3). The average androgen levels
were highest in the male fish, intermediate in the females

80

NOAA Technical Report NMFS 102: Marine Ranching

~

50

.~

40

_

~

n;

~

30

Ql

20

~

.~

Cii
:::>

E

... contro

_____

:::>

()

~
.

10
.~

0

May

t

Jun

Jul

+

Aug

Sep

d ..

Sterile... Control

Figure 4
Cumulative seawater survival of control and sterile fishtransferred from the freshwater hatchery in Seattle to net
pens in seawater during 1985. Groups were transferred in
May and in July.

Oct

I

Seawater Entry

Seawater Entry

1'1 May release~ June release
20

~
"0
Q)

Ul

ell
Q)

Q)

a: 10
.<::.

Ul

0.1

~

..c:

B

ell

()

0.0

0

Control

Sterile1986-

Control

Sterile1987

There was some return of the fish from the sterile groups
to the hatchery. When the data are expressed as percent
of total catch, a greater proportion of the sterile groups(11%) returned to the hatchery compared to the controls(8%).

Discussion_

The fish from the androgen-treated groups (steriles) survived and contributed to the fisheries for at least one year
beyond the normal time of adult maturation, as anticipated. However, the overall performance of the sterilegroups of fish appeared to be poorer compared to controls;
growth rate was slower, seawater survival was slightly
reduced, and the fishery contribution showed a 30% reduction. The reason for the reduced performance of the sterile
fish is not clear.
Previous studies on the release of sterile salmonids havealso shown a reduced contribution or survival of the sterile
fish. Coho salmon releases from the Capilano Hatcheryin British Columbia indicated that the fishery contributiorl

Figure 5Contribution of contr')l and sterile group of fish to thefishery during 1986 and 1987. Fish were released from the
Puyallup Hatchery in May and June 1985. Bars indicate
mean of replicated groups.

of the sterile group was only 45 %Jthat of the control fish
(Solar et al. 1986). Releases of sterile coho and kokanee
salmon (0. nerka) into a lacustrine environment suggested
that survival or recapture of the sterile fish was markedly
reduced (Parkinson and Tsumura 1988). Releases of sterilechum salmon (0. keta) from the west coast of Vancouver
Island resulted in no recoveries of the sterile fish (E.M.
Donaldson, Department f)f Fisheries and Oceans, West
Vancouver, B.C. V7V 1N6. Canada, pers. commun.,
October 1988). Possible causes could be speculated for the
reduced contribution of the sterile fish. Sterile fish may
have reduced survival owing to poor physiological adaptability or reduced ability to avoid predators, among otherpossibilities. Alternatively, reduced contribution or recovery of sterile fish may be apparent because they are lessvulnerable to capture gear. Furthermore, migration patterns of the sterile fish may differ from those of normal fish
so that the steriles do not enter traditional fisheries.
Reduced growth or development of the sterile fish ineither fresh water or seawater environments may result in
reduced physiological adaptability. Our findings of slightly
retarded growth and seawater adaptability support this_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Dickhoff et al.: Release of Hormonally Sterilized Coho Salmon

•

50

IZI

13
E21

40

81

May Control
May Sterile
June Control
June Sterile

Percent 30
of total
20

10
0

e

f-

c

0
0>
(])

0

t

0

a.

CfJ

c

0
0>
(])

0

"u
~

co

Qi

z

U

co

t

0

0

a.

CfJ

~

u
co

:'i:

<I:

t

Qi

0

z

CfJ

-0

a.
c

ro

(])

U

0

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:'i:

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ro

0

2

C
:J

CIl

:r:

-0

CfJ

:::l

Qi

0

a.
~
n;

CIl

Qi

:J
Cl.

0

0>
:J
Cl.

c

Cl
:::l

ll.

hypothesis. The lowered levels of blood androgens may be
one cause of reduced growth, since growth-promoting effects of androgenic hormones are well-established (Higgs
et al. 1981). On the other hand, the pattern of thyroid hormones during smoltification and initial seawater survivalof the sterile fish did not show significant differences compared to control fish.
The reduced level of androgens in the hormonallysterilized fish suggests that not only the gametogenic activity but also the steroidogenic capacity of the gonadal
tissue has been modified. The source of the measured circulating androgens in the sterile fish may be the interrenal
gland. In addition to possible growth retardation, thereduced levels of androgens in the sterile fish may affecttheir behavior. Androgenic hormones contribute to aggressiveness, and such a behavioral trait may be important in food capture or other survival behaviors. Routesof out-migration or homing migration may be partly dependent on reproductive steroids, although our data do notindicate major differences in the geographic distributionof the fish as assessed by their appearance in specificfisheries.
It can be concluded from these studies that the releaseof hormonally neutered fish from hatcheries results in an
extended time for harvest of fish. However, the reduced
numbers of sterile fish caught may not justify this benefit.
Our present findings, as well as the previously publishedresults on releases of sterile salmonids, do not support
widespread application of sterile salmon as a management
tool for fisheries enhancement at the present time. Further
research is needed to determine the causes of the reduction in contribution by the sterile fish. It is conceivable thatpossible developmental or physiological deficiencies ofsterile fish may be compensated for by restoring the normal androgen levels in the fish.

>.

Figure 6
Percent of total catch in 1986 for each group of fish
released from the Puyallup Hatchery. Bars indicate
mean of replicated groups. Fisheries were separated
as Oregon troll and sport; British Columbia (BC)troll, sport, and net; Washington (WA) ocean troll
and sport; and Puget Sound net and sport fisheries.

Acknowledgments_

This work was supported in part by grants from Washington Sea Grant (Project R/A 49) and the National
Science Foundation (#DCB 8615521) to W.W. Dickhoff.
We thank the following individuals for their assistance inthe many phases of this work: Don Ferron and Larry Peckof the Washington Department of Fisheries; F. William
Waknitz and Ron Sailer of the National Marine FisheriesService; Melinda G. Bernard of the University of Washington and Dr. Samuel Milham of the Washington Department of Social and Health Services.

Citations_

Dickhoff, W.W., L.C. Folmar, and A. Gorbman.
1978. Changes in plasma thyroxine during smoltification of coho
salmon, Oncorhynchus ktsutch. Gen. Compo Endocrino!. 36:
229-232.
Donaldson, E.M., and G.A. Hunter.
1982a. Sex control in fish with particular reference to salmonids.
Can. J. Fish. Aquat. Sci. 39:99-110.
1982b. The ocean release and contrIbution to the fishery of allfemale and sterile groups of coho salmon (Oncorhynchus kisutch). In
Proc. Int. Sytnp. Reprod. PhysioL Fish: 1-61982, Wageningen,the Netherlands (C.J.J. Richter and H.J.Th. Goos, comptlers),
p. 78. Centre for Agricultural Publishing and Documentation(Pudoc), Wagenins"n.
Higgs, D.A., U.H.M. Fagerlund, ]G. Eales, and JR. McBride.
1981. Application of thyroid and steroid hormones as anabolic
agents in fish culture. Camp. Biochem. Physio!. 73B: 11-3-176.
Hunter, G.A., and EM. Donaldson.
1983. Hormonal sex control and its application to fish ~ultL!re. In
Fish physiology (W.S. Hoar, D.]. Randall, and E.M. Donaldson,eds), p. 223-203. Acad. Press, NY, Va!. 9B.
Hunter, G.A., E.M. Donaldson, F.W. Goetz, and P.R. Edgell.
1982. Production of all-female and sterile coho salmon, and experimental evidence for male heterogamety. Trans. Am. Fish.

82

NOAA Technical Report NMFS 102: Marine Ranching

Soc. 111: 367?372.
Parkinson, E.A., and K. Tsumura.
1988. Growth and survival of hormone-sterilized coho (Oncorhynchus kisutch) and kokanee salmon (0. nerka) in a lacustrine env:ronment. Can. J. Fish. Aquat. Sci. 45:1490-1494.
Solar, 1.1., I.J. Baker, E.M. Donaldson, G.A. Hunter, and E.T. Stone.
1986. Coded wire tag recoveries from the first release of all-female_

and sterile groups of coho salmon (Oncorhynchus kisutch) into themarine environment. Can. Data Rep. Fish. Aquat. Sci. 609,
29 p.
Sower, S.A., and C.B. Schreck.
1982. Steroid and thyroid hormones during sexual maturation ofcoho salmon (Oncorhynchus kisutch) in seawater or fresh water. Gen.
Compo Endocrinol. 47:42-53.

Large-Scale Culture System for Attaching Microalgae

NOBUHIKO TANAKA
National Research Institute oj Aquaculture
Fisheries Agency
Nansei, Mie 516-01, Japan

ABSTRACTA stable microalgae foodsupply is necessary for the mass-production of marine animal seedto support marine farming in the coastal waters of Japan. Thus, a new apparatus for the masscultivation of attaching diatoms is described. Composed of a cylindrical glass vessel (diameter10 em, length 100 em), nylon brush, and stainless steel rings, it is designed to maximize thesurface area for diatom growth, and allow easy harvesting. After the initial inoculation of diatoms,
filtered natural seawater is continuously flowed through the vessel under natural light conditions.
A maximum of about 350 g of diatoms (wet weight) per month is produced with a harvest interval of three days. The diatoms harvested were useful as food for young sea cucumber and scallops.
An attempt to culture monospecific diatom, using the modified apparatus and application of theapparatus to tertiary treatment of waste water, is also mentioned.

Introduction_

It is becoming increasingly important to effectively utilize
the coastal fisheries areas when we consider the changes
occurring internationally-especially under the enactment
by many countries of a "200 mile exclusive zone." Injapan, sea farming is considered a useful technology andis playing a greater role than ever before in the resource
management of the coastal fisheries. Nowadays, various
kinds of seed of marine animals are produced and liberated
to natural !1abitats. In order to supply seed on a mega-scale,the stable mass-production of food organisms for these larval and young animals is necessary and has become a subject of primary importance.
"Attaching microalgae," particularly diatoms, are wellknown as an important food for young abalone, sea cucumbers, and sea urchins. Furthermore, it has been foundthat attaching diatoms promote the settlement and metamorphosis of marine animal larvae such as sea urchin,sea cucumber, and sea moss (Tani and Ito 1979; Z. Ikeda,
Okayama Prefectural Fisheries Station, Ushimado, Oku.
Okayama 701-43,japan, pers. commun. August 1988; andKitamura and Hirayama 1987, a and b; respectively). Tani
and Ito (1979) examined the effects of attaching diatoms on
the settlement and metamorphosis rate by using thepluteus larvae of sea urchin. They reported that larvae only
settled on the bottom of tanks containing attachingdiatoms, and that the metamorphosis rate to young sea

urchin increased with the number of diatoms on thebottom.
Attaching diatoms have been cultured on the surface of
polyvinylchloride or polycarbonate plates in tanks withflowing seawater. In the seed production system for abalone
and other species, larval and young animals are usually
reared together on the same plates. The balance between
production and consumption of the algae plays an important role in the effective production of seed, and food deficiencies occur frequently owing to overcrowding.
In the present paper, the author describes a new apparatus for the mass-cultivation of attaching diatoms, andits various applications. The apparatus made it possible
to isolate the process of algal culturing from the rearingof seed animals. The new source of harvested massproduced cells may lead to a better technology for the seedproduction of useful marine animals.

Growth of Diatoms that attach
in Natural Seawater_

Attaching diatoms characteristically adhere to various
living or nonliving substrata, taking up nutrients fromthe surrounding seawater. If sufficient amounts of freshseawater are continuously supplied, they can even growin seawater which is very poor in nutrients. Figure 1 shows
the growth rate of Nitzschia closterium in flowing nutrient83

84

NOAA Technical Report NMFS 102: Marine Ranching

/

~'if
w
....J
u 103

I

/
/

V
I

l

_

i

2

10 1:-------''------:-:lo'"=o---'-----::-zo':-:o:--·-L--3Loo---'I-----I.--l-'-O-O--'--·-2-'-O-O--'--~-_I_IM_E_-_h_o_u_r_-----'

poor natural seawater « 10 lAg atomic inorganic NIL and1 lAg atomic P/L as phosphate) comparable with that in abatch of the nutrient-enriched "Erd-Schreiber" culture
medium (more than 1400 J.Lg atomic inorganic NIL and
6 J.Lg atomic P/L as phosphate) (Tanaka 1984, 1985;'.
The maximum yield of cultured diatoms is strongly
dependent on the available surface area for cell attachment.
Generally, maximum cell density is about 10 5 -10 6 cells
per cm 2 with excess cells seeming to scale off the subsUata
when overcrowding occurs.
Thus, the two factors, seawater flow rate and surface
area for cell attachment, are of primary importance in thedesign of apparatus for the culture of attaching diatoms.

Cultivation Apparatus andHarvest of Cultured Diatoms_

The apparatus, illustrated in Figure 2, is composed of acylindrical glass vessel (diameter 10 em, length 100 cm),nylon brush with stainless steel axis, and stainless steel
rings. The nylon brush, also 10 cm and 100 crn, has 78,000
filaments, the diameter of each being 0.22 mm. Consequently, the surface area is about 3 m 2 per brush. The
cultured diatoms attached to the filaments are harvested
by moving the stainless steel rings up and down.
Approximately eight liters of a diatom suspension containing a few grams of diatoms (wet weight) was inoculated
into the vessel. After thirty minutes, attachment of inoculated diatoms to the brush filaments was completed andsand-filtered natural seawater, which removes particles >50
J.L!min diameter, was continuously flowed through the vessel
from the lower side at the rate of at least 40 Llh.

Figure 1
Growth curves of Nitzschia closterium in abatch of nutrient-enriched culture
medium (left) and in running nutrientpoor natural seawater (right). After
Tanaka (1984).

During seven to ten days cultivation under natural light
conditions, the diatoms proliferated and the nylon brushbecame dark brown in color because of the high densityof cells. At this time the first harvest was made. A small
portion of the diatoms always remained on the filaments
after harvesting, thus re-inoculation was not necessary.
Thereafter, cultured diatoms were harvested at an interval of several days. The relationship between the yield of
the harvest and the period of harvest interval is illustrated
in Figure 3. As calculated from the figure, the maximum
yield per month was about 350 g wet weight with a harvestinterval of three days. The data in Figure 3 was obtained
from late autumn to early spring and, from the author's
experiences, reflects expected yields the year round as well.
The composition of diatom harvests changed seasonally.
However, the major species were always Nitzschia spp.,
Navicula spp., a Pleurosigma sp., and an Amphora sp. Tanaka(1987a) described the successional sequence of marine
attaching biocommunities on fresh substrata. In general,
attaching biocommunities are dominated in order bybacteria, motile solitary diatoms, nonmotile colonial
diatoms and larger sessile plants and animals. The major
diatoms cultured in the apparatus all belonged to the motile
solitary diatom group occurring in the earliest stage of attaching diatom succession. The progress of diatom succession seems to be retarded with renewal of the brush surface after intermittent harvesting.
Under the continuous running of the apparatus, populations of filamentous green and blue-green algae gradually increased, which seemed to suppress the growth of
diatoms. They were quite cohesive and were not removedby the up and down movement of the rings. Consequently
the nylon brush needed to be replaced by a new one at

__________________________ Tanaka: Culture System for Attaching Microalgae

r

out

85

100

ntn
•
,•

r

Vi

2

.D

v

"!:-A

a;
>.

(;1

.
•
.'••

so

.....
'5

<!J

3

,•

•

I.

•
o

'2

4

6

8

10 12
days

lG 18 20 22

Figure 3
The relationship between the yield and the period of harvestinterval

I

Table 1
Rearing experiment of blueish type sea cucumber Stlchopus
japonicus Selenka led with frozen attaching diatoms.

t
in

Body
(mm)

Figure 2
Schematic diagram of the mass-cultivation apparatus for attaching microalgae. (A) cylindricalglass vessel; (B) nylon brush; (C) stainless steel
rings.

an interval of three months in summer and four months
in winter.
The harvested diatom cells formed suspended flocs,
which were easily collected by sedimentation within several
to ten minutes. These living diatoms can be used easily
as food for abalone and other species because of theiradhesive character which enables them to attach to substrata such as polyviny1chloride plates. The cells can be
stored in a freezer after centrifugation and remain usable
as food without appreciable decrease in performance (seediscussion below).

Rearing of Young Sea Cucumber_

Frozen attaching diatoms have been reported to be good
food for young sea cucumbers by Yanagibashi et al. (1984).
Ikeda and Kusaka of the Okayama Prefectual Fisheries Sta-

Body
wet
(mg)

Individuals

Initial

1.7

0.3

62000

After 34 days

14.3

91.3

36000

Survival(%)

58.5

tion also examined the food value of frozen attachingdiatoms cultured by the author, using the present apparatus(Table 1; Z. Ikeda and K. Kusaka, Ushimado, Oku, Okayama 701-43, Japan, unpub!. data). In this study the average body length of sea cucumbers increased from 1.7 mm
to 14.3 mm within only 34 days, much greater than theliberation size of 10 mm which is the adopted standard in
Okayama Prefecture. The body weight increased from 0.3
mg to 91.3 mg. A total wet weight vf20 kg frozen diatoms
was necessary for the production of 3.3 kg of sea cucumber
seed. These results show that the cultured diatoms havea very high level of performance as food for sea cucumber.
In addition, the supply of food is easily controlled by theseparaiion of algal and seed production and a higher seedproduction efficiency results in comparison with the former
method. vVhen using the same polyviny1chloride plate for
producing both diatoms and young sea cucumbers, it takes
at least six months for seed to reach about 10 mm in length
as opposed to approximately one month for the growth ofan even larger seed with the new techniques.

86

NOAA Technical Report NMFS 102: Marine Ranching_

Table 2
Species compositions of microalgae in the seaW'iter and the contents of intestinal tract of bivalves at Gokasho
Bay, Mie Prefecture (Tanaka 1987b). A: noble scallop Chlamys nobilis (Reeve); B: pearl oyster Pinctadafucata(Gould); C: oyster Crassostrea gigas (Thunberg); D: mussel Mytilus edulis Linne.
Seawater contents (%)
1987

Planktonic species
Peridinium sp.
Gymnodinium nagasakiense
Gyrodinium spp.
Dinophysis acuminata
Dic/yocha fibula
Polykrikos spp.
Prorocentrum spp.
Heterosigma akashiwo
ChattOCtrOS spp.
Eucampia sp.
Rhizosolenia sp.
Skeletonerna costatum

1 Jan.

20 Feb

23 Mar

3.2

1.3

17.8
0.2
9.0
0.5
0.5
0.4
8.9
0.1

1.3
0.6
0.6
1.3
65.1
2.5

92.9
3.5
2.2

62.4

Intestinal contents (%)
10 Feb. 1987
A

B

C

5.5

0.8
0.8

1.1

31.5

26.1

12.1
2.2

D

14.8

1.1

24.8

13.8

Epiphytic species
Coceoneis spp.
Nitzschia spp.
Navicula spp.
Coscinodiscus sp.
Gomphonerna sp.
Others

36.3
11.0
15.4
4.4
2.2
11.0

15.4
10.0
20.0
5.4
6.2
10.0

17.6
10.6
10.1
3.7
1.6
14.3

39.3
13.1
11.5
1.6
1.6
18.0

- - - - - - _ .. _ . _ -Rearing of Young Scallops_

The author has examined the intestinal contents of four
species' bivalves taken from natural conditions (Table 2;
Tanaka 1987b). These data do not necessarily reflect theexact compositions of food algae because of the destruction of naked flagellates and planktonic diatoms with thinsilicic frustules in the intestinal tracts. However, attachingdiatoms are undoubtedly an important part in the foodcomposition of the bivalves' diet. In fact, attaching diatoms
released from their substrata are observed in natural
seawater, particularly in the innermost portion of Gokasho
Bay, which is used as a shellfish culture ground (pers.
observ.). Tanaka (1987b) also reported that the densityof "drifting" attaching diatoms in seawater was 10 3 -10 5
cells per liter all the year round in the innermost portionsof Ago Bay (depth ::::2-5 m), Mie Prefecture, Japan.
In Japan, young or adult bivalves have scarcely beenreared in tanks except during scientific experimentation.
When rearing experimental bivalves, it is tedious for researchers to culture a large amount of food microalgae suchas Chaetoceros and Isochrysis. If the diatom cells culturedJ.sing
the present apparatus are' useful as food for bivalves, thescientific study of bivalves will become less difficult.
The author examined the growth and survival of two
kinds of young scallop (noble scallop Chlamys nobilis Reeve

and Japanese scallop Pecten albicans Schr6ter) fed solely
with attaching diatoms. Fresh diatoms were dissociatedwith an ultrasonic generator to each cell and dispersed ina tank through which sand-filtered seawater flowed(Tanaka 1988, unpub!. data). In the case of the noble
scallop, the shell height and wet weight with shell increased
from 23.0 ± 3.0 mm and 2.5 ± 0.9 g to 27.1 ± 3.7 mm
and 3.4 ± 1.3 g, respectively, within 50 days rearing. The
survival rate was high (97.1 % ) compared with that of thecontrol experiment (29.0%) without feeding. In the caseof Japanese scallop, the shell height and wet weight withshell also increased, from 19.8 ± 1.9 mm and 1.1 ± 0.3 g
to 23.4 ± 2.1 mm and 1.8 ± 0.5 g, respectively, within thesame time period. Although the growth ofJapanese scallop
was low, a high survival rate of 92.5 % was obtained in
the experimental groups, compared to only 2.5% in thecontrol without feeding. These results show that cultured
attaching diatoms are useful at least as supplementary foodfor both scallops.

Single-Species Culture_With the process of mass-culturing diatoms mentioned
above, various kinds of unfavorable diatoms can easily
contaminate the apparatus. The production of mono-

____________________________ Tanaka: Culture System for Attaching Microalgae

Table 3
Ratio (% cell number) of Navicula ramosissima in the harvest
obtained by the large scale system for single species cultureof attaching microalgae.

size)

Yield inwet wI.

DateofharvestTime(days)

ramOSlsszma

Otherdiatoms'

1987
20 Nov
04 Dec.
16 Dec.
28 Dec.

(0)
(8)
(20)
(32)

100.00100.00
99.97
99.95

0.00
0.00
0.00
0.01

0.00
0.00
0.03
0.04

1988
05 Jan.
13 Jan.

(40)
(48)

99.65
94.65

0.09
3.82

O.~ti

Navicula

87

Protozoa(g)-----_._.-

1.53

lightl
506
7.90
37.10

1

2UO
38.50

diatom cells

Figure 4
Methodology for unialgal cultivation.

"Predominantly Nitzschia clostcriurn

40

A

species diatom cultures, having high growth rates and the
maximum food value for a targeted marine animal, wasdesired. The author modified the present apparatus in an
attempt to culture Navicula ramosissima (a strain isolated by
Saga Prefectural Sea Farming Center) by the process illustrated in Figure 4. As shown in Table 3, the unialgal
culture was maintained for forty days. The research fordevelopment of the unialgal mass-culture system is continuing and the final results will be published later.

oApplication to
Waste Water Treatment

30_

As mentioned earlier, attaching diatoms can proliferate incontinuously supplied nutrient-poor fresh seawater andalso in a nutri,,:nt-enriched medium with efficient use ofnutrients. Therefore, the continuous flow system of thepresent apparatus can be easily applied to tertiary treatment of waste water. At the present time, the removal of
inorganic nutrients from waste water after decompositionof organic matter is rather neglected in Japan.
The uptake rates of nutrient salts by attachiug diatoms
were examined by using a miniature version of the apparatus (Tanaka and Ohwada 1986) The diameter andlength oithe vessel were 5 cm and 50 cm, respectively. The
brush had 21,000 filaments which were 0.20 mm indiameter, yielding a total of 0.33 m 2 surface area. The
relationship between the uptake of nutrients and their concentration in seawater under the experimental conditions
is illustrated in Figure 5 and 6. The results show thatdiatoms can efficiently remove the nutrients, particularly
phosphate P (Fig. 6), from seawater. By harvesting diatoms
from the apparatus at suitable intervals, diatoms would reo

..

50

B

'

~~­

p

100

.--

x

I
100
Concentration (Ilg atoms NIL)

Figure 5
The r~lationshlp betwpen diatoms uptake of nitrogen (g atomequivalent) and nitrogen concentration in seawater. Flow rateis 2.41 Llh. (A) Nitrogen source is N0 3 ; (B) nitrogen source
is NH 4 .

main in their active growing phase and take up the nutrient
salts from the tlowing seawater.
There seems, however, to be many technical problems
in the application of the apparatus to waste water treat-

88

NOAA Technical Report NMFS 102: Marine Ranching

Citations

o

10

20

Concentration (lJg atoms PjL)
Figure 6
The relationship between diatom uptake of phosphorus CJ.tg atomequivalent) and phosphorus concentration in seawater. Flow rateis 2.41 Llh. X signifies that nitrogen source is N0 3 ;signifies that nitrogen source is NH 4 .

°ment systems. For example, a portion of nitrate is reduced
to nitrite by passing through the apparatus. Nitrite is toxic
to various marine animals. More experimental work nf:'eds
to be conducted to resolve these problems.

Acknowledgment
This investigation was supported by the Marine Ranching
Program sponsored by the Agriculture, Forestry, and Fisheries Research Council (MRP V-2-(1)-1-b and IV-l-(2)-1-c).

__

Kitamura, H., and K. Hirayama.
1987a. Effect of primary films on the settlement of larvae of a
Bryozoan Bugula neritina. Nippon Suisan Gakkaishi 53:
1377-1331.
1987b. Eflect of cultured diatom films on the settlement of larvaeof a Bryozoan Bugula neritina. Nippon Suisan Gakkaishi 53:
1383-1385.
Tanaka, N.
1984. The cell division rates of ten species of attaching diatoms innatural seawater. Nippon Suisan Gakkaishi 50:969-972.
1985. An application of dialysis bags; measurement of in situ growthnUl' of naturally attached micro-algae.
Nippon Suisan Gakkaishi
51:745-748.
19!17a. Microorganisms and attaching diatoms. In Marine fouling organisms and aquaculture (T. Kajiwara and K. Koseikaku,eds.), p.18-27. (In Japanese.)
1987b. Attaching diatoms as natural food for bivalves, and its
cultivation. Suisan Doboku 24:37-41. (In Japanese.)
1988. Improvement of fish culturing ground by using bottom layerseawater. b, Marine Ranching Program (Itayagai, Akagai) Progress Report 8, p. 19-22. Jpn. Sea Reg. Fish. Res. Lab. (InJapanese.)
Tanaka, N., and K. Ohwada.
1986. Profitable use ufbottom layer seawater. In Annual Research
Report of Marine Ranching Program, p. 182-183. Agri. Forestry
Fish. Res. Counc. (In Japanese.)Tani, Y., and Y. Ito.
1979. Effect of attaching diatom on the settlement and metamorphosis of larval sea urchin. The Aquaculture 27:148-150. (InJapanese.)
Yanagibashi, S., T. Yanagisawa, and K. Kawasaki.
1984. A studv on the rearing procedures for the newly settled youngof a sea cucumber, Stichopus Japonicus, with special reference to the
supplied food items. The Aquaculture 32:6-14. (In Japanese;
English summary.)

The Importance of Smolt Development to Successful
Marine Ranching of Pacific Salmon

W.S. ZAUGG AND C.V.W. MAHNKEN
Northwest Fisheries Science Center
National Marine Fisheries Service, NOAA
2725 Montlake Boulevard East
Seattle, Washington 98112

ABSTRACT
Fall run, underyearling chinook salmon (Oncorhynchus tshawytscha) released from four different
hatcheries into the Columbia River system migrated faster as distance from the point of releaseto the estuary increased. Also, migrants traveling greater distances were more inclined to moveto midriver by the time they reached the estuary. Fish released in various stages of smolt development, as measured by gill Na + - K" ATPase activity, exhibited differences in migratory behavior
and survival to adulthood. Those with more complete prerelease development a) migrated seaward
more rapidly and were recovered at the upper entrance to the estuary in greater numbers thanfish showing little or no smolting tendency at release, b) were recovered more frequently in midriver
locations as opposed to nearshore areas for fish less well developed at release, and c) survived
to adulthood in greater numbers. This study indicates that the degree of prerelease smolt development affects postrelease behavior and survival and is an important facet of the hatchery rearing
period.

Introduction_

Ultimately, the measure of success in the marine ranchingof hatchery-reared salmonids is how many juveniles survive and contribute as adults. Although there are manyenvironmental and developmental factors involved in determining survival or contribution, none of these can be
designated most important all of the time. For example,
one year a specific ocean condition may playa predominant role in determining survival, whereas another year
the primary regulator of survival may be predation in theestuary, disease in the hatchery population, malnutrition,or any other of many factors. Investigators have proposedthat survival of hatchery coho salmon (Oncorhynchus kisutch)
in the northeastern Pacific Ocean off the coasts of northwestern United States and Canada is much better in yearsof strong upwelling (Gunsolus 1978; Nickelson 1986).
Others have suggested that survival is density dependent(McGie 1981; McCarl and Rettig 1983) especially in yearsof low upwelling (McGie 1984; Peterman and Routledge1983). Fisher and Pearcy (1988) found that high mortalityof coho salmon juveniles occcurred within one month ofocean entry and that poor survival was not associated withstarvation or low growth rates. They suggested that highpredation may be responsible for low survivals and that
this condition may be intensified in years of low upwelling. Hvidsten and Hansen (1988) reported increased numbers of adult Atlantic salmon (Salmo salar L.) recovered fromhatchery smolts released during high water discharge andalso concluded that predation during low discharge was
responsible for decreased survival.
General health or cond;tion of hatchery fish is known
to influence ocean survival. High rearing densities adversely affected survival of coho salmon (Fagerlund et al.
1983; Sandercock and Stone 1982) and yearling springchinook salmon (0. tshawytscha) O.L. Banks, Abernathy
Salmon Culture Technology Center, Longview, WA
98623, pers. commun., Nov. 1989). High rearing densities
appear to affect smolt physiology by retarding developmentof increased plasma thyroxine levels, gill N a + - K + ATpase activity and blood sodium regulatory ability (Schreck
et al. 1985; Patino et al. 1986). Other hatchery conditions
that create stress also affect the ability of the juvenile salmon
to develop and function normally (Schreck 1982; Wedemeyer et al. 1984)_
Few studies have looked at the relationship between
smolt development in the hatchery and postrelease performance (e.g., seaward migration and survival to adulthood).
89

90

NOAA Technical Report NMFS 102: Marine Ranching

Among other changes, active seaward migration of smolts
is accompanied by elevated levels of gill Na + - K + ATPase
activity (Zaugg and Wagner 1973; Bjornn et aI. 1978;
SchrecketaI. 1980; Hartetal. 1981; Buckman and Ewing
1982; Zaugg 1982a; Weitkamp and Loeppke 1983; Rondorf et aI. 1985, 1988; Zaugg et aI. 1985; Rodgers et aI.
1987), gill succinic dehydrogenase activity (Langdon and_Thorpe 1985; Chernitsky 1986), and skin guanine content(Rodgers et aI. 1987).
Greater adult contributions have been compared tohigher gill Na + - K + ATPase activity at release in coho
salmon (Wahle and Zaugg 1982). Soivio and Virtanen(1985) reported that adult recapture rates were higher
in hatchery-reared Atlantic salmon that had been

Table 1
Release dates and mean weights of underyearling fall chinook salmon from 15 Columbia River hatcheries (Vreeland 1990).

_ _ _ _ _ _ _ _ _ _ _ _ Zaugg and Mahnken: Smolt Development and Marine Ranching of Pacific Salmon

91

judged to be better smolts using a series of physiologicalindices.
This report 1) examines in- and between-year variationsin adult survival of fall chinook salmon released as underyearlings from fifteen Columbia River Basin hatcheries,2) looks at the influence of migration distance on rate of
migration and horizontal position of juvenile migrants asthey approach the estuary and, 3) reports adult returns
from juveniles released during five successive years at one
specific hatchery in comparison to degree of smolt development as measured by pre-release gill N a + - K + ATPase
activity and by post-release migratory behavior.

to the recovery point at Jones Beach by the number of days
from the first day of release to the date of median fishrecovery. In 1979 underyearling chinook salmon withcoded wire tags (some groups in replicate) were released
at approximately the same time in June from four hatcheries located at varying distances from Jones Beach. Migrants were captured at Jones Beach with purse and beachseines as described earlier. Adult recovery information was
obtained from the Pacific Marine Fishery Commission,
Portland, Oregon, and from Vreeland (1990). Adult
recoveries were estimated from samples of the commercial
and sport fishery catches and hatchery returns.

Materials and Methods

Results_

All fish used for gill ATPase determinations were underyearling fall chinook salmon. Fish were taken randomly
from production ponds (biweekly) by dip net, killed by ablow to the head, weighed (g), and measured (fork length,mm). Gill filaments were trimmed from the arches, placedin buffered sucrose, and stored at - 25°C until analysis of
Na + .. K + ATPase activity (/Amoles Pi . mg protein - I • h - 1)
as described by Zaugg (1982b). On each sampling date during the period 1978-80, samples of gill fllaments were takenfrom 30 fish. These were divided into 10 assay samples,
each containing gill filaments from 3 fish. In 1981 and198:2, 10 to 40 fish were taken on each sampling date andused for individuai ATPase analysis.
Migrants were captured daily in the Columbia River at
Jones Beach, Oregon, 75 km upriver from the mouth andidentified from coded wire tags. Captures were accomplished nearshore by seining from the beach with a 95-mseine and in deep-water, midriver channels using a purse
seine (Dawley et al. 1985). Numbers of migrants caught
were adjusted to a standard fishing effort. Migration rates
were estimated by dividing the distance from release points_

In a 4-year study described by Vreeland (1990), fallchinook salmon released as underyearlings from 15 Columbia River hatcheries weighed less than 10 g (Table 1).
Although annual differences in weight were not great at
any given hatchery there were significant differences between hatcheries. Usually, each hatchery released about
the same time of the year for each year of the study. Percent total adult recoveries and between-year rank orders
for each hatchery are shown in Table 2. Most rank orders
were ones and twos, and fewest were threes and fours
observed for adult recoveries of fish released in 1980.
Nevertheless, the general random order of rank indicatesthat there is much between-year variability in total adultrecoveries among the groups of fish released from the 15
hatcheries during the four-year period.
Underyearling chinook salmon were released from four
Columbia River Basin hatcheries in 1979, presumably inabout the same stage of development, prior to any increasein gill Na + -K + ATPase activity (Table 3). Migrants
captured at Jones Beach showed that those fish released
at greater distances traveled downstream at higher rates

Table 3
Changes in migrations rates with distance from point of release for tagged 'mderyearling chinook salmon
released from hatcheries and caught at Jones Beach.
Caught at
Jones BeachAt release-------_.
Hatchery
Kalama Falls
ToutleToutleW'lshougal
Washougal
Little White
Little White

__.

----

Dare:
June1979

Wt.
(g)

NumbertaggedGill
ATPase

30
17
17
14
14
22
22

:l.5
2.8
2.8
4.8
4.8
4.3
3.7

214,500
12,000132,000
93,700154,500
177,800
264,800

7
7
9
9
10
10

Migration
distance
(km)

Beach

Purse

seine

seine

66
85
85
138
138
186
186

2,799
85
973
318
634
221
400

206
11
108
43
104
131
161

92

NOAA Technical Report NMFS 102: Marine Ranching

-

30

--

20

_

>-

C'll
"C

--E

~

Q)

...C'll

I:
0

;;

10

...ClC'll

:E

0
0

50

100

150

200

250

Migration distance (km)

~

15
Q)

...III
~

C.
.c:

--

Figure 1
Increase of median migration rate with
distance traveled by underyearling chinook
salmon. Seven tagged groups were released
from 4 hatcheries during 14-30 June 1979
(Table 3) and migrants wcre captured at Jones
Beach with a beach or purse seine. Correlation coefficients for migration rates vs.
distance are purse, 0.94(P<0.01); heach, 0.99
(P<O.OI). Data from Dawley et al. 1985.

10
III

Co)

to

Q)

aJ

5

0
;;
C'll

ex:

0
0

50

100

150

200

Migration distance (km)Figure 2
Ratio of the number of underyearling chinook
salmon caught in the beach seine to thenumber of thuse caught in the purse seine at
Jones Beach YS. distance migrated, 14-30
June 1979. Correlation coefficient 0.93
(P<O.OI).

(Fig. 1). Those captured in midriver with the purse seine
traveled faster than those captured near shore with thebeach seine (Fig. 1). In addition, fish traveling farther werecaught in increasing numbers in the midriver purse seine(Fig. 2), indicating movement from shoreline to midrivermigration with time and with distance from release. Theseobservations are summarizeo in Figure 3.
Figure 4 presents an idealized profile for gill Na + -K +ATPase activity generally observed in hatchery populationsof anadromous salmonids during smolt development, whenfish are <::ither held for extended periods in the hatcheryenvironment or ;-eleased to migrate seaward. The shaded
portion under the profile represents that percent of the total
area under the curve that is completed by the time of ahypothetical release. We have used this percent as a basis
to evaluate the relationship between gill Na + -K + ATPase
activity in groups of uuderyearling chinook salmon released
from the Spring Creek National Fish hatchery during 1978
through 1982, and post rele?.se performance, as reflectedin migratory behavior and survival to adulthood (Fig. 5).

This percentage was compared to the numbers of smolts
captured at Jones Beach (migration distance = 194 km)
and to adult recoveries from fish released in each of those
years (Table 4). Correlations and significance of the datacollected during the study are also shown in Table 4.

Discussion_

The four-year study of underyearling fall chinook salmon
released from hatcheries in the Columbia River Basinreported by Vreeland (1990) illustrates that considerable
variability in adult recoveries exists from year to year
among the several production facilities. Rank order information suggests that fish released from most of the hatcheries in 1980 performed better than fish released in otheryears. It would appear, therefClre, that conditions in theestuary and ocean were more favorable for fish released
in 1980 than those for fish released in the other three yearsof the study. Fisher and Pearcy (1988) have shown that

_ _ _ _ _ _ _ _ _ _ _ _ Zaugg and Mahnken: Smolt Development and Marine Ranching of Pacific Salmon

I:

-

-

93

Mid river

o

co

(,)

o

..J

...

CI)

Transitional

>

a:

Ocean

Parr

Figure 3

Summary of expected migratory behavior for underyearling fall chinook salmon released into the Columbia Riversystem and completing smolt transformation during
migration.

Distance

>>

Q)

VI

«I

a..

l-

fish

e(

T

~

Figure 4

I

+«1
Z

=
Time

the success of any year class of coho salmon may be determined soon after ocean entry, and this may also be thecritical time for juvenile chinook salmon. If so, the degreeof smolt development at that time may be a significant
contributing factor to survival.
Nevertheless, among the 15 hatcheries shown here, thepatterns of adult recovery varied widely in an inconsistentmanner. For example, adult recoveries from the Little
White Salmon hatchery (river km 261) ranged from only
0.02 to 0.03 percent during the four years of the study
whereas recoveries from the Spring Creek hatchery (locatedonly 9 km further upstream) were 50-fold greater. Fishreleased from the Bonneville hatchery (31 km downstream)
had adult recoveries that were intermediate between theother two hatcheries during the initial two years (1979-80)
and similar to Spring Creek for the final two years(1981-82). These observations strongly suggest that hatchery rearing methods and practices greatly influence survival to adulthood.

Illustration of a typical gill Na + - K + ATPase activity profile for hatchery-reared anadromous
salmonids undergoing parr-smolt transformationand either retained at the hatchery or released
to migrate seaward. The shaded area represents
that portion of the total area under the curve completed by the time of a hypothetical release.

Variability in gill N a + - K + ATPase activity profiles inchinook salmon reared at the Spring Creek hatchery from1978 to 1982 is further evidence that physiological development in hatchery-held salmon can differ from one year
to the next. Important, but subtle differences in rearing
methods and diets may have greater influences on juvenile
development and survival than is commonly thought.
Dawley et al. (1986) reported that migration rates ofunderyearling chinook salmon in the Columbia River increased with distance traveled. However, these investigators did not assess possible differences in degree of smolt
development in the fish used for their study. The degreeof smolt development reached in steelhead (0. mykiss) at
the time of release affected rates of migratiOn (Zaugg and
Wagner 1973). As the act of migration proceeds, smolt
development is intensified (Zaugg 1982a; Zaugg et al.
1985; Rondorf et al. 1985, 1988). In the present study
fish released 186 km from Jones Beach (Little White
Salmon hatchery) probably underwent more extensive

94

NOAA Technical Report NMFS 102: Marine Ranching

20

_

~

1978

15
10
5
20
15

511

10

t

5

til

20

·rl

p..

~
0

!-. 16~·rl.::; 12
.jJ

~

~
~
+:-;

8

1981

+'

III

z

.-i
.-i
'rl

Figure 5

/

12
8

0

4

16

~

1982

~- --~~-:.'--'"'

12
8

~"

4
Feb

Mar

Apr

May

smolt development during migration and thus exhibited
more rapid downstream movement over the total distance traveled than did fish released closer to the capture site (Kalama Falls, Toutle, and Washougal hatcheries). It appears that more completely smolted fish moveoffshore to faster-moving midriver waters as indicated byboth faster migration rates and higher percentages of
migrants being caught in the midriver purse seine. The
ratio of numbers caught in the beach seine to numberscaught in the purse seine decreased as the distance traveled
increased.

Jun

Gill Na + -K + ATPase activity
profiles for underyearling fallchinook salmon at Spring Creek
National Fish Hatchery, 1978-82.
Arrows indicate the date of final
release (groups were also releasedin March and April). The shaded
areas represent that portion of
the total area under the curve(dashed lines) completed by the
final release dates. Spring Creek
hatchery is located at river km
269 on the Washington shore of
the Columbia River.
prt =protein.

Generally, underyearling chinook salmon, as well as
yearling coho salmon, migrate more rapidly when released while gill N a + - K + ATPase activity is declining(following a previous increase and peak) than when theactivity is on the increase (before peaking, Zaugg 1982a).
When releases are made during the period of decline,
however, ATPase activities are rapidly re-elevated as
migrants move downriver. Ewing et al. (1984) showedthat underyearling spring chinook salmon released
later (mid-June vs. mid-May) migrated faster and inequal numbers. However, when released in August these_____________ Zaugg and Mahnken: Smolt Development and Marine Ranching of Pacific Salmon

95

Table 4Comparisons of shaded areas under ATPase profiles (expressed as percent of the total area under the curve, Fig. 5) to various
measurements of post-release performance of all fall chinook salmon released (March, April, and May each year) from Spring
Creek National Fish Hatcherya.
Year ofrelease'

Percent
ATPase curve'

1978
1979
1980
1981
1982

65
80
100
0
66

Percent
caught inpurse seine'Ratio
beach/purse
seine!

0.14
0.17
0.20
0.12
0.14

0.018
0.036
0.031
0.006
0.009

6.9
3.6
5.3
18.1
14.1

0.87
1.01
1.47
0.40
0.43

0.86
P<O.1

0.77
P<0.2

0.84
P<O.1

0.83
P<O.1

0.86
P<O.1

0.78
P<O.1

0.93
P<0.2

0.93
P<0.020.87
P<0.05Percent
caught atjones Beachd

Percent
adult recovery"

Correlation coefficients and significance% ATPase% Caught (total)% Caught (purse)

Ratio

0.85
P<0.05'Spring Creek National Fish Hatchery is located at river km 269 on the Columbia River.
'Three releases were made each year, in March, April, and May'Percent of the total area under profiles in Figure 5, depicted by shadin~.
Ipercent of all fish reieased I.March, April, and May) caught at Jones Beach (rkm 75) with both beacn and purse seines. Numbers adjusted
to a standard fishing effort (Dawley et al. 1985).
'P~rcent of all fish released (March, April, and May) caught at jones Be·.ch i,rkm 75) in the mid-river purse seine. Numbers adjusted to a
standard fishing effort (Dawley et al 1985).
j Ratio of numbers of migrants caught at jon<:s Beach in the beach seine to numbers caught in the purse seine for all fish released each year
(March, April, and May).
'Includes adults caught in the commercial and sport fishery, and returns to the Spring Creek hatchery from all three releases each year. Data
from Pacific Marine Fishery Commission, Portland, OR and Vreeland (1990).

salmon showed reduced migration and an increase instream residence.
The importance of elevated gill Na + -K + ATPase activity for successful adaptation to seawater has been
demonstrated in hatchery- and laboratory-reared steelhead(Adams et al. 1975), coho salmon (Harache et al. 1980),
and Atlantic salmon (McCormick et al. 1987; Besner and
Audet 1988). Observations suggest that smolts actively
migrating seaward in the natural environment also require
high gill Na + -K + ATPase activities for successful transition to seawater.
We have attempted to determine whether smoltingassociated pre-release increases in gill N a +-K + ATPase
activity are related to post-release behavior and survivalof underyearling chinook salmon. In order to relate the
enzyme activity quantitatively to post-release behavior
and survival we have used as a measurement that portionof the total area under the ATPase profile curve which iscompleted by release time. This method takes into accountpost-release migrational characteristics that appear to be

more influenced by the time-dependent development
pattern of the enzyme activity than by the absolute value
at the highest point. By applying this analysis to the gill
Na+-K+ ATPase activity profiles observed for five successive years in underyearling fall chinook salmon at the
Spring Creek hatchery, we obtained results which support
assumptions that the degree of smolt development is related
to the numbers of migrants reaching the estuary, their location in the river, and to percent adult recovery. Although
the percent ATPase completed by the May release of 1982
is similar to the percent in 1978 (66 and 65), other observations for that year (migrants caught in the purse seine,beach/purse seine ratios, and adult recovery) more closely
resemble the values obtained in 1981. The total area underthe 1982 profile is small compared with the years of better
survival (1978-80) and it appears that this may also indicate poor smolt development during the hatchery rearing period,
If the degree of smolt developmem reached by the timeof release is important to survival, and that degree of

96

NOAA Technical Report NMFS 102: Marine Ranchingdevelopment is inconsistent from one year to the next, asseen at the Spring Creek hatchery, then it hecomes important to identify and control as many of the variables
involved as possible. Although factors causing variable
smolt development in the Spring Creek fish during thefive-year study remain unidentified, there are kno',vn
culture practices and conditions that are candidates. Ogata
and Konno (1986) demonstrated that additional dietary
lipid may promote smolt development in cherry salmon(0. masou). Other dietary ingredients undoubtedly influencesmolt development and may need closer scrutiny to insure
more uniform smolting patterns. Growth rate, temperature, and size are interdependent and can affect the rateand extent of smolt development. Although better adultreturns are generally associated with larger juveniles there
was no significant relationship between size at or time ofrelease and adult recovery in the Spring Creek study(Zaugg 1989). Disease and disease treatments, pond denslties, and stresses accompanying normal and abnormal
hatchery operations must certainly cause year-to-ycar
variablility in the ability of hatchery-reared fish to develop
properly. These and other, perhaps yet undetermined factors, must surely be important to the success of a hatchery
program.

Acknowledgments
We thank W. Dickhofffor preparation offigures and hatchery personnel for their help and cooperation.

Citations
Adams, B.L., W.S. Zaugg, and L.R. McLain.
1975. Inhibition of saltwater survival and Na-K -ATPase elevationin steelhead trout (Salmo gairdneri) by moderate water t~mpera­
tures. Trans. Am. Fish. Soc. 104:766-769.
Besner, M., and C. Audet.
1988. Smoltification and ability of Atlantic salmon smolts to acclimate to seawater transfers. In Aquaculture Assoc. Can. Bulletin
88-4, September (S.L. Waddy, ed.), p. 7-9.
Bjornn, TC., R.R. Ringe, and P. Hiebert.
1978. Seaward migration of Dworshak Hatchery steelheac trout
in 1976. Univ. Idaho, Forest, Wild!. Range Exp. Stn .. Tech.
Rep. 6: 1-45.
Buckman, M., and R.D. Ewing.
1982. Relationship between size and time of entry into the sea a:ld
gill (Na + K)-ATPase activity for juvenile spring chinook
salmon. Trans. Am. Fish. Soc. 111:681-687.
Chernitsky, A.G.
1986. Quantitative evaluation of the degree of parr-smolt transformation in wild smolts and hatchery juveniles of Atlantic salmon(Salmo salar L.) by SDH activity of chloride cells Aquaculture
59:287-279.
Dawley, E.M., R.D. Ledgerwood, and A.L. Jensen.
1985. Beach and purse seine sampling of juvenile salmonids in the
Columbia River estuary and ocean plume. 1977-1983. Vol. II:
Data on marked fish recoveries. U.S. Dep. Commer., NOAA_

Tech. Memo. NMFS F/NWC-75, 397 p.
Dawley, E.M., R.D. Ledgerwood, TH. Blahm, C.W. Sims,
J.T. Durkin, J.T. Kirn, A.E. Rankis, G.E. Monan, andF.J. Ossiander.
1986. Migrational characteristics, biological observations, andrelative survival ofjuvenile salmonids entering the Columbia Riverestuary 1966-1983. Final report to Bonneville Power Adm.,
Portland, OR, April. 250 p.
Ewing, R.D., C.E. Hart, C.A. Fustish, and G. Concannon.
1984. Effects of size and time of release on seaward migration ofspring chinook salmon, Oncorhynchus tshawytscha. Fish. Bull., U. S.
82:157-164.
Fagerlund, lJ.H.M., J.R. McBride, B.S. Dosanjh, E.T. Stone, andl'·.K. Sandercock.
1983. Influence of culture density on juvenile coho salmon production ami ocean survival. Smolt releases in 1979 and 1980 from
C~pilano hatchery.
Canadian Technical Report of Fisheries andAquatic Sciences 1229.
Fisher, J.P., and W G. Pearcy.
1988 G;owth of juvenile coho salmon Oncorhynchus kisutch off
Oregon and Washington, USA, in years of differing coastal upwellmg Can. J. Fish. Aquat. Sci. 45:1036-1044.
Gunsolus, R.T
1978. The status of Oregon coho and recommendations for managing the prodl:ction, harvest, and escapement of wild and hatcheryr"art·.J stocks. Oreg. Dep. Fish WilclI. Proc. Rep., Portland, OR,
59 p.
Harache, Y., G. Boeuf, and P. Lasserre.
1980. Osmoti~ adaptation of Oncorhynchus kisutch Walbaum. III: Survival aJld growth of juvenile coho salmon transferred to seawaterat various times of the year. Aquaculture 19:253-273.
Hart, C.E., G. Concannon, C.A. Fustish, and R.D. Ewing.
1981. Seaward migration and gill (Na-K)-ATPase activity of springchinook salmon in an artificial stream. Trans. Am. Fish. Soc.
110:44-50.
Hvidsten, N.A., and L.D. Hansen.
1988. Increased recapture rate of adult Atlantic salmon, Salmo salarL., stocked as smolts at high water discharge. J. Fish BioI.
32:153-154.
Langdon, J .S., anr! J.E. Thorpe.
1985. The ontogeny of smoltification: developmental patterns ofgill Na + /K + -ATPase. SDH, and cWoride cells in juvenile Atlantic salmon, Salmo salar L. Aquaculture 45 :83-90.
McCarl, B.A., and R.B. Rettig.
1983. Influence of hatchery smolt releases on adult salmon
production and its variability. Can. J. Fish. Aquat. Sci. 40:
1880-1886.
McCormick, S.D., R.L. Saunders, E.B. Henderson, and P.R. Harmon.
1987. Photoperiod control of parr-smolt transformation in Atlantic
salmon (Salmo salar): changes in salinity tolerance, gill Na + -K +ATPase actIvity, and plasma thyroid hormones. Can. J. Fish.
Aquat. Sci. 41:1462-1468.
M,Gie, A.M.
1981. Trends in escapement and production of fall chinook andcoho salmon in Oregon. Oreg. Dep. Fish Wildl., Fish Div. Info.
Rep. 81-7, 44 p.
1984. Commentary: evidence for density dependence among coho
salmon stocks in the Oregon Production Index area. In The influence of ocean conditions on the production of salmonids in the
North Pacific: '. workshop (W.G. Pearcy, ed.), p. 37-49. Oregon
State Univ .. Sea Grant Coli. Prog., ORESU-W-83.
Nickelson, TE.
1986. Influences ufupwelling, ocean temperature, and smolt abundance on marine survival of coho salmon (Oncorhynchus kisutch)
in the Oregon Production Area. Can. J. Fish. Aquat. Sci. 43:
527-535.

_____________ Zaugg and Mahnken: Smolt Development and Marine Ranching of Pacific Salmon
Ogata, H., and S. Konno.
1986. Growth response and smolt production of 1 year cherrysalmon fed with diets having different protein and lipid levels.
Bull. Jpn. Soc. Sci. Fish. 52:313-318.
Patino, R., C.B. Schreck, J.L. Banks, and W.S. Zaugg.
1986. Effects of rearing conditions on the developmental physiology of smolting coho salmon. Trans. Am. Fish. Soc. 115:
828-837.
Peterman, R.M., and R.D. Routledge.
1983. Experimental management of Oregon coho salmon (Oru:orhynchus kisutch): designing for yield of information. Can. J. Fish.
Aqua!. Sci. 40:1212-1223.
Rodgers, J.D., R.D. Ewing, and J.D. Hull.
1987. Physiological changes during seaward migration of wild
juvenile coho salmon (Oncorhynchus kisutch). Can. J. Fish. Aqua!.
Sci. 44:452-457.
Rondorf, D.W., M.S. Dutchuk, A.S. Kolok, and M.L. Gross.
1985. Bioenergetics of juvenile salmon during the spring outmigration. Annual Rep. (1983) to Bonneville Power Administration,
Portland, OR, 78 p.
Rondorf, D.W., J.W. Beeman, M.E. Free, and D.E. Liljegren.
1988. Correlation of biological characteristics of smolts with survival and travel time. Annual Rep. (1987) to Bonneville Power
Administration, Portland, OR, 96 p.
Sandercock, F.K., and EJ. Stone.
1982. A progress report on the effect of rearing density of subsequent survival ofCapiiano coho. In Proc. North Pacific Aquacult.
Symp.; Aug. 1980, Anchorage, AK (B.R. Melteff and R.A. Neve,ed.), p. 151. Alaska Sea Grant Rep. 82-2.
Schreck, C.B.
1982. Stress and rearing of salmonids. Aquaculture 28: 241-249.
Schreck, C.B., S.E. Jacobs, J.L. Specker, and W.A. Sandoval.
1980. Effects of transportation on outmigration and fitness formarine survival of Columbia River salmon. Completion Report.
Oregon Coop. Fish. Res. Unit, Oregon State Univ., Corvallis,
OR, 108 p.
Schreck, C.B., R. Patino, C.K. Pring,J.R. Winton, andJ.E. Holway.
1985. Effects of rearing density on indices of smoltification and performance of coho salmon, Oncorhynchus kisutch. Aquaculture 45:345-358.

97

Soivio, A., and E. Virtanen.
1985. The quality and condition of reared Salrno satar smolts in relation to their adult recapture rate. Aquaculture 45:335-343.
Vreeland, R.R.
1990. Evaluation of the contribution of fall chinook salmon rearedat Columbia River hatcheries to the Pacific salmon fisheries. Final
Report (1989) to Bonneville Power Administration, Portland,
Oregon, 113 p.
Wahle, RJ., and W.S. Zaugg.
1982. Adult coho salmon recoveries and their Na+-K+-ATPase
activity at release. Mar. Fish. Rev. 44(11):11-13.
Wedemeyer, G.A., OJ. McLeay, and C.P. Goodyear.
1984. Assessing the tolerance of fish and fish populations to environmental stress: the problems and methods of monitoring. In
Contaminant effects on fisheries (V.W. Cairns, P.V. Hodson, andJ.O. Nriagu, eds.), p. 164-195. John Wiley & Sons, Inc., NewYork.
Weitkamp, D.E., and R.R. Loeppke.
1983. Physiological monitoring of smoltification and stress in midColumbia chinook and steelhead, 1983. Report, Document no.
83-1130-0110, Parametrix, Inc., Bellevue, WA, 54 p.
Zaugg, W.S.
1982a. Relationship between smolt indices and migration in controlled and natural environments. In Proc. Salmon and Trout
Migratory Behavior Symposium (E.L. Brannon and E.O. Salo,eds.), p. 173-183. Univ. Washington, Seattle, WA.
1982b. A simplified preparation for adenosine triphosphatase determination in gill tissue. Can. J. Fish. Aquat. Sci. 39:215-217.
1989. Migratory behavior of underyearling Oncorhynchus tshawytscha
and survival to adulthood as related to prerelease gill Na +-K +ATPase development. Aquaculture 82:339-353.
Zaugg, W.S., and H.H. Wagner.
1973. Gill ATPase activity related to parr-smolttransformation andmigration in steelhead trout (Salrno gairdnen): influence of photoperiod and temperature. Compo Biochem. Physiol. B, 45:955-965.
Zaugg, W.S., E.F. Prentice, and F.W. Waknitz.
1985. Importance of migration to the development of seawater
tolerance in Columbia River anadromous salmonids. Aquaculture 51:33-47.

Control of Skin Ulcers in Young Bluefin Tunain Fish Farming
HIROSHI SAKO
Nansei National Fisheries Research InstituteOhno, Saeki, Hiroshima 739-04, JapanYASUO INUI and SATOSHI MIWA
National Research Institute of Aquaculture
Nansei, Watarai, Mie 516-01, Japan

ABSTRACT
Pathologial, bacteriological, and chemotherapeutic studies were carried out to clarify themechanism of skin ulcer formation and to control the disease in young bluefin tuna (Thunnus
thynnus). The structure of bluefin tuna skin is principally the same as that of other fishes; however,
the epidermal layer is very thin and fragile, and handling promotes the development of skin ulcers.
Histopathology revealed various inflammatory reactions and an increase in the bacterial content
within the ulcer foci. Bacteriological examinations showed that Vibrio, which is not ordinarily
isolated from normal skin, became dominant in the infected area. The fact that the Vibrio wasalso isolated from the kidneys of fish with advanced skin ulcers indicates that the ulcer foci werea possible entrance for bacteria into the body. Study on the responses of the bacteria isolated
from the skin ulcer to various antimicrobial agents indicated that Vibrio was specifically sensitive
to sodium nifurstyrenate (NFS-Na). A bath treatment with NFS-Na decreased the mortality offish suffering from skin ulcers formed as a result of their transportation by boat for examination.

Introduction_

Bluefin tuna, Thunnus thynnus, is one of the most important commercial species in Japan. It is well known thatyoung bluefin tuna are very fragile and handling resultsin high mortality (Ueyanagi et al. 1973). Almost all thefish captured show severe skin sulcers and die. A large
portion of the mortality during captivity is caused by orat least related to the skin ulcer. Thus, it is very important to control the skin ulcer to promote the bluefin tunaranching program.
This paper describes pathological, bacteriological, andchemotherapeutic studies carried out to clarify the mechanism of skin ulcer development and to lead to the development of control measures against the disease.

waters of Kaminokae, Nakatosa-cho, Kochi Prefecturefrom July to August 1981-85. The tuna were kept infloating net cages (4 x 4 x 4 m) settled in Kaminokae Bay
and were fed sand lances (Ammodytes personatus). In someexperiments they were transported to our laboratory inNansei-cho, Mie Prefecture by fishing boat in a live well(1.5 x 1.5 x 0.8 m), and reared in round water tanks (diameter 4.3 m, depth 0.8 m, net vol. 8,000 L) on land, with
continuously supplied seawater. These laboratory-rearedfish were also fed sand lances. The fish were transferredfrom boats to pens directly with a hand net. However, fromthe transportation boat to land tanks, they were transferred
into 20-L containers (1 fish at a time) with a hand net andthen transferred to the tanks.

Pathological Observations of Skin Ulcers

Materials and Methods_

Experimental Fish
The fish used in the present experiments were young
bluefin tuna captured by surface trolling in the offshore

For pathological observation of the ulcers, various stagesof ulcer foci were sampled. They were fixed in Bouin's solution for 10-24 hours, embedded in paraffin and sectioned
at 5 !Jm. The sections were stained with either hematoxylin-eosin Or Giemsa.
99

100

NOAA Technical Report NMFS 102: Marine Ranching_days, while no treatment was done in the other tank. Eachgroup was reared with the same water supply which ranged
in temperature from 25 to 28° C and were fed sand lances
daily. Mortalities of the two groups were compared after
11 days.
To study the effect of NFS-Na on the bacteria found in
the skin ulcers, infections were produced artificially in 30
young bluefin tuna with a cotton glove. They were divided
into 2 groups each kept in separate tanks (8,000 L) as
previously described. In one tank NFS-Na was dissolvedin the rearing seawater to a concentration of 5 ppm for 30
minutes once a day for two days: the first treatment wasdone just after handling, and the second one was done justafter 24 hours sampling. No treatment was done on theother group. Two fish were removed for bacterial examination from each group 2,24, and 48 hours after the contact with the skin. The water temperature ranged from 25
to 26° C during this experiment. Methods for counting thenumber of bacteria and for the identification of bacterial
flora in the skin and kidney were principally the same as
those mentioned above, although seawater and ZoBell
2216E medium were used as the diluent and culture
medium. Responses of the isolates to NFS-Na, chloramphenicol (CP), oxytetracycline (OTC), spiramycin (SPM),
ampicillin (ABPC), colistin (CL), oxolinic acid (OA), andsulfadimethoxine (SDMX) were tested. Minimum inhibitory concentrations (MIC; JAg/mL) were determined by thestandard agar plate dilution method using the ZoBe1l2216E
medium. Each drug was diluted by the serial two fold dilutions from 100 to 0.025 JAg/mL. Inoculated plates were
cultured at 25°C for 24 hours.

Bacteriological Examinations of Skin Ulcers
Skin ulcers were produced experimentally by gently seizing
fish at the caudal peduncle with a cotton glove. Usually
a severe ulcer developed on the portion of the skin contacted by the glove. Ulcers were induced in twenty young
fish ranging from 55 to 90 g by handling them; three fish
were used for each of the bacteriological examinations performed at 0 and 24 hours after contact with the skin. The
fish were reared in the pen. The water temperature ranged
from 25 to 30° C during this experiment.
The number of bacteria in the ulcer foci of the skin wasdetermined by the spread plate technique. A portion (2 x I
cm area) of skin was excised aseptically and homogenizedwith 10 mL of saline solution (0.8% NaCI and 1.0% KCI).
After three 10-fold dilutions of the homogenate, 0.1 mLof each was spread on the duplicate plates of B medium(Simidu and Hasuo 1968). After incubation at 25-30° C
for 5 days, the colonies were counted. Bacterial colonies
were collected randomly and used for the identification ofbacteria. For the identification of bacteria, Gram staining,cell form, motility, catalase, cytochrome oxidase, pigment
production, OF and gas production from glucose were
tested. To determine the invasion of bacteria into the internal organs, a loopful of blood from the kidney was
streaked on B medium.

Chemotherapy of Skin Ulcers
by Sodium Nifurstyrenate
Three hundred young bluefin tuna (70-200 g) were transported by fishing boat from the Kaminokae pens to ourlaboratory. The trip took about 24 hours. Just after arrival
they were divided into 2 groups, each kept in separate tanks(8,000 L) as previously described. Sodium nifurstyrenate(NFS-Na) was dissolved in the seawater of one tank to aconcentration of 5 ppm for 30 minutes once a day for two

Tissue NFS-Na Concentration
after Bath Treatment
To determine the changes in tissue NFS-Na concentration,
15 tuna were treated with NFS-Na at 10 ppm for 30~

Epidermis

Dermis}MuscleFigure 1

Structure of normal young bluefin tunaskin.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Sako et al.: Skin Ulcers in Young Bluefin Tuna•

4!l.'.

layers: the outer layer or epidermis, and the inner layer
or dermis (Fig. 1). The epidermis consists of outer squamous epithelial cells, mucous cells, clavate cells, and germinal cells. The dermis consists of collagenous connective
tissue layers of different densities. The inner margin of thedermis is bounded by a muscle layer abundant in bloodvessels. There are layers of pigment cells in the marginal
portions of the dermis, adjacent to both the epidermis andthe muscle layer. Thus, the structure of young bluefin tuna
skin is principally the same as that of other fish, although
the skin of young bluefin tuna is very thin and fragile.
Because of its fragile nature, handling results in the development of skin ulcers in young bluefin tuna.

tlOUi1lJ"lS*"VI4J"

Figure 2

Pathology of Skin Ulcers

Ulcerated skin of young bluefin tuna.

The skin ulcer developed most frequently from the central
to the posterior part of the lateral body. The ulcer was also
commonly observed on the skin of the caudal fin, abdomen, head, and anterior part of the lower jaw (Fig. 2).
Exfoliation of the epidermis, hemorrhage in the germinal
layer and both pigment cell layers, and inflltration of thelymphoid cells in the dermis were common pathologic
features of the skin ulcer (Fig. 3). In severe cases lymphoidcells infiltrated the muscle layer causing the dermal layers
to split. In more advanced cases the dermis completely
exfoliated and the naked muscle was observed.

minutes in a tank (8,000 L); two fish were sampled at 0,
2,6, and 12 hours after treatment. The sampled fish were
killed with a blow, blood was taken from the heart, andthe liver, kidney, spleen, red muscle, and ordinary muscle
were dissected and immediately frozen in acetone and dry
ice. The plasma was separated by centrifugation and alsofrozen with dry ice. The frozen samples were later used
for NFS-Na analysis. NFS-Na was extracted from homogenized tissues with ethyl acetate and purified using SEPPAK C18. Quantitative analysis ofNFS-Na was performed
with a high-performance liquid chromatography using FineGel 110 with eluent of acetonitrile-methanol-0.02 M phosphate buffer, pH 5.5 (2; 5; 3, v/v).

Results101

Bacteriological Examinations of Skin Ulcers
Severe skin ulcers appeared 24 hours after contact with thecotton glove. Development of the skin ulcer was fast probably due to the high water temperatures (25-30°C). Allof the fish examined died within 48 hours after the glove
contact. Changes in the bacterial flora and their numbersin the foci are shown in Table 1. The number of bacteria
in the skin just after glove contact was 0.80-1. 2 x 10 3_

Structure of the Skin
The skin of the young bluefin tuna is composed of two

}

Ulcer
Figure .3}

Dermis (remaining)}Muscle

The foci of the skin ulcer ofa young bluefin tuna. Epidermis is exfoliated and alarge number of lymphoidcells have infiltrated the dermis. Disturbance of the dermal layer is also seen. Arrow
indicates lymphoid cells.

102

NOAA Technical Report NMFS 102: Marine Ranching_

Table 1
Numbers of bacteria and bacterial flora in the skin ulcers of young bluefin tuna after handling.
Time after
handling(h)Bacterial flora'(no. of colonies)
No. of bacteria(cfu/cm')

Fish no.

Skin ulcer

0

1
2
3

No
No
No

1.2 X 10'
8.0 X 10'
1.1 X 10'

0

24

4
5
6

SevereSevereSevere4.5 x 105
2.6 x 10°
2.3 x 10·

11

0

0

8.5 x 10'/mL

11

3

0

Seawater'Bacterial flora: A = Vibrio; B
coccus; and G = Others.

A

B

C

D

E

28

0

Bacteria isolated
from kidney

F

G

Total

29

13

73

None
None
None

12

VibrioVibrioVibrio

0

0

0

0

10

25

Pseudomonas; C = Moraxella or Acinetobacter; D = Flavobacterium or Cytophaga; E = Staphylococcus; F = Micro-

colony-forming units (cfu)/cm 2 , increasing almost 103
times to 0.45-2.6 x 10 6 cfu/cm 2 within 24 hours. Just
after handling with the glove, the genera Flavobacterium/
Cytophaga and Micrococcus were dominant, and Pseudomonas,
Moraxella/Acinetobacter and Staphylococcus observed in smaller
numbers. * No bacterium was isolated from the kidneys ofthe fish at this stage. After 24 hours however, Vibrio became
predominant in the more advanced ulcer foci and was also
isolated from the kidneys of the fish at this stage. Vibrio
was a predominant genus in the seawater used for thestudies.

Chemotherapy of Skin Ulcers by NFS-Na
The survival of young bluefin tuna with or without NFSNa treatment after transportation from the Kaminokae
pens to Nansei are given in Figure 4. The number of deathsin the treated group was much smaller than that in the nontreated group for two days after the transportation. Almost
all of the fish that died exhibited severe ulcers on their bodysurface. However, the ulcers of NFS- N a treated fish weregenerally less severe compared with those of nontreatedfish.
Changes in the number of bacteria in the skin andkidneys after the bath treatment of NFS-Na are given in
Table 2. Two hours after glove contact, the number ofbacteria in the skin of treated and nontreated fish were
nearly the same, and no bacterium was isolatt:d from thekidneys of either group. After 24 hours the number ofbacteria in the contacted skin was 0.4-1.4 x 10 7 cfu/cm 2
and 2.1-4.1 x 10 7 cfu/cm 2 for NFS-Na treated fish and•Using only the several characteristics tested in this study, it was difficult
to distinguish Flavobacterium from Cytophaga and Moraxella from Acinetob:u:ter;therefore, we refer to them together.

.\0.

NFS - Na treated fish
Non treated fish

1/1

100

"'-0-0--~.s;

0..........0--

...

\

::I
1/1

'0

Iz
::I

8 _•

50
Medication

L-:.__

I~'_2..........

-~--------.-e-e_.

4_
_6
Time
(days)

8__
10_------'

Figure 4
Effect of 5 ppm sodium nifurstyrenate bath administration for
30 min per day (2 days) on the mortality of young bluefin tuna
after transportation from Kaminokae to N ansei by a fishing boat.

nontreated fish, respectively. At that time, 6.6-8.8 x 104cfu/g kidney tissue of bacteria were isolated from thekidneys of nonmedicated fish, whereas no bacterium was
isolated from those of NFS- N a treated fish. Bacteria wereisolated from the kidneys of both treated and nontreatedfish after 48 hours.
Changes in the bacterial flora in the skin and kidney after
the bath treatment are given in Table 3. Before medication, Pseudomonas, Moraxella/Acinetobacter, Flavobacterium/
Cytophaga, Staphylococcus, and Micrococcus were the main
genera isolated from the skin. The native flora remained
constant in NFS-Na treated fish after two hours, whereas
Vibrio became predominant in the skin of nonmedicatedfish. After 24 hours Vibrio was the predominant isolate

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Sako et a1.: Skin Ulcers in Young Bluefin Tuna

103

Table 2
Effect of sodium nifurstyrenate (NFS-Na) bath administration on the number of bacteria
in the skin ulcers and kidneys of young bluefin tuna.
No. of bacteria (skin: cfu/cm2 ; kidney: cfu/g)
Time after
handling(h)Nontreated fish

NFS-Na treated fish
Fish no.

Skin

Fish no.

KidneyoKidney

Skin
2

1
2

2.0 x 10
2.3 X 102

~

2

3
4

2.0 X 102
5.0 X 1025
6

3.8 X 102
4.0 X 10224

7
8

1.4 X 10'
4.0 X 106910

2.1 X 10'
4.1 X 10'

8.8 X 104
6.6 X 104

48

11
12

1.0 x 104
1.4x 10613

3.4 x 10'
1.0 X 104

1.0 X 103

1.9 x 10414

not detected « 1.0 x 102 cful g).

Table 3
Effect of sodium nifurstyrenate (NFS-Na) bath administration on bacterial flora in the skin ulcers and kidneys of young
bluefin tuna. Bacterial flora: A = Vibrio; B = Pseudomonas; C = MoraxellalAcinetobacter; D = FlavobacteriumlCytophaga; E =Staphylococcus; F = Micrococcus; G = Others.
Bacterial flora (no. of colonies)
Time after
handling
(h)

Organ

A

0

Skin

-

2

Skin

0

4

3

24

Skin
Kidney

0

23

0

Skin
Kidney10
16

48

Nontreated fish

NFS-Na treated fish

.

B

4
0

C

0
0

D

15

0
0

E

F

0

0

0

0

0
0

0
0

G

2

2
0

Total

E

A

B

C

D

0

6

8

3

24

11

0

1

2

0

5

20

25

23

24-

1
0

0
0

0
0

0
0

0
0

0
0

24
24

15
1

0
0

0
0

0
0

0
0

0
0

0
0

15
1

16
16

F

G

Total

4

2

24

not tested.

found in both the skin and kidneys of nonmedicated fish,
whereas Pseudomonas was most prevalent in the skin of
NFS-Na treated fish. However, after 48 hours Vibrio also
dominated the skin of treated fish and were isolated fromthe kidneys as well.
Sensitivities of bacteria isolated from the skin ulcers andkidneys to antimicrobial agents are given in Table 4. * The
MIC ofNFS-Na to the natural bacterial flora isolated fromthe skin before medication was 12.5-25 ~g/mL for Pseudomonas, 25 ~g/mL for MoraxellalAcinetobacter, 6.25-25 ~g/mL
for FlavobacteriumlCytophaga, 0.39 ~g/mL for Staphylococcus• Drug sensitivities were tested for several isolates of each genera. Because
sensitivity was sometimes different among the isolates, we observed arange of MIC's within genera.

and 3.13-6. 25 ~g/mL for Micrococcus. The MIC of NFSNa to Vibrio, which was the primary pathogen isolated fromthe skin ulcers and kidneys of nonmedicated fish 2 and 24
hours after glove contact, was 0.10-0.78 ~g/mL. The Vibrio
spp. were also sensitive to CP, but less sensitive or resistant to GTC, SPM, ABPC, CL, GA, and SDMX. After
48 hours the MIC of NFS-Na to the Vibrio isolated fromboth the skin and kidneys of NFS- Na treated fish was

1.56-6.25 ~g/mL.

Tissue NFS-Na Concentration
after Bath Treatment
Tissue NFS-Na concentrations following a single bathtreatment of 10 ppm of NFS-Na for 30 minutes are given

104

NOAA Technical Report NMFS 102: Marine Ranching_

Table 4
Sensitivity of bacteria isolated from the skin ulcers and kidneys of young bluefin tuna to various antimicrobial agents. Abbreviations of antimicrobial agents: NFS-Na = Sodium nifurstyrenate; CP = Chloramphenicol; OTC = Oxytetracycline; SPM
Ampicillin; CL = Colistin; OA = Oxolinic acid; SDMX = Sulfadimethoxine.
= Spiramycin; ABPC
Time
after
handling Medica(h)
tion
0

2

24

None

Skin

Genus
of
isolatesNoof isolates
tested NFS-Na

Minimum inhibitory concentration(l-Ig/mL)
CP

OTC

SPM

ABPC

CL

OA

SDMX

12.5-25
0.78-50
12.5-50 25-~200 25-~200
100
25
50
~200
12.5
6.25-25 0.20-0.39 6.25-12.5 0.78-100 0.20-1.56
0.39
1.56
~200
0.78
0.05
3.13-6.25 0.20-0.78
3.13-25 0.20-6.25 0.20-1.56

3.13
25
3.13

100-~200- ,12.5-25100
6.25-100
25
~200

25

3.13-~200

3.13-6.25

12.5-100~200 0.78-~200

50-~200

Pseudomonas
MIA'
F/C b
Staphylococcus
Micrococcus

3
3
2
1
3

NFS-Na Skin

Pseudomonas
MIA
F/C

3
1
2

12.5-25 0.78-1.'i650
6.25

25-~'200

100-~200

0.78-6.25

None

Vibrio6

0.10-0.78 0.39-1.56

25-10050-~200

25-~200

Pseudomonas

6

Skin

NFS-Na Skin
None

48

Site
of
isolation

Skin,
VibrioKidneyVibrioNFS-Na Skin,
Kidney Pseudomonas

Skin,
VibrioKidney

None

~200

50
~200

25··5025-~20()0.78-3.13

1.56

3.13-~200

12.5-~200

6

0.20-0.39

1.56

50-100

~200

~200

~200

12.5-~200

~200

7
3

1.56-6.25
1.56
6.25-25 0.78-3.13

100

~200

~200

~200

~200

~200

50-~200

100-~200

0.39-1.56

1.56-100

1.56-12.5

12.5-10040.20-0.39

50

~200

~200

12.5-~200

12.5-50

3.13-~200

3.13-50 0.10-0.78

1.56'MIA = MoraxellalAcinetobacter.
bF/C = FlavobacteriumlCytophaga.

' - ~ not tested.

Table 5
Changes in concentration of sodium nifurstyrenate in various organs of young bluefin tuna after bathadministration of the agent. Assay sensitivity limit: 0.05 J.lg/g.
Concentration of sodium nifurstyrenate(l-Ig/g)Time after
medication

Fish
no.

Liver

KiC.ney

SpleenRed
muscleOrdinarymusclePlasma

0

1
2

0.07
0.10

0.42
0.51

0.08
0.16

0.41
0.31

<0.05
<0.05

0.65
0.69

I

2

0.20
0.09

0.37
0.19

0.08
0.06

0.27
0.19

<0.05
0.09

0.36
0.31

1
2

<0.05
<0.05

0.11
0.24

<0.05
<0.05

<0.05
<0.05

<0.05
<0.05

<0.05
<0.05

<0.05

0.05

<0.05

<0.05

<0.05

<0.05

2
6
12

in Table 5. The NFS-Na levels in all tissues examined werehighest just after the medication: 0.42-0.51 IJg/g in thekidney, 0.31-0.41IJg/g in the red muscle, and 0.65-0.69
IJg/g in the plasma. After 6 hours NFS-Na levels became
undetectably low in all tissues except the kidney. NFS-Na
levels in the kidney were similarly undetectable 12 hours
after the treatment.

Discussion_

The structure of the skin of young bluefin tuna is principally the same as that of other fish. However, the epidermal layer is very thin and fragile. It is evident that
because of the fragile structure of the epidermis ulcers easily
develop in the skin. The histopathological examination

_ _ _ _ _.

Sako et at.: Skin Ulcers in Young Bluefin Tunarevealed various kinds of inflammatory reactions and anincrease of bacteria in the skin foci. The bacterial flora of
the skin of healthy young bluefin tuna mainly consistedof Pseudomonas ,Moraxella/Acinetobacter, Flavobacterium/Cytophaga, and Mi,;rococcus. These bacteria are the common
genera which appear on the skin of marine fish (Horsley
1977). Vibrio; which is a common bacterium in seawater,
was not isolated from the skin of healthy young bluefin
tuna. Thus, it seems that healthy young bluefin tuna
have certain indigenous bacterial flora different from thatof seawater. A facultative pathogen in seawater, Vibn'obecame predominant in advanced skin ulcers; the skinlesion it seems provides a favorable condition for Vibrio
growth. The Vibrio sp. isolated from the kidney was identical with the ones which predominated in the foci of theskin ulcers; the skin ulcer is possibly an entrance forbacteria into the body.
Bath administration of NFS-Na to young bluefin tuna
after the transportation from Kaminokae to N ansei decreased mortality probably by retarding ulcer development. As Vibrio isolated from the skin ulcer was highly
susceptible to NFS-Na, it is clear that this chemical treatment suppressed the growth of the pathogens in the skin,slowing its invasion into the body, at least for a shortperiod. Responses of various bacteria isolated from the skin
to NFS-Na suggest that this medication inhibited thegrowth of Vibrio without influencing the indigenous bacterial flora in the skin. Thus, NFS-Na is considered an
ideal antimicrobial agent to control skin ulcers. However,Vibrio resistant to NFS-Na increased in ulcer foci of theskin in advanced ulcers after 48 hours. In most cases a 10
ppm bath treatment increased tissue NFS-Na concentrations for several hours to higher levels than the MIC needed
to inhibit Vibrio growth. However, the levels fell and wereundetectably low within 12 hours. Therefore, it is neces-sary to treat with NFS-Na more than twice a day to maintain high tissue NFS-Na levels. Further studies are needed
to determine the optimum schedule uf NFS-Na treatment
and to find more effective antimicrobial agents to control
the skin ulcer of young bluefin tuna. Vibrio was also sensitive to CPo However, because CP is not legally permitted
in fish culture in Japan, the use uf this drug should be
avoided.
Improvement of handling techniques is another way to
reduce the occurrence of skin ulcers. '-IVe have found thata black polyethylene bag with many small holes is very
useful for various kinds of handing. When a young bluefin
tuna is introduced into the polyethylene bag in seawater,
they usually become quiet in a short time. Althoughholding the fish with bare hands easily results in thedevelopment of skin ulcers, the handling of fish in the bag
does not produce the severe ulcer.

105

Acknowledgments_

This research was supported by a Grant in Aid of Ministryof Agriculture, Forestry and Fisheries (MRP-88-III-3-1).

Citations_Horsley, R.W.
1977. A review of the bactenal flora of teleosts and elasmobranchs,
including methods for its analysis. ]. Fish BioI. 10:529-553.
Simidu. V., and K. Hasuo.
1968. An improved medium for the isolation of bacteria frommarine iish. ]. Gen Microbiol. 2:355-360.
Ueyanagi, S., K. Mori, Y. Yasuo. and A. Suda.
1973. Report on experiments on the development of tuna culturing techniques (April, 1970-March, 1973). Far Seas Fish. Res.
Lab., S series, 8, 165 p.

Successful HOTAC Methods forDeveloping Scallop Sowing Culture in the
Nemuro District of East Hokkaido, Northern JapanHIROSHI ITO
Hokkaido National Fisheries Research Institute(formerly: Hokkaido Regional Fisheries Research Laboratory)
Fisheries Agency
Japan Ministry of Agriculture, Forestry and Fisheries
116 Katsurakoi, Kushiro, Hokkaido 085, Japan

ABSTRACT
Successful results with sowing culture (bottom culture) of the Japanese scallop, Patinopecten
yessoensis, were achieved by using the "Hotate"-aid-conglomerate (HOTAC) methods in Nemuro
district, which is located in east Hokkaido, northern Japan. Nemuro district scallop landings
have increased more than tenfold in about ten years from the mid-1970s to mid/late-1980s.
HOTAC methods were established using and integrated method (mandala) based on 1) the mass
production of seed, 2) the control and monitoring of the entire culture system, and 3) the intellegent and proper use of human resources. The HOTAC operations contributed technologicalinnovations in the areas of both hardware (e.g., larval monitoring devices, wide-area telemeter,
HOTAC-modelled intermediate culture cage) and non-hardware (e.g., scientific knowledge,
strategic manuals, use of human resources) components. Both components are being utilized ona widespread basis in Hokkaido. Consequently, the scallop landing in 1988 contributed a reliable
11.4% share to Hokkaido's fisheries production. The HOTAC achievement led clearly to a basic
conclusion that the effective improvement of manpower founded on a science was the essential
element among the non-hardware components which allowed the successful realization of an
improved industrial scallop culture.

Brief View of theJapanese Scallop Fishery_

In Japan, references to the sC:-~lop fishery usually refer to
the Japanese scallop, Patinopecten yessoensis, fishery, whichsurpasses other scallop species in scale of landings. Thisfishery evolved rapidly after the 1970s because of the successful development of hanging (suspending) and sowing(bottom) culture in northern Japan, mainly in Hokkaido(Ito 1988; Figs. 1-2). Before the late 1960s, the scallop
fishery depended on wild resources. Relatively high-level
catches had been recorded until the mid 1940s (Tanaka
1963); however, low level catches occurred during nearlya quarter of a century period from the mid-1940s to thelate-1960s. During the end of the 1960s, industrial scallop
cultures developed owing to an innovation in seed production using wild spats (Ito 1986c; Ito et al. 1986). In
1988, the production of sowing culture and wild scallops
amounted to 159,689 metric tons (t) and hanging culture

reached 181,929 t, for a total production of341,618 t. The
value was 78,674 million yen (524 million U.S. dollars:
calculated on the dollar = 150 yen).
The major landings have always been around Hokkaido
in northern Japan. Scallops caught in Hokkaido represented 77 % of all Japanese scallop production from bothwild and cultured stocks during the period 1910-88. With
the mid-1970s and the early-1980s an epoch ended, marking the beginning of the mass production period (Ito 1984a;
1984d; 1985a). During this period, serious problems withproductivity stagnation were caused by mass mortality inhanging cultures, lack of seed for sowing culture, and industrial anxiety for a conventional culture method. So, a
new culture technology was necessary to further develop
the scallop culture industry; however, there was a lack ofscientific knowledge to support the new epoch of a mass
production period.
The author began to investigate the possibility of designing a new culture system for Japanese scallop i~ a typically
107

108

NOAA Technical Report NMFS 102: Marine Ranching

_
145 E

OKHOTSKSEA
45"NFigure 1
The Hokkaido and Nemuro Districts in japan: contours are depths in meters.

350.000I!

1910-23:Temporary high level catch period
1924-32:Stable h \gh level catch per lod
1933-44:Extreme high level catch period
1945-68:Stable low level catch period

Ul

Z

~
o

--j-----------,I,·1······~·__··

1969-76:Hanglng culture deveLopment per led

1977-88:Sowlng and hanging culture mass
product Ion per lod

~::E

I

I

i

------r-- ---- ---j--------....
I

i

I
,
•
•
I
I
-----··----r----------------------1------------t----------t---·------t·----------t--·-------,--------1--------·--ill''
I I I I I i i !,-·--·-·--·I-·---------I-----------r-----------,-----------r-----------,-----------I----- -I ----------r-----------

Z

o

§
::l

o

oa:

-----------.----- ------------- .-.. --II.

--------'------------,..--

I

o
1900

,- ··--·---[-----------r-------·-·

1950

i
2000

YEAR

Figure 2
Yearly changes in fishery production, in metric tons, of the japanese scallop, Patinopectenyessoensis, 1910-88. • = totalforjapan; 0 = totalforHokkaido. Source: japan
Ministry of Agriculture, Forestry, and Fisheries.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Ito: HOT AC Methods for Developing Scallop Sowing Culture

unproductive area such as Nemuro district in the
mid-1970s (Ito 1983). At that time, efforts to culturesc:allops remained unsuccessful in Nemuro district becauseof many factors. This difficult state typified and emphasized
the problems facing the Japanese scallop culture industry
that occurred broadly over the northern Japanese scallop
culture areas. This paper focuses on the establishment ofan economical culture production for scallop fishermen
using new and effective research methods.

Scallop Mariculture_

The author has explained the concept (mandala) ofJapanese scallop mariculture with a mandala diagram (Ito1989a) because of the recent evolution of scallop culturing
into a complicated industrial structure. The mandala concept comprehensively considers aspects of science, sociology, and economics. Technologically, the mariculture
process of the Japanese scallop has three stages: a seed production phase, a culture phase, and a harvest phase (Fig.
3). The seed production phase is composed of two processes: wild spat collection and intermediate culture. The
culture phase is performed by using one of two methods:
sowing culture or hanging culture. During the harvest
phase, sowing-cultured scallops are generally harvested bya scallop dredge when four years old, and hanging-cultured
scallops are usually harvested at an age of two years old.

109

WILD SPAT COLLECTION(EMBAYMENT or OFFSHORE SPAT COLLECTION)

1]

SEED PRODUCTION

INTERMEDIATE CULTURE_11

SOWING CULTURE(BOTTOM CULTURE)

l_'_,,,I,,,HANGING CULTURE(SUSPENDING CULTURE)

I

Figure .3

The process of Japanese scallop mariculture.

Abashiri and Soya on the Okhotsk Sea coasts, because there
were obstacles to progress. In the meantime, a partial
harvest had been realized from the extremely productive
culture grounds off the coasts of Abashiri and Soya,although the culture technology remained undeveloped.

HOTAC Operations
Background of Scallop Culture
in Nemuro District_

Before 1945, relatively high catches were recorded from
Nemuro waters (Fig. 4), the value of which ranked second
only to catches from the coastal waters of the Okhotsk Sea
off Hokkaido (Tanaka 1963). This was caused partially by
the higher level of wild stocks, which were sustainableowing to the relatively lower catch rates of the undevelopedor developing facilities (e.g., boats and gears) for scallop
fishing. Secondly, Nemuro's fishermen utilized a wider
fishing area, which before World War II included Kunashiri Island and the south Kuril Islands. After that time,
the catch remained small until 1980 because of the low levelof wild stocks (Fig. 5). The scallop fishery in Nemuro Bay
was closed for two years (1975-76) owing to an exhaustion of resources (Ito 1983). Meanwhile, the establishmentof the 200-nautical-mile exclusive zones reduced the
Nemuro's fisheries production after 1977. Because the
Nemuro community is based mainly on fisheries, its
economy declined and required new resources. To solve
this problem, an industrial program for scallop enhancement was started in the late 1970s, which employed sowing culture technique on a large scale. This start came to
the Nemuro district later than other districts, such as_

The purposes of designing the industrial scallop culture
program in Nemuro are summarized as follows: 1) todevelop a sowing culture system, 2) to create commercial
stocks, 3) to increase fishermen's incomes, and 4) to activate community economics (Fig. 6). However, there werefour main barriers for the development of a culture system
in Nemuro district (Ito et al. 1989):• Limited seed supply:no spat because of unsuccessful wild spat collection,
few seed supplied from seed market,
mass mortality of hanging culture at seed supply areas.
• Limited amount of culture grounds:
international dispute with the USSR,
suitable bottom habitat in existing grounds limited.
• Starfish predation high in southern area.
• Weak manpower levels due to irregular flow and typeof information on scallop culture technology provided tofishermen and persons concerned.
The essential roots of these problems were common to
the general impediments in the Japanese scallop mariculture. The first was the lack of seed; no spats wereavailable for seeding because of the unsuccessful efforts to

110

NOAA Technical Report NMFS 102: Marine Ranching
145 E

_

g

n m

I!

OKHOTSK! Ii !

.
i i " 5i i i ! i ! i Ii lO
Ii I
!

Ii!

10

i

!

I

f

y.m

'?#

~

~
~

,
OCEAN

Figure 4
The Nemuro District in .Japan: contours are depths in meters.

collect wild spat (Ito 1984c). Moreover, few seed were
supplied from the main seed supplier areas in Funka Bayof southwest Hokkaido, which suffered mass mortality intheir hanging cultures (Ito et al. 1986). Thus the seed production phase around Hokkaido suffered from both unsuccessful offshore wild spat collections and a chronicallyinsufficient seed supply. The second problem was a limitedarea for culture grounds caused by both an international
dispute with the U.S.S.R., which occupies territory eastward of Nemuro waters, and the limited amount of bottom habitat suitable as scallop habitat. As no culture

ground is unlimited in size, the effective utilization ofsuitable areas is of general and current interest. The third
was the large population of starfish in N emuro Bay, southof Nemuro Straits. Only a few older scallops remained in
the area (Ito et al. 1989; Fig. 7). Removal of a starfish
population from a culture ground is an annual process forcreating sowing culture, however, the starfish density in
Nemuro Bay was the highest among Hokkaido coasts. The
fourth problem was the lack of scallop enterprisers. A low
morale existed because of irregular information available
on current technology for scallop mariculture. In general,

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Ito: HOTAC Methods for Developing Scallop Sowing Culture, 5000
.~2.

L

,

'04'

1<7?

?70

'0

a •..... 0

a

a

1345

a

a

2

7700

"05

a

a

a

'74

a

.'OR

.'75'

a

a

79

"a

1599

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Figure 5
Yearly changes in the landings of Japanese scallop from Nemuro waters, 1945-88. Yearly totalled values are from Hokkaido Prefecture. The author compiled the values of the sowing culture harvest.

DEVELOP SOWING CULTURE SYSTEM

1CREATE COMMERCiAL STOCKS IN NEMURO!

INCREASE FISHERMAN'S INCOME!

~.ACTIVATE COMMUNITY ECONOMIC_S_

Figure 6
Purposes of the scallop culture program in Nemuro District.

many ignored the possibility that the use of manpower
could be improved. At that time, the scallop culture technicians attempted to develop a primary stage; however,
hasty conclusions were made. Many fishermen, culture
technicians, administrators, and even onlooking scientists believed that the scallop mariculture could be easily
established anywhere without further investigation.
This was a serious problem; how to develop a scientifictechnology combining private enterprise and research
investigations.

The author designed the further investigation withcoworkers of acquaintances in the industry. We sought
authorization for our large scale research that was to be
combined with culture enterprise activities. There was little
3uppOrt and budget for the scientific research in this program by the official organizations which would contribute
their activities to the improvement of the fishery. Therefore, the author formed a research team called the"Hotate" -aid-conglomerate (HOTAC), which consistedof coworkers belonging to several organizations concernedwith scallop culture: Fisheries Cooperative Associations.
Town Offices, Fisheries Extension Offices, and others.
HOTAC was based on freedom of association, and its
membership could be described as one based on "Jingi,"aJapanese social code comprising justice, benevolence, andcompassion. The HOTAC research was operated on alarge scale. Although it required a large budget, there was
no official support. We raised funding by gathering flexible and reasonable payment in our shares from the culturerelated organizations. In time, a governmental researchbudget, within the limits of the Marine Ranching Program,
eventually supported the program, but only after confirmation of successful harvests of the cultured scallop from
Nemuro's grounds. The HOTAC research activities were

112

NOAA Technical Report NMFS 102: Marine Ranching<

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Figure 7
Distributions of the Japanese scallop and starfish in Nemuro Bay, south of the Nemuro Straights,
during a period of low wild-stock concentrations of the scallop prior to the beginning of the sowing
culture program in the late 1970s.

supported by their self-funded budgets during a criticalduration of time, The HOTAC style of operating remains
unique inJapan. HOTAC research methods were appliedin three stages:• Bottom habitat analysis.
• Removal of starfish.
• Seed sowing.
• Harvest.

• Larval monitoring for wild spat collection by Fisheries
Cooperative Associations and fishermen.
• Juvenile care check for intermediate culture.
• Population survey of cultured resources in a rotational
planting ground.

First, there are the self-supplying seed production
methods (seed collected by the fishermen themselves),
which come from two new technological processes: one isfor wild spat collection in waters less suitable for s~allop
culture where low densities of scallop larvae exist (Ito etal. 1988; Ito 1990; 1991, Fig. 8) and another is for intermediate culturing in waters that are frequently stormtossed and visited by drift ice (Ito 1986b). Additionally,
floating seeds from a seed market are introduced if selfsupplied seeds are lacking. Usually, in Nemuro waters,
there is a very low density of larvae and the opportunities
to collect spats come too late. Conditions for wild spat

A detailed HOTAC culture system was designed for
Nemuro waters and its process is explained as follows:• Seed production:
wild spat collection,intermediate culture,
if a lack of seed, introduction from seed market.

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Ito: HOTAC Methods for Developing Scallop Sowing Culture

•

a

10

113

l

•

100 1000LARVAL ABUNDANCE

IND.N/m'3• ••Figure 8
Typical larval distributions of Japanese scallop off east Hokkaido in early June. Although sufficient levelsof larvae existed in the northern area, enabling spats to be collected, few larvae appeared in Nemuro waters
in the southern area.

collection are not always critical in other waters off Hokkaido. Second, the bottom habitats are searched for thepresence of cultures, and the particular culture grounds
to be sowed are selected. Third, starfish are removed byscallop fishermen by means of scallop dredges and traps
from the culture ground prior to seed sowing. One to three
thousand metric tons of starfish were landed in a yearlyclearance of every rotational planting ground in Nemuro
Bay (Ito et al. 1989). In the fourth step, 50-150 million
seeds are sown annually on selected rotational bottoms.
Finally, the selectively sowed seeds are later harvested as
four-year-old scallop from that particular culture ground.
An immediate feedback of the HOTAC operation results
evolved making the new HOTAC methods innovativetechnology. HOTAC manuals, along with the following
new hardware, were developed for the strategy designed
from HOTAC operations:• Mass-productive HOTAC cage for intermediate culture.
• HOTAC anchor system of intermediate culture for clearing trouble of drift ice.
• HOTAC flow production system for mass seed production.
• HOTAC optional underwater TV system with high-finecamera for cultured population survey.
Fisheries Cooperative Associations and their fishermen
only are permitted to conduct direct industrial actions
related to fisheries (by the Japanese fishery law). Therefore,
all industrial action of economic importance was accomplished by Fisheries Cooperative Associations and groupsof scallop fishermen according to the HOTAC manuals
under the control of the HOTAC culture strategy.

Results and Conclusions• Computerized devices for scallop larval monitoring.
• Wide-area telemeter for culture condition monitoring.
• Effective HOTAC spat collector for lower larval density.

_

After the HOTAC operations, commercial stocks werecreated from the sowing culture (Ito et al. 1987, 1988, 1989;

114

NOAA Technical Report NMFS 102: Marine Ranching_,..----------------------------------------,
100
WILD

SCALLOP. ind./m 2-. . . .-= ~ -.oWAGE.YEARSTARFISHES.ind. /m 2

Figure 9Distributions of sowing-cultured Japanese scallop and remaining starfish on a rotational culture ground in Nemuro Bay, south N emuro
Straits, after implementing culture operations (Ito et al. 1988).

Fig. 9) and fishermen harvested the cultured stocks andincreased their incomes as follows:• Commercial stock is created by sowing culture.
• Fishermen harvest improved resource and increase theirmcomes.
• Community economics become active.
• Culture system requires completion of essential elements:
seed production, culture control, and creative us,e ofmanpower.
Moreover, the community became economically active,
even though the fisheries activities in Nemuro district had
previously fallen to a low level since the establishment of
the 200-nautical-mile exclusive zones in 1977. In the midto-late 1980s, the scallop production value from Nemuro
waters increased twelve times (eight times as adjusted by

the consumer price index) from that of the mid 1970s(Fig. 10).
The HOTAC strategy of how to make a culture systemformed from results of HOTAC operations, and from thefollowing HOTAC-developed innovative technologies.
Excellent wild spat collections from 1982 to 1988 wereachieved with an explorative survey method for low density larvae (Ito 1990, 1991). The automated hardware
for larval monitoring was developed with the supportof special manufacturers (Ito 1985b, 1991). Marketabledevices were obtained, such as the shape quantificator fordiscriminating species (CIA-HTT, Olympus Co. Ltd.) andthe wide area telemeter for monitoring sea environments(SEACOM, Sanyo-suiro Co. Ltd.). A strategic manual isavailable for wild spat collection (Ito 1986a). Masses ofqualified seeds were sowed on selected rotational bottoms(Ito 1989b). More productive seeds were produced with

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Ito: HOTAC Methods for Developing Scallop Sowing Culture

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Figure 10
Yearly changes in the production value of Japanese scallop from Nemuro waters, 1970-88.

the novel mass production methods using new HOTACmodelled cages (Ito 1984b; 1986b). In this industrial program, a successful method for wild spat collection and an
effective culture system have been introduced and incorporated synchronously from the HOTAC operations by
Fisheries Cooperative Associations and groups of scallop
fishermen (Ito 1984c, 1984e). Some of the new hardwareand non-hardware components of successful HOTAC
results are being used on a widespread basis in Hokkaido.
For example, spat collections in the open sea off Hokkaido
have been stabilized by wide scale larval monitoring which
directly imitates HOTAC methods (Ito 1991). Thisstabilization is due to the author and HOTAC members
lecturing at every annual culturist meeting such as Eastand North Hokkaido Scallop Culture Technology Meeting
since the early-1980s (Ito 1984a, 1986b).
In conclusion, the culture system requires the completion of three essential elements: mass production of productive seed, entire control of profitable culture, andintelligent and as well as proper use of human resources(Ito 1989a). The three elements are systematically related
to each other in the mandala formation. The author explains with common Japanese terms that the three elements of seed production, culture control, and manpower
improvement are "Tanezukuri," "Gyobazukuri," and"Hitozukuri," respectively. Basically, "Hitozukuri" ormanpower improvement founded on science is the essential element other than equipment which allowed us torealize an industrial scallop culture.

Acknowledgments_

The author wishes to express sincere thanks to the following coworkers of the HOTAC team, who have left Nemuro
district after verifying successful results: Toshikazu Fuji-

moto, Takao Sasaki, HarUo Moriya, Tohru Ikeda,
Tadashi Abe, and Yukiyasu Nakata for thier expertise and"Jingi. "Citations_

Ito, H.
1983. Existing state of scallop sowing culture in Nemuro Straits.
Hokusuiken News (29), Hokkaido Natl. Fish. Res. Inst., p. 2-4.
(In Japanese. )1984a. Memorandum of scallop mariculture in Hokkaido. Hokusuiken News (30), Hokkaido Natl. Fish. Res. Ins!., p. 3-4. (InJapanese.)
1984b. Improvement of facilities for intermediate culture ofJapanese scallop in Shibetsu, Nemuro, east Hokkaido. Hokusuiken News (30), Hokkaido Natl. Fish. Res. Inst., p. 4-5. (InJapanese.)
1984c. New movement on wild spat collection ofJapanese scallopin Nemuro waters. Hokusuiken News (30), Hokkaido Nat!. Fish.
Res. Ins!., p. 5-8. (In Japanese.)
1984d. Overview on seed sowing ofJapanese scallop in Hokkaido.
Hokusuiken News (31), Hokkaido Natl. Fish. Res. Ins!., p. 2-4.
(In Japanese.)
1984e. Existing information on wild spat collection of Japanesescallop in Hokkaido. Hokusuiken News (31), Hokkaido Nat!.
Fish. Res. Ins!., p. 5. (In Japanese.)
1985a. Seed input and catch/harvest of Japanese scallop in Hokkaido. Hokusuiken News (32), Hokkaido Nat!. Fish. Res. Ins!.,
p. 3-4. (In Japanese. )1985b. Handy computery devices for microscopic measuring ofJapanese scallop larvae. Hokusuiken News (33), Hokkaido Nat!.
Fish. Res. Ins!., p. 7-9. (In Japanese.)
1986a. A flowchart for wild spat collection of Japanese scallop.
Hokusuiken News (34), Hokkaido Natl. Fish. Res. Ins!., p. 3-5.
(In Japanese.)
1986b. Technological elements of intermediate culture to produce
a mass ofJapanese scallop seeds for sowing. Textbook of the third
lecture meeting ofJapanese scallop mariculture, Kita-nippon Kaiyo
Center (Sapporo), p. 29-33. (In Japanese.)
1986c. Mariculture ofJapanese scallop. In Edition of culture andenhancement in fisheries; 12th volume of bibliographical intro-

116

NOAA Technical Report NMFS 102: Marine Ranching

duction of agriculture, forestry and fisheries research (A.
Koganezawa, ed.), p. 221-231. Agr. Forest. Fish. Res. Council Secretariat, Japan Ministry of Agr. Forest. Fish. (In Japanese.)
1988. Sowing culture of scallop in Japan. In New and innovativeadvances in biology/engineering with potential for use in aquaculture; Proceeding of the fourteenth U.S.-Japan meeting on
aquaculture (A.K. Sparks, 00.), p. 63-69. U.S. Dep. Commer.,
NOAA Tech. Rep. NMFS 70.
1989a. Concept in mariculture of Japanese scallop. Scallop(Kushiro) 2:89-97. (In Japanese.)
1989b. A new view on sowing culture ofJapanese scallop from seedling angle. Scallop (Kushiro) 2:99-103. (In Japanese.)
1990. Some aspects of offshore spat collection ofJapanese scallop.
In Marine farming and enhancement; Proceedings of the fifteenth
U.S.-Japan meeting on aquaculture (A.K. Sparks, ed.), p.
35-48. U.S. Dep. Commer., NOAA Tech. Rep. NMFS 85.
1991. Wild spat collection ofJapanese scallop and related technological innovation in Nemuro Waters, east Hokkaido. Fish.
Engineering 27(1):37-55. (In Japanese; English abstr.)
Ito, H., S. Tanaka, and T. Wakui.
1986. Japanese scallop. In Senkai Yoshoku (Mariculture in_shallow waters) (Y. Oshima, ed.), p. 419-445. Taisei Press(Tokyo). (In Japanese.)Ito, H., Y. Yano, and Y. Sakai.
1987. Distribution and growth ofJapanese scallop sowed in eastern
Hokkaido coasts. Prog. Rep. Marine Ranching Program in itemsof bay scallop and ark shell (7), Japan Sea Nat!. Fish. Res. Ins!.,
p. 113-130. (In Japanese.)
1988. Conditions of offshore spat collection and distribution andgrowth of sowing culture population of the Japanese scallop,
Patinopecten yessoensis, off east Hokkaido. Prog. Rep. Marine
Ranching Program in items of bay scallop and ark shell (8),Japan
Sea Nat!. Fish. Res. Ins!., p. 119-154. (In Japanese.)
1989. An analysis of seed and ground effects on sowing culture of
the Japanese scallop, Patinopecten yessoensis, in Nemuro coasts ofeast Hokkaido. Prog. Rep. Marine Ranching Program in itemsof bay scallop and ark shell (9), Nansei Natl. Fish. Res. Inst., p.
121-160. (In Japanese.)
Tanaka, S.
1963. Some problems on fishery and researches of the scallop,
Patinopecten yessoensis, around Hokkaido. Symposium at 1963
meeting, Jpn. Soc. Sci. Fish., p. 142-150. (In Japanese.)

The Use of Aquaculture for Enhancement of theCommon Property Fishery in Oregon, Washington, and Alaska

JOHN L. PITTS
Department of Agriculture
406 General Administration Bldg., KU-14
Olympia, Washington 98504-0641

ABSTRACTPrivate and public sector aquaculture has been used for over 100 years in Pacific Northwest
states to enhance wild stock salmon fisheries. The three states are compared regarding legal andregulatory constraints, operations, technical approaches, and measure of success. Various species
are discussed along with problems associated with various culture regimes. Basic information
on success or failure of programs is presented and species are cited.

Introduction_

Oregon, Washington, and Alaska have developed different
and unique approaches to enhancing the common property
fishery in marine waters using aquaculture technology.
This discussion, limited to salmonid species, describes the
structure of each state program and its contribution toaquaculture methods.

State of Oregon_

Some of the first private salmon hatcheries were constructed in Oregon in the 1870s. These private efforts werelater replaced by public hatcheries in response to fisherydeclines and habitat loss from dam building on the Columbia River. In the late 1960s, there was resurging interestin salmonid culture in the private sector. In 1971, statelegislation was passed, and a new private, commercial
ocean-ranching industry created in Oregon. The originallegislation authorized permits for chum salmon (Oncorhynchus keta) hatcheries only. In 1973, state law was amended
to allow chinook (0. tshawytscha) and coho salmon (0.
kisutch) permits and eventually (1979) ones for pink salmon(0. gorbuscha) as well (Ocean Resources Law Program1979). The commercial salmon rancher must have a permit for each species of salmon it releases. The permits areissued by the Oregon Department of Fish and Wildlife after
extensive review and public hearings. Various concerns arestill being raised about commercial salmon ranching in thestate. Potential genetic impacts and fish straying to or fromprivate salmon hatcheries are the issues most often raisedin this ongoing debate. Estimation of straying is not anexact science, and concern is expressed owing to the comparatively large number of salmon released by private
hatcheries compared to releases from public hatcheries(Cummings 1987).
Oregon's private salmon ranching industry consists oftwelve hatcheries with permits. The three largest operations release chinook, coho, and chum salmon: 1) Anadromous, with release sites at Coos Bay; 2) Oregon-Aqua
Foods, with a release site at Newport; and 3) OregonPacific Salmon Ranch, with a release site south of Gold
Beach. The Domsea facility at Suislaw Bay last releasedfish in 1983. The eight other permits, issued for various
locations along the Oregon coast, are for small operations
allowed to release chum salmon only.
Oregon has experienced variable success in private
salmon ranching over the last 15 years. The eight small
growers have reared and released chum salmon with very
little success (returns averaging less than one percent). The
chum salmon have been found to have little or no resistanceto bacterial disease in the hatchery and high mortalities
have occurred. There are also unresolved questions relating
to the carrying capacity of the estuarine systems wherethese fish have been released. Experimental results at
Oregon State University have also been disappointing,where chum returns 1-1.5 percent of release. Chum salmon
is not a major contributor to the private ocean ranchingeffort in Oregon and there is little evidence to indicate that
117

118

NOAA Technical Report NMFS 102: Marine Ranching

additional effort will occur in the near future CW. McNeil,
Hatfield Marine Science Center, Newport, Oregon, pers.
commun., Jan. 1989).
Most of the capital investment for ocean ranching has
centered on chinook and coho salmon. It is estimatedthat more than $80 million of private investment has
been expended for ocean ranching development in the past
15 years. The numbers of coho salmon released fromprivate hatcheries gradually increased from 88,000 in
1974, to a peak 23.9 million in 1981 and 23.1 million in1982 (Mayo 1988). Releases have declined since that peakeffort. The three major companies plan to release over
5 million coho salmon in 1988. The average ocean catch
plus the average return to private hatcheries for coho
salmon from 1978 to 1987 was 2.24 percent while the combined average for 1985-87 was 4.55 percent (Mayo 1988).
Improved return percentages were seen after the EI Nino
event of 1983-84. The contribution of private hatcheries
to the commercial and recreational fishery (common property) has been significant in recent years. The averageocean catch for coho salmon between 1985 and 1987 was
662,000 fish. Sixteen percent (109,000) were from private
ocean ranching hatcheries, nearly equal numbers (105,000)
from the natural spawners, and the primary contribution(448,000) was from the state and federal hatchery systems(Mayo 1988).
Increased interest and effort has been placed on production of spring and fall chinook salmon since the early 1980s.
Release efforts for chinook salmon have increased relative
to the total numbers of coho salmon released, but the totalchinook salmon release has been variable. Total releasesof nearly 4 million chinook salmon occurred in 1983 and1984 but declined to slightly over 2 million in 1986. The
chinook salmon ocean catch plus returns to private hatcheries averaged 1.27 percent for 1978-87, but, like the coho
salmon, was far better between 1985 and 1987, averaging
2.51 percent. In 1985, 35,000 chinook salmon were recaptured by private ranching facilities, and those numbers
doubled for 1986 to 70,000 fish. The chinook salmon contribution to the common property fishery by private hatcheries in 1986 was 135,000 fish, but fell to 39,000 fish in
1987 (Mayo 1988).
Private ocean ranchers in Oregon have invested substantial capital in their operations during the last 15-20 years,
but have yet to fulfill the early expectations. A great dealof technical information has been developed regarding
management and husbandry, resulting in better knowledge
and greater efficiency. The industry has gone through anumber of managerial and proprietary changes which haveslowed progress. In addition, regulatory changes by stateagencies, state legislation (passed or proposed), and court
decisions have complicated the development and expansion of ocean ranching in Oregon. The three major companies indicate that they are now marginally profitable or
expect to be so in the near future. Each of the companies_

intends to proceed with their ocean ranching programs,
but all are concerned about regulatory constraints that now
exist or are being considered. Increased public understanding and awareness of the benefits of ocean ranching may
be helpful to the industry in the future.

State of Alaska_

Alaska first established a public salmon ranching programby an act of the state legislature in 1971. Recognizing theserious depletion of natural salmon runs statewide, the state
took action and developed a comprehensive program.
Three years later in 1974, the scope of the program was
expanded with new statutes allowing the private nonprofit
sector to participate in the rearing and release of salmonid
species (Alaska Department ofFish and Game 1986). This
combination of public and private nonprofit hatcheries hasdeveloped into the largest salmon ocean ranching programin North America. Sockeye salmon (0. nerka) production,as part of the total salmonid program, is the largest for thatspecies in the world. The entire Alaskan program is approximately one-half the size of the Japanese ranching
program and nearly equal to the Russian program. In
1987, the returns from both the public and private nonprofit programs accounted for about 20 percent of the total
salmon harvest statewide (Allee 1988).
Presently, the ocean ranching program is administeredby the Alaska Department of Fish and Game, Fisheries
Rehabilitation, Enhancement and Development (FRED)
Division. In 1988, the FRED Division operated 16 hatcheries plus pathology, limnology, and coded-wire tag laboratories. Three hatcheries previously operated by FRED are
now being operated by the private sector through a contractural agreement. Other FRED programs include lakestocking, lake fertilization, comprehensive salmon planning, private nonprofit hatchery permitting, and stream
rehabilitation projects.
Administration of the various public hatcheries is divided
into the following five regions: Southeast, Prince WilliamSound, Cook Inlet, Kodiak and Alaska Peninsula, and theArctic-Yukon-Kuskokwim. Data and statistics are kept for
production, release and return for each species in eachregion. In general, the primary emphasis is on pink andsockeye salmon, followed by chum, coho, and chinook
salmon. In addition, rainbow trout and steelhead (0.
mykiss), grayling (Thymallus articus), and char (Salvelinus sp.)are also managed. Each area has specific management
plans directed at specific enhancement goals for that region
as part of the state plan. Releases of fish from FRED administered facilities increased from 388.4 million fish in
1987 to 412.7 million in 1988. The estimated fishery contribution by FRED hatcheries and projects in 1988 was
5,847,076 salmonid fishes (Holland 1989). Of that total,
the commercial catch represented 3,589,545, the sport

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Pitts: Aquaculture for Enhancement of Pacific Northwest Salmon Fisheries

catch equaled 841,222, and 1,416,309 fish were accounted
for as brood stock.
Some in Alaska described 1988 as the year of theenhancement-produced fish. Extremely low natural returns
would have resulted in poor harvests in many areas, had
it not been for the hatchery programs. In 1988, 91 percent of the entire lower Cook Inlet pink salmon catch and
79 percent of the sockeye salmon catch came from fisheryenhancement projects. The Prince William Sound region
experienced a similar situation with 90 percent of the pinksalmon caught originating from the hatchery programs.
Planted sockeye and chum salmon also contributed to the
Prince William fishery. In essence, economic disaster inthe commercial fishing industry in some regions of Alaska
was averted in 1988 by the significant contribution of stateand private sector hatcheries.
The private nonprofit hatchery (PNP) program wascreated in 1974 and established under the administrationof the Alaska Department of Fish and Game. The PNP
program, administered by the FRED division in cooperation with the department's fisheries management divisions,carries out regulatory responsibilities related to public andprivate aquaculture in Alaska. Seven regional PNP associations have also been formed which cooperate with the
Alaska Department of Fish and Game in developing andmaintaining salmon production plans and rehabilitationand enhancement activities. Each association comprises a
representative from the commercial, sport and subsistence
fishermen, as well as members of local communities.
Regional planning teams develop regional salmon plans
which are mandated by regional charter. The funding
necessary for the PNP corporations has been obtained
primarily through a revolving loan fund administered by
the Alaska Department of Commerce and Economic Development. Loans up to $10 million are available for individual projects with a pay-back period of over 30 years(Alaska Department of Fish and Game 1986). A total of
29 PNP hatchery permits have been issued since 1974;
three permits have been given up. Twenty-two of the hatcheries with permits are in operation and 19 had returns ofadult salmon in 1988. In addition, 36 scientific/educational
permits for aquaculture research projects or school district
programs were issued in 1988 (Holland 1989).
It was estimated that 14.3 million adult salmon, originally released as juveniles from PNP facilities, were harvested in common property fisheries or returned to hatchery harvest areas in 1988. In Prince William Sound, PNP
hatcheries contributed an estimated 8.7 million pinksalmon, representing over 87 percent of the total pinksalmon harvest in that area (Holland 1989).
Clearly the FRED Division and PNP hatcheries havemade significant and substantial contributions to the common property fishery in Alaska through their public andprivate aquaculture programs. Unfortunately, reductions
in state funding for the FRED Division have occurred

119

each year since 1986. A key issue in the debate over funding is whether primary users should pay an increased shareof the enhancement costs. Fishermen assert that they arelarge contributors to the state's general fund and that additional fees should not be imposed on them for enhancement. This political controversy has been debated since1986 and will most likely continue to be an issue in the
Alaskan ocean ranching program.
Another controversy regarding aquaculture also exists.
Development of salmon net-pen farming in the private
sector has created a situation that has resulted in a two year
moratorium. Commercial fishermen concerned with potential biological and economic problems have successfully
lobbied the state legislature to stop or stall the developmentof this new industry. Net-pen farming advocates point tostate documents that indicate the net economic gains fromnet-pen culture and cite positive examples of salmon farming in Europe and Canada as reasons to create a favorable
climate for similar developments in the state. The biologicalpotential appears to be unlimited, but the political controversy is intense.

State of Washington_

Private, for-profit ocean ranching is not presently allowedin the state of Washington. In the late 1970s and early
1980s this issue was debated in the state legislature andbills were introduced; however, efforts to establish private
salmonid enhancement were rejected. Numerous issues
emerged during the debate, a few of which are worth
exploration.
By the 1960s and 1970s, the Pacific Northwest had comeclose to losing major runs of Columbia River salmon. Someof the Columbia runs were even considered for endangered
species status. At one time, annual anadromous salmonid
runs were as high as 15 million fish per year, but numerous
impacts had drastically reduced those former numbers.
Losses from hydro-power dams were cited as the primarycause, but reductions also occurred from irrigation, flood
control, overfishing, and poor logging, grazing, and farming practices. Similar concerns existed for the Puget Soundruns because of habitat loss and overfishing. In 1977, thestate established an objective of increasing the public catchof salmon by Washington citizens and appropriated$30 million for this effort. Again, in 1980, an additional$70 million was authorized for the Salmon and Steelhead
Conservation and Enhancement Act (Washington State
Department of Fisheries 1988). To some, it appeared thatprivate ocean ranching would be consistent with these
efforts, but numerous questions and political disputes
emerged.
During the debate, the Washington Department of Fisheries (WDF) remained neutral but provided important
information related to commercial ocean ranching. The

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NOAA Technical Report NMFS 102: Marine Ranching

three areas sited for special attention were 1) biologicalconsiderations; 2) regulatory considerations; and 3) fiscal
considerations. There was a dearth of information regarding the biological questions. What would result if large
numbers of fish were released into finite systems which had
undetermined carrying capacities? Examples were citedwhere enhancement of some species may have impacted
other species within the region. Numerous variables existed, but ultimately there was no clear demonstration thatprivate ocean ranching would result in a net gain to the
public fishery. The regulatory questions (area 2) related
to the priority of ocean ranching versus enhancement of
the existing salmon resource as administered by the department. The fiscal concerns (area 3) questioned the abilityof WDF to administer a new ocean ranching program
under the existing budget. As previously stated, the option for commercial ocean ranching was not approved by
the Washington State Legislature.
The existing enhancement programs into open watersof the state include both public and private efforts. The
public effort consists of the Washington Departments ofFisheries (anadromous fish) and Wildlife (steelhead), theUniversity of Washington School of Fisheries, and the U.S.
Fish and Wildlife Service. Private non-profit organizations(sport fishing and enhancement groups) release fish throughcooperative efforts with WDF. Indian tribes release fishas part of their commercial effort and therefore, are thesingle exception to the prohibition on private for-profit
ocean ranching in the state. The tribes, as sovereign nations, are not constrained by state laws; however, close
cooperation exists between state, federal, and tribal hatcheries that assures coordination of effort for the various
enhancement programs.
The Washington Department of Fisheries is the leadagency and the primary source of salmonid enhancement
within the state. For the live years from 1983 to 1987" theWDF released an average of 246 million salmon each year.
The total release effort from all sources was 341 million
fish in 1986 and 337 million fish in 1987. These yearly
releases are critical to the maintenance of the salmonid runsin the waters of the state. A summary of total plantingsby all contributors in 1987 is listed below:
WDF hatcheries - 249.6 million
WDF cooperatives - 12.2 million
Tribal hatcheries - 42.0 million
U. S. Fish/Wildlife - 33.7 million
University of Washington - 0.2 million(Abrahanson 1988).
Survival rates of released fish are quite variable dependingon species and time and point of release. In an effort toincrease survival rates, many fish are now impounded in
freshwater and marine net pens. Free release into theenvironment has been delayed for a few weeks to a few_

months allowing the fish to acclimate and grow in confinedprotection. In early testing in South Puget Sound, coho
salmon survival, using traditional release technology
equaled 10 percent, while the use of delayed-release sites
increased survival to 14.5 percent. Estimates in other areas
indicate even higher survival rates depending on the species
and the management strategies used. Presently there are
25 saltwater delayed-release facilities operating in Puget
Sound. Delayed-release facilities also operate on the coastand in the Columbia River.
An impressive example of the net pen delayed-releaseprograms in South Puget Sound is the program operated
jointly by WDF and the Squaxin Tribe, located at Squaxin Island. The program provides a substantial fishery forthe tribe, as well as other commercial and sports fisheries
in the area. There was virtually no commercial coho salmon
fishery in the Squaxin Island area prior to the project inthe early 1970s. In an early study (1974-79), the tagging
survey revealed an annual recovery of 17.1 percent (Rensel
et al. 1988). The commercial net fishery benefited mostfrom the program, and as a result of that early success,the delayed-release program in that area has made a tenfold increase in their release effort.
Net-pen sites also exist as part of the volunteer enhancement program. An important part of this effort was
stimulated with the passage of the Washington State
Volunteer Cooperative Fish and Wildlife Act of 1984. Thisis a popular and successful program. In 1988, WDF issued
approximately 150 permits for cooperative projects. These
efforts include net pens, egg tubes and egg boxes instreams, aquariums in schools and small hatcheries constructed and operated by volunteers. There have been
recent proposals to increase these efforts, especially netpen facilities. There is even interest by some commercial
fishermen to establish private, nonprofit programs modeled
after the Alaskan programs.
A small, but efficient farmed salmon industry also exists in Puget Sound. The industry has grown slowly overthe past 20 years, and 13 farms are now established andgrowing fish. Production is primarily Atlantic salmon(Salmo salar), but coho and chinook salmon and steelhead
are also being grown. Fish farmers have offered to provide unused portions of their net pens as part of theenhancement effort in the state. Ifutilized, this effort would
be in cooperation with the WDF. Although enhancement
could be supplemented in this way, the future expansionof the salmon farming industry is presently uncertain.
Demographic and use conflict constraints have resulted inpolarization of the issue by affected parties. Resolution of
the problem may ultimately occur in the court system,
unless some acceptable compromise can be developed.
In 1986, salmon represented 25 percent of the total
harvest (202.5 million pounds) of all marine shellfish andfinfish caught or cultured in Washington State (Hoines
et al. 1987). The estimated contribution from release of

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Pitts: Aquaculture for Enhancement of Pacific Northwest Salmon Fisheries

cultured salmonids for common property enhancement
varies by region and species. At least 65 percent of the total
Puget Sound fishery harvest is provided by enhancement
programs. The estimate for the coastal sport and commercial fisheries, which are dependent on the Columbia Riversystem is even higher, at 80-85 percent. The stated goalof WDF is to perpetuate and enhance the runs of salmon
by operating a hatchery system to produce artifically rearedfish and by enhancing spawning runs with the protection
and improvement of salmon habitat. It is clear that a viable
and sustainable long term salmon fishery could not exist
in Washington State without enhancement programs. The
future of enhancement will depend on continued stateand federal support and the continued cooperation ofvolunteerism.

Conclusion_

Creative solutions to maintain our salmon resource for the
future must be supported and constantly re-evaluated.
Aquaculture, both private and public, has played an impOltant role in the history of enhancement of the salmonid
common property in the waters of Alaska, Washington,
and Oregon. Without development of the necessary
management and husbandry technologies, viable runs ofsalmon would have been lost. It remains to be seen whatrole the private and public sectors will play in salmonid
enhancement. The uncertainties of federal and state funding, participation and contribution by the commercial
industry, the role of tribes, and the expansion of private
farming and ranching will all affect enhancement in the
future.
As the demand for all fishery products for consumption
and industrial use continues to expand at a rapid rate, thelimited resource becomes more valuable. The record
market values for salmon in 1988, which parallel mostfishery products, is an example of the market demand

121

driving the price of the product. Numerous fisheries aroundthe world have been depleted and the world catch remains
static while demand outstrips supply. Aquaculture, bothprivate and public, will play an ever-increasing role insolving this problem, and should be viewed as a tool to
be used wisely for the benefit of present and future
generations.

Citations
Abrahamson, P.
1988. A detailed listing ofliberations of salmon into the open watersof the State of Washington during 1978. WDF Report No. 267.
Alaska Department of Fish and Game.
1986. Alaska statutes and regulations of private nonprofit salmon
hatcheries. Alaska Dep. Fish Game.
Allee, B.
1988. Salmon ocean ranching in Alaska,. FRED Division, Alaska
Marine Resource Quarterly, Vol. III, No. 1.
Cummings, E. T.
1987. Private salmon hatcheries in Oregon. Fish Div., Oregon
Dep. Fish Wildlife.
Hoines, L., and D. Ward.
1987. Washington State Sport Catch Report, WDF, 115 General
Administration Bldg., Olympia, WA 98504.
Holland, J.
1989. FRED 1988 Annual Report to the Alaska State Legislature(Alaska Department ofFish and Game, eds.). P.O. Box 3-2000,
Juneau, Alaska 99802-2000.
Mayo, R.D.
1988. An assessment of private salmon ranching in Oregon. The
Mayo Associates, 108 South Washington, Suite 204, Seattle,
Washington 98104, 85 p.
Ocean Resources Law Program.
1979. Ocean Law Memo, Issue 14. Ocean Resources Law Program, School of Law, University of Oregon, Eugene, Oregon.
Rensel, J.E., R.P. Harris, and T.J. Tynan.
1988. Fishery contribution and spawning escapement of coho
salmon reared in net pens in wuthern Puget Sound,
Washington. No. Am. J. Fishery Management 8:359-366.
Washington State Department of Fisheries.
1988. Annual Report, W.D.F., 115 General Administration Bldg.,
Olympia, Washington 98504.

Incidence of Fish Pathogenic Viruses among Anadromous
Salmonids in the Northern Part of Japan, 1976-1987

T. KIMURA and M. YOSHIMIZU
Laboratory of Microbiology, Faculty of Fisheries
Hokkaido University3-]-] Minato-cho
Hakodate 041, Japan

T. NOMURA
Hokkaido Salmon Hatchery
Nakanoshima 2-2, Toyohiraku
Sapporo, Hokkaido 06], Japan

T. AWAKURA
Hokkaido Fish Hatchery
Kitakashiwagi 3-373, Eniwa
Hokkaido 06]-14, Japan

ABSTRACTDuring the period from September 1976 to December 1987, various species of mature salmonid
fish, including masu (Oncorhynchus masou), chum (0. keta), pink (0. gorbuscha), kokanee salmon(0. nerka), charr (Salvelinus leucomaenis), and rainbow trout (0. mykiss), were examined to provide
information on the distribution of pathogenic viruses in northern Japan. Virus inspections wereconducted on ovarian fluids, mixed kidney and spleen specimens, epithelial tumor tissues, andblood samples. Four viruses were isolated during the course of this investigation. Infectious
hematopoietic necrosis virus (IHNV) was found in the ovarian fluid of chum and masu salmon.
Oncorhynchus masou virus (OMV), discovered in 1978 and specific to masu salmon, has been isolated
from ovarian fluids and epithelial tumor tissues at 13 sampling sites. Chum salmon virus (CSV)
was isolated from mixed kidney and spleen specimens from healthy chum salmon in 1978 andagain in the ovarian fluids of masu salmon in 1987 at two localities on the coast of the Sea ofJapan. Infectious pancreatic necrosis virus (IPNV) was isolated from masu salmon at two locations: once from tumor tissue in 1981 and a second time from an ovarian fluid sample in 1987.
Viral erythrocytic necrosis (VEN) was found at four locations in the erythrocytes of chum andpink salmon in waters along the Okhotsk coast. Cytoplasmic particles with a hexagonal profile
were found in the erythrocytes by electron microscopy.

Introduction_

Information on the distribution and incidence of fish
pathogenic viruses is important for the prevention of transmission to the progeny of mature salmonids. Therefore,
we studied the occurrence of pathogenic viruses among
mature salmonids in the northern part ofJapan. Here, we
introduce the results of our investigation from September
1976 to December 1987.

Materials and Methods
Fish Used
From September 1976 to December 1987, we collected
6125 ovarian fluid specimens from 6 species of 11,095
females and 21 seminal specimens from 2 species of
155 males of mature salmonid fishes. Until 1978, 100 fish
were sampled at each collection site and were pooled into
10 specimen lots. Subsequently 60 fish were used, and
123

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NOAA Technical Report NMFS 102: Marine Ranching

\

\

\
\

\
Figure 1
Waters in Hokkaido and northern part of Honshu where salmonid populations were sampled andexamined for presence of IHNV, OMV, IPNV, and CSV, and coastal waters of Okhotsk wherecertain species were examined for VEN, 1976-1978. 0 = Hatchery or fish farm; R = River;
H = Hatchery; L = Lake; P.F.E.S. = Prefectural Fisheries Experimental Station.

specimens were collected individually. Species sampled included masu (Oncorhynchus
masou), chum (0. keta) , pink (0. gorbuscha) , and kokanee salmon (0. nerka) , charr(Salvelinus leucomaenis) , and rainbow trout (0. mykiss) from the following 60 collecting
stations: catching stations (29 in Hokkaido, 5 in Honshu), hatcheries (6 in Hokkaido, 9 in Honshu), 10 fish farms and 1 lake all in Hokkaido. From 1981 to 1987,
140 tumor tissues observed among 4115 fish were used for Oncorhynchus masou virus(OMV) inspection. Furthermore, 190 mixed kidney and spleen specimens were takenfrom 858 of these fish and blood smears prepared from 660 fish were employed forvirus inspection and for microscopical examination for evidence of viral erythrocytic
necrosis VEN, respectively. Thin sections of blood of these fish were observed byelectron microscopy (EM). Collection sites of the specimens are noted on the mapof Figure 1.

_
1: Tonbetsu R.
2: Kitamihorobetsu R.
3: Tokushibetsu R.
4: Horonai R.
5: Okkoppe R.
6: TokoroR.
7: Abashiri R.
8: Shari R.
9: Iwaobetsu R.
10: Ichani R.
11: Shibetsu R.
12: Nishibetsu R.
13: Fuuren R.
14: Bettoga R.
15: Kushiro R.
16: Tokachi R.
17: Teshio R.
18: Nobusha R.
19: Shokanbetsu R.
20: Chitose R.
21: Shiribetsu R.
22: Shubuto R.
23: Toshibetsu R.
24: Toppu R.
25: Assabu R.
26: Shiodomari R.
27: Hekirichi R.
28: Shiriuchi R.
29: Yuurappu R.
30: Bifuka
31: N ishiokkoppe
32: Kamikawa-A
33: Kamikawa-B
34: Mori H.
35: Otobe H.
36: Kumaishi H.
37: Toya L.H.
38: Toya L.
39: Shikotsu L.H.
40: Nobusha H.
41: Memuro
42: Sarabutsu
43: Hidaka-A.
44: Hidaka-B.
45: Nakashibetsu
46: Shakotan
47: Oippe R.
48: Aomori P.F.E.S.
49: Towada L.H.
50: Hei R.
51: Tsugaruishi R.
52: Tsugaruishi H.
53: Yamagata P.F.E.S.
54: Chuuzenji L.H.
55: Nikko H.
56: Gunma-K P.F.E.S.
57: Gunma-H P.F.E.S.
58: Gifu P.F.E.S.
59: Miomote R.
60: Jintsu R.

_ _ _ _ _ _ _ _ _ _ Kimura et al.: Pathogenic Viruses among Anadromous Salmonids in northern Japan

Collection of Ovarian Fluid Specimens
Ovarian fluid specimens were collected according to themethod of Yoshimizu et al. (1985). A sterilized automatedpipette tip was inserted into the urogenital opening of themature fish. One mL of ovarian fluid was taken from thefish and sterilized by one of two methods. Until 1981, afJltration method with a millipore fJlter HA (0.451lJll) was
employed and subsequently the antibiotic treatment
method of Amos (1985). Both fJltrate and antibiotic treatedspecimens were transported to the laboratory in ice.

Virus Inspection and Identification
RTG-2 (Wolf and Quimby 1962) and CHSE-214 (Fryer
et al. 1965) cell lines cultured in roller tubes or 24-welltissue culture plates were employed for virus inspection.
We inoculated 0.1 mL of specimen into 2 tubes or wells,
and observed them for 10 days at 15 0 C. Isolated viruses
were identified using the rabbit antisera against infectious
hematopoietic necrosis virus (IHNV), OMV, and infectious pancreatic necrosis virus (IPNV), and chum salmon
virus (CSV). Some ovarian fluid specimens that showed
positive results of virus inspection were measured for virus
titer using the R TG-2 cell line with the microtiter plate.
For the inspection of VEN, smears of erythrocytes were
fixed by methanol, stained by 10% Giemsa solution, andviewed by light microscopy ( x 400). Thin sections of theerythrocytes were prepared from specimens in which we
found inclusion bodies, and the virus particles were observed by E.M.

Isolation of the Virus
From 1981, epithelial tumor tissues observed around themouth were used for the OMV inspection according to themethod of Yoshimizu et al. (1987). Tumor tissue was cut
off from the fish and disinfected with iodophore (50 ppm,
15 min), washed with Hanks' balanced salt solution(HBSS) containing antibiotic, and brought to the laboratory with ice.

Light and Electron Microscopy
Prior to egg collection in female fish, blood was collectedfrom the veins under the backbone of the tail for electron
microscopy; 1 or 2 drops of blood was fixed in 1 mL of
1. 25 % glutaraldehyde with O. 05M phosphate buffer's
saline (PBS, pH 7.2) and 4% sucrose. After 1-h fixation,
the blood was washed with PBS, centrifuged at 3000 rpm
for 10 min, and postfixed in 2% osmic acid. After collection of the eggs, blood was collected in a capillary tube froma small hole opened in the kidney and spread on a glass
slide. After air-drying, it was fixed with methanol for 20
min and stained with 10% Giemsa solution.

Results and Discussion

125

_

IHNV
Results of the virus inspections are shown in Figure 2. Also
included are the results of the examination of blood smears
for VEN. IHNV was isolated from the ovarian fluid (eachof 10 pooled specimen lots) of 100 chum salmon at the
Abashiri River in 1976 and at the Yuurappu River in 1977.
In the following year, IHNV was discovered at the Mori
Hatchery in masu salmon; the incidence of infection was
60 percent. For three consecutive years, from 1979 to 1981,
the entire physical facilities at Mori received an annual
disinfection with chlorine, while the eggs were treated withiodophore. As a result of this cleaning project, IHNV has
not been isolated again from mature masu salmon at theMori Hatchery until now (Awakura, unpubl. data).
In 1980, IHNV was isolated from rainbow trout at the
Aomori Prefectural Fisheries Experimental Station andfrom kokanee salmon at the Towada Lake Hatchery. The
incidence of infection was 8 and 3 percent, respectively,
increasing the next year to 42 and 70 percent. In 1982,
infection rates at the Towada Lake Hatchery had increased
98 % owing to a failure to disinfect the facilities (Yoshimizu et al. 1988a). The difference between Mori and
Towada lake Hatcheries suggests that to prevent IHNV
outbreak, early measures to disinfect the eggs and facilities are very important. IHNV was also isolated from rainbow trout at the Chuzenji Lake Hatchery in 1983 with afrequency of 8 percent.
Recently, in 1985, IHNV was isolated from the ovarian
fluid of masu salmon taken from the Shari River; the incidence of infection was 60 percent. In this case, infectivity of IHNV in the ovarian fluid was measured at 10 2
TCID 50 /mL with the exception of 2 fish whose infectivity was 10 4 TCID 50 /mL. All eggs and facilities had been
disinfected by iodophore before the early eyed stage, thus
avoiding an outbreak of IHNV.
In Hokkaido, most of the hatcheries culturing masu
salmon also culture chum salmon. when we compared thesusceptibility of chum and masu salmon to IHNV, chumsalmon showed low mortality (less than 25 %), comparedwith masu salmon (Yoshimizu et al. 1989). Recently, an
epizootics oflHNV among chum salmon at Kitoi, Russell
Creek, and Eklutna in Alaska was reported (Follett 1987)
and again at Iwate Prefecture in Japan (Yoshimizu et al.
1988b). Thus IHNV is not a virus to be neglected whenraising chum salmon.

OMV
OMV was first isolated from ovarian fluid specimens ofmasu salmon at the Otobe Hatchery in 1978 with an infection rate of 7.5 percent. In 1978 the rate increased to
61 and in 1983 to 75 percent (Yoshimizu et al. 1988a).

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NOAA Technical Report NMFS 102: Marine Ranching_--------

Figure 2
Location of rivers, lakes, hatcheries and fish
farms where IHNV, OMV, IPNV, and CSV
were isolated; and coastal waters where VEN
infected fish was found, 1976-1987. . :IHNV; . : OMV; t::..: IPNV; .A.: CSV; 0:
VEN.

Over an 8-year period the virus would be detected in fish
at a total of 13 locations in northern Japan. This virus was
specific to masu salmon and could not be isolated fromother species of salmonid fish. Recently, a herpes virus
neutralized with anti-OMV rabbit serum was isolated fromjuvenile coho salmon (0. kisutch) cultured in fresh water(Horiuchi et al. 1989). Renibacterium sglmoninarum and Flexibacter columnaris were also isolated at the same time.
It appears that OMV belongs to the herpes viruses andhas a pathogenicity to salmonid fish, as well as an oncogenicity (Kimura et al. 1980, a and b; 1981, a, b, and c;
1983; Yoshimizu et al. 1987). Although the size of this virus
is 200 to 240 nm (Kimura et al. 1981a), a 0.45 JAm membrane fUter reduced the infectivity by 99.4 percent. In 1982
we decided to compare the fUter sterilization and antibiotic
treatment methods using ovarian fluid sampled at the
Otobe Hatchery. Although OMV was not isolated fromthe filter sterilized specimens, it was found in 21 percentof the samples treated with antibiotic only. Because of theseresults, we changed the method of sterilization of ovarian
fluid specimens to the antibiotic method (Yoshimizu et al.
1988a). Following that change, we isolated OMV from six
locations that year: the Otobe, Mori, and Shakotan Hatcheries, the Aomori P.F.E.S., and the Shiribetsu and Oippe
Rivers (Yoshimizu et al. 1988a). The following year (1983),
OMV was discovered at the Fuuren River to an evengreater degree. From the autumn of 1983, when we suggested iodophore treatment at the early eyed state, thenumber of places where OMV has been isolated has decreased and in 1986, OMV was not isolated from thelocalities where we collected specimens (Yoshimizu et al.
1988a).
From 1981, we observed the body surface, especiallyaround the mouth, and found epithelial tumors at 12

_ _ _ _ _ _ _ _ _ _ _ Kimura et al.: Pathogenic Viruses among Anadromous Salmonids in northern Japan

localities. The same basal epithelial tumors have beenpreviously reported at several localities in Japan (Kimura
1976). Sano et al. (1983) also isolated the herpes virus,
yamame tumor virus (YAV), from tumor tissues of masu
salmon at Niigata Prefecture. OMV was isolated from all
the epithelial tumor tissues used for the virus inspection
by means of either the primary culture of co-culturingmethod (Yoshimizu et al. 1987). Tumors induced by OMVwere histopathologically similar to those of the tumors
observed on the parent fish (Yoshimizu et al. 1987).
At the Otobe Hatchery, OMV was isolated annuallyfrom 1978, and the incidence of tumor bearing fish wasincreasing. In 1983, we examined the infectivity of variousorgans of masu salmon at the hatchery. Although OMV
could be isolated from the ovarian fluid specimens of thesefish, OMV could not be isolated from the kidney, spleen,
liver, intestine, and heart tissues. The infectivity of the
OMV in the ovarian fluid was also low, ranging from
101.8 to 10 21 TCIDso/mL. In the autumn of 1984, all fishcultured in this facility were killed and the facility disinfected with chlorine. Then fish were transplanted from
Kumaishi Hatchery where no¢Inis had heen isolated.
Because Otobe Hatchery did not keep brood stock, we
could not check the mature fish; however, tumors induced
by OMV were not recognized among the fingerlings(Yoshimizu et al. 1988a).
In the case of the Aomori P. F. E. S. in 1981, three kindsof viruses, OMV, IHNV, and IPNV were isolated fromthe same tumor tissue. Additionally, in the case of the
Shiribetsu River (1983) all the fish bearing the tumor were
tagged, indicating they had been cultured and released
from the Shiribetsu Hatchery (Yoshimizu et al. 1988a).
OMV was isolated from either ovarian fluid or tumor tissue
at all 13 locations where we examined more than 60 individual specimens (except 4 hatcheries). This suggests thatOMV is distributed widely in the northern part ofJapan.

CSV
CSV (chum salmon virus) (Winton et al. 1981) was isolated from kidney and spleen mixed specimens collectedat Tokushibetsu River in 1978 (Winton et al. 1981). Thisvirus was recognized as an orphan virus and did not show
severe pathogenicity for salmonid fish (Winton et al. 1981).
In 1986 an unknown disease broke out among masu salmon
near Tokushibetsu, and CSV was isolated from the diseased fish (Yoshimizu 1988). The next year, in 1987, CSV
was isolated from ovarian fluid of mature masu salmon at
Shokanbetsu River and Shubuto River, both located on
the Sea ofJapan coast. We need to study the pathogenicity of CSV in masu salmon.

VEN
An agent of viral erythrocytic necrosis (VEN) could not127

be isolated with the tissue culture method. We therefore
used Giemsa stain for erythrocytes and observed inclusion
bodies. In 1980, lout of 60 chum salmon collected fromthe Abashiri River showed a positive result and, in 1981,
the same inclusion bodies were found in chum and pinksalmon collected from the Tokushibetsu River, Horonai
River, and Shari River, and again in the Abashiri River.
We found the iridovirus in thin sections of erythrocytes ofchum salmon collected from the Abashiri River (Yoshimizu
et al. 1988a).

IPNV
IPNV was isolated from tumor tissue of masu salmon with
OMV and IHNV at Aomori P.F.E.S. in 1981 and also
from the ovarian fluids of masu salmon cultured at the
Gunma P.F.E.S. in 1987 (Yoshimizu et al. 1988a). According to the annual reports of the Hokkaido Fish Hatchery (1976, 1981, 1982), IPNV has been isolated from theovarian fluid of masu salmon, rainbow trout, and coho
salmon cultured in fresh water fish farms, but the prevalences were not high.

Conclusion_

From the results of this investigation, IHNV, OMV,
IPNV, CSV, and the agent of VEN were distributed
widely in the northern part of Japan. In most cases, fish
infected with these viruses were masu salmon. An effective method for reducing the incidence of these pathogenic
viruses is presently needed.
Four viruses and an agent of viral erythrocytic necrosis
were isolated during the course of this investigation.
1. IHNV was isolated at 7 collection sites from either masu
or chum salmon.
2. OMV was first discovered in masu salmon in 1978.
OMV was isolated from ovarian fluid or epithelial
tumor tissues. The incidence of OMV was decreased
when we suggested iodophore treatment at the early
eyed stage.
3. CSV was discovered in healthy chum salmon at theTokushibetsu Hatchery in 1978 and again from theovarian fluids of masu salmon at two places on the Sea
of Japan coast in 1987.
4. IPNV was isolated from tumor tissue of masu salmon
at Somori P.F.E.S. in 1981 and also from ovarian fluidof masu salmon at Gunma Prefecture in 1987.
5. VEN was found in the erythrocytes of both chum andpink salmon taken in the waters along the Okhotsk
coast.

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NOAA Technical Report NMFS 102: Marine Ranching

Acknowledgments
The authors wish to express their sincere gratitude to]. L.
Fryer, Oregon State Universy; ].R. Winton, National
Fisheries Center, U.S.A.; and Hokkaido Salmon Hatchery; Hokkaido Fish Hatchery; Aomori, Yamagata, Gunrna, and Gifu Prefectural Fisheries Expaimenlal Stations
for their assistance.
This study was supported in part by research grant MRP
83-V-1-21 and MRP 86-V-1-21 from the Mini~try ofAgriculture, Forest and Fisheries; a grant from the]apanU.S. Cooperative Science Program under the]apan Society for the Promotion of Science; a grant (No. 5800001)
in aid for scientific research provided by the Ministry of
Education, Science and Culture; and the Research Fundof the]apan Fisheries Resource Conservation Association.

Citations
Amos, K.H. (ed.).
1985. Procedures for the detection and identification of certain fish
pathogens. Am. Fish. Soc., Fish Health Section, 1141'.
Follett, J.
1987. 1986/1987. IHNV findings in chum salmon. In IHNVWorkshop; 4 & 5 June 1987, Big Lake, Alaska, p. 1-4. Dep.
Fish Game.
Fryer, J.L., A. Yusha, and K.S. Pilcher.
1965. The in vitro cultivation of tissue and cells of Pacific salmon
and steelhead trout. Ann. N.Y. Acad. Sci. 126:566-586.
Hokkaido Fish Hatchery.
1976. Annual Report of the Hokkaido Fish Hatchery, p. 194-195.
1981. Annual Report of the Hokkaido Fish Hatchery, p. 191-192.
1982. Annual Report of the Hokkaido Fish Hatchery, p. 221-222.
Horiuchi, M., M. Miyazawa, M. Nakata, K. lida, and S. Nishiuura.
1989. A case of herpesvirus infection of freshwater-reared coho
salmon Oncorhynchus kisutch in Japan. SuisanzoushokL 35:
297-305.
Kimura, I.
1976. Tumors in lower vertebrates. In The cancer (T. Sugiyama
and Y. Yamamura, ed.), p. 270-283. Iwanami Shoten, T:>kyo.
Kimura, T., M. Yoshimizu, and M. Tanaka.
1980a. Salmonid viruses: a synctytium forming herpesvirus fromlandlocked Oncorhynchus masou. Fish Health News 9(1):iii.

_

1980b. Salm'mid viruses: effect of Oncorhynchus masou virus (OMV)
in fry of chum salmon (Oncorhynchus keto). Fish Health News9(1):;i-iii.
1981b. Studies on a new virus (OMV) from OncDrhynchus masouII. Oncogenic nature. Fish Patho!. 15:149-153.
1981c. Fish viruses: tumor induction in Oncorhynchus keto by theherpesvirus. In Phyletic approaches to cancer (C.J. Dawe et al.,eds.), p. 59-68. Jpn. Sci. Soc. Press, Tokyo.
1983. Susceptibility of different fry stages of representative salmonid
spt·cies to Oncorhynchus masou virus (OMV). Fish Patho!' 17:
251-258.
Kimura, T., M. Yoshimizu, M. Tanaka, and H. Sannohe.
1981a. Studies on a new virus (OMV) from Oncorhynchus masouI. Characteristics and pathogenicity. Fish Palho!' 15:143-147.
Sano, T., H. Fukuda, N. Okamoto, and F. Kaneko.
1983. Yamame tumor virus: lethality and oncogenicity. Bull. Jpn.
Soc. Sci. Fish. 49: 1159-1163.
Winton, J.R., C.N. Lannan, J.L. Fryer, and T. Kimura.
1981. Isolation of a new reovirus from chum salmon in Japan.
Fish Patho!' 15:155-162.
Wolf, K., and M.C. Quimby.
1962. Established eurythermic line of fish in vitro. Science 135:
1065-1066.
Yoshimizu, M.
1988. Chum salmon ViruS (CSV) isolated from masu salmon(Oncorhynchus masou). Tech. Rep. Hokkaido Salmon Hatchery(Fish and eggs) 157:36-38.
Yoshimizu, M., and T. Kimura.
1990. Viral infections of cultured fishes in Japan. In The Second
Asian Fisheries Forum (R. Hirano and I. Hanyu, eds.), p.
959-962. Asian Fisheries Society, Manila, Philippines.
Yoshimizu, M., T. Kimura, and J.R. Winton.
1985. An improved technique for collecting reproductive fluid
samples from salmonid fishes. Prog. Fish.-Cult. 47: 199-200.
Yoshimizu, M., M. Tanaka, and T. Kimura.
1987. Oncorhynchus masou virus (OMV): incidence of tumor development among experimentally infected representative salmonid
species. Fish Patho!' 22:7-10.
Yoshimizu, M., T. Nomura, T. Awakura, and T. Kimura.
1988a. Incidence of fish pathogenic viruses among anadromous
salmonid in northern part ofJapan (1976-1986). Sci. Rep. Hokkaido Salmon Hatchery 42:1-21.
Yoshimizu, M., M. Sami, N. Oseko, and T. Kimura.
1988b. Outbreak of IHN in chum salmon. Proceedings of annual
meeting of Jpn. Soc. Sci. Fish., held in Hakodate, 236 p.
Yoshimizu, M., M. Sami, and T. Kimura.
1989. Survivability of infectious hematopoietic necrosis virus in fertilized eggs of masu and chum salmon. J. Aquatic Animal Health
1:13-20.

Ecology and Production of Fish in a
Man-made Sargassum Forest
HIROAKI MATSUNAGA
Nansei National Fisheries Research InstituteOhno, Saeki
Hiroshima Prifecture 739-04, Japan

ABSTRACT
Investigations were carried out to clarify the effects of a man-made Sargassum forest on fish
production, which is needed to support the planned enlargement of the coastal fisheries resource.
The main fish species gathering in the forest included Sebastes inermis, Sebastiscus marmoratus, andHexagrammos agrammus which appeared year round, and Halichoeres poecikpterus and Navodon morkstus
which appeared seasonally. In spring the maximum forest size is reached as well as the numberof phytal animals (e.g., Caprellidea, Gammaridea, Mollusca, and Polychaeta). The latter are
suggested to be the important food resource of these fish.

Introduction_

It has been pointed out that natural Sargassum forests play
an important role in fish production by their impact on
the ecology of fish (Fuse 1962). Recently, artificial Sargassum
forest formations have been examined to increase fisheryresources by expanding the habitable area for fish andshellfish. Various animals gather and form a new community in the man-made forests thus enlarging animal production. There are various relationships between different fish and the forest. Some fish species gather to eat phytal
animals (e.g., caprellids, gammarids, molluscs, and polychaetes) and others to hide. Investigations were carried out
to quantitatively analyze these situations and clarify theeffects of man-made Sargassum forests on fish production(Okamoto et a1. 1987, 1988).

net with different center-net mesh sizes (25.0, 18.8, 15.0,
10.7 mm) were combined (with lengths 60, 60, 60, 30 m,
respectively, all heights 1.5 m) and set from the evening
to the next morning for 16-18 hours, which corresponds
to unit effort. Similar catches were done by surrounding
one group of Sargassum forest (4 x 4 m) composed of 16
blocks (spaced 0.5 m apart from each other) with a trinal
trammel net of 15.0 mm mesh size. After measuring thecaptured fish, stomach contents were fixed and preservedin 10% formalin, and analyzed later. Phytal animals werecollected by diving with 0.3 mm mesh nylon nets, thenfixed and preserved in 10% formalin. Later they were completely separated from seaweed contaminants by being
flltered through a 0.5 mm mesh sieve (Okamoto et aI. 1987,
1988).

Results and Discussion
Materials and Methods__

The man-made Sargassum forests are located off the coastofIhota, Yashiro Island, Yamaguchi Prefecture, in an area
170 x 50 m at a depth of 3-6 m. There are about 700 concrete blocks (mainly 0.75 x 0.53 x 0.53 m) placed on sandwhich are divided into 30 groups of different size (16-50
blocks) (Yoshikawa and Tsukidate 1987, 1988). The species
composition, size frequency, and behavior of fish gathering there was determined by net catches and underwaterobservations which were carried out once to three times
a month from 1986 to 1987. Four kinds of trinal trammel

Fifty fish species were found from December 1986 toNovember 1987. Twenty of these were rare species. The
appearance rate of the most common 24 species is shownin Figure 1 by the CPUE (catch [in number] per unit effort) along with the density of the man-made Sargassum
forest at the time of collection (Yoshikawa and Tsukidate
1987, 1988). There were four types of fish as follows: A
type, appearing almost year-round, including Ditrema
temmincki, Neoditrema ransonneti, Rudarius ercodes, Sebastes inermis, S. hubbsi, Sebastiscus marmoratus, Hypodytes rubripinnis,
Hexagrammos otakii, H. agrammus, Pseudoblennius cottoides;
129

130

NOAA Technical Report NMFS 102: Marine Ranchingmonth

1986/1987

speciesD
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B type, appearing seasonally, including Halichoeres poecilopterus, H. tenuispinis, Navodon modestus (all from spring toautumn) and Pagrus major (from summer to autumn); C
type, appearing by chance (migratory fish), including Sardinops melanosticta and Trachurus japonicus; and D type, inhabiting the sandy bottom, including Limanda yokohamae.
All A and B type species have a close relationship with theseaweed forest. Judging not only from the CPUE but also
from the value to commercial fisheries, S. inermis, S. marmoratus, H. agrammus, D. temmincki, H. poecilopterus, andN. modestus are the most important species. They tended
to be prevalent throughout the investigations which wereconducted from 1983 to 1988 (Okamoto et al. 1987, 1988).

•

•

•
_
Figure 1
Seasonal appearance of fish species (upper)
and total amount of seaweed (lower)(Yoshikawa and Tsukidate 1987, 1988) inthe man-made Sargassum forest.

Figure 2 shows the CPUE fluctuations for five of the prominent fish species. Their ecological features are as follows.
S. inermis juveniles first appear in the spring (Mar.-Apr.);several shoals are observed in some years. Throughout theyear, young (0-2 years old) are observed in groups, staying between or above blocks, and beside or among seaweeds. Most of the larger fish (>2 years old) are assumed
to migrate to the deeper depths. H. agrammus juveniles(type A) settle in the forest during winter Gan.-Feb.). From
the juvenile to the adult stage, they are observed keeping
still above the blocks, sometimes picking the seaweeds forcover instead. The CPUE is greatest in winter (Dec. - Mar.)
when the quantity of seaweeds in the man-made Sargassum

_ _ _ _ _ _ _ _ _ _ _ _ _ _ Matsunaga: Ecology and Production of Fish in a Man-made Sargassum Forest

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H. otakii shows similar ecological features, but the CPUE
is small. H. poecilopterus is a type B species. Increasing
spring (Apr.-May) water temperatures awake this species
from overwintering to begin activity. Overwintering returns again with the decreased temperatures of winter(Dec.). From the juvenile to the adult stage, it is very active and the CPUE is large. N. modestus spawning groups
also are B type, coming in spring (Apr.-May), andjuveniles appearing in summer (Jul.-Aug.). Both of themstay towards the winter (Nov.-Dec.). In contrast to H.
poecilopterus overwintering in the sand, they move to thedeeper depths to pass the winter. No evidence has been
gained to indicate that spawning occurs in the forest, but
it seems a good possibility.
Figure 3 shows the presumed amount of available phytal
animals in the Sargassum forest (per m 2 ) and the composition of stomach contents in the main fish species during
the spring (Mar., Apr., and Jun. 1986) (Matsunaga,
unpubl. data). The biomass of the man-made Sargassum
forest consisted mainly of S. hornen' which is at its greatest
size at that time of year. The amount of phytal animals
peaks in March before the forest reaches its maximum
biomass level in May. The number and wet weight ofphytal animals at this time were 241 (0.48 g) per 1 g wetweight of S. horneri, most of which were caprellidian andgammaridian amphipods. One group of the forest (115.2kg) is estimated to contain 24.8 x 10 6 (49.1 kg) of phytal
animals. In April their levels decrease to 134 (0.20 g) per
1 g of S. hornen', and one group of forest (133.2 kg) is
estimated to have 17.9 x 106 (27.0 kg) ofphytal animals,
also dominated by the caprellidian and gammaridian am-

Figure 2
Seasonal fluctuations of CPUE for themain fish species in the man-made Sargassum forest (Okamoto et aI. 1987).

phipods. In June S. horneri begins to wither and cause asudden decrease in the density ofphytal animals to 25 (0.02g) per 1 g of S. hornen', and 3.6 X 10 6 (2.2 kg) per one
group of the forest. Molluscs (mainly bivalves) and polychaetes replaced the amphipods as the predominant animal
species.
The stomach contents of Sebastes inermis (0-2 years old),
Hexagrammos agrammus, and H. otakii consisted mainly ofamphipods in March and April. Sebastiscus marmoratus andSebastes hubbsi showed similar trends but the percentages
were lower. The reason why S. inermis contains both amphipods and copepods is that it takes drifting organisms
as food. In June, the ratio and amount of amphipods
consumed by the main fish species decreased remarkably,
parallel to the level of prey. As mentioned above, mainfish species depend on these animals as a source of food,so the man-made Sargassum forest should make a large contribution to fish production.
To calculate the extent of which the man-made Sargassum
forest contributes to fish production, knowledge of species
composition, losses due to predation, the reproduction ofphytal animals, and other factors are necessary. Presently
however, it is impossible to analyze this subject thoroughly.
Therefore, only estimations can be carried out. Assumingthat the maximum quantity of prey (49.1 kg) undergo
complete conversion to fish biomass (conversion ratio of
7.3% from rearing experiments [Matsunaga, unpubl.
data], in which fish feed once a day to satisfaction witheuphausia), S. inermis can increase its own weight by 3.6
kg. If we assume that S. inermis gathering in the forest havea daily prey intake rate of 3 % of their total body weight,
which is the maximum ratio of stomach contents against
body weight, then S. inermis can increase its own weightby 450 g from March to June. In addition, assuming a food

132

NOAA Technical Report NMFS 102: Marine Ranching

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intake ratio of 6 % which was gained from the rearing experiments, 900 g of fish can be produced.
These evaluations, which were carried out to study theeffect of man-made Sargassum forests on fish production,
are necessary to accumulate detailed knowledge to support
the planned enlargement of the coastal fisheries resource.

Citations_

Fuse, S.
1962. The animal community of the Sargassum belt. Seiri-Seitai
11; 23-45. (In Japanese; English summ.)
Okamoto, R., H. Mataunaga, H. Usuki, and K. Funae.
1987. Capacity and management of fishes in the man-made Sar-

Figure 3
Abundance of phytal animals on one groupof the man-made Sargassum forest (left), andstomach contents of main fish species (right) in
spring 1986. Where number of food items exceeded 100, the percentage is indicated. N =number; W = wet weight; Sis ~ Sebastes inermis(small); Sil = S. inermis (large); Sm = Sebastiseus marmoratus; Sh = Sebastes hubbsi; Ha = Hexagrammos agrammus; Ho = H. otakii (Matsunaga,
unpub\. data).

gassum forest. Marine ranching progress report of useful seaweed
studying group, Nansei Natl. Fish. Res. Inst., p. 47-52. (InJapanese.)
Okamoto, R., H. Matsunaga, K. Funae, and H. Usuki.
1988. Capacity and management of fishes in the man-madeSargassum forest. Marine r;;,nching progress report of useful
seaweed studying group, Nansei Natl. Fish. Res. Inst., p. 59-68.
(In Japanese.)
Yoshikawa, K., and J. Tsukidate.
1987. Control techniques to form Sargassum forest throughout
the year. Marine r<U1ching progress report of useful seaweed
studying group, Nansei Nat!. Fish. Res. Inst., p. 1-15. (InJapanese.)
1988. Control techniques to form Sargassum forest throughout
the year. Marine ranching progress report of useful seaweed
studying group, Nan.ei Natl. Fish. Res. Inst., p. 1-21. (InJapanese.)Masu Salmon Production Studies of the
Marine Ranching Program

OSAMU HIROI
Hokkaido Salmon Hatchery
Nakanoshima, Sapporo
Hokkaido 062 Japan

ABSTRACT
Results from the masu salmon (Oncorhynchus masou Brevoort) production studies of the Marine
Ranching Program from 1980 to 1988 are reviewed in the present paper. Seeking to ensure adequate production levels of this valuable fishery resource under ever increasing amounts of manmade stress, Japanese scientists have examined important aspects of masu salmon biology andutilized artificial means to supplement the natural stock levels. Using techniques successfullyde·,eloped for the chum salmon (0. keta) , naturally ascending masu salmon were similarly captured and reared under freshwater conditions without food throughout their extended freshwater
migration period of four months, until reaching full maturation. Over 80% of the pond-rearedfish reached full maturity, providing an excellent source of eggs and sperm for enhancement(seedling production) programs and other studies. Serum concentrations of steroid hormones were
measured in addition to their ability to artificially induce germinal vesicle breakdown in vitro.
Other research discussed includes all-female seedling production, migration patterns, smolt production and liberation studies, net-pen culturing, resources analysis, and important genetic featuresof the masu salmon population. These developments have improved artificial propagation methods
and thus resulted in the large scale acceleration of masu salmon resources.

Introduction_

Almost all the salmon resources in japan have been supported by artificial propagation. Four species constitute thebulk of these programs in japan, namely, chum salmon(Oncorhynchus keta), pink salmon (0. gorbuscha), masu salmon(0. masou), and Kokanee (0. nerka). In recent years, chumsalmon resources have risen steadily, to about 160 thousand tons. This noticeable increase is due to the application of studies conducted on the mass production of chumsalmon from 1977 to 1981 by the Agriculture, Forestry,
and Fisheries Research Council Secretariat.
Like chum salmon, masu salmon are one of the important coastal fishery resources in japan. In recent years,
however, the level of masu salmon resources has decreased
markedly, to about two thousand metric tons. Masu
salmon have long freshwater residency periods during boththe fry to fingerling stage and the anadromous migration.
A large number of male fish remain in the rivers andaccomplish their life cycle without travelling to sea. To
increase this resource, it is important to model the natural
behaviors of these fish, especially those concerned withgrowth, smoltification, downstream migration, feeding
migration, sexual maturation, and anadromous migration.
Masu salmon production studies under the Marine
Ranching Program have been conducted from 1980 to 1988
by the Agriculture, Forestry, and Fisheries Research Council Secretariat, focusing on the subjects of sexual maturation, seedling production, smoltification, nutrition, stream
production capacity, smolt-liberation, all female production, seaward-migration, fish disease, pen-culture, resources analysis, genetic features, and imprinting of homestream water. This paper reviews some of the accomplishments of japanese scientist seeking to improve artificial
propagation methods to increase this valuable resource.

Sexual Maturation_

Maturation in rnasu salmon progresses synchronously inthe testicular lobules of males (Hiroi and Yamamoto 1970)
and in the ovarian oocytes of females (Hiroi 1984). As withthe other species belonging to the genus Oncorhynchus, maleand female masu salmon are destined to die after spawn133

134

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Changes in serum estradiol-17fJ levels during sexual maturationin female masu salmon. Oomu coast (17 Nov.), immature fish
Gust over 2 years old) caught in the coastal sea; Shari River (4June and 23 July), maturing fish (3 years old) reared in a holding
pond after being caught near the river-mouth; Shari (4 Sept.),
Shiribetsu (29 Sept.), and Furen (6 Oct.) Rivers, matlln~ fish
(3 years old) from a holding pond (Hiroi et al. 1983).

ing, the final step of their anadromous migration to thehome river from the far seas.
As they return to their natal river from the sea in late
April, masu salmon are extremely immature sexually(Hiroi 1984; Kiso and Kosada 1988). They ripen from lateAugust to September, about four months after entering therivers. Thus, their sexual maturation proceeds rapidly
during the final period of their anadromous migration(Hiroi 1984).
In order to clarify the endocI'ine factors related to sexual maturation, serum concentrations of various steroid
hormones were measured with radioimmunoassay techniques during the anadromous migration of male andfemale masu salmon (Hiroi et al. 1983).
A total of 78 fish (26 males, 52 females) were captured
at sea or in freshwater in 1982 and used in the present
study. Twenty-five of these fish were just over 2-years-oldwhen caught in the coastal sea off Oomu in November.
At this stage, both sexes were extremely immature sexually.
The 12 males were in the late multiplication stage oftesticular maturity (by histological observation, Hiroi andYamamoto 1970) and averaged 0.07% on the gonadosomatic index (GSI, gonad wt. /body wt. x 100). The remaining 13 females were in the oil-drop stage of ovarian
maturity (by histological observation, Hiroi 1984, 1985;
Yamamoto 1970) and averaged 0.5% on the GSI. Twenty-

10

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Nov. 17

Shari
June 4

Shari
July 23

Shari Shiribelsu Furen
Sept. 4 Sept29
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Figure 2
Changes in serum 17(1,20fJ-dihydroxy-4-pregnen-3-one levels
during sexual maturation in female masu salmon. Oomu coast(17 Nov.), immature fish Gust over 2 years old) caught in the
coastal sea; Shari River (4 June and 23 July), maturing fish (3years old) reared in a holding pond after being caiIght near theriver-mouth; Shari (4 Sept.), Shiribetsu (29 Sept.), and Furen(6 Oct.) Rivers, mature fish (3 years old) from a holding pond
(Hiroi et al. 1983).

seven sexually maturing adults were sampled inJune andJuly from fish being reared in holding ponds after theircapture near the mouth of the Shari River at age-3. Thirteen females sampled in June were in the primary yolk
stage (2.9%, mean GSI) and four fish taken in July werein the post-migratory nucleus stage (18.3%, mean GSI).
Male fish sampled in June and July (five each month)
showed the early (1.0 %, mean GSI) and late (8.4 %, mean
GSI) phases of the sperm-formation stage, respectively.
Twenty-six fish sampled ii'om the holding ponds at the
Shari River (early September), the Shiribetsu River (lateSeptember), and the Furen River (early October) were all
fully mature. The mean GSI values of mature females in
the Shari (9 fish), Shiribetsu (6 fish), and Furen River (7fish) were 27.3%,21.8%, and 24.2%, respectively. The
mean GSI value of mature males in the Shiribetsu River(4 fish) was 3.7%.
In female fish, serum estradio!-17f3levels were high midway through vitellogenesis Oune and July in the Shari

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Hiroi: Masu Salmon Production Studies of the Marine Ranching Program

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Changes in serum ll-ketotestosterone and testosterone levels during sexual maturation in male masu salmon. Oomu coast (17Nov.), immature fish (just over 2 years old) caught in the coastal
sea; Shari River (4 june and 23 july), maturing fish (3 years
old) reared in a holding pond after being caught near the rivermouth; Shiribetsu River (29 Sept.), mature fish (3 years old)from a holding pond (Hirai et al. 1983).

River) but significantly lower in fish at the time of final
maturation (September: 2 samplings, one in each of the
Shari and Shiribetsu Rivers; and October: 1 sampling, in
the Furen River) (Fig. 1). These results provide strong
evidence that estradiol-17fJ plays a major role in the synthesis of vitellogenin in female masu salmon as seen inchum salmon (Hiroi 1982, 1985; Ueda et al. 1984).
Serum 170', 20fJ-dihydroxy-4-pregnen-3-one (170', 20f3diOHprog) levels were extremely low in female masu
salmon prior to migration from the sea (in November off
the Oomu coast) and halfway through vitellogenesis (Juneandjuly, Shari River), but elevated dramatically with theonset of ovulation (September: 2 samplings, one in eachof the Shari and Shiribetsu Rivers; and October: 1 sampling, in the Furen River) (Fig. 2). This provides strong
evidence that 17O',20fJ-diOHprog is the natural maturation-inducing steroid involved in final oocyte maturation
as seen in chum salmon (Hiroi 1982, 1985; Ueda et al.
1984).
In males, serum testosterone and 11-ketotestosterone
levels were extremely low in srxually immature fish at sea(November in the Oomu coast) but elevated gradually inthe maturing fish in freshwater (June and july, botho ·················o
Oornu
Nov. 17

Shari
June 4~
Shari
July 23

Shiribetsu

I
I

sept.29~

Figure 4
Changes in serum 17cr,20fJ-dihydroxy-4-pregnen-3-one levels
during sexual maturation in male masu salmon. Oomu coast (17Nov.), immature fish (just over 2 years old) caught in the coastal
sea; Shari River (4 june and 23 july), maturing fish (3 years
old) reared in a holding pond after being caught near the rivermouth; Shiribetsu River (29 Sept.), mature fish (3 years old)from a holding pond (Hirai et aI. 1983).

samples from the Shari River; through September in the
Shiribetsu River) as spermatogenesis progressed (Fig. 3).
This observation suggests that testosterone and ll-ketotestosterone are involved in the process of spermatogenesis in males as seen in chum salmon (Hiroi 1982, 1985;
Ueda et al. 1984).
Serum 17O',20fJ-diOHprog levels, although lower inmales, increased rapidly in mature males (Fig. 4) as previously seen in females. This observation provides strong
evidence that 170', 20f3-diOHprog is involved in the process of spermiation as seen in chum salmon (Hiroi 1982,
1985; Ueda et al. 1984).
The possibility of artificially inducing maturation in vitro
using chum salmon gonadotropin (SCA) and various
steroid hormones to induce germinal vesicle breakdown(CVBD) of oocytes was investigated. Oocytes (444 g in the
total weight) were removed from maturing female (2,080 g

136

NOAA Technical Report NMFS 102: Marine Ranchingin body weight) captured in the middle reaches of the
Shiribetsu River while in the late vitellogenesis phase,about 15 days before ovulation (Hiroi, Ueda, Yamauchi
and Nagahama, unpub!. data).
Twenty oocytes were incubated in vitTV for 72 hours at
15°C in various doses of hormone supplemented ringer
solutions. Although the oocytes were not changed at all by
the incubations of ringer control and testosterone (Table1), oocyte maturations (GVBD) were induced by the incubations of over 0.1 Ilg/mL doses of SGA, 1 Ilg/mL doseof 17oo-hydroxy-4-pregnen-3-one (17oo-OHprog; a substrate
for 1700, 20{3-diOHprog biosynthesis) and over O.Olllg/mL
doses of 1700, 20{3-diOHprog. These results show that it ispossible to induce GVBD artifically (but not ovulation) by
in vitro incubations of 1700, 20{3-diOHprog or using SGA
in maturing oocytes of the late vitellogenesis phase in masu
salmon as previously seen in chum salmon (Hiroi 1982,
1985). In testosterone treatments, a change to a migrated
nucleus in the oocytes was observed only in the 1.0 Ilg/mL
incubation. Serum testosterone levels in female masu
salmon were high throughout the course of anadromous
migration, showing the highest value in mature fish (Hiroi
et a!. 1983) as seen in chum salmon (Hiroi 1982, 1985;
Ueda et al. 1984). The close relationship observed between
estradiol-17{3 and testosterone levels during late vitellogenesis in female masu salmon supports the suggestion that
testosterone may act as a substrate for estradiol-17{3 biosynthesis, but the precise roleg of testosterone in oocyte
maturation are presently unknown.

Seedling Production_

Seedling production was investigated using artificially collected eggs Laken from the naturally migrating, pondcultured, and pen-cultured adults.
Use of the naturally migrating adults required holding
the sexually maturing fish in freshwater ponds for a long
period of about four months. It is known that the sourceof energy for ripening of masu salmon during the long
period of abstinence from food is the neutral fat which thefish have stored in great quantity during their oceanic life
(Nomura 1984; Nomura et al. 1985).
Five factors describe the basic conditions considerednecessary for the long-term holding of sexually maturingmasu salmon taken from rivers. First, the captured fishmust be held in their specific home stream waters becauseof their instinctive homing nature. Second, we have tounderstand the seasonal changes in the degree of sexual
maturation of adults soon after entering each river or catching station. Knowledge of the degree of maturation isnecessary to determine the optimum time for mature fish
selection for the collection of eggs. Because of their extremely immature condition as they enter the rivers, it isimportant for us to improve fish handling methods in order_

Table 1
Effects of chum salmon gonadotropin (SGA), 17a-OHprog,
17 a, 20{J-diOHprog, and testosterone on the induction of
GVBD of masu salmon oocytes in vitro (Hiroi, Ueda,
Yamauchi, and Nagahama, unpuh!. data).
Treatment
Hormone
SGA

17a-OHprog

17a,20p-diOHprog

Testosterone

Ringer control

Oocyte condition (% ± SEM)
Dose
Migrated(lJg/mL) GVBD nucleus Immature
1.0
0.1
0.01
1.0
0.1
0.01
0.001
1.0
0.1
0.01
0.001
1.0
0.1
0.01
0.001

78 ± 225 ± 50100
00080 ± 580 ± 558 ± 2
0
0
0
0

0
0

22 ± 275 ± 548 ± 20100
72 ± 835 ± 2020 ± 520 ± 542 ± 250 ± 5
100
0
0
0
0

0
0
52 ± 20028 ± 865 ± 2000050 ± 5
0
100
100
100
100

to prevent stripping of scales at the time of capture andtransport. Third, the holding waters for the maturing
adults must be kept within an optimum temperature rangeof 8 to 12° C. This can be achieved by mixing spring waterwith the river water. Fourth, water currents in the holding
ponds must be kept slow (under 10 em/sec) to mitigate exhaustion of fish from over-swimming. For masu salmon
operations, holding or rearing ponds with the water supply
welled up from the bottom and with periodic exchangesof new water are most suitable. Fifth, covering the pond
surface from light is essential for resting the fish.
Using a method meeting those basic conditions, longterm holding experiments with spring water were carriedout on a large-scale with migrating masu salmon from 1983
to 1988 (Table 2). The sexually immature adults (about
1,100 g in weight ranging from 230 to 2,0000 g) werecollected every year from late April to late May at thecatching station near the mouth of the Shari River. The
fish were transferred from a catching pool to a transportcar, together with water, using a "fish ladle. " The ladle's
net was made of duck-cloth and had several small holes;
this special net prevented the stripping of scales. Every
morning and evening fish travelled in the car for about one
hour from the catching station to the holding pond sitewhere an immediate transfer occurred. The eight holding
ponds reformed for these experiments were made of concrete (5 m wide, 25 m long, and 0.9 m deep), and had an
up-welled current of spring water (1 m 3 /min) created by

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Hiroi: Muu Salmon Production Studies of the Marine Ranching Program

137

Table 2Long-tenn holding experiments with spring water on naturally ascending masu salmon,
1983-1988. Fish were held without food for duration of experiment.

Year

Numberoffemales

Durationofholding(days)

Rate ofmaturation(females)(%)

Numberof eggs
collected(thousands)

Average numberof eggs
collected
per fish

1983
1984
1985
1986
1987
1988

517
1,169
767
859
343
671

125-133
110-135
103-136
105-135
100-126102-139

43

238
1,082
744
858
354
745

1,301
1,213
1,380
1,222
1,172
1,321

77

84
82
88
86

flowing water one way from the upper third portion of thepond bottom. Ponds were always covered by cheeseclothlike black sheets to exclude light. Immature fish were held
at a density of 600 fish per pond (75 m 3 of water volume)
without food for four months at a water temperature of
9 to 10° C. Recently, over 80 % of the naturally ascending
masu salmon reached full maturity in the holding ponds
under these basic conditions (Table 2).
Egg and sperm collected in early autumn from maturefish were stirred gently and inseminated using a dry
method. Fertilization, namely the activation of eggs, wascompleted by contact of inseminated eggs with water. Fertilized eggs were then washed with up-welled currents andput in a hatchery trough.
The artificial production of seedlings from the collected
eggs of both pond-cultured and pen-cultured adults has
been carried out easily for several generations (Hirai 1984;
Yoshida et al. 1987).

Smoltification_

Although the mechanism of smoltification has not yet been
fully understood, clearly there is a close correlation between
smoltification and the fish's adaptability to sea water andbetween the functions of the thyroid gland and interrenal
gland hormone (Yamazaki and Ma 1985; Yamazaki 1986).
The process of the silvering of body coloration duringsmoltification was induced by treatments of mammalianthyroid hormone powder; however, seawater adaptability
was not accelerated by cortisol treatments (Yamazaki1983).

Nutrition_

Nutrition of the masu (cherry) salmon was studied by
Ogata and Konno (1986). The authors determined that

nonpolar lipid contents in the whole body, dorsal muscle,
and liver of freshwater smolt (approx. 2 years old) are lower
than those of the parr (1 year old). During March throughMay, nonesterified fatty acid levels in the plasma of thesmolt were higher than those of the parr, but the neutral
fat levels in the smolt were lower.
The growth response and smolt production of l-yearold masu salmon were studied by feeding the fish four dietswith varying lipid and protein levels for 120 days. Eachof the following dietary treatments were administered to
55 fish averaging 16 g: HPHL, high protein (41 %)-highlipid (16 %); HPLL, high protein-low lipid (4 %); LPHL,
low protein (24% )-high lipid (14%); LPLL, low proteinlow lipid (2 %). The growth response to these dietary
treatments was as follows: HPHL (final mean body weight,
44.4 g»HPLL (36.5 g»LPHL (29.0 g»LPLL (28.0 g).
Only in the high protein diets did both growth rate andfeed efficiency clearly improve by the addition of lipid(Table 3). In all treatment groups, the growth, feed efficiency, and feed consumption rate accelerated with theonset of smoltification. Percentage of smolt produced were
74.5% in HPHL, 47.3% in HPLL, 29.1 % in LPHL, and16.4% in LPLL, respectively. Thus, supplementation oflipid to diet seems to be a valuable method to promote smolt
production.

Stream Production Capacity_

Environmental devastation in rivers caused by land andindustrial developments in recent years have resulted inserious decreases in stream production capacity which isaffecting the survival of masu salmon from the fry to thejuvenile stage. Marked masu salmon fry (167 thousandfish) released experimentally in the upstream areas of the
Mena River (a tributary of the Shiribetsu River) during
the spring, have been collected only at the lower stream
areas, not at the upper areas a month after the release

138

NOAA Technical Report NMFS 102: Marine Ranching_

Table 3
Response of l-year-old masu salmon to various dietary lipid and protein levels in a 120-day feeding experiment (Ogata andKonno 1986). HPHL = high protein, high lipid; HPLL = high protein, low lipid; LPHL = low protein, high lipid; LPLL
= low protein, low lipid. Each tank contained 55 fish.
Diet
HPHL

Average body weight (g)InitialFinal
Daily growth rate (%)
Feed efficiency (%)
Protein efficiency ratio (%)
Daily feed consumption rate (%)
Protein intake' (g/kg fish each day)
Number of smoll obtained'
Average body weight of smolt (g)

HPLL

LPHL

LPLL

0-89

90-1200-89

90-1200-89

90-1200-89

90-120

15.49
29.97
0.74
55.50
1.23
1.29
5.81

44 41
1.27
65.10
1.45
1.92
8.64

15.83
26.83
0.59
41.50
0.92
1.25
5.63

36.47
0.99
56.70
1.26
1.73
7.79

16.69
23.41
0.38
24.80
0.99
1.19
2.98

29.04
0.69
40.40
1.61
1. 71
4.28

16.06
22.22
0.36
23.60
0.94
1.60
4.00

28.02
0.75
32.90
1.32
2.26
5.65

42
·}3.57

26
39.59

16
30.39

9
34.73

'Difference (P<0.01) can be found among the dietary treatments by X2 test on the number of small obtained.

30(Ohkuma and Nomura 1991). Consequently, a great
number of masu salmon fry, as well as chum salmon fry,need to be scattered at the uppermost part of the streams
lor the industry to effectively utilize the potential productivity of a river.
The successful release of fingerlings (less than 1 year old)in the autumn has been confirmed from the return ofmarked masu salmon adults by Mayama et aI. (1988).

-

25

1:

20

Ol

.--...

Precocious
Male

0)

'iii

3= 15
>-

Smolt-Liberation

_

'

o

lX1

Concerning production of greater than l-year-old (1 +)smoh, it is known that the external control of young masu
salmon growth during each development stage is practical(Mayama et aJ. 1986). This includes first, initial control
to curb sexual maturation of fingerling males (precocious
males); second, the acceleration of growth during the parrstage; third, inhibition of growth through the winter season;and last, the acceleration of growth prior to smoltification.
A diagrammatic illustration of growth control in the smoltliberations of masu salmon fingerlings is shown in Figure
5. Control of smoitification was achieved by appropriately
combining and adjusting water temperature, light cycle
periods, and the quantity of feed. These artificial controls
result in over 90 % conversion using growth controls during the fry to fingerling period. Recently, the return ofadult masu salmon cultured by the methods of smoltliberation described above has been ascertained. A highreturn rate of over 7 % was estimated by the recapture ofmarked fish (Mayama et aI. 1985).

;'

'a
.:ii·

10

5

""'7~"/'/""

ISmolt I /::::;:j;;

•.••

&I..

.'

MJJASONDJFMAM
Con. ! Accelerate! Control

7Accel.

Figure 5
Diagram showing growth control in the enhancement of smolt
masu salmon (age 1 +). Growth curve with solid dots indicatesthe average body weight standard for rearing (Mayarna et al.
1986).

The duration of the period that masu salmon spend in
freshwater prior to smoltification can be reduced to half

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Hiroi: Masu Salmon Production Studies of the Marine Ranching Program

D: External male

(F)

(M)

~

Crossbreeding in autumn

sex hormone treatment after hatching

[ill

or

@] F=::::;==:(XX(Pseudo-M)

~or@
I

I

I

<== l\~ Crossbreeding in autumn
1 year after starting(Normal F)
r-- ..------

__.

:

I

0: External female
xY : Genetic maleXX

Genetic female~ : Pseudo-male@ : Normal female

'1

xx

:

139

I
I

I

'NonMale sex hormone
Male sex hormone Non treatment
treatment !treatment treatment after hatching

female brood(M or F)

Male
or

@]

(Pseudo-M)<. - - -_. - -

i ~~-I ~B<"--Crossbreeding 1n autu=-<iF=' C

2 year after starting
All F ~ Smol t-release~ D
after one half year

Figure 6
Schematic illustration of the production technology of producing all-female brood in masu salmon (Kanazawa and Harako 1985).

that of the normal life cycle (0 + smolt). It is necessary toobtain eggs earlier by artificial means (thereby hastening
production of the young) and then to rear the fish in higherthan-ambient water temperatures (13-15°C) during thewinter season. Earlier egg-taking in the summer has beenaccomplished by methods that control light exposure to theparent held in a pond strain (Konno et al. 1983). Returnsof age 0 + smolt raised from the parent pond strain tohome waters have been confirmed in the Nezugaseki Riverin Yamagata Prefecture (Konno and Abe 1987). Although
only three returning fish were confirmed, it is thought that
releasing age 0 + smolt in the spring season is as effective
as that of age 1 + smolt.

All-Female Production_

All-female fish production, as a means of making smolt
production more efficient, can be carried out by crossbreeding between normal returning females and "psudomales" (the latter are genetic females), as shown in Figure
6 (Kanazawa and Harako 1985). Pseudo-males are produced by immersion treatments of normal female fry ofmasu salmon in solutions of the male sex hormone, 17(1'methyl-testosterone. Pseudo-males tend to form improperly developed vas deferens, and produce sperm withfemale genetic characteristics. Adult returns of the feminized, marked fish have been ascertained in home rivers(Kanazawa and Harako 1987). Though this technology has
not yet reached a mass production stage, it can be said that
this type of smolt production technology has almost been
established.

Seaward-Migration_

Seaward-migrations of smolt occur actively from early April
to early May in the second spring of development, withthe fish moving to the coastal sea until late May. The smolts
entering the sea grow rapidly, feeding upon the abundantfood available in coastal waters. Their main diet at thatstage is small fish (Harako 1983; Kato 1983; Kemuyama
et al. 1987; Kiso 1986, 1987; Miyazawa et al. 1986).
The overwhelming percentage of seaward migrating fish
are female (60 to 96%), indicating that the majority of malemasu salmon juveniles will remain in rivers (Kato 1983;

140

NOAA Technical Report NMFS 102: Marine Ranching

Feeding migratory Stageat Sea(Fishing Mortality)_

Anadromous Migratory
Stage in Freshwater(Fishing Mortality)

June, 32 mos., 96 tds.
(Sprlwning Migration)

Oct. 5, 36 mos., 108 tds.
(Spawning)- - - - - - - - - - --1- - -- --(Northward Moving)
Feb. , 29 mos., 87 tds.

Wintering Stage(Fertil ization)
Oct. 5, o mos., o tds.

I

I

I
Egg Stage(Hatching)Dec. , 2 mos., 6 tds.

IAlevin Stage(Southward Moving)
Oct. , 24 mos., 72 tds.

Stage of OffshoreDistribution
in Summer(Emergence)
Apr. , 6 mos., 18 tds.

(Offshore Moving)
July, 21mOE:. ,

Coastal Sea- (Seaward Migration) Juvenile Stage
Distribution
in freshwater
Apr. , 18 mos. ,Stage
54 tds.

63 tds.

Figure 7
A typical model of the life cycle in masu salmon with calendar month, age in months (mos.) and age in ten-days (tds.) after fertilization(Kato and Hasegawa 1986).

Kemuyama et al. 1987; Kiso 1986; Miyazawa et al. 1986;
Ohkuma 1988; Sasaki et al. 1987). Remaining males inrivers are explained by the observations that the maturation of precocious male parr depends greatly upon thegrowth offish during the fry to fingerling stage (Utoh 1976)
and that the body lipid content of precocious male parris higher than that of smolt soon after the seaward-migration, showing declines of body lipid content with thesmoltification (Nomura 1984; Nomura et al. 1985).

Pen-Culture_

Growth size of the masu salmon juveniles at the beginningof pen-culture requires an initial body weight of over 130 g
by mid-November to ensure proper seawater tolerance(Yoshida et al. 1987). Pen-culture adults grow to about
1,000 g in weight, showing a noticeable delay of growthin the summer after late June.

Resource Analysis_

Stock assessment of the Japan Sea masu salmon popuiation was calculated statistically from the relationship between the total catch and total spawns (Kato and Hasegawa 1986). A typical masu salmon life cycle segmented

into ten-day intervals was chosen for simplifying the statistical analyses of the resources (Fig. 7). The growth (average fork lengths) of adult masu salmon captured by thedrift nets of administrative ships from 1973 to 1980 was
expressed using von Bertalanffy's growth curve:Lt=

54.3758 (1 - e-O.1192(t - 77.1523»),(1)

where t was age (in ten-day units) after fertilization andL t was the fork length at t ten-day units after fertilization(Fig. 8). A relationship between the fork length (L, em)
and the body weight (W, g) of adults, using the findings
from fish captured in the coastal sea off Ishikawa Prefecturein March of 1979, was shown by the following equation:

W = 0.014108L3.

(2)

The masu salmon life span is 3 years (108 ten-day units)with the exception of only a few fish (Ohkuma 1988). It
was assumed that the sex ratio of the fish was 1: 1, theaverage spawn was 1,945 eggs per female, and the average
weight of the total annual catch in the Japan Sea was about
3,000 metric tons. The fishing mortality numbers (whichcorresponded with age composition) calculated from thenumber of fish caught per roll of drift net in each of theten-day periods were obtained from the findings of the drift
net fishery from 1968 to 1980 in the Japan Sea. From this_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Hiroi: Muu Salmon Production Studies of the Marine Ranching Program

141

52
48
44
15
40

E 36

L=54.3757 (l_e- O.l 192 (1-77.15231 )~:r: 32
ft:l

z

(J)
(J)

28

~
:.c 24

10

<1

::;:

o

tr

CD

0

u... 20

16

..--

12

0.85
0.80

8
4

0\.-L~'-::-'---'::-::'----':7-':7--'::-:'"---':--:'-'::!---':-:'----':7-'-::".L.~~~L-J

82

84 86

88

90 92

94

96

98 100 102 104 106 108

82 84 86 88 90 92 94 96 98 100 102 104 106 108
LEMLEMLEMLEMLEMLEMLEMLEMLEML
Jon.
Feb. Mar.
Apr.
May
June JUly
Aug.
Sep.

LEMLEMLEMLEMLEMLEMLEMLEMLEML
Jon.
Feb.
Mar.
Apr.
May
June July
Aug. Sept.

Figure 9
Figure 8

Growth curve of masu salmon adults with both calendar monthand age (in ten-day units) after fertilization, using von Bertalanffy's equation (Kato and Hasegawa 1986).

it was shown that the fish became available to the masu
salmon fishery starting in early March (87 ten-day units).
The masu salmon adults, as shown in Figure 7, seemto begin the wintering stage in December of their third year
(approximately 25 months) to decrease their natural mortality and stabilize their survival rates. The number ofvirgin (or number in the absence of fishing mortality) masu
salmon, N x , at X ten-day units are estimated by theequationwhere No is numbers of fish at 80 ten-day units (lateDecember) and So is the survival rate per ten-day unit.
Accordingly, the weight of a virgin resource fish, Px , in
X ten-day units is calculated by the equation

Curves of relative weight of the virgin (absence of fishing mortality) masu salmon resource (biomass; g), as the survival rate
offish (S) varies from 0.55 to 0.95, by calendar month (E = early,
M = middle, L = late part of month) and age (in ten-day units)
after fertilization. The weight at 80 ten-day units (late December) is 10,000 g (Kato and Hasegawa 1986).

virgin resources seems to be near 0.95 (Fig. 9). Accordingly, the total mortality coefficient, Z, of the virgin resources calculated by the equation
Z = In(So) =

=

M

(3)

can be regarded as the natural mortality coefficient, M.
The fishing resources to decrease from early March (87ten-day units) to middle]une (97 ten-day units). The survival rate of the resources experiencing fishing mortality
seems to be 0.85, which results in a total mortality coefficient (Z) of 0.162 per ten-day unit from Equation 3.
Accordingly, fishing mortality coefficient, F, can be presumed to be 0.111 (total mortality-natural mortality).
Then, the fishing rate (in fish per ten-day units), E, iscalculated as 0.103 from the equationE

where Wx is the weight of a fish at X ten-day units obtained from Equations 1 and 2. The approximate weightof a virgin resource fish at 80 ten-day units, Po, is 10,000
g. Weight after 80 ten-day units can then be plotted against
the survival rate of the fish from 0.55 to 0.95 (per ten-dayunit) resulting in the curves of relative resources weight
shown in Figure 9. Because masu salmon have fewer eggs
per spawn than other fish, the survival rate (So) of the-In(0.95) = 0.051=

F [1 - e-(F+M)/(F+M)].

From the coefficients and rates mentioned above, numbers of fish and numbers of eggs (spawns) in both the virginresources and the resource under fishing mortality pressure can be calculated for each of the ten-day periods.
To determine the optimum starting time for the fisheryin relation to fishing intensity, isopleth curves of both theweights of the total annual catch and the decreased percentage of total spawns (number of eggs) are plotted against

142

NOAA Technical Report NMFS 102: Marine Ranching

the virgin resources in Figure 10. Values are calculatedusing the fishing mortality rate and the survival rate during each of the ten-day periods. The fishing mortality coefficient (F) is plotted from 0 to 0.20 from the starting timeof the fishery at 80 ten-day units (late December) to 108
tt'n-day units (end of the life span in early October thefollowing year) showing availability by age in ten-day units(Q). As shown by the black spot in Figure 10, the present
statuses of both the reproduction rate of the resource (total
spawn) and the fishing mortality coefficient are 10% and0.111, respectively. It is therefore necessary to cut the intensity of the fishing mortality rate by 36 % (0.07/0.111)
to decrease the total catch from 3,000 to 2,500 metric tons
and ultimately improve the reproduction levels of the masu
salmon from 10% to 30 % in total spawn. Although masu
salmon resources of the Japan Sea have a tendency todecrease owing to over-fishing, they are able to increaseduring years where there is an expansion of the numberof effective spawns and smolt-releases.

0.'

108
roo
10.
r02

~ 100

'"0 98
0>

>.

.0

9•

'" 9.
~
92
;'::

/
/

90
.0
0

0

>

«

/

,

/
/

8.
8.

'.0

8.

I

82

eo

2.'

I

2·0

I
I

0.01

0.03

0.05

0.13

O.I~

0.17

_

0.19

Fishing mortality coetficient (F)Figure 10

Isopleth diagram of total catch (by weight) and the percentage
of total spawns (eggs) for masu salmon, against availability rateby age (in ten-day units), Q., and fishing mortality coefficient,
F. Unit of contour numerals are in 1,ODD's of metric tons (Katoand Hasegawa 1986).

Genetic Feature_

Genetic variation and population structure of masu salmon
river populations were examined using electrophoretic
methods to compare enzymatic proteins in samples of fish
Figure 11 (below)

Estimation of genetic distance among twenty populatiuns of masu
salmon in japan. HK: Hokkaido; HN: Honshu (Okazaki 1986).

HK

HN

HK

HN

HK

HN

SHIBETSU RIVERHISHIBETSU R.
HUREH R.
TOKUSHIBETSU R.
UHOZUMAI R.
01 PPE R.
TOHE R.
TESHIO R.
HOZUKA R.
SHIRIBETSU R. (19B2 l
SHIRIBETSU R.(19B3)
CHITOSE R.
JIHZU R.(1982l
JIHZU R. (1983)
SHARI R.
SHOKOTSU R.
HIOMOTE R.
SHIHAHO R.
YOHESHIRO R.
AKA R.

~

I

I

I

I

I
,----.

o

I

i

i

.002

.003

.004

Genetic

D

5ience_________________ Hiroi: Masu Salmon Production Studies of the Marine Ranching Programamong twenty populations collected from eighteen rivers.
Although no clear structuring of the population on a geographic basis was discovered, a rough division into twogroups appeared at the Shiretoko Peninsula (except forseveral river populations), as shown in Figure 11; (I) therivers entering the strait of Nemuro and the Pacific Ocean,and (2) the rivers entering the Okhotsk and Japan Seas
(Okazaki 1986). Still, the genetic independence of river
populations is recognized distinctly. These observations
suggest a possible relationship with the instinctive homing
nature of masu salmon.

CitationsHarako, T.
1983. The biological aspects of seaward migrating juvenile masu
salmon (Oncorhynchus masou) in northern Japan. Marine Ranchmg Program Prog. Rep., Masu Salmon Production (3):63-81,:Iokkaido Salmon Hatchery, Sapporo. (In Japanese.)
Hiroi. O.
1982. Hatchery approaches in artificial chum salmon enhancement. In Proceedings of the 11th U.S.-Japan Meeting on
Aquawlture, Salmon enhancement, Tokyo, Japan (C.J. Sinder'llann, ed.), p. 45-53. U.S. Dep. Commer., NOAA Tech. Rep.
MFS 27.
1984. Technical approaches in production of the seedlings for the~rtificial propagation of masu salmon.
Marine Ranching Program Prog. Rep., Masu Salmon Production (4):120-128, Hokkaido Salmon Hatchery, Sapporo. (In Japanese.)
1985. Sexual maturation. In The survey of fall chum salmon in
Japan (K. Zama and H. Takahashi, eds.), p. 38-52. Fishery
Science Series 55 by supervision ofJpn. Soc. Sci. Fish., Kouseishakoseikaku, Tokyo. (In Japanese.)
Hiroi, 0., and K. Yamamoto.
1970. Studies on the maturation of salmonid fishes - II. Changes
in the testis of the masu salmon, Oncorhynchus masou, during anadromous migration. Bull. Fac. Fish., Hokkaido Univ. 20:252-264.
Hiroi, 0., T. Nomura, H. Ueda, and Y. Nagahama.
1983. Changes in serum concentrations of steroid hormones during spawning migration of masu salmon, Oncorhynchus masou.
Unpub!. data presented at 1983 spring meeting of Jpn. Soc. Sci.
Fish., April, Tokyo. (In Japanese.)
Kanazawa, H., and T. Harako.
1985. Improvement in the appearance rate on the smolt (Oncorhynchus masou) by femininity. Marine Ranching Program Prog.
Rep., Masu Salmon Production (5):31-35, Hokkaido Salmon
Hatchery, Sapporo. (In Japanese.)
1987. Studies on the feminization-Improve the productivity of thesmoltification in the yearling hatchery-reared masu salmon (Oncorhynchus masou). Marine Ranching Program Prog. Rep., Masu
Salmon Production (7):53-58, Hokkaido Salmon Hatchery, Sap'
poro. (In Japanese.)
Kato, F.
1983. The biological aspects of young masu salmon, Oncorhynchus
masou, in the coastal waters of Niigata and Toyama Prefecture.
Marine Ranching Program Prog. Rep., Masu Salmon Production (3):106-115, Hokkaido Salmon Hatchery, Sapporo. (InJapanese.)
Kato, F., and S. Hasegawa.
1986. Stock assessment of the Japan Sea population ofmasu salmon.
Marine Ranching Program Prog. Rep., Masu Salmon Production (6):108-114, Hokkaido Salmon Hatchery, Sapporo. (InJapanese.)143

Kemuyama, A., O. Hasekura, and R. Ohmura.
1987. The fishery and biological aspect ofmasu salmon, Oncorhynchus
rnasou, in the coastal waters of Iwate Prefecture. Marine Ranching Program Prog. Rep., Masu Salmon Production (7): 148-162,
Hokkaido Salmon Hatchery, Sapporo. (In Japanese.)
Kiso, K.
1986. Notes on the masu salmon, Oncorhynchus masou, in the coastal
waters of Miyagi Prefecture, Japan. Marine Ranching Program
Prog. Rep., Masu Salmon Production (6):176-187, Hokkaido
Salmon Hatchery, Sapporo. (In Japanese.)
1987. Notes on the seaward migration and early marine life of masu
salmon (Oncorhynchus masou) in the rivers and coastal waters of
Miyagi Prefecture, Japan. Marine Ranching Program Prog.
Rep., Masu Saimon Production (7):138-147, Hokkaido Salmon
Hatchery, Sapporo. (In Japanese.)
Kiso, K., and S. Kosaka.
1988. Ovarian development of masu salmon Oncorhynchus masou
during their early marine phase in waters near Oshika Peninsula,northeastern Honshu, Japan. Bull. Jpn. Soc. Sci. Fish. 54:
1681-1686. (In Japanese, English summ.)
Konno, S., and M. Abe.
1987. Efficient production of smolts in hatchery-reared masu salmon- Rearing conditions. Marine Ranching Program Prog. Rep.,
Masu Salmon Production (7):43-52, Hokkaido Salmon Hatchery,
Sapporo. (In Japanese.)
Konno, S., S. Nakae, and S. Takahashi.
1983. Observations on the effect of artificially controlled light on
the smoltdication of masu salmon, Oncorhynchus masou - III.
Marine Ranching Program Prog. Rep., Masu Salmon Production(3):26-50, Hokkaido Salmon Hatchery, Sapporo. (In Japanese.)
Mayama, H., K. Ohkuma, T. Nomura, and K. Matsumura.
;985. Experimental release of masu salmon, Oncorhynchus masou,smolts into the Shiribetsu River. Adult returns of marked fish
released in the spring of 1981. Sci. Rep. Hokkaido Salmon
Hatchery (39):1-16. (In Japanese, English summ.)
Mayama, H., K. Ohkuma, and T. Nomura.
1986. Experimental release of masu salmon (Oncorhynchus masou)smolts - Results of adult returns in 1985. Marine Ranching Program Prog. Rep., Masu Salmon Production (6):82-91, Hokkaido
Salmon Hatchery, Sapporo. (In Japanese.)
Mayama, H., T. Nomura, and K. Ohkuma.
1988. Seaward migration and adult return of the marked masu
salmon, Ontwhynchus masou, released in late fall before wintering.
Sci. Rep. Hokkaido Salmon Hatchery (42):21-36. (In Japanese;
English summ.)
Miyazawa, K., O. Hasekura, and R. Ohmura.
1986. The fishery and biological aspect of masu salmon, Oncrrhynchus masou, in the coastal waters of Iwate Prefecture. Marine
Ranching Program Prog. Rep., Masu Salm'Jn Production (6):134-169, Hokkaido Salmon Hatchery, Sapporo. (In JapaDese.OJ
Nomura, T
1984. A study on the physiology 01' masu salmon (Oncorhynchus masuu)- I. Change in crude fat content. Sci. Rep. Hokkaido Salmon
Hatchery (38):33-41. (In Japanese, English mmm.)
Nomura, T., H. Mayama, and K. Ohkuma.
1985. Lipid contents of masu salmon (Oncorhynchus masou) in various
stages of life. Marine Ranching Program Prog. Rep., Masu
Salmon Production (5);10-22, Hokkaido Salmon Hatchery, Sapporo. (In Japanese.)
Ogata, H., and S. Konno.
1986. Growth response and smolt production of 1 year cherrysalmon fed with diets having different protein and lipid levels.
Bull. Jpn. Soc. Sci. Fish. 52:313-318. (In Japanese, English
summ.)
Ohkuma, K.
1988. Sex ratio, age composition, and fork length of masu salmon

144

NOAA Technical Report NMFS 102: Marine Ranching(Oncorhynchus masou), of the Shiribetw River, Hokkaido, japan.
Sci. Rep. Hokkaido Salmon Hatchery (42):37-47.
Ohkuma, K., and T. Nomura.
1991. An approach to the efficient enhancement of masu sGlmon
through juvenile release into streams. In Marine ranching: proceedings of the 17th U.S.-japan Meeting on Aquaculture; 16-·20
October 1988, Mie and Kushiro, japan (R.S. Svrjcek, ed.),p. 151-159. U.S. Dep. Commer., NOAA Tech. Rep. !'<MFS
102.
Okazaki, T.
1986. Genetic variation and population structure in masu salmon
Oncorhynchus masou of japan. Bull. jpn. Soc. Sci. Fis!:. 52:
1365-1376.
Sasaki, F., H. Utoh, and T. Kobayashi.
1987. On the biological study of immature masu salmon Oncorhynchus masou Brevoort, migrating the Syakotan area in Hokkaido.
Marine Ranching Program Prog. Rep., Masu Salmon Production (7):96-137, Hokkaido Salmon Hatchery, Sapporc-. (Injapanese.)
Ueda, H., O. Hiroi, A. Hara, K. Yamauchi, and Y. Nagahama.
1984. Changes in serum concentratiooo of st~roid hormones,
thyroxine, and vitellogenin during spawning migration oftht' chumsalmon, Oncorhynchus keta. Gen. Compo Endocrinol. 53:203-211.
Utoh, H.
1976. Study of the mechanism of differentiation between the stream
resident form and the seaward migratory form in masu salmon,_

Oncorhynchus masou Brevoort - 1. Growth and sexual maturity of
precocious masu salmon parr. Bull. Fac. Fish. Hokkaido Univ.
26(4):321-326. (In japanese, English summ.)
Yamamoto, K.
1970. Reproduction. In Fish physiology (N. Kawamoto, ed.), p.
233-271. Kouseishakoseikaku, Tokyo. (In japanese.)
Yamazaki, F.
1983. Artificially induced smoltification in masu salmon - especiallyon the relation of thyroid and interrenal glands. Marine Ranching Program Prog. Rep., Masu Salmon Production (3): 13-17,
Hokkaido Salmon Hatchery, Sapporo. (In japanese.)
1986. Studies on the acceleration mechanism of artificial smoltification - histophysiological and genetical consideration. Marine
Ranching Program Prog. Rep., Masu Salmon Production(6):46-50, Hokkaido Salmon Hatchery, Sapporo. (In japanese.)
Yamazaki, F., and H-F. Ma.
1985. Changes of endocrine organs associated with smoltification- smoltification and endocrine organs ofFI hybrids between masu
and pink salmon. Marine Ranching Program Prog. Rep., Masu
Salmon Production (5):55-62, Hokkaido Salmon Hatchery, Sapporo. (In japanese.)
Yoshida, F., K. Kasahara, H. Suenaga, and T. Fujiwara.
1987. Experimental seawater rearing of masu salmon, Oncorhynchus masou - results of experiment in j 986. Marine Ranching Program Prog. Rep., Masu Salmon Production (7): 163-172, Hokkaido Salmon Hatchery, Sapporo. (In japanese.)Nutritional Approach to the Productionof Masu Salmon (Oncorhynchus masou) Smolt

HIROSHI OGATA and T AKESHI MURAl
National Research Institute of Aquaculture
Inland Station, Tamaki
Mie 519-04, Japan

ABSTRACT
Little attention has been paid to the possible role of nutrition in the field of salmonid smolt
production. At the physiological level, the parr-smolt transformation (smolting) accompanies amarked decline in reserve nutrients in the body and an increase in oxygen consumption. The
elevated catabolic status observed during smolting suggests that the nutritional requirements ofsmolt must be different from those of parr. A 120-day feeding test was conducted to study theeffects of dietary proteins and lipid levels on growth and smolting of yearling masu salmon (meanbody weight, 16 g). The following four diets were used in this study: HPHL, high protein
42%-high lipid (16%); HPLL, high protein (42% )-low lipid (4%); LPHL,low protein (24%)high lipid (14%); LPLL, low protein (24% )-low lipid (2 %). The growth response to these dietary
treatments was as follows: HPHL (final mean body weight, 44.4 g) > HPLL (36.5 g) > LPHL
(29.0 g) = LPLL (28.0 g). Only in the high protein diet group, both growth and feed efficiency
were distinctly improved by lipid supplementation. In all treatment groups, growth, feed efficiency, and food consumption rate were accelerated with the onset of smolting. The percentagesof the smolts obtained were 74.5%, 47.3%, 29.1 %, and 16.4% for HPHL, HPLL, LPHL, andLPLL, respectively. The improvement of fish performance seemed to result from enhancementof the digestible energy content in th~ diet and from elevation in the dietary levels of essential
fatty acids. The present results show that nutrition affects growth as well as smolting.

Introduction_

Young anadromous salmonids exhibit characteristic morphological, physiological, and behavioral changes during
the parr-smolt transformation (smolting) prior to actual
seawater entry (Hoar 1976; Folmar and Dickhoff 1980).
Methods for controlling and enhancing the smolting havebeen intensively studied based on physiological data. At
present, physiological treatments such as temperature,salinity, and photoperiod regimes are known to influence
growth and smolting drastically (Saunder and Henderson
1970; Wagner 1974; Knutsson and Grav 1976; Ewing etal. 1980; Clarke et al. 1981; Sato et al 1986). On the other
hand, little attention has been paid to the possible rolesof nutrition in smolt production. Unlike physiological andendocrinological treatments, nutritional treatment might
indirectly stimulate the transformation.
At the biochemical level, the smolting accompanies amarked decline in reserve nutrients (lipid and glycogen)in the body and an increase in oxygen consumption (Fontaine and Hatey 1950; Saddler et al. 1972; Ota and
Yamada 1974; Woo et al. 1978; Sheridan et al. 1985;
Sheridan 1986; Virtanen 1987). From a nutritional pointof view, the elevated metabolic status of smolting fish seems
to be reflected in body composition changes, thus the nutritional requirements of smolt would be different from thoseof parr. Therefore, we have conducted several nutritional
studies to develop a diet formulated for the production ofmasu salmon (Oncorhynchus masou) smolts. Some of theresults will be summarized in this report.

Comparison of Body Composition
between Smolts and Parr_

There has been little information published on the nutritional requirements of smolting masu salmon. We initially
examined the differences in body composition between
145

146

NOAA Technical Report NMFS 102: Marine Ranchingsmolts and parr of masu salmon during March throughMay (Ogata and Konno 1986). The most striking difference found was in the body lipid content as has been shownin other salmonids. The nonpolar lipid contents in thewhole body, liver, and skeletal muscle were clearly lower
in the smolts than in the parr, while no difference in thepolar lipid contents was detected (Fig. 1). During this same
period the trend for nonpolar lipids in the body mirroredthat of neutral fat (triacylglycerol) in the blood, where
neutral fat levels were always lower in the smolt than in
the parr (Fig. 2). In contrast, the smolts showed higher
fatty acid levels in the blood than the parr throughout thisperiod (Fig. 3). Thus during smolting, the body's sourceof energy reserves decreased markedly, and the metabolism of nutrients was intensified, probably owing to theaccelerated excretion of certain hormones. Based on thesefindings, we proposed the idea that supplementation oflipids to the diet of fish undergoing smoltification w:mld
lead to an improvement of growth, energy utilization, andthe entire smolting process as a consequence.

• parra smolt

Q.
~

" 400

"E

lJ)

•

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-

s

P

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CI)

c:::

o

o

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Whole
body
L-

.

s

P

Muscle

s

P

Liver
-'

Figure 1
Comparison of lipid contents between the smoIts and parr ofyearling masu salmon (Ogata and Konno 1986): S = smolts;
P = parr.

+

CU

cu

Polar lipids

600

II)

--...

IlllR Neutral lipids

o

--

_

Two feeding tests were conducted to examine the effects
of dietary lipid content on growth and smolting using
underyearling and yearling masu salmon. In the first study
using underyearlings, four test diets containing 4%,8%,
12 %, and 16 % lipid were prepared using a mixture ofpollock viscera oil and soybean oil (2: 3, v/v) as the lipid
source. Vitamin-free casein supplemented with amino acid

E

5

o

Effects of Lipid
Supplementation to Diet

cu

_

t

200

+ +

+t
¢

a

<}

0

t •
?

¢

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+
¢

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CD

Z

0
March

April

May

_ _ _ _ _.______------lFigure 2
Changes in the neutral fat levels in the plasma ofyearling masu salmon from March through May(Ogata and Konno 1986).

_ _ _ _ _ _ _ _ _ _ _ _ Ogata and Murai: Nutritional Approach to the Production of Masu Salmon Smolt

600
CQ

E

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(/)

CQ

Q.

~400

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w

147

:t
~ 200

o

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Z

Ol..----------'--------'-------'April
May
March

mixture was the protein source (Ogata et al. 1983), andcrude protein levels of all the diets were adjusted to about
40%. Each replicate of 40 fish (mean weight 1.46 g) were
stocked in a PVC tank. Each of the four dietary treatments
consisted of duplicate tanks where fish were fed each of thefour test diets. Well water at 15°C was supplied continuously. Fish were fed by hand to satiation twice daily, 6 days
per week for six weeks.
Measured after six weeks, food consumpton rate decreased linearly as the dietary lipid level increased (Table1). The percent weight gain for the 6 weeks also showeda similar relationship (data not shown). These results indicate that for masu salmon weighing less than 4 g, excessive dietary lipid content depressed food consumption
and consequently growth.
In the second study, we examined the effects of dietary
lipid and protein levels on performance of the yearling fishundergoing smolting. In this study, white fish meal wasused to provide about 41 % crude protein in diets No.1
and 2, and 24% in diets No.3 and 4 (Table 2). Pollock
viscera oil was also supplemeq.~ed to elevate the dietary lipid
contents of No. 1 and 3. Thus four test diets were prepared:
high protein (41 % )-high lipid (16%), HPHL; high protein (41 % )-low lipid (4%), HPLL; low protein (24%)high lipid (14%), LPHL; low protein (24% )-low lipid(2 %), LPLL. Fifty-five fish (16 g mean body weight) were
distributed randomly into four PVC tanks, which were continuously supplied with well water at 15°C. Each tank contained one treatment. The fish were fed their respective
test diets by hand to satiation twice daily, 6 days per week
for 120 days Uanuary through May). Smoltification wasdetermined using the methods of Kubo (1980).
The growth response to these dietary treatments was asfollows: HPHL, final mean body weight, 44.4 g; HPLL,

Figure 3
Changes in the fatty acids in the plasma of yearling
masu salmon from March through May (Ogata andKonno 1986). NEFA = non-esterified fatty acids.

Table 1

Performance of underyearling masu salmon after six weeks
of being fed the experimental diet. Values are the averageof two duplicate tanks containing forty fish each.
Protein
lipid
Diet

(%)

Average bodyweight (g)InitialWeightgain

Final

Daily foodconsumption

(%)

(% )
-------,._-

I

2
3
4

40-4
40-8
40-12
40-16

4.06
3.84
3.76
3.58

1.46
1.45
1.45
1.46

178
165
159
145

2.00
1.84
1.80
1. 75

._-----

Table 2

Formulations of experimental diets (% by weight).
Diet no.
Diet composition
White fish meal
Brewer's yeast
Torula yeast
Pollock viscera oil
Dextrin
Cellulose flour
Mineral mix
Vitamin mix
CMC'
Crude protein
Crude fat

64.64
5.00
3.00

2

3

4

64.64
5.00
3.00

35.91
2.78
1.67

35.91
2.78
1.67

12.00

0

12.00

0

5.00
2.86
2.50
2.00
3.00

18.00
1.86
2.50
2.00
3.00

18.00
21.14
3.00
250
3.00

30.00
21.14
3.00
2.50
3.00

40.9
15.6

40.9
3.9

24.3
14.2

24.1
2.2

'Carboxymethyl cellulose sodium salt.

148

NOAA Technical Report NMFS 102: Marine Ranching_

Table .3
Performance of yearling masu salmon after 120 days of feeding the experimental
diets." HPHL = high proteiL, high lipid; HPLL = high protein, low lipid;
LPHL = low protein, high lipid; LPLL
low protein, low lipid.
HPHL

HPLL

LPHL

LPLL

(n

(2)

(3)

(4)

Average body weight
InitialFinal
Weight gain (%)
Feed efficiency
Daily food consumption (%)

15.48
44.41
187
0.60
1.34

15.83
36.47
130
0.48
1.29

16.69
29.04
0.31
1.27

16.06
28.02
74
0.28
2.33

Number of smolt obtained h

41/55

26/55

16/55

9/55

74

'Each tank contained 55 fish.
hNumber of smolt obtained relati\"e to initial number of fish. Differences in numbersof the smolt obtained were statisti,:ally significant (x2·test, P<O.OI) among the dietary
treatments (Ogata and Konno 1986).

1--36.4 g; LPHL, 29.0 g; LPLL, 28.0 g (Table 3; Fig. 4).
As seen in the growth response, the best feed efficiency wasachieved by using the HPHL diet. Thus only when fish
were given a high protein diet, did both growth response
and feed efficiency dearly improve. Lipid supplementation to the high protein diet distinctly improved the rateof smolt production, and the percentage of smolts obtained were 74.5 %, 47.3 %, 29.1 %, and 16.4% for HPHL,
HPLL, LPHL, and LPLL, respectively.
These results show that nutrition affects growth as wellas smolting and suggest that lipid supplementation to a dietis a valuable method for promoting smolt production.
However, Plotnikoff et al. (1983, 1984) reported that
dietary treatments failed to show any effects on the osmoregulatory abilities of chinook salmon before seawater
entry, even though growth, food, protein, and energy
utilization were improved by feeding a high lipid diet. Morestudies on the effects of dietary composition, not only on
the apparent rate but also on the completeness of smolting, are needed to elucidate the relationship between nutrition and smolting.

1
1

40

High protein - High lipid

2 High protein' Low lipid3

Low protein - High lipid

4

Low protein - Low lipid......

-

~
~

en
Q)

30

~

3

>-

4

"C

0

.c
Q)

en

...

III
Q)

>
oct 2015

JanConclusion

2

Feb

Mar

Apr

May

_

In the present report, we found differences in the bodycomposition of underyearling and yearling masu salmon,
and their response to a diet fortified with lipid. Supplementation oflipid over 4% in dietary lipid level depressed
the food consumption and growth of the former fish. By
contrast, when they were given a diet enriched with lipid
slightly prior to the onset of smolting, growth, feed efficiency, and smolting rate were distinctly improved. In a

Figure 4
Changes in mean body weights of the fish during the test period.

later study, these improvements were shown to result not
only from the enhancement of the digestible energy content in the diet but also from the elevation in the dietarylevels of essential fatty acids (Ogata and Murai 1989).

_ _ _ _ _ _ _ _ _ _ _ _ Ogata and Murai: Nutritional Approach to the Production of Masu Salmon Smolt

Acknowledgments_

Financial support for these studies was provided by Marine
Ranching Program from the Ministry of Agriculture,
Forestry, and Fisheries of Japan.

Citations_

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kisutch), chinook (0. tschowytscho) and sockeye (0. nerko.) salmon.
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Ewing, R.D., H.J. Pribble, S.L. Johnson, C.A. Fustich, J. Diamond,and J .A. Lichatowich.
1980. Influence of size, growth rate, and photoperiod on cyclicchanges in gill (Na+K)-ATPase activity in chinook salmon (Oncorhynchus tshowytscho). Can. J. Fish. Aquat. Sci. 37:600-605.
Folmar, L.C., and W.W. Dickhoff.
1980. The parr-smolt transformation (smoltification) and seawater
adaptation in salmonids. A review of selected literature. Aquaculture 21:1-37.
Fontaine, M., and J. Hatey.
1950. Variation de la teneur du foie en glycogene chez la jeunesaumon (Salmo salar L.) au cours de la "smoltification." Compte
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Hoar, W.S.
1976. Smolt transformation: evolution, behavior and physiology.
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1976. Seawater adaptation in Atlantic salmon (Salrno salar L.) at
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Kubo, T.
1980. Studies on the life history of the masu salmon (Oncorhynchus
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Ogata, H., and T. Murai.
1989. Effects of dietary fatty acid composition on growth and smolting of underyearling masu salmon, Oncorhynchus rnasou. Aquaculture 82:181-189.

149

Ogata, H., S. Arai, and T. Nose.
1983. Growth response of cherry salmon Oncorhynchus masou andamago salmon O. rhodurus fry fed purified casein diet supplemented
with amino acids. Bull. Jpn. Soc. Sci. Fish. 49:1381-1385.
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Plotnikoff, M.D., D.A. Higgs, B.S. Markert, B.S. Dosanjh,
J.R. McBride, and J.T. Buckley.
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1984. Nutrition and marine survival of chinook salmon (Onc01hynchus
tshowytscho) II: Further investigation of the potential role of smolt
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Saddler, J.B., K.V. Koski, and R.D. Cardwell.
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Sheridan, M.A.
1986. Effects of thyroxine, cortisol, growth hormone, and prolactin on lipid metabolism of coho salmon, Oncorhynchus kisutch, during smoltification. Gen. Compo Endocrinol. 64:220-238.
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Compo Biochem. Physiol. 80B:671-676.
Virtanen, E.
1987. Correlations between energy metabolism, osmotic balanceand external smolt indices in smolting young salmon, Salrno salar
L. Annu. Zoo!. Fenn. 24:71-78.
Wagner, H.H.
1974. Photoperiod and temperature regulation of smolting in steelhead trout (Salrno gairdnen). Can. J. Zool. 52:219-234.
Wood, N.Y.S., H.A. Bern, and R.S. Nishioka.
1978. Changes in body composition associated with smoltificationand premature transfer to 3eawater in coho salmon (Oncorhynchus
kisutch) and king salmon (0 tschawytscha). J. Fish. Bio!. 13:
421-428.

An Approach to the Efficient Enhancement of Masu Salmon
through the Release of Juveniles into Streams

KAZUMASA OHKUMA and TETSUICHI NOMURA
Hokkaido Salmon Hatchery
Fisheries Agency ofJapan
2-2, Nakanoshima, Toyohira
Sapporo 062, Japan

ABSTRACTThe masu salmon (Oncorhynchus masou) is one of the most important fishery resources in northern
Japan along with chum (0. keta) and pink (0. gorbuscha) salmon. In the last decade, the chumsalmon resource has increased dramatically, while the overall levels of masu salmon have decreased. This is due to several complex factors involving the biological characteristics of masu
salmon and human activities. Considering the present number of facilities and the constraints
on the annual budget, it is difficult to quantitatively increase smolt production using present
methods. In this paper we discuss the release of masu fry upstream in the spring, a new approach
which, when used in combination with other methods, can help increase smolt production without
requiring additional investments in new man-made hatcheries. In our study, efficiency of smoltification was confirmed by measuring the resulting fingerlings in the fall. It is suggested that the levelof masu salmon returning to the study area (Mena River), which is the highest in over fifty years,
may be a result of this new technology. In addition, we review similar research on fingerlings
released just prior to the wintering period. The river's maximum hatchery potential is realized
when fry release is properly timed at locations with existing smolt development habitat.

Introduction_

Chum salmon (Oncorhynchus keta) resources have increased
dramatically in the last decade, marking 100 years since
artificial salmon propagation was earnestly introduced in
Hokkaido. Conversely, masu salmon (0. masou) levels seemto have decreased. Considered one of the important coastal
fishery resources in northern Japan, an increase in themasu stocks would have significant economic benefits. In
this report, we summarize the situations and problems
around masu salmon propagation, especially in Hokkaido.
The effectiveness offry release to the uppermost positionsof tributaries and fingerling release before wintering arealso discussed. Both are newly introduced concepts recently
investigated under the Marine Ranching Program.

History of the Masu Salmon Fishery_

Accurate landing statistics of masu salmon in coastal andoffshore waters alone are not available. However, changes
have been observed in masu salmon catches in the rivers

where artificial propagation has been carried out in Hokkaido (Fig. 1). For comparison the level of chum salmon
harvested in the coastal areas and rivers in Hokkaido isalso presented. In comparison with chum salmon increases,
masu salmon catches are stagnant. This may be the resultof several complex factors, one being the masu salmon's
intrinsic biological characteristics and another the activerole of humans, which we discuss later in this text.

Masu Salmon Biological Characteristics
Life Cycle-The life cycle of the masu salmon is schematically shown in Figure 2. Masu salmon spawn at theuppermost positions of tributaries in the fall, emerge as
fry from the redds, disperse during the spring flood, andbegin growth. After spending one year in freshwater, mostreach 10-11 cm in fork length, undergo smoltification, andmigrate downward to the sea. The remainder either spend
an extra year in freshwater prior to migrating, or, as in
the case of precocious male fish, spend their whole life in
freshwater (Tanaka 1965; Machidori and Kato 1984). The
masu salmon which migrate to the sea spend one year
151

152

NOAA Technical Report NMFS 102: Marine Ranching

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Figure 1
Annual change in masu salmon catch in rivers of Hokkaido and in chum salmon catch in rivers and coastal areasof Hokkaido. Chum salmon data prior to 1951 from Mihara et al. 1951. Other information from Hokkaido Salmon
Hatchery, Activity Department (unpubl. data).

AGE

I

0

1

Precocious male.. ...... .... ...

I

RIVER
Freshwater life
I................
. . . . . . ............

SEA

2

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Figure 2
Life cycle of masu salmon in northern Japan.

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_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Ohkuma and Nomura: Approach to Enhancement of Masu Salmon

there, then migrate back to the coastal area around theirnatal river's mouths. Entering the rivers soon after returning, they spend the summer in the deepest depths of therivers, then continue upstream to their spawning area in
the fall.
Enhancement-The problems facing masu salmon propagation range widely. Owing to low food productivity inrivers where masu salmon spend at least one year before
migrating to the sea, the standing crop of fish is easily
depressed. There are two biological factors which affect thestanding crop. One is regulation of growth and the otheris control of total biomass; neither of which seems capableof bringing about either an explosive increase or a deadly
decrease in the amount of masu salmon stock. This appears
to be a survival strategy for masu salmon that depend
heavily on rivers with low food productivity.
Human activities such as the linearizing of stream
courses and the covering of stream banks with concrete
reduce the amount of suitable fish habitat. Furthermore,dams and other facilities in the rivers prevent upstream
migration for masu salmon during spawning and also thedispersion of fry.
The artificial propagation of this species poses various
problems. Masu salmon are caught at a fish weir installednear the river mouth in the spring to avoid illegal catches
upstream. For this reason, they must be held in ponds formore than two months until fall, and consequently, thenumber of deaths during this period is rather high. Recent improvements in the holding technique have reduced
the mortality of masu salmon during this period (Hiroi
1988). The annual release of artificially produced masu fry
is conducted every year in a manner similar to that used
for chum fry by releasing large numbers from only a few
points in the middle reaches of the rivers. Furthermore,angling for the resulting fingerlings by sport fishermen isalso thought to be extremely harmful on the propagationof masu salmon.
Comparing our ability to use female adult masu with
our ability to use female chum salmon for extraction, it
is clear that the average number of masu eggs collectedin Hokkaido is lower than that of chum salmon because
ofloss during the holding period (Fig. 3)-a great loss of
eggs that are necessary for the production of seed. The
highest average number of eggs per fish was obtained fromfish in the Shiribetsu River. 1 Adult masu salmon are cap-'''Number of eggs per fish" refers to the highest average rate of egg
stripping efficiency to total female masu salmon caught at the weir, notfecundity of fish.
No. of female salmon caught and stripped
Yearly rate
x 100%.
No. of female salmon caught at the weir
Average rate

:I: yearly rate
No. years.

153

%

'50

1940

'60

'70

'80

'90

Yea r
Figure 3

Annual change of rate of availability of female masu salmon whichwere caught for artificial propagation (Hokkaido Salmon Hatchery, Activity Dept., unpub\. data.)

VI

~ 20
~

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VI
II..
II..

o

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III

::lE
::l

z

1920

'30

'40

'50

'60

'70

YEAR
Figure 4

Change in the number of fishways constructed annually in
Hokkaido. (Data from Fisheries Dept., Hokkaido government.)

tured in the fall in the Mena River, a branch of the Shiribetsu. Because capture occurs closer to their spawningperiod, the holding time before the eggs are taken is shortened, thus reducing stress to the fish during maturation.
Figure 4 shows the annual change in the number offishways installed next to dams or other facilities from 1920
to 1981. Although the number of fishways has increased

154

NOAA Technical Report NMFS 102: Marine Ranching

_

(/)

:::E

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Q

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o

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w

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:::E
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10

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HEIGHT (m)Distribution of the height of dams where fishways are
installed in Hokkaido. (Data from Hokkaido government.)

Fisheries Resources Protection Act (effective 1951)* Protective area ----- 32 areas in Hokkaido ---------------------------(in these areas, no one is permitted to catch any
aquatic animal and plant throughout the year)*

Hokkaido PrefecturallnIand Waters Fishery Adjustment (effective 1964)* Prohibition against catching Pacific salmon,
except "yamabe," masu salmon juveniles* Prohibition against catching "yamabe" during
their seaward migration period
Area A: April 1 to May 31
Area B: May I to June 30* Prefectural "yamabe" protective area -----12 areas in HOkkaido-.------.-*(in these areas, only "yamabe" catches are prohibited during
the following periods:
Area A: June 1 to December 31
Area B: July 1 to December 31)

Figure 6
Regulations governing masu salmon catch in freshwater, in Hokkaido.

in recent years, most of them have been installed next todams which have a height of less than 5 meters (Fig. 5),
and many dams are still left without any route for fish to
migrate upstream.
The salmon fishing regulations for the inland waters of
Hokkaido are complex and strict (Fig. 6). Thirty-two areas
are designated as protected areas by the Fisheries Resource
Protection Act of 1951. In these areas, catching or collecting any kind of aquatic animal or plant is prohibIted
throughout the year. Hokkaido Prefectural Inland Waters
Fishery Adjustment additionally forbids all Pacific salmon
fishing except for "yamabe," the fingerling of masu
salmon. In the case of yamabe, this adjustment forbids
fishing during the two-month period of their seaward

migration which varies geographically. Finally in 12 prefectural yamabe protective areas, the adjustment extends thisban from the end of the migration period through the last
day of the year. Therefore it is possible to angle masu
salmon in many locations, even in the 12 regulated areas,
but only during the open periods.

Present Fishery Techniques_

Re1ea.se of Juvenile Fish
Although smolt production and release is the main technique used to enhance this resource in the Marine Ranching Program (Mayama 1991), it is difficult to enlarge smolt

___________________ Ohkuma and Nomura: Approach to Enhancement of Masu Salmon

155

Table 1
Data on released fry and their return during the period of
the experiments. WL is the distance from the center ofthe nucleus to the edge of the first freshwater annulus of
the scale and is indicated in mean value.
Average fork Number Average fork
length in thelength atofreleasereleased fry
summerBrood(em)year Date of release(em)(thousands)--------

points

<I

o

N

t

A) Fry release1980
late May 1981
1981
late May 1982
1982 24-25 May 1983
1983 28-29 May 1984
1984 21-22 May 1986
1985 20-21 May 1986
1986 26-27 May 1987

Brood
year

Year
of
returnB) Adult return'
1976
1979
1977
1980
1978
1981
1979
1982
1980
1983
1981
1984
1982
1985
1983
1986

Figure 7
Location of the Mena River. Masu salmon fry had been released
from the points indicated by triangles before 1983 and released
from the points indicated by arrows with controlled number offish from tributaries since 1983.

production in the hatchery with the present facilities andannual budget. Therefore, it is hoped that this method canbe used in combination with other effective strategies.
Accordingly, we have experimented with the following two
approaches stated previously. One is to release fry in theuppermost positions of as many tributaries as possible, andthe other is to release fingerlings before the wintering
period.

Fry Release and Sampling Method
The fry release experiments were held in the Mena River,a branch of the Shiribetsu River (Fig. 7). Prior to 1983,
large numbers of fry (from about 300,000 to 1,000,000
per site) were released from only a few locations (Shiribetsu Hatchery and several other sites upriver). Beginning in 1983, smaller numbers of fry (usually 30,000
to 50,000 per site) were released at each of a larger
number of release points in order to improve fry dis-

4.05
3.5
4.62
4.85
5.26
4.73
4.55

1,221
522
400
800
630
600
627

7.7
9.6
9.0
8.5
8.5

river

WL of
3 yearfemale fish'
(mm)

WL of
3 yearmale fish'
(mm)

1,200
1,578
660
679
931
537
425
1,268

0.378
0.365
0.423
0.411
0.407
0.436
0.450
0.428

0.390
0.336
0.442
0.426
0.408
0.426
0.468
0.447

Cateh
in the'Fish measured were predominantly of native origin.
'From database used by Ohkuma (1988).

persion and to maximize the productivity of the river
system.
The information about those released fry is shown in
Table lA. These averages are obtained from a single observation point in the middle reaches. The 1981 released
group (the 1980-brood-year group) grew very slowly, andconsequently, the average fork length of the group did notreach over 8 cm during the summer. Many masu salmon
adults migrated upstream over the fish weir in the fall of
1981. Because swimming fry, assumed to be wild fish, wereconfirmed in most of the tributaries in the spring of 1982,
we released masu fry only to the lower areas of the riverfrom the hatchery in that year. Therefore, it is highly
probable that the value of 9.6 cm in average fork length
better represents the fish which originated by natural
spawning. Results obtained after the 1983 release represents that of released fish growth after summer, and consequently the average fork length reached over 9 cm before
wintering, showing improvement over released fish measured in 1981.

156

NOAA Technical Report NMFS 102: Marine Ranching_

Number of fry released to the Mena Rever

T
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Adult return information is shown in Table 1B (Ohkuma
1988). The scale radius, or distance from the center of thenucleus to the edge of the freshwater annulus, was measured in order to estimate growth during their freshwater
life. It shows that the radius of the 1982 brood year group
was comparatively large.
In order to confirm the effectiveness of multiple point.
upstream fry released with respect to dispersion, the relationship between the number of released masu fry andreturning adults in the Mena River was investigated (Hokkaido Salmon Hatchery, unpub!. data; Fig. 8). Although
the number of released fry had been small until around1950, it reached over 1 Y2 million at various times after that.
As for the adult return, it had increased by over 1,000 in
1952, but it decreased again in the late 1960s. In 1970 the
Mena River was designated as a yamabe protective area,
and coincidentally, the number of returning masu salmon
increased to more than 1,000 for several years afterwards.
U nexplainably, it again fell in the early 1980s. Since 1983,
when the dispersing method took place in earnest, the adultreturn increased gradually in 1986 and 1987 after reachinga bottom in 1985, even though the number of released fry
were maintained at low levels. In 1987, more than 2,000
returning fish marked the highest level of returns in 50
years.
In the artificial masu salmon propagation program being
carried out in Hokkaido at the present time, fry are re-'80

Year of return

Figure 8
Changes in the number of
released fry (upper) and returned adult masu salmon(lower) in the Mena River, abranch of the Shiribetsu
River. No fry were released
officially in 1966. (Hokkaido
Salmon Hatchery, Activity
Dept., unpubl. data.)leased into middle reaches of rivers at a size of 4 to 5 em
in fork length. Because of poor swimming ability of thesesmall fry, it is difficult for them to disperse upstream;
therefore, food productivity in the areas upstream from therelease locations cannot be utilized effectively. On the other
hand, the new method we have examined at this time
resolved this problem by releasing fry to the uppermost
tributary positions, the numbers of which depend on thestream's carrying capacity. This method is superior to thepresently used release method because it uses the wholestream for smolt production. Although it requires more
effort at the time of release, we believe it results in improved
smolt production and adult returns.

Fingerling Release
The release of fingerlings took place in the fall before
wintering in the Mena and Shubuto Rivers, in 1982 and1985, respectively (Mayama et a!. 1988; Fig. 9). There isa large dam for production of electric power in the Shiribetsu River. Because the area upstream from the dam cannot be utilized for salmon reproduction or propagaton, theartificial propagation has been taking place in the Mena
River only. The masu salmon of this river spend the summer in the deepest depths of the Shiribetsu. In the fall they
enter the Mena River to spawn and, as discussed earlier,are caught with almost fully matured gonads. Thus, a high_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Ohkuma and Nomura: Approach to Enhancement of Masu Salmon

Sea of Japan
Shiribetsu

R.::Ji/:~"157<t Release in fall of 1982...

Release in fall of 1985",illYSea of Okhotsk

Paci fic

o
I

6

Ocean

8 10kmI

Figure 9

Location of the Shubuto River and the Mena River where masu salmon fingerlings were experimentally released before
wintering.

rate of utilization for egg extraction is maintained (Fig. 3).
Fingerlings were released from three points in the Mena
River and from four points in the Shubuto River. The locations for fingerling release were chosen using the following criteria: a slow rate of river flow, presence of a largepool nearby, and ease of fingerling dispersion from thearea. After wintering in a suitable space, released fingerlings migrate to the sea the next spring. When they migrateback to the Suttsu coast in the spring two years after release,
they are caught in a stationary net located in the nearby
coastal area.
Table 2 shows information on fingerling release and theirreturn as adults. In November 1982, 53,700 year-old
fingerlings of the 1981 brood year (9.11 em average fork
length) were released into the Mena River marked byclipped right ventral fins. In the same way, 135,000 fishof 1984-brood-year fingerlings (9.74 em average fork
length) were released to the Shubuto River in 1985, withclipped adipose fins. The released fish dispersed within ashort period and most of them were thought to havemigrated to the sea as smolt the following spring.
Only 0.1 % of the released fingerlings, 35 fish, returnedto the coastal area from the 1981-brood-year group. However, the catch of the 1984-brood-year group released in
Shubuto reached 1,183 fish, or about 0.9%, which isalmost 10 times the level of the 1981 release. While thesize of the river and coastal catches of the Mena River stock
were almost the same in 1983, the catch at the Shubuto
River in 1987 was much lower than the coastal catch. One
explanation for this is that most of the fish returning to
the Shubuto River may have already gone upstream
through the trapping site before the weir was installed inAugust.
These contrasting results between the return rates of thetwo release groups were supposed to be due mainly to thedifference in the size of each fingerling group at the timeof release. It was estimated that the percentage of the fish
which could reach the size of 11-12 em (assumed smallest

158

NOAA Technical Report NMFS 102: Marine Ranching_

Table 2
Data of released fmgerling and their return. The return rate of the 1984 brood year group was almost ten time as high as therate of the 1982 brood year group (Mayama et al. 1988).

Brood
year

ReleasedtoFingerling release
Mena R.
1981
Mena R.
1984

Mena R.
Shubuto R.

OriginRiver
and year,planted

Date

Number of
fingerlings

Fork length
at release(cm)

Body weightat release(g)

Clipped fin

Rate of matured
male fish(%)

4-5 Nov. 1982
30 Oct.-2 Nov. 1985

53,700135,000

9.11
9.74

9.36
10.70

right ventral
adipose

0.7
9.5

Year ofreturnNumber ofcatch along
the coast

Number ofcatch inthe river

Number of
total
catch

Adult return
Mena R., 1982
1981

1984

53

42

95

1984

1987

1,183

131-

1,314

Brood
year

Shubuto R., 1985

Fork length and body weightof captured marked fish
FL (cm)BW (g)

female
male

57.68
53.08

2,460
1,550

female
male

56.68
52.18

2,320
1,550

-Most of masu salmon returning to the Shubuto River had already gone upstream and the rest of them were thought to have been captured
at the fish weir in the river.

size for smoltification) was low in the 1981-brood-year
group, while the number of fish reaching that size in the
1984-brood-year group was large.
During the winter season, the standing crop of foodorganisms (predominated by the order Diptera) reaches its
greatest level (Atoda and Imada 1972a, 1972b), and thefeeding activity of masu fingerlings is lowest (Mayama etal. 1988). The amount of drifting organisms per unit
volume is kept at high levels throughout the winter.
Though the discharge of the river increases during thefollowing spring rise period, it is thought that there is still
sufficient capacity to assure the growth of fish remaining
in the river even after adding fingerlings there before
wintering (Mayama et al. 1988).
It is also well known that crude fat content is closely
related to feeding activity and metabolism (Ota and
Yamada 1974). The change in the crude fat conter,t ofmasu salmon fingerlings proves that there is a reductionof feeding activity in the winter and an increase in feeding
activity in early spring (Nomura 1984; Fig. 10).

Conclusion_

Although smolt release is said to be the most effective
method of enhancing masu salmon resources, it is difficult to increase the number of smolt because of the highexpense and large facilities needed for rearing. On the other
hand, a fry release program does not impose higher ex-

.,..

5

; 4

C
o

u

3

IV

.. 2

."
:>

U1
J

A

SON

1982

0

J

F

M

A

1983

Figure 10
Seasonal changes of crude fat content of masu salmon juvenile
in the Mena River. Bars indicate the range of standard deviation (Nomura 1984). J = July; A = August; S = Sept., etc.

penses, although the survival rate and growth ofjuveniles
afterwards closely depends on the conditions at the timeof release. Consequently, this method of enhancement may
sometimes lead to smaller numbers of smolt migrating to
the sea. The effectiveness of fingerling releases before thewintering period has performance characteristics somewhere between fry and smolt release methods, and is effective in the rivers where the circumstances become worsein the summer season. Thus, by combining fry and fingerling release methods with the smolt release program, it

____________________ Ohkuma and Nomura: Approach to Enhancement of Masu Salmon

may be possible to efficiently and economically mcreasemasu salmon resources.

Acknowledgments
We would like to thank H. Mayama of the Hokkaido
Salmon Hatchery for his valuable guidance and helpful
cooperation throughout the experiments. We are also
grateful to K. Matsumura and H. Honma of the Hokkaido
Salmon Hatchery; T. Wajima of the Suttsu Fisheries
Cooperative for their helpful assistance; and S.C. Hasbrouck of Asahi Culture Center, Sapporo, for his assistance in the English translation.

Citations
Atoda, M., and K. Imada.
1972a. Studies on the aquatic insect fauna and environmental conditions of the Chihase River, Hokkaido. Sci. Rep. Hokkaido Fish
Hatchery (27):59-95.
1972b. Studies on the aquatic insect fauna and environmental conditions of the Shakotan River, the Kenichi River and the OtoshibeRiver, Hokkaido. Sci. Rep. Hokkaido Fish Hatchery (27):
97-149.
Hiroi, O.
1988. Sexual maturation and long-time holding experiments innaturally ascending masu salmon. Marine Ranching Program
Progress Report of the Hokkaido Salmon Hatchery on masu
salmon production (8): 1-8. (In Japanese.)

159

Machidori, S., and F. Kato.
1984. Spawning populations and marine life of masu salmon(Oncorhynchus masou). Int. North Pac. Fish. Comm. Bull. (43):1-138.
Mayama, H.
1991. Efficient techniques for producing masu salmon smolt andimproving adult returns from outplantings. In Marine ranching:proceedings of the 1988 U.S.-Japan meeting on aquaculture (R.S.
Svrjcek, ed.), p. 1-8. U.S. Dep. Commer., NOAA Tech. Rep.
NMFS 102.
Mayama, H., K. Ohkuma, and T. Nomura.
1988. Seaward migration and adult return of the marked masu
salmon, Oncorhynchus masou, released in late fall before win tering. Sci. Rep. Hokkaido Salmon Hatchery (42):21-36.
Mihara, T., S. Sato, T. Hachiya, and M. Ichikawa.
1951. Studies of the fluctuations of fishery conditions of chumsalmon in Hokkaido (I). Sci. Rep. Hokkaido Salmon Hatchery6(1-2):27-133.
Nomura, T.
1984. A study on the physiology of masu salmon (Oncorhynchus masou)- 1. Change in crude fat content. Sci. Rep. Hokkaido Salmon
Hatchery (38):33-41.
Ohkuma, K.
1988. Sex ratio, age composition, and fork length of masu salmon(Oncorhynchus masou), of the Shiribetsu River, Hokkaido, Japan.
Sci. Rep. Hokkaido Salmon Hatchery (42):37-47.
Ota, T., and M. Yamada.
1974. Lipids ofmasu salmon - II. Seasonal variations in the lipidsof masu salmon parr during the life in fresh-water. Bull. Jpn.
Soc. Sci. Fish. 40(7):699-706.
Tanaka, S.
1965. Salmon of the north Pacific Ocean - Part IX. Coho, Chinook
and masu salmon in offshore waters. 3. A review of the biologicalinformation on masu salmon (Oncorhynchus masou). Int. North Pac.
Fish. Comm. Bull. (16):75-135.

Present Status and Future of the
Marine Ranching Program

AKIMITSU KOGANEZAWA
Marine Ranching Program
Agriculture, Forestry, and Fisheries Research Council
Research Division, Fisheries Agency
1-2-1 Kasumigaseki, Chiyoda-ku, Tokyo 100, Japan

ABSTRACTThis paper reviews several major fisheries research programs in Japan leading up to andincluding the Marine Ranching Program. Conducted during the 1980s, the Marine Ranching
Program integrates the research capabilities of thirty-six academic, governmental, and private
institutions in a three-phase program leading to the initiation of "Multiple-Resource Cultivation Systems." These systems take a comprehensive approach to marine aquaculture by combining biological, physical, and engineering sciences to improve entire environments within theocean ecosystem to create, in turn, more productive and more manageable aquaculture areas.
The resulting technology optimizes ecosystem components such as water flow and natural vegetation to support symbiotic relationships between plants, animals, and the ocean and thus to leadto the creation of areas for natural propagation of important commercial species. Results of thisprogram will support future projects including "the Coastal Fishery Ground Development Program" and the "Marin-novation Plan."Introduction_

Remarkable progress has been made in the area of technical developments for the increase of important coastal
fisheries resources during the past two decades. Projects
promoted by the Ministry of Agriculture, Forestry, andFisheries (MAFF) have played a vital role in the realization of cultivated fisheries in Japanese coastal and offshore
areas under the current policy which has established a
200-mile fishery zone.
Following the dawn of the ocean development age, theCouncil on Marine Science and Technology was organized. In 1963 it produced a historically monumental reporton a plan for scientific and technological goals for thedevelopment of ocean resources. This specific report, called"The First Action Program," identified the areas thatshould be promoted primarily by the government. Among
those projects, the cultivation of ocean fisheries was naturally listed as one of the most important topics.
The Shallow Sea Special Program (inJapanese, "Senkai
Betsuwaku Kenkyu" or "Comprehensive Research on theDevelopment of the Fishing Grounds for the Aquaculture
and Propagation in the Shallow-Sea Areas") was designed
and carried out from 1970 to 1974. From 1977 to 1981,

partly based upon the Important Species Large-Scale
Aquaculture Experimental Program done by contract with
the Fisheries Agency, MAFF, The Special Salmon Project (or "Comprehensive Research on the Developmentof the Large-Scale Cultivation Technologies for Anadromous Salmon and Trout") was conducted, expanding
the results of the previous effort.
In response to the establishment of the 200-mile sovereignty zone policy on fisheries resources in 1977, we started
to redevelop our coastal and offshore fisheries by focusing
on new types of technology. Thus, the "Marine Ranching
Program" was developed. Initiated in 1980, the nine-yearlong project was designed to enhance the cultivated, or nonconventional fisheries of important species in the coastaland offshore areas of our nation. This program is recognized as the technical foundation for the realization ofcultivated oceanic fisheries into the 21 st century. The common but unofficial title of "The Marine Ranching Program" has become a very popular nickname among
fishery-related communities; however, the program isofficially called' 'Comprehensive Research on the Development of the Domestication System for the Coastal Fisheries
Resources." The word domestication is used to express
the goal of creating more manageable, important fisheries
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NOAA Technical Report NMFS 102: Marine Ranching

resources in the coastal and offshore areas and of promoting
their cultivation like that of domestic animals on land.
The following discussion outlines our efforts, progress,
results, and prospects for the future in these threeprograms.

Shallow Sea Special Program:
1970-74_

This program focused on the control of diminutive factors
on fish, shellfish, and seaweed throughout their life cycleand on the control of important environmental conditions.
It was an epoch-making program because the results of theresearch had to be demonstrated by in-situ experimentation. It should be recognized as the first program in which
researchers in the fields of marine biology and marine
engineering worked together.
The target species were scallop (Patinopecten yeSJI;ensis)
along the Okhotsk coast (northeast side of Hokkaido),
abalone (Haliotis discus hanna!) along the San-riku (thenortheast Pacific coast of the northern Main Island), redseabream (Pagrus major) in the Seto Inland Sea (semi-dosed
sea in western Japan) , and Kuruma prawn (Penaeusjaponica)in Yamaguchi and Oita Prefectures (western edge of Seto
Inland Sea). The major important technologies that are
now the foundation of the recent Coastal Fishing Ground
Development Program (in Japanese "Engan Gyogyo Seibi
Kaihatsu Keikaku") and sea-farming in general weredeveloped through this program. These technologies include, but are not limited to the formation of mother scallop
schools, the development of seaweed fields, the development of appropriate methods of releasing Kuruma prawns
into tideland areas, and the acoustic conditioning of red
seabream. The significance of predators was also recognized as one of the most important problems facing technologies enhancing propagation in the ocean environment.

Special Salmon Program: 1977-81_

This program involved the large-scale production andsystematic release of salmon fingerlings. Deployment wasachieved in almost all of northern Japan, before the implementation of the U.S. and U.S.S.R. 200-mile zone
policies. This program should also be recognized as a verysignificant effort in the history of world fishery resource
development.
This challenging program resulted in the production andrelease of chum salmon (Oncorhynchus keta) fingerlings whichreached 4-2.24- billion in number (equivalent to 14-0 thousand metric tons in total weight in 1987). It also contributedin educating many scientists, researchers, and technicians,
bringing rapid technical improvements to many areas:
fingerling release into rivers (Hokkaido); at-sea rearing

and release of chum salmon (northeast Pacific coast); andtechnology to transport fish that grow up in other areas
to the coast of the Sea of Japan.
There were also advances in the field of new species
introduction, namely coho salmon (0. kisutch). This
research has resulted in a large-scale tracking survey ofjuvenile and homing adult fish released in the coastal andoffshore areas. We can say that this program has led to
the recognition of new research topics, such as the importance of feeding and imprinting to breeding and fingerling production.

Marine Ranching Program: 1980-88_

The marine ranching system is considered to be important not only for its contribution to research and development activities, but also as a public works project
managed by the government. It has contributed manytechnical developments to a wide spectrum of marine
aquaculture activities (i. e., offshore fish-cage development
program). On the other hand, as a public works project,
it has contributed the construction oflarge-scale propagation fields and artificial reefs under the Coastal Fishing
Ground Development Program. Red seabream is a typical
species shoes propagation has been successfully developed.
The Marine Ranching Program has been executed byintegrating almost all of the research facilities from private,public, and academic institutions, such as the national andprefectural research laboratories, universities, and industrial research centers. In 1985, some thirty-six institutions
were united together and committed to progress in this effort. It was also recognized that we would have to copewith many unknown and less-known fields to enable us
to cross over to the use of an ocean ecosystem from ourpresent use of conventional aquaculture and propagation
systems. Based upon such recognition, The Marine Ranching Program has involved not only the fishery-related fields
but also other biological, physical, and engineering sciences
and technologies as well. This program consisted of fivemain categories which are divided into three phases according to its objectives and subsequent progress (Fig. 1).
Phases I and II, conducted from 1980 to 1985, have alreadybeen finished with success after the expenditure of a total
budget of 2.2 billion yen. During Phase III (1986-88),
1.2 billion yen was invested to initiate the MultipleResource Cultivation Systems, thereby combining andorganizing the results of the previous phase's research.
Each phase is outlined below.

Phase I (1980-82)
The total stock of a fishery resource depends upon mortality during the early stages of growth. During Phase I,
ecological studies were conducted that highlighted this_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Koganezawa: Present and Future of the Marine Ranching Program

A

D

Phase I: 1980-82

Phase III: 1986-88

Ecological study on:
Masu salmon
Horse mackerel
B1uefin tuna
Rounder
Bay scallop
Seaweeds

Study of multipleresource cultivation
technology and new
fisheries systems

163

C
Phase II: 1983-85
Study of production
systems for selectedfish and shellfish

B

E

Phase I: 1980-82

Phase I: 1980-85

Study on thetechnologies ofenvironmental control:
Water column
environment
Sea floor environment

Study of support
technology:
Disease prevention
Optimization of living
environments
Environmental
monitoring system

Figure 1

Relationship between the five catagories (A-E) of the Marine Ranching System, which were performed in three phases.

critical time for selected species. Other environmental
studies on the control of water-flow and sea-bottom characteristics were also executed. The focal point of Phase I
projects was to determine how, when, and where the bestareas exist for us to approach the improvement of survival
rates of fish during the juvenile stage of growth.
In order to organize information on groups of organisms
sharing similar habitats and other characteristics, wecategorized plant and animal species according to similarities in their life cycle. In some cases a single, selected
species may represent an entire group for a certain category. Six groups were selected. They are as follows:• Cherry salmon (Oncorhynchus masou)-fish which spawn
after anadromous migration to rivers and estuaries;• Japanese horse mackerel (TrachurusJaponicus)-a species
that spend its juvenile stage under the drifting seaweed;• Bluefin tuna (Thunnus thynnus)-a species that migrates
ocean-wide;• Halibut (Paralichthys olivaceus) , and flounder (Limanda
herzensteinz)-migratory bottom fish;• Bay scallop (Pecten albicans) and ark shell (Scapharca broughtonil)-nonmigrating, sedentary fish which generally
inhabit sandy bottoms;• Sea oak (Eisenia bicyclis), sea trumpet (Eclonia cava), andgulfweed (Sargassum julvellum)-large perennial algae
which are located over rocky bottoms.

Phase II (1983-85)
The technologies proposed for the cultivation of the selected
species resulting from Phase I research were examined atsea. As their effectiveness in controlling various aspects ofthe sea environment was measured, concurrent researchon the structural and engineering technologies supporting
those facilities, installations, and related equipment wasalso conducted. In addition, research was performed for
optimizing other aspects of the ecosystem (i.e., indigenous

164

NOAA Technical Report NMFS 102: Marine Ranchingfish-life in the food chain) to address the area of feeding
and other vital predatory or symbiotic factors for cogeneration with the important species.

Phase III (1986-88)
In order to effectively utilize the natural productivityof the sea, it is necessary to develop and construct suitable coexisting systems in both time and space dimensions among the multiple oceanic species while focusing
on the selected important ones. We tried to develop a
Multiple-Resource Cultivation System to upgrade thetotal productivity of the sea through the cultivation ofsome specific fish and shellfish. With this in mind, Phase
III was started in 1986, based upon the results of Phase
II research.
The multiple species selected included salmon, redseabream, abalone, and sea urchin-species for which
cultivation technology had been developing. At the sametime, the anticipated new fishery system for multiple
resource cultivation was examined and integrated with theconventional technologies of propagation and aquaculture.

Conclusion__

The research findings of the last phase are expected to provide the building blocks of fundamental technologies andbasic knowledge to support several projects including1) the Coastal Fishery Ground Development Program;2) sea-farming programs; and 3) the "Marin-novation
Plan." The Marin-novation Plan is currently being developed as a new integrated concept, combining fish cultivation with conventional fisheries as well as coastal area
development (including design, deployment of port facilities, warehouses, and fish-processing plants). The plan isstill only at a conceptual stage; no research and development programs or public works programs have been initiated yet
We expect these research efforts to contribute technicaldevelopments in the cultivation of our fishery systems to
support marine ranching into the 21 st century. It is essential to realize that a close relationship and exchange of information must always be maintained among all the relevant scientists, researchers, and indeed the administrative
staffs as well.

The Application of Current Techniquesin Molecular Biology for Detection and Control of
Infectious Diseases in Salmonid Aquaculture

ALFRED C. FOX, CINDY K. ARAKAWA, and JAMES R. WINTONu.

S. Fish and Wildlife Service
National Fisheries Research Center
Building 204, Naval Station
Seattle, Washington 98115

ABSTRACTIn recent years, significant progress has been made in the diagnosis and control of important
human and animal diseases through the application of new techniques in molecular biology. These
new techniques are being used to solve problems of salmonid aquaculture caused by those viral,bacterial, and deep tissue protozoan pathogens that do not respond to chemotherapy. Currently,
losses from these diseases can only be prevented by efficient detection and avoidance of exposure
to the pathogen. In the future, control of many fish diseases will rely upon the development ofeffective vaccines and genetically engineered molecules to prevent losses in geographic areas where
pathogens are enzootic. This paper discusses the use of monoclonal antibody and DNA probe
technologies to detect fish diseases and to create and test genetically engineered vaccines forenhancing the survival of Pacific salmon reared in aquaculture.

Introduction_

Losses caused by infectious diseases remain one of the mostimportant constraints to success in salmonid aquaculture.
While some pathogens respond to drug or chemical control methods, many of the most significant diseases of
salmon and trout are untreatable. Losses due to viruses,
intracellular or drug-resistant bacteria, and some of the
deep-tissue protozoans can only be prevented by avoiding
exposure. This method relies upon the use of sensitive
detection methods for the disease agents, the selection of
disease-free animals, and the rearing of fish in pathogenfree water. The strategy is time consuming, expensive, andoften impractical where pathogens are enzootic and thewater supply cannot be treated. Recent advances in molecular biology have provided new tools for the rapid and sensitive detection of these diseases and for the developmentof genetically engineered vaccines for use in salmonid aquaculture. New detection methods, based upon the use of
monoclonal antibodies and DNA probes, promise to be
more rapid, sensitive, and cost-effective, while the genetic
engineering of new types of vaccines and the creation oftransgenic fish will allow aquaculturists to rear fish thatare more resistant to enzootic pathogens.

Monoclonal Antibodies_

Over a decade ago, Kohler and Milstein (1975) publisheda method for the creation of single clones of antibodysecreting mouse cells that could be propagated indefinitely
in tissue culture and that would produce a single type ofantibody. These "monoclonal" antibodies (MAbs) aresuperior to animal antisera for many applications because
they are highly specific and very consistent. Several groups
working with diseases of salmonid fish have used thistechnology to establish MAbs against antigens of infectious
hematopoietic necrosis virus (IHNV) (Schultz et aL 1985;
Ristow and Arnzen 1988; Winton et al. 1988), viral hemorrhagic septicemia virus (VHSV) (Enzmann et aL 1988;
Lorenzen et al. 1988), infectious pancreatic necrosis virus(IPNV) (Wolski et aL 1986; Caswell-Reno et aL 1988),
Yersinia ruckeri (Austin et aL 1986), Aeromonas salmonicida(Austin et aL 1986), Renibacterium salmoninarum (BKD)(Arakawa et al. 1987; Kaattari et aL 1987), Vibrio anguillarum (Goerlich 1987), Vibrio salmonicida (Espelid et aL
1988), and Ceratomyxa shasta (Hoffmaster et aL 1988).
These monoclonal antibodies have been used to distinguish among strains of IHNV (Ristow and Arnzen 1988;
Winton et al. 1988), IPNV (Caswell-Reno et aL 1988),
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NOAA Technical Report NMFS 102: Marine Ranching

BKD (Arakawa et al. 1987), and Vibrio sp. (Goerlich 1987)
recovered from fish in different geographical areas and help
provide a better understanding of the epizootiology andantigenic variation of the bacterial and viral isolates.
Monoclonal antibodies have also become important
reagents for the development of improved detection
methods for fish pathogens (Austin et al. 1986). Because
MAbs are very consistent and do not cross-react with otherantigens to any significant extent, it is possible to design
more sensitive assays allowing the detection of very low
levels of antigen in infected fish. In addition, MAbs canbe used to select or identify mutant strains of viruses orbacteria with altered properties (e. g. virulence) that will
be effective as a vaccine against the wild-type isolates.

Recombinant DNA Technology_

Among the most commonly performed operations ofmolecular biology are the cloning and sequencing of genes(Maniatis et al. 1982). In addition to providing fundamental knowledge about the structure and relation of genes andtheir products, this technology provides a powerful tool for
detecting pathogens. By cloning either a DNA COPy of themessenger RNA from a specific gene or fragments of DNA
from the pathogen into a bacterial plasmid and expressing these in E. coli, it is possible to obtain a large amountof DNA with a nucleotide sequence that is homologous roa portion of the pathogen genome and that will bindstrongly and specifically to it. Synthetic DNA can also be
produced by automated chemical methods from an established sequence. This complimentary DNA (cDNA) canbe labeled with radioactivity or an enzyme and used as a"probe" for the direct detection of very small amounts ofthe genetic material of the pathogen. Synthetic DNA"primers" have recently been used to amplify a specificsequence of DNA by a new technique known a~ thepolymerase chain reaction (PCR) (Saiki et al. 1985, 1988).
This method uses two primers and repeated rounds ofpolymerization to amplify nucleic acids with very low copy
numbers to detectable limits (Guatelli et al. 1989). In
addition to screening for genetic traits, this technique has
been applied to detection of the human virus HIV-1 (Ouet al. 1988) and will soon be available for other animal
diseases and genes. While still under active development,
this technology promises to revolutionize fisheries genetics
as well as the detection of fish diseases.
A second application of recombinant DNA technology
is the development of new types of vaccines. "Subunit"
vaccines can be made by inserting the gene for an important surface antigen of a pathogen into a bacterium which
can then synthesize (express) high levels of the protein
antigen as the bacterial cells multiply. Bacterial expression
systems for production of the surface glycoprotein ofIHNV
and the major capsid protein of IPNV are under develop-_

ment at Oregon State University and workers in France
and Belgium have collaborated to produce a subunit vaccine against VHSV.
Another novel type of vaccine produced by recombinant
DNA technology is the insertion of pathogen gene sequences into a "viral vector." The ideal vector is a large
DNA virus such as vaccinia, a poxvirus originally used tovaccinate humans against smallpox. This virus can accommodate large amounts of inserted DNA and animals canbe infected with recombinant virus without producing
disease. During replication of the avirulent recombinant,the inserted gene sequences are expressed, producing
antigens which immunize the host. One problem with thisapproach for vaccination of fish is the current lack of asuitable vector. The only large DNA viruses of fish areeither relatively pathogenic (iridoviruses) or are not widelydistributed geographically (herpesviruses). If a suitable vector can be found, it is likely that this technology would be
successful in fish.

Improved Detection of
Salmonid Fish Pathogens_

Serological tests using polyclonal rabbit (or other vertebrate) antisera have been widely used for detecting fish
pathogens. One of the newer techniques, the enzyme-linked
immunosorbent assay (ELISA) has been used as a rapid
and sensitive test for A. salmonicida (Smith 1981; Austin
et al. 1986; Adams 1988), Y. ruckeri (Austin et al. 1986),
BKD (Dixon 1987; Pascho and Mulcahy 1987), IPNV
(Nicholson and Caswell 1982; Dixon and Hill 1983; Hattori et al. 1984; Rodak et al. 1988), IHNV (Dixon and
Hill 1984; Parkyn and Littlepage 1988), and VHSV (Dixon
and Hill 1984).
A rapid ELISA-type assay where antigens are spotted
onto filter paper and detected by labeled antisera (dot-blot)
was reported by Sakai et al. (1987) for BKD and by
McAllister and Schill (1986) for IHNV, VHSV, and
IPNV. While these techniques initially used polyclonal
rabbit antisera to detect the antigens, the development of
monoclonal antibody-based ELISA and dot-blot assays will
improve the precision of the tests.
Monoclonal antibodies have been used to detect IHNV
antigen in cells and tissues of infected fish by immunofluorescence (LaPatra et al. 1988), immunohistochemical
staining (Yamamoto et al. 1988), and by ELISA (Parkyn
and Littlepage 1988; Arakawa, unpublished results) while
Lorenzen et al. (1988) reported MAbs against VHSV wereeffective in detecting the virus by ELISA and immunofluorescence. Austin et al. (1986) used MAbs against
Y. ruckeri and A. salmonicida to improve a novel" dipstickELISA."
Although fish have a less sophisticated immunologicalsystem than higher vertebrates, it is possible to detect

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Fox et al.: Detection and Control of Diseases in Salmonid Aquaculture

recent and past infection of fish based upon the presenceof circulating antibodies. In addition to the traditional
serum neutralization tests for viruses and agglutination or
precipitation tests for particulate or soluble antigens,
ELISA technology has been developed for detecting antibody in either vaccinated fish or fish recovering from infection (Bortz et al. 1984; Cossarini-Dunier 1985; Kodama
et al. 1985; Hamilton et al. 1987; Thuvander et al. 1987).
While caution should be used in the interpretation of
ELISA data (Thorburn and Jansson 1988), this tool willfind increasing use as a method for evaluating the immune
state and past exposures of fish to pathogens.
Complimentary DNA probes for fish pathogens are now
being evaluated as diagnostic reagents. Workers in thelaboratory of Dr. Leong at Oregon State University havecloned the genes of IHNV (Kurath et al. 1985) and sequenced the gene coding for the glycoprotein (Koerner etal. 1987) and the nucleoprotein (Gilmore and Leong 1988).
Recently, our laboratory has begun using a synthetic
cDNA probe made from a portion of the published sequence of the IHNV nucleocapsid gene. We are testing
this probe on IHNV infected cells and tissues to determine
if the probe will allow the detection of very low levels ofviral genomic or messenger RNA.

Vaccines Against
Salmonid Fish Diseases_

Currently, the only commercially licensed vaccines for use
in salmonid aquaculture are preparations made from killedbacterial cultures (bacterins) of V. anguillarum, V. ordalii,
V. salmonicida, Y. ruckeri, and A. salmonicida. These vaccines
are generally effective, safe, and can be delivered by waterborne exposure.
Both killed and live-modified (attenuated) viral vaccines
have been tested for protection of salmonid fish (Ellis 1988).
While killed viral vaccines are safe and relatively effective,
the high levels of antigen required and the apparent needto deliver the vaccines by injection make them expensive
and somewhat impractical for use. Genetic engineering
techniques have been used in an attempt to reduce someof these disadvantages by producing large amounts of pure
antigen at lower cost.
Subunit vaccines consist of only the portion of a pathogen (usually a single protein antigen) that will stimulate
protective immunity. While they can be prepared byextraction from large amounts of infectious material, themost efficient method involves cloning the gene for the
major antigen into a rapidly growing bacterium (e. g.,
E. coli) and immunizing animals with a lysate of killedcells. These preparations are regarded as having a highlevel of safety. Because these bacterial expression systems
are quite efficient, the cost of producing the antigen isrelatively low.

167

One problem with subunit vaccines produced by cloned
inserts in E. coli has been the inability of bacteria (procaryotes) to fold and process certain types of antigens in
a completely normal way, making the synthesized protein
unlike the native structure. Techniques to avoid this shortcoming involve the use of very short peptide vaccines that
do not have to be folded and eucaryotic expression systems(yeasts, insects, and cell cultures) that can produce authentic antigens.
The development of recombinant virus vectors is anotherway to safely express high levels of authentic antigens. A
large virus (e.g., vaccinia) can accomodate several gene
inserts making polyvalent vaccines possible. This methodof vaccination has the additional advantage of stimulatingother forms of immunity (interferon, etc.) as the vector
replicates. However, until the discovery of a suitable vector for the vaccination of fish, this method of protecting
salmonid fish will remain theoretical.
Subunit vaccines for protection of fish against IHNV,
VHSV, and IPNV are under development. The subunit
preparation composed of a cloned insert of the transmembrane portion of the IHNV(glycoprotein has been reported
to confer protection to fish (Gilmore et al. 1988). A subunit
vaccine against IPNV is under development (Leong et al.
1988). While some time and further experimental work will
be required before these vaccines are fully tested and madeoptimal for protecting fish by waterborne delivery, it appears that subunit vaccines offer the best combination ofsafety and low cost.
Attenuated viral vaccines can be delivered by simple
exposure and the weakened pathogen can be allowed toreplicate in the animal, conferring an immunity that isoften superior to that provided by killed vaccines. Because
attenuated strains have the potential to revert to a virulent
type or replicate in unwanted ways, the testing required
for this type of preparation is usually extensive and theinitial cost high.
Historically, attenuated viral vaccines were developed byserial passage of wild-type virus in cell cultures until thestrain showed significant reduction in virulence. This required expensive testing. An attenuated IHNV strain wastested with encouraging results (Fryer et al. 1976), andde Kinkelin et al. (1980) described a thermoresistant variant of VHSV that could be used to protect rainbow trout.
Recently, an attenuated strain ofIHNV was developed by
growing a wild-type virus in the presence of monoclonal
antibodies against the virus, causing the selection of mutants with altered growth properties. Some of these mutants
were also reduced in virulence and were able to protect
rainbow trout against IHNV infection (Roberti 1988).

Future Developments_

The techniques of molecular biology will continue to be

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NOAA Technical Report NMFS 102: Marine Ranching

applied toward the solution of problems in salmonid aquaculture, resulting in greater production of healthy animals.
One area in which significant interest has developed is theinsertion of novel genes (or multiple copies of existing
genes) into salmon and trout. While initial studies havefocused upon the gene for the growth hormone, someworkers have begun a search for the genes responsible forcertain aspects of the fish immune system and the basis
for the resistance of some species or stocks to specificdiseases. These genes would be attractive candidates forcreation of transgenic fish having improved survival in thepresence of enzootic pathogens. Another possibility is theinsertion of the genes for a more sophisticated immune
system, perhaps from humans. While seemingly futuristic,
the tools to perform these genetic manipulations are in hand
(Mosier et al. 1988).
In addition to a key role in the development of subunit
vaccines, molecular techniques are providing details of thenucleotide sequence responsible for key receptor sites on
the surface of cells or pathogens. These are believed to serve
as recognition and attachment points for complimentarysites on some viruses and bacteria. The engineering ofspecific molecules to block these sites is being explored asa control method for acquired immune deficiency syndrome in humans. This technology may one day be applied to fish as well.

Citations_

Adams, A.
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Arakawa, C.K.,J.E. Sanders, andJ.L. Fryer.
1987. Production of monoclonal antibodies against Renibacterium
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Austin, B., I. Bishop, C. Gray, B. Watt, andJ. Dawes.
1986. Monoclonal-based enzyme-linked immunosorbent assay forthe rapid diagnosis of clinical cases of enteric redmouth and furun·
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D.P. Anderson.
1984. The immune response in immunized and naturally infected
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Caswell-Reno, P., V. Lipipun, P. Reno, and B. Nicholson.
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Ellis, A.E. (ed.).
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Hamilton, A.J., M.J.M. Fallon, J. Alexander, and E.J. Canning.
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Physical Considerations for the Designof Algal Drift Traps
SHIGERU KAWAMATA
National Research Institute of Fisheries Engineering
Ebidai, Hasaki, Kashima
Ibaraki 3I4-01:, Japan

ABSTRACT
Commercially important algal herbivores, such as abalones and sea urchins, feed mainly on
detached pieces of macrophytic algae called algal drifts, and rarely on the attached forms. Articial structures built to trap these drifts have been incorporated in projects seeking to develop
abalone and sea urchin propagation grounds in Japan. Only recently, however, have scientificstudies on the trap design been conducted. This paper is one of the first contributions with thisapproach. Two hydraulic characteristics of algae were investigated. First, specific gravity wasobserved to vary by season, age, and species. The rough ranges of specific gravities in seawaterof Laminaria spp. and Eisenia bicyclis were 1/40"-' 1120 and 1/25"-' 1110, respectively. Second, it was
found that the friction drag coefficient of L. religiosa fronds was increased considerably by theircorrugated shapes. The trapping effects of the block-type trap in a two-dimensional vertical steadyflow were studied with scale model experiments. It was revealed that there exists an optimum
trap height for maximizing the trapping efficiency of the block. A method is presented which
provides a rough estimate of the trapping efficiency when the block height is greater than or equal
to the optimum value.

Introduction_

Large brown algae of the order Laminariales are an important food of abalones and sea urchins, two commercially
important species of nearshore rocky areas. In these waveexposed areas most of the biomass produced by these algae
is estimated to be unavailable to the algivores for the following reasons. Abalones and sea urchins feed mainly on
detached pieces of attaching macrophytes called algal drifts,
but rarely on the attached forms (Olsen 1968; Shepherd
1973; Dayton 1985; Imai and Kodama 1986). The detached algae are so easily moved by water motion that mostof them are swept out of the habitats.
InJapan, both field researchers and planners of government-funded projects building abalone or sea urchin propagation grounds have been trying to trap algal drifts withvarious types of structures. However, the projects haverelied on intuition, and their field surveys have focusedsolely on quantifying the amount of trapped algal drifts or
examining the change of the resulting herbivore biomass.
Without giving greater attention to physical considerations,
one cannot hope to design the best possible trap.
A few scientific papers concerning the design of algal drift
traps have appeared recently; this paper deals with thedevelopment of systematic approaches to the complicatedand vague problem of how to maximize and estimate theeffects of the algal drift traps. First, the physical characteristics of detached algal fronds, a little known area, are discussed. Based on the results of experiments using artificial
and natural fronds under controlled conditions, important
physical indices were developed to estimate the motion ofalgal drifts. Second, owing to the variety of conceivablestructural configurations which are possible, the algal drift
traps have been broadly classified into two types, block andscreen. The former type is an impermeable structure
formed by close-packed concrete blocks or natural stones
and is commonly used for the construction of aquaculture
grounds. Its trapping effects in relation to a two-dimensional vertical steady flow are described in detail in the text.
A more detailed discussion of the screen type, mentioned
only briefly here, can be found in Kawamata (1987).

Hydraulic Characteristics
of Algal Drifts_

Algal drifts are flat, floppy, and ruffled fronds released fromthe substrate, with a density only slightly greater than
171

172

NOAA Technical Report NMFS 102: Marine Ranching_

Table 1

Table 2

Specific gravity of attached Lamirw.rio. collected off Taneichi,
Iwate, 1987.

Specific gravity of drifting Eisenia bicyclis collected off
Choshi, Chiba.

DateSpeciesAge(yr)

No. ofsamplesSpecific gravity(average ± SD)

Date

No. ofsamplesSpecific gravity(average ± SD)

11 Mar.
10 Jul.
11 Mar.
10 Jul.

L. religiosa
L. japonica
L. religiosa
L. religiosa

1
1
2
2

9
10
17
10

1.063 ± 0.003
1.052 ± 0.003
1.068 ± 0.007
1.076 ± 0.004-

14- Apr. 1987
21 Aug. 1987
03 Mar. 1988
12 Nov. 1988

5
49
10

1.066 ± 0.011
1.128 ± 0.038
1.080 ± 0.008
1.088 ± 0.016

seawater, which makes them fairly lightweight in seawater.
Owing to the increased surface area of their corrugatedbodies, they experience a greater drag force than a flat plateof the same dimensions. That is the reason why detachedalgae may be easily carried away, even by a slow current,
or may be raised from the sea bottom by turbulence inrough seas.
Forces governing the behavior of an algal drift are thedrag imposed by the fluid, buoyancy-reduced gravity, andthe elastic force against bending. Elasticity is one of theimportant factors to which attention should be paid when
making models of the algal drifts. For instance, a flexible
model with only a little corrugation can be gradually turned
up from its edge, even by a relatively slow current, whilea stiff one cannot. Most algal drifts may be sufficiently flexible to be considered non-elastic bodies. Thus model algal
drifts used experimentally should be made of flexible
materials which deform well in moving water.
The hydraulic characteristics of algal drifts have not been
sufficiently investigated yet. In order to improve on thislack of information, the author presents the results ofsample surveys and experimentation using natural fronds.

Specific Gravity
Tables 1 and 2 show the specific gravities of attached
Laminaria spp. and drifting Eisenia bicyclis, which werecollected near the shores of Taneichi, Iwate, and Choshi,
Chiba in different seasons. The specific gravities of thealgal fronds Sa were measured through the following
formula:Ws---W-flW'(1)

where s is the specific gravity of the seawater, W is theweight of the frond in air, fl W is the weight of the frond
in seawater, which was measured by underwater balance.
On one occasion, 10 July 1987 (Table 1), cultivatedL. japonica were collected in place of wild one-year-old
L. religiosa, which could not be found at the sampling of
Laminaria off Taneichi. In the coastal area L. rel~r:iosa isbinennial but most of the individuals disappear in a year
and L. japonica is cultivated with culture lines in the sea(K. Chiba, Iwate Prefectural Northern Sea Farming
Center, Taneichi, Kunohe, Iwate, 039-13, pers. commun.,Nov. 1989). Taxonomically, however, both species closely
resemble each other in regard to both the morphology anddistribution (Miyabe 1902). Yabu (1964) proposed to treat
L. religiosa as varieties of L. japonica. Kawashima (1989)
mentioned that L. religiosa was originally derived from biennial Laminaria such as L. japonica and turned to an annual
under severe environmental conditions such as high watertemperature or shortage of nutrients as it is distributed into
the warm current regions. He also stated that L. religiosa
could turn back to a biennial according to environmental
conditions. L. japonica is thus morphologically similar to
L. religiosa, and both species can be regarded as being
almost equal in specific gravity to each other. Specificgravities of L. japonica are close to the values of one-yearold L. religiosa early in summer; these gravities have also
been measured by Kawamata and Hagino (1987).
The density of Laminaria fronds tended to increase withaging except during the first summer after becoming sporophytes. This trend seems to be connected to mucus concentrations since most parts of the body with higher proportion of mucus had a smaller density (Kawamata and
Hagino 1987). Mucus is a photosynthetic product. Therefore the idea that mucus has a smaller density because of
its higher water content, agrees with the fact that the density of one-year-old Laminaria fronds is minimized early insummer when their rapid growth, which began in thewinter, ceases (Abe et al. 1985). The increase in frond
density with aging after this point might be due to an increase in the ratio of tissue which is greater in density andwhich stiffens the frond.
Both the density of the E. bicyclis frond and its seasonalchange were greater than the Laminaria spp. E. bicyclis isa perennial. The seasonal variation in density of E. bicyclis
probably depends on the seasonal variation in the dryweight content of the frond. According to Asakawa et al.
(1988), the dry-weight content of E. bicyclis vaired
withseason, high (30%) in summer and fall, and low (10%)
in winter.

173

Kawamata: Design of Algal Drift Traps

For the purpose of this study, the specific gravity ofseawater is about 1.025; therefore, the specific gravities inseawater of Laminaria and Eisenia fronds can be regarded
as about 1I40 rv 1l20 and about 1/25 rv 1l1O, respectively.

Table 3Laminaria rcligiosa fronds used for the friction drag test.

Dg

(2)

Blade area(em l )

InvestigatorNo.

Toda (1983)

PI
P2
P3
P4

320
122
220
380

6.74
9.27
7.40
8.41

2157
1131
1628
3196

Kawamata and
Hagino (1987)

P5
P6
P7
P8

244221
148
264

6.89
7.08
4.38
7.29

1681
1565
648
1925

Friction Drag Coefficient
The drag exerted on an algal drift depends on its changeable shape, and the incident angle and velocity of the current. The following are experimental results from Toda
(1983) and Kawamata and Hagino (1987) who measured
the friction drag exerted on the L. religiosa fronds shownin Table 3 flapping in uniform flow, whose stipes were tiedwith string to a spring balance. In these cases, the friction
drag coefficient Cf is defined by the following formula(Schlichting 1968):

Mean blade
width
(em)

Blade length(em)back sides by controlling the surrounding fluid motion.
• The screen type, which entangles drifting algae with little
variation of the flow.

where D is the total friction drag exerted on the frond as
measured by the spring balance, g the gravitational acceleration, p the density of the fluid, u the current velocity, andA the blade area. Figure 1 illustrates the friction dragcoefficients against the Reynolds number R[ = ul/v,
where I is the blade length and v kinematic viscosity of thefluid. Hino and Utahara (1977) measured the friction dragwhich acted 1- or 2-cm wide, I-m long vinyl films flapping in a uniform flow. They obtained a greater friction
drag coefficient than that of a smooth, flat plate at zeroincidence, as shown in Figure 1. However, the friction dragcoefficients of the L. religiosa fronds were even larger thanthose of the vinyl films. This indicates that the corrugatedshapes of algal drifts are also one of the important factors
governing the motion.
It should be noted that the methods of Toda and thoseused by Kawamata and Hagino were slightly different.
Toda used a frond tied with a single string that allowed
the frond to rotate around the string. Kawamata and
Hagino put a frond on a thin steel bar, which was fixedparallel to the direction of the current, by tying it loosely
at several points to the flume wall with strings in order toinhibit rotation. The friction drag coefficients obtained by
Toda were a little greater than those obtained by Kawamata and Hagino as a result of these differences inmethodology .

Two Typical Types of
Algal Drift Traps
In general, algal drift traps may be divided into the following two types:• The block type, which traps algal drifts on the front andThe block-type trap produces turbulence, including flow
separation mentioned later. Quite a few studies are available on the velocity profile and the turbulence characteristics in the vicinity of a block (Pande et al. 1980; Nakagawa
and Nezu 1987). However, the information provided bythese studies is far from sufficient for the purposes of thisstudy, because the behaviors of algal drifts are related toboth the stochastic phenomena in the turbulent flow andthe fine structure of the algal drift. In this paper, therelationship between the hydrodynamic processes andbehaviors of algal drifts are experimentally described froman engineering viewpoint.
As previously stated, the trapping effect of the screentype trap has been experimentally explored and discussed
in detail by Kawamata (1987). In a steady flow, the screen
is very effective in trapping algal drifts and the trapping
effect varies little with current velocity. In an oscillatory
flow induced by waves, however, the screen is far lesseffective, because algal drifts entangled with the screen are
dislodged by the oscillatory flow at once. Eubenthic animals are thus unlikely to capture the moving drifts.

Block-Type Traps in Two-Dimensional
Vertical Steady Flow_

In order to explain simply the important flow patterns andbehaviors of algal drifts in a two-dimensional vertical flow
let us consider a thin rectangular block held on a flat bed
in a free-surface steady flow as shown in Figure 2. The flow
around the block is characterized by two separation
bubbles. The first is found on the upstream side of theblock, where the boundary shear layer on the bottom first
separates at a point upstream of the block and then re-

174

NOAA Technical Report NMFS 102: Marine Ranching_

5r-----r-..--.--r--,-T""T""..----.------r-,.-,.-~_._....,.....,._--..._____,r___r_...__......_r_1

4
3

2

10-1

8
6

Cf

5
4

3
2

10-2
@

8

6
5
4
32

3

4 5 6

8 10 5

2

3

4 5 6

8 10 62

8

R1=ull )I
Figure 1

Friction drag coefficient Cf versus Reynolds number R,; comparison of Laminaria religiosa fronds and otherflat objects. u = current velocity, l = length of an object. v = kinematic viscosity of fluid. Each mark in
the graph represents the frond described in Table 3: • = Pl, • = P2, .4 = P3, ~ = P4,O = P5,
o = P6, t::. = P7, V = P8. @ ~ average of the friction drag coeffi.cients of vinyl films (Hino andUtahara 1977); CD = friction drag coefficient of smooth flat plate at zero incidence (Schlichting 1968), <D= regression line of the frond of P2, C = 503 R,- 0.718.
fattaches to the boundary. The downstream separation
bubble is created by the flow passing over the block which
separates on the top of the block and reattaches to thebottom. These separated flows which reattach to the boundary at a downstream point give rise to recirculation regionswith reversed flow.
When an algal drift is released on the upstream side of
the block, there are four distinguishable phases in its
behavior which are dependent on current velocity. In thefirst phase there is a state of no movement because thecurrent is too slow. In the second phase a drift is transported to and captured near the separation point aheadof the block. In the third phase it passes over the block andfalls into or is trapped by the downstream separation bubble
with a certain probability according to the flow velocity.
In this case it is moved back by the reversed flow where
it stays immediately behind the block. In the presence ofhigh flow rates there is no probability of its staying near
tbe block and thus we see the last phase. At the thresholdsof each phase, there are three characteristic velocities, the"ccitical velocity for movement," the "critical jumping
velocity," and the "critical non-stay velocity." These processes have not been quantified yet but may be schematically summarized as in Figure 3. As Postoma (1967)
mentioned, critical values in sediment transport depend
on current velocity only indirectly; the important factors
are the tractive forces acting on the bottom, such as theroughness of the bottom and turbulence. However, because
this paper does not aim at hydrodynamic calculations, it
is sufficient to use flow velocity.

Trapping Efficiency of the Block
Because algal drifts seem to be trapped most frequently

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Kawamata: Design of Algal Drift Traps

175d

Reattachment
point

Figure 2
Schematic diagram of the free surface steady flow past a submerged block. A = upstream separation bubble;
B = downstream separation bubble; d = water depth; h = block height, d = boundary layer thickness; Urn =mean bulk flow velocity in the uniform flow section; U, = Urn d/ (d - h) expresses mean bulk velocity of the flow
contracted by the block.

I

Never stay i ng
for a long time

....

>.

- - - - - - - - - - - - -- Critical non-stay velocityUoStaying on
the downstream

QJ

>

....C

......QJ:::I- - - - - - - - -- - - - Critical jumping velocity()

Obstructed on
the upstream side
- Critical velocity
for movement

Figure 3
Schematic diagram of variation of the trapping effectagainst current velocity.

on the downstream side of an obstruction in nature, theauthor has investigated the trapping effect in the third
phase in detail. Reduced scale hydraulic experiments were
performed which studied the behavior of model algal drifts.

acrylic plastic boards in the middle of the flume. A 5-mm
thick plate-shaped block of height h (2 cm to 15 cm) andwidth to span the entire channel was fixed to the bottom
in the middle of the test section. Subcritical uniform flow
conditions were set up in which the variation of the freesurface by the block was very small. The Frode numbers
Fr = Um/{id were 0.04 to 0.07 and the Reynolds numbers
R, = Umd/v were 25500 to 48800, where Um is the meanbulk velocity in the uniform flow section, and d the water
depth. Considering the hydraulic characteristics of the real

Trapping effect

Materials and Methods-Experiments approximating a
one tenth scale were conducted in a horizontal flume, 39-m
long, 40-cm wide, and either 30-cm or 40-cm deep. A test
section was set up for the release of model drifts by firstcovering the channel bed over a length of 360 cm with

176

NOAA Technical Report NMFS 102: Marine Ranching

_

Urn

0

0.8

>c:

(J

Q)

l1~Q~o;em/sec
8.5
8.5
10.5
10.5
12.2
12.2

d

em
30
40
30
40
30
40

(J

.... 0.6
Q)

C)

c:

.~

a. 0.4........
~

01

~

0

0.1

0.4

0.3

0.2

0.5

hid
Figure 4
Trappmg efficiency versus dimensionless block height (hi d).
velocity in the uniform flow section; d = water depth.

algal drifts mentioned above, the first model drifts weremade of boiled Undo.ria pinnatijirkl blades, whose dimensions
were 9 mm x 100 mm. The model drifts were released into
the flow about 180 cm upstream from the block with a toolthat made them start moving on the bottom with aminimum of turbulence. Most of the released model drifts
soon passed over the block by passing the second phase.
The model drifts passed the block stochastically, staying
for a long time in the third phase, having been trappedby the downstream separation bubble. The trapping efficiency of the block was defined as the probability that adrift of particular hydraulic characteristic, should betrapped permanently behind it. A minimum of three replicates of 15 model drifts each were released at one time.
About five minutes after they reached the block, both thenumber of the drifts passing over the block and the number staying behind it were counted for each experiment.
Fifteen models were thought to be about the maximum
number which could be liberated at one time without
becoming entangled; an observation time of five minutes
was considered sufficient for the drifts to be stabilized.
The trapping efficiency for each experimental condition
was calculated as follows:

Trapping
efficiency

Ummean bulk flow

Total number of drifts staying
behind the block(3)

Total number of drifts passing
over the block.

Results-The observed values of the trapping efficiencies
were plotted against the dimensionless block height hi din
Figure 4. The trapping efficiency increased with height
below a certain value. However, when the block heightexceeded this value the trapping efficiency decreased. Thiswas unexpected because the length of the downstream
separation bubble increases approximately in proportion
to the height (Pande et al. 1980). The variation of the trapping efficiency against the block height can be explainedby the following two effects. The first positive effect is theprotection of an algal drift which stays behind the blockfrom the turbulence. For example, the downstream separation bubble produced by a higher block in the turbulent
boundary layer prevents a larger vortex coming over theblock from carrying away algal drifts caught within it.
Therefore, the block height should be greater than a certain
value in order to protect algal drifts from being removed

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Kawamata: Design of Algal Drift Traps

downstream. On the other hand, a second negative effectof height occurs, which destroys the boundary layer andcontracts the flow. The original flow velocity at the level
closer to the bottom is slower in the boundary layer. A
higher block increases the velocity of the flow on the downstream separation bubble, which forces the fluid inside it
to recirculate. At the same time, especially in shallow water,a higher block also increases the velocity by constricting
the cross-section area of the flow. These make the shear
stress between the main stream and separation bubble
greater, and consequently the recirculation flow, which acts
on a drift behind the block forcing it to rise out of thereversed-flow region, faster.
The reattachment point is, on average, where an objectof the same density as the fluid in which it is transported
from the separation point should settle on the downstreambottom. Therefore an algal drift past the block should tend
to fall down on the bottom a little upstream of the reattachment point because of the action of its underwater
weight. The underwater weight also acts to prevent an algal
drift located closely behind the block from being raised up.
The effects of the underwater weight on the motion of thealgal drift diminishes relative to drag force when the current velocity increases. Thus, when the block is muchhigher than the boundary layer thickness, the trapping
efficiency is reduced. The interaction of the two positive177

and negative effects establish the optimum block heightvalue to trap algal drifts on the downstream side. The
optimum height might be the minimum one at which thevortices shed in the area upstream from the block do notreach the bottom immediately behind the block throughthe downstream separation bubble. The value may dependon the boundary layer thickness or the upstream turbulence, both of which this study does not examine. The
following part of this paper is limited to the range of theblock height greater than the optimum value.

Indicator of Trapping Efficiency
Figure 5 shows the conversion of Figure 4 into the relationship between the mean bulk velocity of the flow contracted by the block, U, = Umd/(d - h), and trapping
efficiency. The mean bulk velocity, U" explains the traping efficiency quite well except for the lowest height. Thissuggests that the drag force, which governs the motion of
the algal drift, should be represented in a particular situation. Here the drag exerted on an algal drift flapping ina steady flow of velocity U" denoted by D" was measured
as the representative value of the drag. The relative magnitude of D, and the weight of the drift in water, l1 W, would
indicate the trapping efficiency. This supposition was
experimentally verified.

\

CD

~\

0.8

e

\

\

>.

\

0

\

c:

\

CU

0

CD
\

0

0.6

0

CU

C)

c:

o \\
(]

. ••

\tEe
CD

...C'O

h(cm)

0.2

()

()\ ()

a. 0.4
a.

~

~\

0 2.0
CD 3.5e 5.0() 10.0
15,0

•

\

\

'\

\

()

<9

",

()',

'-e.....

"°0~------;5:-------;1~0----1~5----2LO---.....J25

Uc(Cm/SeC)

Figure 5
Relationship between trapping efficiency andU, (mean bulk velocity of the flow contracted
by the block) obtained by the rearrangement of
Figure 4.

178

NOAA Technical Report NMFS 102: Marine Ranching_

Table 4
Scale models of algal drifts and associated hydraulic conditions.
Hydraulic conditions'
Dimension(mm)Material of scale model

I1W'(dyne)

Dragb(dyne)

Um(em/sec)

d
(em)

(em)

M1

9 x 100

Boiled blade of Undan·a pinnatifida

6.4

30

5

10 x 100

Nylon textile

1.6

1.21 u l.36
0.83 u 1.66

12.2

M2

12.2

30

5

M3

10 x 100

Nylon textile

2.7

0.83 u 1.66

12.2

30

5

M4

10 x 100

Nylong textile

5.5

0.83 u 1.66

12.2

30

5

M5

10 x 100Polyester textile

3.7

0.83 u 1.66

12.2

30

5

M6

10 x 100Polyester textile

5.6

0.83 u 1.66

12.2

30

5

M7

10 x 100Polyester textile

8.2

0.83 u 1.66

12.2

30

5

M8

10 x 100

Celophane film

8.8

12.2

30

5

M9

20 x 200

Boiled blade of Undaria pinnatifida

28.7

2.85 u 1.38
18.8 uO. 9 ,

17.7

60

10

MlO

18 x 200

Cellulose acetate film

38.2

21.8u1.08

17.7

60

10

No.

'I1W = weight of drift in water.
bcurrent velocity (em/sec).
u'Um = mean bulk velocity over the block; d = water depth; hMaterials and Methods-Ten sorts of model drifts weremade using U. pinnatijida blades and man-made materials
including nylon, polyester, cellophane, and cellulose
acetate. Releasing experiments were conducted as previously described. Table 4 indicates the physical propertiesof the models (M 1-M 10) and hydraulic conditions underwhich the drag values were determined. Models M8 andM 10 were adequately ruffled by hand because their original
bodies were so flat that they often remained glued to thebottom.
Results-Figure 6 shows experimental results. Most of theplotted values approximated the broken line (estimated byhand) with the exception of models M1 and M9 which wereboth made of boiled U. pinnatijida blades. These models
had lower trapping efficiencies, probably because the viscosity resistances acting on their smooth peripheries to raisethem up from the bottom were greater than on the othermodels with rough textures.
I t was indicated, however, that the ratio Dc / Ii. W might
be used to get a rough estimate of the trapping efficiency
in actual fields.

Discussion_

Information is still insufficient to indicate fully the proper
practical design for this type of algal drift trap. However,
it is easy to estimate the effects of the algal drift trap withexisting information. Presented below are some useful suggestions for designing a block-type trap long enough to behblock height.

governed by the principles involved in a two-dimensionalvertical flow.
• The "optimum value" is probably the best height unlessthe trap is permeable. Algal drifts are likely to be trappedon the upstream side of a high trap with a high efficiency, but in practice, algal drifts transported toward thetrap stop a certain distance upstream of it, where they
are easily moved sideways even by slow transverse currents. Therefore the trap h.;:ight should be the minimum
value for the retention of the algal drifts behind the trap,that is, the optimum value, so as to make them jumpover the trap and be caught behind it easily. Moreover,
special attention should be paid to the fact that the
optimal height of a permeable trap such as the typedeveloped by Kawamata (1988) is greater than that of
an impermeable one.
• The trap should be set up in as uniform a flow as possible: In turbulent flows, oncoming vortices over thebottom may raise algal drifts behind the trap. In waveinduced oscillatory flows, vortices are alternately generated on both sides of the trap without the creation ofrecirculation regions; therefore, algal drifts are unlikely
to stay around the trap. This also indicates that the trap
should be placed on as flat a bottom as possible and that
other structures ought not be located either parallel toor near it. This is because artificial obstacles, as well as
rugged sea bottom, break the benthic boundary layer
and induces vortices.
(jonsidering these actors, traps are probably less effective in shallow water near the shore because stronger

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Kawamata: Design of Algal Drift Traps

179

I
I
I

0.8

>()

(J{,
,
I

C

I

\@
,

Q)

()

,

0.6

~,

G)

Q)

\

\

C)

C 0.4

~

Q.
Q.

@ \\

CU

@

~

I-

.,
@,,

0.2

,,

,,

'@'t ,,,,..............

Figure 6

"

0
0

10

20

30

40

"'"

\&

Dc/aW

wave action and rugged bottoms made by erosion do not
produce uniform fluid conditions. On the contrary, indeeper water the oscillatory flow induced by waves weakens
and near-steady flows, such as tidal and ocean currents,
prevail. In addition, the seabed in these regions is generally flatter owing to sedimentation of sand and absence ofscouring. Thus, from the physical viewpoint, traps will
have a greater effect in deeper water than in shallower
zones.
Moreover, distribution of algal vegetation is in generaldifferent from that of the algivores. Macrophytic algae
dominate on hard substrates close to shore and are lessabundant in deeper water, while algal herbivores, especially sea urchins, tend to live in deeper water away fromthe zone of dense macrophyte forest (Dayton 1985; Kawamata and Hagino 1986). Such an ecological phenomenon
also supports the proposal that traps should be set up in
deep, barren grounds to supply hungry herbivores withalgal drifts.
In conclusion, the trapping efficiency of the block-type
trap is probably estimated by the current velocity and thefriction drag coefficients of algal drifts, as described in
Figure 1, and also by the relationship between the trapping efficiency and DJ f!,. W shown in Figure 6.

Citations_Abe, E., M. Kakiuchi, K. Matsuyama, and T. Kaneko.
1985. Seasonal variations in growth of the blade in Laminaria religiosa
Miyabe of Oshoro Bay. Hokkaido. Sci. Rep. Hokkaido Fish.

50

Relation between the trapping efficiency and Dc / AW. Dc =drag exerted on an algal drift flapping in a steady flow of
velocity U c ; !:J. W = weight of an algal drift in water;
numbers in 0 = nos. of the models described in Table 4.

Exp. Stn. 27:101-110. (In Japanese.)
Asakawa, A., K. Ohwada, and N. Tanaka.
1988. The seasonal variation in chemical composition of Eisenia
bicyclis and Ecklonia cava, collected from the coast of Shima Peninsula. Bull. Natl. Res. Inst. Aquaculture 13:33-44-.
Dayton, P.K.
1985. The structure and regulation of some South American kelp
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Hino, M., and H. Utahara.
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Kawamata, S.
1987. Drift algal traps to feed benthic algal feeders. Fish. Eng.
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1987. Experimental investigation on turbulent structure of back-

180

NOAA Technical Report NMFS 102: Marine Ranchingward-facing step flow in an open channel. J. Hydraulic Res.
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Olsen, D.A.
1968. Banding patterns in Haliotis. I: Some b.:havioural considerations and the effect of diet on shell coloration for Haliotis ruft;cens,
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Postoma, H.
1967. Sediment transport and sedimentation in the estuarine environment. In Estuaries (G.H. Lauff, ed.), p. 158-179. Am.

_

Assoc. Advancement Sci., Washington, D.C.
Schlichting, H.
1968. Boundary-layer theory, 6th ed. McGraw-Hill, New York,
747 p.
Shepherd, S.A.
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