10NOAA Technical Report NMFS 10

Proceedings of the Seventh
U.S.-Japan Meeting on
Aquaculture, Marine Finfish
Culture, Tokyo, Japan,
October 3-4, 1978
Carl J. Sindermann (Editor)

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

Panel Chairmen:
SHIGEKATSU SATO - JapanWILLIAM N. SHAW - United States
August 1984

u.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Marine Fisheries Service

NOAA TECHNICAL REPORTS NMFS
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fishery agreements and policies. NMFS also assists the fishing industry through marketing service and economic analysis
programs, and mortgage insurance and vessel construction subsidies. It collects, analyzes, and publishes statistics on various
phases of the industry.
The NOAA Technical Report NMFS series was established in 1983 to replace two subcategories of the Technical
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Scientific investigations that document long-term continuing programs of NMFS, intensive scientific reports on studies ofrestricted scope, papers on applied fishery problems, technical reports of general interest intended to aid conservation andmanagement, reports that review in considerable detail and at a high technical level certain broad areas of research, and.
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NOAA Tech nical Report NMFS 10

Proceedings of the Seventh
U.S.-Japan Meeting on
Aquaculture, Marine Finfish
Culture, Tokyo, Japan,
October 3-4, 1978
Carl J. Sindermann (Editor)

Under the U.S.-Japan Cooperative Programin Natural Resources (UJNR)
August 1984

u.s. DEPARTMENT OF COMMERCE
Malcolm Baldrige, Secretary

National Oceanic and Atmospheric Administration
John V. Byrne, Administrator

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

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

Shigekatsu Sato - Japan
William N. Shaw - United Statesii

CONTENTS
Papers presented by Japanese panel members:
FUKUHARA, O. Development of biological characters in early stages of seed production of commercially important marine
fishes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MATSUSATO. T. Present status and future potential of yellowtail culture in Japan .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
OKAMOTO, R. Present status of red sea bream in Japan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
TANIGUCHI. M. Practical problems in finfish culture in Kochi Prefecture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3
11
17
21

Papers presented by U.S. panel members:
ARNOLD. C. R. Maturation and spawning of marine finfish
STEVENS, B. Striped bass culture in the United States. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

25
29

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

iii

Joint Statement of the UJNR
Aquaculture Panel
October 3-4, 1978, Tokyo, JapanThe seventh session of the UJNR Aquaculture Panel convened in Tokyo, Japan, October 3-4,
1978. The subject of the session was marine finfish culture, excluding ocean ranching.
Mr. Haruhiko Horikawa, Director General, Secretariate, Agriculture, Forestry and FisheryResearch Council, and Mr. Toshio Sugawara, chief, International Development Division, Scienceand Technology Agency, presented welcoming addresses and opening remarks.
Panel members and observers were introduced by respective chairman. Seven technical papers
on finfish culture were presented by members of both panels. Presentation of technical papers wasfollowed by discussion periods.
During the business session the scientist exchange program was reviewed and suggestions for
future exchanges were presented. It was concluded that scientists from Japan, including Mr. T. Matsusato, would be sent to the United States to study fish pathology in 1979.
The U.S. panel presented five proposals:I) That Japanese scientists contribute to and utilize the National Registry of Marine Pathology.
2) That the UJNR Aquaculture Panel support ICES in developing the Index of Marine Aquaculture
Diseases.
3) That the UJNR Aquaculture Panel support a review on the effects of pollution on marine andfreshwater aquaculture.
4) That Japanese scientists participate in the National Aquaculture Information System at theVirginia Institute of Marine Science.
5) That Japanese scientists participate with the University of California in a joint study on abaloneseeding.
The Japanese Panel responded positively to items 2,4, and 5. Proposals I and 3 will be given further consideration and correspondence will be exchanged on all five proposals.
A report on the ongoing cooperative study related to summer oyster mortality and the development of disease resistant oyster seed was presented by the Japanese Panel. The Japanese Panel also
recommended that a joint study on oyster breeding be developed.
The U.S. Chairman discussed plans for the 1979 UJNR meeting on freshwater finfish culture.
Field trips are planned including visits to catfish and bait fish farms and processing plants in thesouth, and salmon and trout farms and fish hatcheries in the northwest. Seattle, Washington, wassuggested as the meeting site. A tentative travel schedule was presented. Ideally, the date of the next
meeting will be in the autumn of 1979.
Respectfully submitted
Shigekatsu Sato - Japan
William N. Shaw - United States

Development of Biological Characters in Early Stagesof Seed Production ofCommercially Important Marine Fishes
OSAMU FUKUHARAI

INT,RODUCTION
In recent years, substantial progress in aquaculture technology
has allowed the mass production of useful marine fishes.
Presumably these efforts were undertaken since natural seedresources for farming were limited and the fishery of some
economically important species had markedly decreased. Total
production of marine fish fry reaches over 5 million seedlings
annually, much of which is attributable to red sea bream, Pagrus
major, (Fig. 1) as described by the Japan Fisheries Resource Conservation Association (1977) and Yamaguchi (1978). Aquaculturists have successfully reared larvae and fry from naturally spawned eggs to maturity, mostly for stocking net cages but also for the
release program by prefectural and national hatcheries in order torecruit natural stocks within the Seto Inland Sea. Similar programs have been carried out for other species such as porgy,parrotfish, and Kuruma prawn. Much experimental work has beenaccomplished to identify optimum conditions for survival in both
artificial and natural habitats. These investigations contribute to
our knowledge of survival and yield of liberated animals.
In order to ascertain optimum environmental rearing conditions
and habitat structures as well as optimum seed size for release, it isuseful to study the development of morphological characteristics
of fry in relation to their behavioral development in given environments. The development of biological characteristics in bothreared and wild fish is not well known.
This paper describes briefly the morphological development of
the red sea bream, Pagrus major, porgy, Acanthpagrus schlegelii,
and parrotfish, Oplegnathusfasciatus, on which artificial propagation and releasing programs have been performed extensively inJapan. The significance of differentiation during the life cycle ofthese fishes is stressed. Furthermore, the adaptability of seedlings
to changing environmental conditions during cultivation is
discussed for various developmental stages with special reference
to the optimum stage for releasing and intensive farming.
Discussion and conclusions are based on morphological observations of external organs, i.e., fins, scales, and transverse stripes,
from fishes reared under laboratory conditions.

Figure 1.-SeedUngs of red sea bream, PGgrus mqjor, reared from eggs andraised In net cages.

during the entire rearing period, as well as during and just prior to
the spawning period. The main steps in the operational procedures
for mass propagation are outlined diagrammatically in Figure 2.
The life cycles of most fishes used for aquaculture are controlled
artificially; this is also the case with the red sea bream, porgy, andparrotfish. Control of the whole life cycle, breeding the fish fromegg to maturity, allows a continuous high production of seeds forany of these species. Therefore, techniques for complete control ofthe life cycle should be increasingly adopted for the mass propagation of useful marine organisms. The main procedures of larvalrearing of the three most important species, red sea bream, porgy,
and parrotfish, are outlined below.

REASONS FOR THE DEVELOPMENT OFMASS PRODUCTION PROCEDURES
Environmental rearing conditions significantly affect somebiological characters of artifically produced juveniles. It istherefore desirable to control important environmental factors

I Nansei Regional Fisheries Research Laboratory. Ohno-cho, Saeki-gun, Hiroshima Prefecture, Japan 739-04.

3

ISPAWNER~U-_u~U_-_~UU~_~U_UUU __ UU..j NATURAL STOCKSEEDCOLLECTION//"RELEASING

k•••••••'.
HARVEST

L

SEED PRODUCTION - - - -- - - - - - - - ARTIFICIAL PROPAGATION -------.-~

Figure 2.-0utUne of operational procedures for artificial mass propagation ofmarine fisb. Upper units sbown in broken Unes are probably found In natural
grounds and tbose sbown In soUd Unes sbow tbe sequence of artificial propagation. WUd nsb are sometimes captured as seed IIsb for net-cage culture, andraised fisb are aiso released to recruit tbe natural resources. Spawners can beobtained among tbe raised IIsb.

Figure 4.-Tbe smaUest plastic containers used for larval rearing. Tbey are
usuaUy InslaUed Indoors or under cover.

Egg Collection
Parental fish are kept in tanks on land for natural spawning.
Spawners are taken from fish raised from egg to maturity, or they
are captured as adults from wild stock. In either case, adultspawners 3-6 yr old are usually maintained at a density of 1-3
fish/m 3 in net cages of about 70-100 m3 capacity or in settlingtanks of 10-100 m3 volume until the spawning season approaches(Fig. 3). A higher percentage of fertilization and viable hatchedlarvae occur in natural spawning, when compared with artificial
fertilization techniques. Therefore, natural spawning is preferred.
In general, it is possible to obtain more than 90% fertilization and
2 to 5 million viable eggs from one female during the spawningseason when using natural spawning techniques.

stage, about 20-35 d after hatching depending on ambient watertemperature.
Larvae are initially fed marine rotifers, Brachionus plicatilis,(Fig. 5) cultured artificially with phytoplankton in the tank. In
general, the density of rotifers in the rearing tank is maintained at
a level of more than 5 individuals/m!. Trochophores of theJapanese oyster, Crassostrea gigas, are used as food organisms for
initial feeding in small-scale culture, but are not utilized forfeeding larvae in large-scale culture due to the difficulty of securing and preparing large numbers. Copepods (Tigriopus japonicus)(Fig. 5) are then introduced into the rearing tanks as the fish approach the juvenile stage and their initial feeding period overlaps
partly with that of marine rotifers. Artemia nauplii are occasionally supplemented to the T. japonicus diet. Minced and/or chopped
meat of fish, shellfish, and artificial combined diets are given justprior to and after the transitional phase. An experiment on synthetic diets has been carried out recently that would allow pellet
feeding at very early stages. It is hoped that there will soon besome progress in this field.
High mortality during rearing trials is occasionally encounteredat the transitional phase from larva to juvenile. Low mortality,

Figure 3.-Spawned elllls are coUected In a fine-mesbed net tbrougb tbe outlet of
tbe concrete tank containing parent fisb.

Larval Rearing
Newly hatched larvae are usually maintained in 1-100 m 3
capacity rearing tanks (Figs. 4, 7) at a density of about 5-50
larvae/!. Water in the tank is exchanged as needed during the initial 2 to 3 wk and exchange rates gradually increase. "Flowthrough" systems are employed after the transitional or juvenile

Figure 5.-Marlne rotlfer, BrachiollllS ptica/ilis (left) and copepod, TigrioplIs
j/JpolliclIS (rlgbt) cultured under laboratory conditions.

4ammonium sulfate/m 3 , 50 g calcium superphosphate/m 3 , and 109
urea/m 3 • Inocula of single-celled algae (Chiorella), called green
water, are then introduced into the tank and cultured to a concentration of about 20-30 million cells/mI. This is used to feedmarine rotifers (Brachionus plicatilis) and copepods (Tigriopus).
Recently, bread yeast has been employed as a supplementary
foodstuff for zooplankton culture, due to the long period needed
for blooming of Chiorella and the huge number of rotifers needed
in large-scale fish propagation.
The density of marine rotifers cultured with green water is commonly only 50-70 individuals/ml; for rotifers cultured with bread
yeast, it is common to obtain a density of 500 individuals/mI. The
culture of marine rotifers with bread yeast, however, creates somenutritional problems involving fatty acids, causing high mortalities and skeletal deformities in the reared fishes (Kitajima et aI.
1977; Fukuhara 1977a).
After several trials to avoid the ill effects of yeast feeding, it
became clear that using a mixture of yeast and cultured Chiorella
decreased the influence of yeast feeding mentioned above.
Therefore, combined feeding of both yeast and algae is employed
to culture food organisms at high densities. This seems to produce
rotifers of high nutritional quality. Culture techniques of the
copepod Tigriopus japonicus are not as efficient as those of themarine rotifer. Densities between about 1,000 and 2,000 individualslI are obtained at practical levels.

however, is observed generally after metamorphosis. Therefore,
reliable estimates of survival potential are possible beyond thisstage. Survival can be > 50% or < 5% of the initial stock. One of
the most important factors in continuous aquaculture operations is
to obtain stable survival rates.
Metamorphosed fish are usually transferred from indoor rearing
tanks to rearing facilities such as floating net cages or large outdoor tanks (Figs. 6,7). When net cages are used, an electric bulb isoften installed at night above each of them to attract plankton
which enter the net cage through the mesh. This procedure is continued for a few days after transfer of the fish from the tanks to thecages. Fish are transferred with a siphon and/or container. Densities of 1,000 to 3,000 fish/m 3 are used to rear fish up to 10-20mm SL; thereafter, stocking density in floating net cages is reduced as the fish grows.

Plankton Culture
Large tanks are generally used in culturing phytoplankton andzooplankton (Fig. 7). First, agricultural fertilizers are added to thesettling tank of cultured phytoplankton at the rate of about 100 g

DEVELOPMENT OF EXTERNAL ORGANS
Optimum utilization of the designated species at each developmental stage may be based on observations of morphologicalfeatures which affect behavior and habitat, not only in the wild
but also under rearing conditions.

Fin Development
The fin is a functionally important and prImitive organ intimately related to locomotion. In most species, fins are formed at
an early stage in the life history. Figure 8 illustrates contourchanges of fins in reared red sea bream and parrotfish from newly
hatched larvae to juvenile stages (Fukuhara 1976a; Fukuhara andIto 1978). Fin development of porgy is comparable with that ofred sea bream (Fukuhara 1977b). Larvae at this stage swim in theupper layer of the rearing tanks by undulating body movements
until Stage D. Postlarvae with a continuous fin fold are subject towater movement from aeration in the rearing tank. Striking
behavioral changes, however, are observed after the Stage E
juvenile. Most of the surviving red sea bream and porgy swim in
the lower layer of the rearing tank. Cannibalism, as well as territorial and aggressive behavior patterns, is observed. Those patterns are more pronounced for red sea bream fry than for parrotfish. At this juvenile stage, living food organisms such as marine
rotifers and copepods are replaced by ground food such as minced
and/or chopped meat of mussels and fishes.
During ray development in paired and unpaired fins, segmentation of each fin commences at the size range of 6-8 mm SL and iscompleted at about 10 mm SL except for the pectoral fin which iscompleted at about 18 mm SL in red sea bream and parrotfish,
and at 15 mm SL in porgy. After the completion of ray segmentation, branching begins. Branching in the three species is complete
at about 30 mm SL. Segmentation and branching are significant
characters in ascertaining the functional development of the fins.
Functional changes of the fins are induced by the progress of

Figure 6.-Floating net cage, 5 lC 5 lC 4 m used for rearing of ftsh after metamorphosis. Mesh size of net is changed according to ftsh growth.

Figure 7.-Outdoor tanks utlUzed for phytoplankton cultures; sometimes they
are also employed for raising Juveniles.

5Figure 8...-Semldlllllramm.tlc dr.wlng of no development of red sea bream(left) and parrotlbb (rlgbt). Scales denote 1.0 mm.

segmentation and branching, which largely influence the development of larval behavior.
Metamorphosed fish with completely segmented fin rays are
hardy during transportation from rearing tanks to succeeding rearing facilities such as outdoor tanks or floating net cages. Juveniles
of about 30 mm SL, with branched fin rays, display new behaviors
which more closely approximate those of the adults.
Morphological development of paired fins is similar to that of
unpaired fins.

sea bream (Fukuhara 1976b) and porgy, and about 2 wk forparrotfish (Fig. 10). The scales increase in length as the fish grow,while the outline of the scales changes from the placoid to ctenoid
type. The size of the fish at which the scale assumes ctenoid form
is 30 mm SL for red sea bream and porgy and 50 mm SL forparrotfish. Structural features of the scales - ctenii, ridges, andgrooves - increase in number as the fish grow.

Scale Development

Transverse stripes of red sea bream and porgy are not clearly
distinguishable in the adult form, but are quite clear in adultparrotfish. Band formation in each species occurs during the earlystages of its life history. The black stripes are thou~ . to be involved in concealment, communication, and advertisement. Formation of black stripes of each species shown in Figure II begins
before and continues after the transitional phase when thejuveniles attain about 8.0-10.0 mm in standard length (Fig. 12).
Transverse stripe formation is complete in about 2 wk for red
sea bream (Fukuhara 1978) and parrotfish (Fukusho 1975), andabout 3 wk for porgy, appearing at the anterior portion near thehead for parrotfish and porgy, and the posterior portion for red sea
bream (Fig. 11).
Functionally, completion of the formation of transverse stripes
in the juveniles may be adaptive for concealment after the transi-

Formation of Black Stripes

The functional role of scales is generally considered to be protection of the body surface from external stimuli or variations inenvironmental conditions. Scales of the fish treated in this paper
are of the ctenoid type. Based upon their functional role only,
development of scales reflects the increased ability of the fish toendure and adapt to various stimuli encountered in changing environmental conditions, such as water temperature, salinity, andwater current.
Formation of the scales is shown in Figure 9. In the three
species considered, squamation occurs at the transitional phasefrom postlarva to juvenile (i.e., 7 mm SL for red sea bream, 10mm SL for porgy, and 12 mm SL for parrotfish) and forms quickly, taking about 1 wk from initial formation to completion for red

6

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A

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Figure '.-Dlagrammatic illustration of squamatlon In the three species, red sea
bream (upper left), porgy (right), and parrotftsh (lower left). Scales denote
1.0 mm.

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MORPHOLOGICAL DEVELOPMENT AND
RELATION TO BEHAVIOR~.

.~ ...~ _ . .

A similar sequence in the development of morphological andbehavioral changes is observed in all three species. In Figure I>,
the sequence of development of morphological characters in red
sea bream is illustrated, along with various behavioral changes of
the red sea bream observed in the rearing tank.
Formation of the observed organs begins before and is com·pleted after the transitional phase from postlarva to juvenile. At
the same time, feeding habits change from a diet of live foodorganisms, such as rotifers and copepods, to a diet of dead foodconsisting of minced meat of mussels and fishes. Behaviorally,
fish which have swum in the upper layer of the rearing tank moveto the middle and/or lower layers; this new mode occurs
simultaneously among the fish.
In conclusion, it is assumed that during the transitional period
in morphological development and behavioral characteristics,
namely between about 8 and 10 mm SL, the fry are very sensitive
to variations in environmental conditions. At 30 mm SL, forma·tion of such external morphological features as fins, scales, and.L£!!fII'. . "
.

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16

18

STANDARD LENGTH

Figure to.-Relation between developmentalstqe of squamation aDd studanl
length for (left to rlght) red sea bream, porgy, aDd parrotftsh. Refer to FIpre'
for Illustratiou of tbe developmentalstqe for each species.

tion from the pelagic environment in which they have been living
to a new habitat where rocks and vertical seaweeds are added.
7

A

A

E

B

F

H

Figure n.-Band formation of red sea bream (left) and porgy (right).
Sc:aIes denote 1.0 mm.

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,

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transverse stripes, are mostly completed and these features arenearly equivalent to those of the adults. Therefore, it is consideredreasonable in terms of the functional development of organs andadaptability of fish to environmental conditions, that a size of 30
mm SL is suitable as the minimum seedling size for farming andreleasing.
To obtain high survival rates of liberated animals, it is probably
effective to use artificial reefs as protective areas from predation,
incidental catching, and starvation during the critical phase immediately after release, It is also desirable to reduce the increasing
overfishing of natural stocks, especially on young stages, and toobtain seed fish for net-cage culture by means of artificial rearing
from eggs rather than by catching young wild fish, Gradually, fish
farmers have realized the implications of these theories and now
few farmers produce seeds for pen culture by themselves,

,

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C: "

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10

Figure 12.-Development of black stripes plotted against standard length forred sea bream (left) and porgy (right). Refer to FlllUre n for the developmental
stage.

Standard length(mm)Morphologicaldevelopment

.'".
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Ftaure 13.-Sequence of development and differentiation for various organs and hehavlor patterns In red sea breamreared under laboratory conditions.

8

ACKNOWLEDGMENTS

1978. Morphological studies of larva of red sea bream - III. Formation of
black stripes. Bull. Nansei Reg. Fish. Res. Lab. 11:1-8.
FUKUHARA, 0., and K. ITO.
1978. On the formation of the fins and squamation in the Japanese parrot
fish, Oplegna/hus fascia/us reared in the laboratory. Bull. Nansei Reg. Fish.
Res. Lab. 11:9-17.
FUKUSHO, K.
1975. Development of color pattern in Oplegna/hus fascia/us, useful indicator
in rearing. [In Jpn., Eng!. summ.] Jpn. J. Ichthyo!. 22:23-30.

I am deeply grateful to M. Fujiya for his advice and criticalreading of the manuscript. I also thank H. Rosenthal and K.
Sokolski for their useful comments on the manuscript.

LITERATURE CITED

JAPANESE FISHERIES RESOURCE CONSERVATION ASSOCIATION.
1977 . Present status and problems on seed production techniques for red sea
bream. lIn Jpn.) 179 p.

FUKUHARA, O.
1976a. Morphological studies of larva of red sea bream - I. Formation of
fins. lIn Jpn., Eng!. summ.] Bull. Nansei Reg. Fish. Res. Lab. 9:1-11.
1976b. Morphological studies of larva and red sea bream - II. Early development of squamation. Bull. Nansei Reg. Fish. Res. Lab. 9:13-18.
1977a. On the skeletal abnormalities of reared red sea bream. [In Jpn., Eng!.
summ.] The Aquiculture 25(2):41-45.
1977b. Some morphological observations on larvae and juveniles of the
kurodai, Mylio macrocephalus (Sparidae:teleostei) reared in the laboratory.
Bull. Nansei Reg. Fish. Res. Lab. 10:1-16.

KITAJIMA, C., H. IWAMOTO, and S. FUJITA.
1977 . Relation between curvature of vertebral column and undeveloped swim
bladder in hatchery-reared red sea bream, Pagrus major. Bull. Nagasaki
Pref. Inst. Fish. 3:23-32.
YAMAGUCHI, M.
1978. The basics and practices of red sea bream culture. [In Jpn.]
kouseikaku, Tokyo, 414 p.

9

KouseishaPresent Status and Future Potential of
Yellowtail Culture in JapanTOSHIHIKO MATSUSATOIBACKGROUND

Kagawa Prefecture. Before this time, there were many short-termfish farms. In these, anchovy were held as bait for skipjack
fishing, and the red sea bream and other fishes were maintained.
Noami chose yellowtail of the many kinds of fishes and selected
Adoike as the first location for yellowtail culture for the following
reasons: 1) Young yellowtail bring a high price at the OsakaKyoto marketing area. Areas of "hamachi," "fukura," and "buri"
consumption are shown in Figure 2. 2) In addition to having good
culture characteristics, yellowtail is considered a "lucky" fish.
Table 1 gives the names of this fish at each growth stage. 3)
Juveniles measuring 5 to 150 mm ("mojyako") are found near

About 9,000 yr ago, the Japanese lived mostly along the coast
and used many kinds of fishes as food. Fish bones were found inshell heaps on the coast of Tokyo Bay and were identified as
belonging to 10-12 species including tuna, common mackerel,anchovy, common sea bass, red sea bream, black sea bream,
flounder, mullet, horse mackerel, and yellowtail.
The Japanese like to eat fish; however, until 1950-55 low yields
of commercial fisheries and inadequate culture methodology
limited the supply of edible fishes. Moreover, the Japanese preferraw fish rather than cooked fish. Raw fish, called "sashimi," requires very careful preparation. The quality of the meat is affectedby changes in temperature that occur in refrigeration and freezing.
Fish meats that can be used for sashimi are 3 to 10 times more expensive than the same kind of fish meats unsuitable for sashimi.
Thus, culture and preservation methods are important in preparing
sashimi.
Figure I compares the prices of live and dead red sea bream.
Prices of live and dead yellowtail vary more than those of red sea

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0

DISTANCE FROM THE OSAKA FISH MARKET(HRS BY CAR)

Figure I.-Prices of live and dead red sea bream in different districts (after Vagi
1974).

bream. The price of dead fish ranges from 150 to 200 yen/kg; live
fish cost from 750 to 800 yen/kg. Although cultured horsemackerel, Trachurusjaponicus, are fed cheap horse mackerel fromcommercial fisheries, the cultured fish are very high priced(Statistics and Survey Division, Ministry of Agriculture, Forestry
and Fisheries, Japanese Government 1960-79).
Fish culture started in Japan in the 9th century with carp. In
1928, Sakichi Noami initiated yellowtail culture at Adoike,

1 Nansei Regional Fisheries Research Laboratory, Ohno-cho, Saeki-gun. Hiroshima Prefecture, Jap~n 739-04.

Figure 2.-Areas of haniachi, fukura, and burl consumption.

11

Table I.-Name changes of growing yeUowtall.

Body length(em)Commonand local
names

0-10

20

30

40

80
(2 yr
old)

Mojyako
Abuko

WakanaYazu
Hideriko

HamachiWakanago
Wakashi
FukuraTsubasu

Inada
Ao
Aoko
YalO

WarasaWarasaba
MegiroHanagiro90(3 or 5 yr
old)
Buri
Doburito captive fish. 5) There were many fish holding ponds along thecoast of the Seto Inland Sea, and local fish growers were experienced in fish husbandry. Noami was one of the pioneers inthis field. 6) The biological characteristics of yellowtail are usefulin culture. Table 2 shows some of the more importantcharacteristics.
Hamachi culture started in 1928 but, unfortunately, did not advance substantially for 20 yr.

ADVANCEMENT OF YELLOWTAIL CULTURE
floating seaweeds and can be collected easily with nets. A map of
the mojyako collecting areas is shown in Figure 3. 4) After the
mojyako stage, the feeding habits of yellowtail change from eating
crustaceans to fish. Cannibalism and biting increase the frequency
of injury and it is estimated that 11 to 20% of the population areaffected. However, cannibalism is useful when feeding dead fish

After the end of World War II, many restrictive regulations
were rescinded and hamachi culture developed rapidly. The
number of culture areas expanded considerably. However, theamount of yellowtail caught by fishing boats stayed the same about 30,000 to 40,000 tons. Weights of cultured and captured
yellowtail are shown in Figure 4. Despite technical and economic

10

9

8

7

0
0
0

6

...0 5

"
til
z

0

~

4

Figure 3.-Yellowtall seed collecting sites.
3

Table 2.-Some biological cbaracterlstlcs of cultured yellowtail, Seriola quinqueradiata.
Distribution

2

Pacific Ocean and Japan Sea

Optimum water temperature
Biological minimum size

4-5 kg (body weight)

Fecundity

5-30 x 10'oPeriod of embryonic development(fertilization to hatch out)

YEAR

Egg size

1.25 mm (floating egg)

Critical size in food change

40 mm (BL). 1.0 g (BW)Daily feeding ratio

30 g (BW) : 60%
100 g: 28%
150 g: 18%
500 g: 12%700 g: 10%

Growth rate

10-20 g (BW): 10% (per day)
400-500 g : 22%
1.000 g: 1%
2,000 g: 0.5-0.8%

Oxygen consumption"GII--~..-. . . . --ri-.....--.---...,....-r--""""'..--........
--rl1965
1970
1975
1961

Figure 4.-Welghts (tons) of cultured and wild yellowtail from 1961 to 1976.

difficulties, the yellowtail culture industry has advanced. The expansion of hamachi culture is shown in Figure 5. (Yagi 1974.)
The main reasons for the advancement of hamachi culture are1) economics, 2) techniques, and 3) the ability and determinationof fish culturists.

1.000g: 7%
1,400g: 4%

Economic Factors
The decrease in the availability of desirable fish species isshown in Figure 6, and the changes in prices of feed and cultured
fish are shown in Figure 7. Fisheries economists define the ratio

360-500 ml O/kg per h

12

1500

Figure 5.-Expanslon of yellowtail culturing areas from 1928 to 1975 In Japan.
CI:II'

Red Se. Bre.m.....

Z 1000

Il.I
~

5

4

500

o
o
o

-

enZ" 3

Common Meckerel
Anchovy
Send Lence
Cod

o

I-

2

057

19&0

19&5

19 0

llH3

YEAR
Figure 7.-Prlces of feed nsh and highly graded cultured fish and shellfish.

Kuruma Prawn
SawaraBlue CrabI, Hl55

19'60

19'65

1956. The second stage, from 1957 to 1967, was characterized bysudden growth. During this period, floating net cages weredeveloped and suitable areas were used to culture yellowtail. Two
infectious diseases, nocardiosis and pasteurellosis (bacterial tuberculosis), appeared. The third stage, which began in 1968, wascharacterized by long-term culture of yellowtail for production of"buri" (larger than 3.5-4 kg in body weight). During this period,
the culture of buri increased. By the end of 1974, cultured buri
and hamachi could be found in the public fish markets of mostcities. Culture methods and materials have changed considerably.

1974

YEAR
Figure 6.-Changes In the annual production of wild marine fish and shellfish
In Seto Inland Sea from 1953 to 1974.

in price of feed to cultured fish as an R - value. R - values in hamachi
culture are consistently II or 13. Hamachi culture is unprofitableif growers cannot obtain feed fish at a price which is 1/11 or 1/13of the price of cultured hamachi.
Production costs of the average commercial hamachi grower
are as follows:
juveniles
feed
labor
equipment
all other costs

Technical Factors
Techniques of yellowtail culture have changed. For example,
mojyako were 10-15 cm in body length in 1964 and 1965; atpresent, most are 1.5-2.5 cm in length. However, the survival rateof the latter is two to three times higher than that of the former.
Higher survival is possible because juveniles are fed fish meat,and drugs, antibiotics, and vitamins are used. Also, treatment of
cultured yellowtail to prevent vibriosis and other diseases has
been developed (Fig. 8).

2 to 30%
30 to 70%
10 to 30%
5 to 20%
5 to 20%

Ability and Determination of Fish Culturists

Generally, growers pay particular attention to the prices ofjuveniles, feed, and marketable adults.
The development of yellowtail culture has proceeded in fourstages. The first stage, early development, occurred from 1928 toGenerally, fish culturists in Japan are highly competent.
Pioneer fish culturists belonged to the social and economic middle
13

CUl TURE TYPES
F1.0ATlNG NET CAGEla.ha",)I

I NET ENCLOSURE !lA1lI( ENCLOSUllE METHOD
F1.0ATWIG NET CAGE 12.12.10",

WittE NET CAGEI!2-15 I" DlAMETERIIi, ANCHOVY

I

III' SAND LANCEI8IIIALL)

I

I

I

,
SANO LAllCEiLARGEr COMMON MACKEREL

FOODS~-.wJ'I SA!!!l!E

!

I

I

!ACCIDENTSDISEASES

I PARA.S1T1C DISEASES CAUSED BY MONOGENETIC TREMATODESIVIBRIOSISI
I NUTRITIONAL DISEASES LACK OF V.a. GROUP./I PASTEURELLOSISNOCARDIOSISOTHERS:RED TIDEPCB CONTAMINATION

I

1949

I,

CULTIVATED

.'.

11155

1HO

~
,.8.

7

...

V

./

"~O~

V

I

STREPTOCOCfOSIS•U

MASS MORTALITY
CAUSED BY

L11£1) T1DE

~ ~ ~ ~
1170

YEAR

--

I

MASS MOftTCAUSED BY

RED T1DE

0~ ~
1175

l1H8

Figure S.-Problems related to the development of hamachi culture.

Juveniles

class. Now, most of their successors have graduated from fisheryhigh schools or universities. Fish culturists are determined to be
successful since the quality of their lives has improved substantially since they started yellowtail culture.

Today, about 50 million juveniles are collected per year, about
10-25% of the yellowtail juvenile population. Collecting juveniles
may become more difficult, and their price may rise yearly. Thesedifficulties will press for the hatchery production of juveniles.

PRESENT STATUS AND PROBLEMS OF
YELLOWTAIL CULTURE

Pollution and Self-Contamination

Today, hamachi culture has been developed along a major portion of the coast of Japan. Some figures relevant to yellowtail
culture in 1977 are as follows:

Pollution from industrial wastes and sewage in the Seto Inland
Sea is one of the most typical examples, and pollution in yellowtail aquaculture areas is another type, eutrophication. Pollution
causes eutrophication which causes red tides and the accumulation of some heavy metals in fishes. Self-contamination by
feeding yellowtail is shown in Figure 9. Mass mortalities ofcultured yellowtail caused by lack of oxygen in the water occur
when there is much self-contamination.

1) collecting and juvenile production farms: 82 (200 persons)2) number of juveniles: 18 million3) commercial yellowtail farms: 3,809 (11,222 persons)4) area: 5,431 km 25) yield (weight per square meter): about 20 kg/m 26) feed fish consumed: 10 million tons7) number of feed fish: 82 million8) yield of cultured yellowtail: 101,618 tons (yellowtail accountfor about 95% by weight of the cultured fishes).

Losses From Disease
Losses caused by diseases of cultured yellowtail in 1972 areshown in Table 3. The value of the losses in 1972 was about 600
million yen. Losses from diseases have increased. At present,
25-30 diseases of cultured yellowtail are known; nocardiosis,
pasteurellosis, and streptococcosis are the most serious. The

Problems in yellowtail culture include 1) a stable supply ofjuveniles, 2) pollution and self-contamination from metabolic
products and feed, 3) losses from disease, and 4) shortage of feed
fish.
14

FEED
3.2l1
(100'lfo),t

FEED RESIDUE
0.05l1(2'lfo)INGESTION
2.lIl1(1I0'lfo)I
W:T~R

SUSPI?1_DED
MATT!"
0.05l1(2'lfo)SOLUBLE
0.2l1(8'lfo), . ONE YEAR OLD FISH
• 0 YEAR OLD FISH------- SOME FISHES REMOVED-ALMOST ALL FISHES REMOVED

Figure H.-Reported eplzootlcs related to transportation of live ftsh with nocardiosis In 1972.

CONSUMPTION BY THE FISH
2.3l1
(72'lfo)
I

I

I

t

t

FECES
0.1l1
(3'lfo)

URINE
0.5l1
(15'lfo)Figure 9.-Partltioning of "self contamination" (as nitrogen content).

Tabie 3.-Losses from disease in 1972.
DiseasePasteurellosis
Nocardiosis
Vibriosis
Microsporidiosis
DropsyLymphocystis
Nutritional disease
Mass mortality from red tide
Others
Total

Loss (x 1,000 yen)
518,000
4,400
6,000
8,200

Figure 12.-D1stributlon of streptococcosis In 1975.

o100
50,8002,800
4,500
594,800

FUTURE POTENTIAL OF
YELLOWTAIL CULTURE
In the first meeting of the UJNR Aquaculture Panel in 1971,
John Glude reported on marine fish culture in Japan. He discussed
some future problems in yellowtail culture in his report (1974):"Production from yellowtail farming is limited to approximately
the present level because of government restriction on the numberof young fish which can be taken from coastal waters." The levelat that time amounted to only 30,000 tons, and the number ofcollected juveniles was 10-30 million. At present, the number ofyellowtail juveniles caught along the coast of Japan is estimated at
200 million annually. Half of the juvenile population now has
been used. The price of cultured yellowtail has remained the same
(1,000-1,200 yen/kg) for the past 3 yr in spite of two- to threefold increases in the cost of juveniles.
Furthermore, areas suitable for yellowtail culture have been
completely used. It is difficult to predict the potential of yellowtail
culture, but it is unlikely that marine fish culture, including
yellowtail, will ever fail in this country.
The potential of yellowtail and other cultured fishes is asfollows:

geographic distribution of these three diseases is shown in Figures
10, 11, and 12.

Figure 10.-Dlstrlbutlon and expansion of pasteurellosis from 1964 to 1972.

1) Production of yellowtail will reach 150,000 tons within a
few years and will stay at that level.
2) Many kinds of fishes will be cultured.
3) Production of yellowtail juveniles by artificial fertilization
will begin in a few years.
4) The weight of culture marine fishes will reach 250,000 tons.
5) Halibut culture will grow rapidly.

Availabillty of Feed Fishes
Fishes usable as feed are listed in Figure 8. Today, obtaining
and keeping feed fishes for yellowtail culture is not very difficult,but may become more difficult each year.
15

LITERATURE CITEDSTATISTICS and SURVEY DIVISION, MINISTRY of AGRICULTURE, FORESTRY and FISHERIES, JAPANESE GOVERNMENT.
1960-79. Annual report of catch statistics on fishery and aquiculture, 19601979.
YAGI, T.
1974. A study on the market system of the coastal fisheries landing 1-45.

GLUDE, J. B.
1974. Marine fish culture in Japan. In Proceedings of the First U.S.-Japan
Meeting on Aquaculture at Tokyo, Japan, October 18-19, 1971, p. 115-121.
U.S. Dep. Commer., NOAA Tech. Rep. NMFS CIRC-388.

16

Present Status of Red Sea Bream in JapanRYO OKAMOTOIINTRODUCTION10In Japan, the total production of marine fishes in aquaculture
reached 110,000 t in 1976. This was about 1% of the total fisheryproduction and most of it was yellowtail. Recently, the productionof sea bream in aquaculture has increased. Sea bream was not independently mentioned in the fishery statistics until 1969.
The reasons for the increase in sea bream production are summarized as follows: 1) In 1970, the production of yellowtail in
culture was 30,000-40,000 t. This met the demand, causing adecline in price. 2) The capture of young yellowtail "Mojako" inthe sea was estimated to be 50-60 million (now more than 100
million). We became anxious about its influence on the fisheryand natural resources of yellowtail. 3) The culture of red sea
bream was profitable in view of its growth, survival rate, andmarketability, based on experiments on the coast of Seto Inland
Sea and Kyushu, the southeast region of Japan. 4) Sea bream is
more resistant than yellowtail to unfavorable environmental conditions, such as "red tide." 5) Artificial mass seedling production
systems of sea bream had already been established. Yellowtail
culture still depends on natural seedling production. Since we startwith seedlings in marine aquaculture, it is important whether wecan produce them artificially.
Imai (1970)2 defined "through culture" as the system of artificial and intentional production from egg to adult. Red and black
sea bream cultures are already in the stage of "through culture."
Culture of yellowtail, yellowjack, horse mackerel, and other fishes
are near this stage. The following is a survey of recent techniques
and production in the culture of red sea bream in Japan.

9(x10,OOOtons)

8

7

6

5
4

/~

3

2
0

(x1,OOOtons)

/

6

--0/

5

4
("'.OOOtons)-

SEA BREAM

3

2

HORSE MACKERELAND YELLOW JACKOTHERS. __ .0.--.0'--'0·--·0.".-. __ •RECENT INCREASE OF SEA BREAM
CULTURE PRODUCTION IN JAPANAND ITS SIGNIFICANCE

1965

66

67

68

69

70

71

72

73

74

75

76

Figure I.-Annual fish production by marlculture. (Calendar year: seed nsh
production excepted.)

Most fish culture production has been occupied by yellowtail.
Gradually other fishes have been cultured, especially sea bream.
Sea bream culture production increased and reached 6,639 t (Fig.
1). This quantity was 700 t more than the natural fishing production of sea bream (red, black, crimson), 5,916 t, in 1976 in the
Seto Inland Sea, a known fishing ground for sea bream.
Development of sea bream culture by area and year is shown in
Figure 2. In the beginning, these cultures were developed on thewest coast of Kyushu Island and the outer coast of Shikoku Island.
Because plenty of natural seedlings were supplied and growth wasbetter in warmer conditions, they were able to pass the winterseason in these areas. With the establishment of the artificial
seedling supply system, the culture gradually extended to the Seto
Inland Sea, the central Pacific coast and the west Japan Sea coast.
Table 1 shows the contribution of yellowtail and sea bream to thetotal aquaculture production of marine fishes. The contribution ofsea bream varied from 1.1% (1970) to 6.1% (1976), whereas thatof yellowtail decreased by 5.6%. These statistics indicate that theconventional method of aquaculture of marine fishes had beenreformed to the system of "through culture." This had a significant effect on the history of technical development of marine fishculture in Japan.

AN OUTLINE OF AQUACULTURETECHNIQUES IN RED SEA BREAM
CULTURE
Seedling Production'Nansei Regional Fisheries Research Laboratory, Ohno-cho, Saeki-gun, Hiroshima Prefecture, Japan 739-04.
'No Literature Cited section was supplied by the author.

Since red sea bream is not only a valuable fish but also has animportant association with Japanese customs, research into arti17

I

JAPAN SEA COAST ( WEST )PACIFIC COAST ( SOUTH)
Pacific coast
North

1972

74

1970
71
72
73
74
75

76
78
EAST CHINA SEA

MiddleJapan Sea COas

South North

2
2

west

East
China
Sea

Seto
Inland

coast

Sea

413
684
769
1286
1664
2049
543
539

11
27
178
497
292
594
483
73

Total

538
930
1318
2740
3298
4462
6572
100

Figure 2.-Annual production of cultured sea bream by region (metric tons).

or streaming, and light. At the current technical level, the survival
rate at this stage is 20-30%. A seedling is about 80 yen in themarket (1978).

Table i.-Production ratio of yeUowtall and sea bream In
nsh culture (%).
Percentage yield offish culture

Year

Yields offish culture (t)Yellowtail

Sea bream

1970
1971
1972
1973
1974
1975
1976

43,91062,91278,723
83,76997.08497.997109,257

98.6
98.1
97.7
95.8
95.5
94.2
93.0

1.6
1.8
3.2
3.6
4.5
6.1

Culturing

1.1I) Suitable conditions for a farma. Calmness and slow tide: These conditions are necessary
for safety of the cage.
b. Depth and water exchange: Water depth should be twicethat of the cage and water movement should be 5-15
cmls to avoid a decrease in dissolved oxygen caused by
the stagnation of water and the generation of sulfides.
Fast stream flows cause the net of the cage to move up,
resulting in damage to the fishes inside it.
c. Water temperature: Between 20° and 28°C, red sea
bream has the greatest appetite and shows the fastest
growth. Over 29°C, it is active but this temperatureeasily causes physiological stress. Under 20°C, appetite
decreases gradually, and growth is slower. Under 12°C,
it scarcely feeds. Under 10°C, weight decreases because
it is not feeding and the fish is, consequently, in danger.
At 11°C, if the temperature is rising, it begins feeding
activity, but if the temperature is falling, it becomes
totally inactive. When the temperature falls slowly, it
stays alive at 8°C; on the other hand, when thetemperature falls rapidly, it dies at 11°C.
d. Water quality: The inflow of sewage or industrial wastewater must be avoided. Inflow from a river is also
undesirable because it causes an extreme drop in salinity. Red tide regions should also be avoided.
e. Transportation: It should be convenient to carry foodand seedlings to the farm.

ficial seedling production started in 1887. However, mass production research did not begin until 1965. The generation time of thisspecies in the sea is 4 or 5 yr; in "through culture" it is 2 yr at theearliest, or at latest, 3 yr. Fertilized eggs can be collected infloating net cages or culture tanks from cultured spawners in May
and June, when water temperature is usually 17 0-21 0c. After
hatching, with larval development, food should be changed fromlarval bivalves to marine rotifers, then to marine copepods. Minced fish is given 30 d after hatching (12-55 mm in total length).
During the first 20 d, pond water for rearing should be kept stationary, except for aeration, to protect larvae and living food fromflowing away. Sudden changes in environmental conditions, suchas water temperature, light, and aeration, should be prevented.
The accumulation of NH 3 , N0 2 , and N in the pond originatingfrom la~vae and food should be monitored. These often pollute thepond water.
Seedlings for release or culture should be more than 50 mm intotal length because they must be able to feed completely on
minced fish, protect themselves from predators, and be fit for theenvironmental conditions of water temperature, water movement18

f. Easy care for general control.
2) Culturing apparatus and capacity
From the early days, banks or nets have been used to divide
an inlet or bay. Floating net cages are now used 99% of thetime. The rafts or floats, equipped with culture nets (5 msquare and deep or 8 m square and 6 m deep), are anchored.
As the fish grow, the smaller mesh is replaced by larger
mesh. The widespread use of floating net cages owes totheir ease of use, low cost, convenience, and high productivity per area. Productivity when using banks is < 1 kg/m J ;that of nets is 6-7 kg/m J when fishes are more than 500 g.
In the latter method, when fishes are 3 g, the capacity is
about 1 kg/m J , at 20 g it is 2-3 kg/m J , and at 200 g it is 4-5
kg/m J .
3) Feeding and growth
Recently, advances have been made in the development of
the quality of artificial compound food, but this artificial
food comprises only 0.5% of the total food consumption.
Most of the food consists of minced fish such as anchovy,
sand eel, mackerel, and mackerel pike. The daily feeding
ratio is 6-8% of the body weight in fish < 1 yr-old, 5-6% in
1 yr-olds, and 4-5% in 2 yr-olds during the period when thewater temperature is high. The conversion efficiency is
8-10 over the total culture period (Fig. 3).
The growth curve in culture is shown in Figure 4.
Cultured red sea bream grow to be 200 g in a year, 600-800
gin 2 yr, and 1-1.2 kg in the third winter. Wild red sea
bream need 4-5 yr to reach I kg; wild black sea bream growmore slowly.
4) Body coloration
Since early times, red sea bream has been admired andvalued for its elegant shape and bright crimson body color,
as well as its taste. Though red sea bream has been cultured
for a long time, it was not until recently that its culture

1300

1100
1000
900

-" 800

.
0:

700
i"

600

'" 500
0
0

lQ

400
300
200
100
June

1100
1000
900

700

~

500

i
.;

H

!i]. 600
0

B ......'

(00

_ •.-

300

.\'5

/

____..L

lQ

j'

c

".

./

. . . <.....

200
100

.. '

..

.. '
'

•• , .• ·0'"•0........ 0··

i

~
0

lQ

.....

'"
0

~

Dec.

June

June

June

CONCLUSION

~

.'"

June

became widespread. One of the reasons for its slow spread
was that its color changes from crimson to black. Cultured
sea bream that are black have a low market price. Much
research has been done on the biochemistry of pigment,
coloring, and food on fishes; however, no definite techniqueto maintain the crimson body color has been developed.
Based on breeding experience, the following methods are
known to be effective: 1) Use of red shrimp, Metapenedpsis
barbatus as food, and 2) deepening the cage and shading itfrom sunlight. The solution to this problem is one of themost important considerations in aquaculture of thisspecies.
5) Disease
With the development of the aquaculture industry of red sea
bream, knowledge of various diseases and abnormalities
that occur in culture are accumulating. When many fishes
are reared over a long period, diseases are apt to occur
because of the intensive culture and efficient fattening of
the fishes. Today about 10-15 kinds of diseases are known.
These include lymphocystis, vibriosis, and some nutritional
diseases. Flexibacter causes one of the worst infectious
diseases.
6) Loss in the process of rearing
Loss is mainly caused by diseases and escapes. Diseases areprevented by proper selection of farm grounds, suitable
feeding, and proper density of fishes. Escapes, owing todamage of the cage nets, failure to exchange nets, or flows
caused by typhoons, can be prevented by adequate control
systems. Currently, the loss of I yr-old fish is 2-10%, andthat of 2-3 yr-old fish is 1-3%.

1300

~

June

Figure 4.-Growth In cultured and wUd sea bream. A: Kumamoto Prefecture
Fishery Experiment Station, 1969; B: Fish farm In Sblzuoka Prefecture, 1974;
C: Wild population of red sea bream (Mlo 1962); D: Wild population of black sea
bream (Ohshlma 1942).

1200

" 800

o

1200

Aug-

Apr.

Aug.

As mentioned above, "through culture" of red sea bream is wellestablished, though there are still problems with diseases and bodycolor (Fig. 5). These problems may be solved in a few years.
However, the culture of red sea bream is done as a sideline compared with that of yellowtail. Culturists are hesitant to begin the
monoculture of red sea bream, in spite of its seedling availability,

Dec.

Figure 3.-Growth aDd dally feedlq ratio In cultured red sea bream. A: Kumamoto Prefecture Flsbery Experiment Station, 1969; B: Fish f-= In Sblzuoka
Prefecture, 1974; C: Wild population of red sea bream (Mio 1962); D: Wild
population of black sea bream (Obshlma 1942).

19

14 00

Yen /

Kg)

1300

1200

1100

1000

900

800

700

600

500

400
Figure 5.-Prlce orrresh fish at nsh markets. "Live nsh," In which
condition the cultured fish Is usually marketed, Is priced hl&her thanrresh fish. For example, the prices or cultured red sea bream andyeUowtail In December 1975 (Hiroshima fish market) were 1,8002,000 and 1,000-12,000 yen/kg, respectively.

300

200

100

67

68

69

70

71

72

73

74

75

t, it will remain a valuable fish. The establishment of culture techniques and management policies which take into account the particularities of this species are now needed.

strength, yields, and prices as compared with yellowtail. An important factor in this hesitation is the uncertainty in the future
that, when culture production of red sea bream is 50,000-100,000

20Practical Problems in Finfish Culture in
Kochi Prefecture
MICHIKO TANIGUCHP15COMPONENTS OF MAJOR FISHERIES IN
KOCHIPREFECTURE

14

.3

.2

Kochi Prefecture is located on the southern part of Shikoku
Island. The climate of the district is generally temperate throughout the year, but the district is subject to frequent typhoons during
the summer and suffers severe disasters. Kochi is also affected by
the Black Current running off Shikoku Island (Fig. 1), so that thefisheries of this district have depended mainly on migratory
fishes, such as skipjack tuna, frigate mackerel, common mackerel,and horse mackerel. The major fisheries and their yields in Kochi
are shown in Figures 2 and 3. The yield of marine fish culture isthird in amount, and second in value.

1350

140

0

145

0

11

'"o
Z

10

....

9

~ 8

:g 7
Z
0<

~

oJ:

....

5
4

0

150

r-+----J__+""'-t-=--t-- 45 °Figure 2.-Amount of products for the respective nsherles In Kochl Prefecture.
Multiple bars are additive.

~K~~~a P.

A
Ehime

30

Pelagi:. long lining for tunal ~rf?kuShima P.
•

if

;

\..

~~hiC.

, ,.'-

Nomi
Bay

~

20

~

...C

Figure t.-Locatlon of Kochl Prefecture and Its marine culture grounds.

~~arine culture

COMPONENTS AND YIELDS OFFISH CULTURE",_",/_0"._--olnshore pole and line fishingfor skipjack••, Eelculture.-:::._.Triangular set net_,-0-'

The components and yields of marine fish culture are summarized in Table 1. Marine fish culture is primarily represented
by that of yellowtail, Seriola quinqueradiata; the amberjack,
Seriola purpurascens, and the red sea bream, Pagrus major, haveminor roles in fish culture. Sukumo City, in the western part ofKochi Prefecture, is the most important city in the yield of
cultured fish; Susaki City, in the middle part of Kochi Prefecture,
is second in the production of cultured fish. The products of bothcities depend mostly on the culture grounds of Sukumo Bay(Sukumo City) and Nomi Bay (Susaki City), respectively.
Eel culture has been performed mainly in open fields in the
middle part of Kochi Prefecture - Nankoku City, Kochi City,.-=-:-:--=-:~~S-::;':-""'F-::'-~O:-'-"f;a:~~~~eand line fishing
1972

1974

1976

Figure 3.-Yield for the respective nsherles In Kochl Prefecture.

Tosa City, and other areas. About 4,000 tons of products, worth 5
billion yen, are produced annually.

METHODS OF EEL CULTURE IN
KOCHIPREFECTURE
Recently, a new culture method has been developed and is
replacing the earlier method. This method, extensively used in
Kochi Prefecture, is technically derived from the horticulture of'Kochi Prefectural Fisheries Experiment Station. Uranouchi. Susaki, Kochi.
Japan.

21

Table I.-Yields of marine fish culture.
Yields (tons)
Numberofculturists

Area under(m l )

Yellowtail

Tosa
Susaki
Nakatosa
Kubokawa
Nakamura

10
307
6
I

4,894
55,574
1,929
1,0'10

263
2,099
192
137

Tosashimizu

5
181
196

2,821
46.89082,464

355
2,214
4,663

Localities

Otsuki
SukumoCommoncultivation

Spanish paprika and cucumber using a polyvinyl sheet hOlJlse anda boiler. The characteristic of this new method, "the polyvinylsheet-pond method," is that a sheet-pond is set in a polyvinyl
sheet house which keeps the water, heated by a boiler, at about
25°C. Since this culturing method was designed in 1974 at Kochi
Prefecture, culture yields have increased rapidly.
The structure of this equipment is shown in Figure 4. The circulating water, heated by the boiler, runs through a metallic pipe~
Yo /I/, /,... polyvinyl sheet roof
polyvinyl sheet wall pond:

polyvinyl She~et•. , ~

post..

r---<e
pipe

•

915

2

sheet zinc

:~.

',.

sand

Q

/

63

8
84

2

Marine fish culture is divided into the following three types
based on the characteristics of the culture grounds: The inner bay
type, the outer bay type, and the offshore type. These characteristics are summarized in Table 2 and their crawl (an enclosure inshallow waters - as for confining lobsters) structures are shownin Figures 5, 6, and 7. The daily task of rearing fish is easier andthe construction of the floating nets is less expensive in the inner
bay type as compared with the other two types. The problem with
the inner bay type, however, is that pollution of the water of theculture ground occurs in a short time. Therefore, fish culture of//

Figure 4.-Schematle Ilgure of the polyvinyl sheet pond.

Table 2.-Characteristics for each type of marine fisb culture.
Culture ground
Characteristics

Inner bay

Outer bay

Offshore

Maximum velocity of current

25 cmls
0.3 m
5-10 m

50 cmls2m
22-30 m100 cmls
8m
150-200 m

1-2

3
15 cmls
20 km
submerging

830 cmls

Maximum wave height
Wave length
Maximum degree in

Beaufort's wind scale
Maximum wind velocity
Distance of storm in typhoon
SystemRed seabream

MARINE FISH CULTURE.

b/Yellowjack

horsemackerelset in the polyvinyl sheet pond, so that the pond water is warmed
indirectly. This method is remarkably different from the earlier
Shizuoka method. After the elvers are caught and put into thepond in early spring, the water is immediately heated and maintained at a temperature of about 25°C. To control growth of green
algae, the pond water must be changed once a day.
The advantages of this method are the efficient and rapid
growth of eels, the decrease in mortality of elvers, and the prevention of disease in winter and early spring. The disadvantage of thismethod is that some problems, e.g., breakdowns in electric current or thermoregulatory problems, can cause serious damage andeven death of numerous eels. Also, diseases which appear inwarmer seasons arise in all seasons. Another problem with thisnew method is that the profit of the culturist decreases from year
to year because expenses for materials, fuel, and electricity increase in relation to the current economic conditions.

r-..

;;; //-

Amberjackfloating

floating andsubmerging

Material of frame

bamboo and ironsynthetic fiber(long line)

iron

Material of nelling
crawl or cage

synthetic fibersynthetic fiber"only"

synthetic fiber

and wire22

and wirebuoyancy for construction. The best mooring method of the offshore type is to moor it directly to the two parallel long lines. The
float buoyancy of the mooring lines and the net cages should be at
the minimum, since the respective floats have a buffer action. An
example of this type of structure is given in Figure 7. In using thepolyethylene net, the structure is almost the same as in the outer
bay type, but a heavier sinker and more burly rope must be used. It
is also important to protect the fishes from sharks and puffers.
This type of structure has been tested in the culture of bluefin tunaat sea by the staff of the Kochi Prefectural Experimental Station
since 1976. Recently, "the iron-frame sinker" and "the doublebottomed-net" were designed; the former is effective in obtaining
the maximum volume of net crawl, and the latter is effective inprotecting the fishes from sharks and other predators.
In the offshore type, a high rate of water exchange maintains
the water quality in the cage. The disadvantage of this type is that
construction materials are more expensive than in the other types.
Also, the risk of typhoon damage is strongest in this type. Consequently, the offshore type has not spread among fish culturists.
However, these improved structures have lasted for several years
without any serious accidents despite the occurrence of typhoons
in Nuno, Tei, and Sukumo.

W.L.

polyethylene rope 11 24rnm

FFigure 5.-Yellowtail mariculture facilities In embaymental farming ground. A,
polyethylene rope, 24 mm, n 3; B, stone, 7·8 kg; C, bamboo frame; D, polyethylene ftber, 4Ol)d/40, 7 knot; E, frame Une, 10 mm; F, anchor 50 kg; G
styrol noat, 56 cm, length 90 cm, buoyancy 200 kg.

+

+

+

this type is continued only in areas where water exchange in theculture ground is comparatively good. The inner bay type is usedin fish culture in Nomi Bay of Susaki City.
The outer bay type is used in Sukumo Bay where fish culture
has been carried out extensively over the last 7 yr. Crawl construction of this type is well adapted to use in Sukumo Bay because of
its oceanographic features. In this bay, we cannot use metallic
frames and cages which are supposed to be physically strong,
because the wave length is too short to move the structuressmoothly in stormy weather. Crawl constructions designed for
Sukumo Bay (Fig. 6) lasted for a long time without accident
despite the occurrence of typhoons. The disadvantages of the outer
bay type are summarized as follows: I) This type is comparatively
expensive, because it requires many materials and a large boat forrearing fish, 2) it takes much time to go to the rearing point fromthe base point because both points are usually distant, and 3) it isdifficult to go to the rearing point in bad weather. It is also difficult to take care of and observe the condition of reared fishes
because the net cages are sunk down about 2 or 3 m.
In the offshore type, various considerations are required inplanning the construction of the cage. The most important points
involve the mooring method and attaining the appropriate,.... .......

-~~l8-----'i~·tm~
_____
~

~
_______ ~

~'E

.Om

~"I

I I I J , I I I I I I II I i I I Ii I Ii I III

F

i~

/G

A~~il)-...,,__ H

iFIgure 7.-Structure of offshore type mariculture facIUtles. A, polyethylene
rope, 65 mm; B, styrol noat, buoyancy 200 kg; C, polyethylene rope, 24 mm;
D, polyethylene rope, 48 mm; E, wIre net, 4.2 mm, length 6.5 cm; F, concrete
block 7 t; G, Iron frame (six set combIned); H, styrol noat, buoyancy 200 kg; I,
welded part; J, steel galvanized pipe, 50 mm.

+

0-1 r-----";I''''''''''''l----j!==+-t=~F'l--j!=~fi''l----I'''..".,''k-----.......,f-o
F

+

+

+

+

0

SOCIAL PROBLEMS IN MARINEFISH CULTURE
~

.

J

.

' ....

. .

~~.

Marine fish culture is controlled by licensing. Licenses areusually given to fisheries cooperatives, but are seldom given tofisheries producers' cooperatives. The fisheries cooperatives are
not directly involved in fish culture, but each member of theassociation does it independently under licenses which restrict the
number of fishes reared, the number and the setting places of thecrawls and cages, and so on. The prefectural authorities who areresponsible for total management have the viewpoint that the
overproduction of yellowtail should be prevented by limiting thenumber of cultured fishes for each fisheries cooperative. They also"t,,~Figure 6.-Structure of outer bay type marlculture facIUlIes. A, styrol noet,buoyancy 200 kg; B, concrete block 2.5 t; C, polyethylene rope, 25 mm; D,polyethylene rope, 30 mm, length 20 m; E, polyethylene rope, 25 mm, length
15 m; F, smaU ftoat, buoyancy 1.5 kg; G, polyethylene rope,
16 mm; H,polyethylene rope, 30 mm, length 20 m; I, sand bag, 20 kg; J, polyethylene
rope, 16 mm; K, moorIng buoy; L, polyethylene rope, 25 mm, length 90 m.

+
+
+

+

+

+

+

23

encourage each culturist to change the fish species. Their policy
strives to stabilize business, prevent water pollution, and preserve
natural stocks of yellowtail which had been caught during the early stages of fish culture.
There are a few problems in marine fish culture. Water pollution of the culture ground is the most serious one in the inner bay
type. In recent years, red tide and oxygen deficient water have appeared frequently in warm seasons. Therefore, cultivation in theseplaces should be stopped. Fish culturists now wish to move to theouter bay or offshore, although this is difficult to coordinate withother fisheries. The staff at my Institute is doing experiments torefresh culture ground environments. Part of the present fishculture will have to change to other fisheries such as fish farming
without feeding.
A serious economic problem is profitability. Fish culturists areat a disadvantage because of the low price of their products andthe high costs of construction and food for the fish. To solve thisproblem, one must examine whether other species are suitable forcultivation.
Fish disease is another serious problem for the fish culturist.
Major diseases of cultured fishes are pasteurellosis (pseudotuber-culosis), nocardial infection, and Streptococcus infection. Thesediseases cause great economic loss for the culturist; there is nopractical, effective medicine for nocardial and Streptococcus infections. A study of these diseases has continued since 1971 toprevent damage from these diseases at my experimental station.
Since diseases of cultured fish have become more complicatedfrom year to year, the culturist should have the ability to make theprimary diagnosis competently. Culturists are educated about
diseases and taught some routine tests, including the medicine
tolerance test, of pathogenic bacteria at fishery service stations
that are located in several districts of Kochi Prefecture. The purpose of these stations is to provide executive and technicalguidance. The staffs at these stations keep in close contact with
culturists in developing their plans for dealing with fish diseases.
Although many problems exist in marine fish culture and eel
culture, these aquacultures will maintain a major position in thefisheries of Kochi Prefecture from ecological, biological, andeconomic standpoints.
The author wishes to thank the staff of the Kochi Prefectural
Fisheries Experiment Station for their helpful suggestions.

24Maturation and Spawning of Marine Finfishl
C. R. ARNOLD 2

INTRODUCTION

before laboratory spawning can occur. This period is usually of afew months in duration in temperate and subtemperate fish but
may be very long in subtropical species. This period also varies for
one time spawners and continuous spawners. Once the refractory
period and the necessary lengths and rates of change from each of
the four annual seasons to another are determined, temperatureand photoperiod control should induce spawning and provide alarge volume of usable eggs and milt.
Temperature and photoperiod control, with knowledge of therefractory period and seasonal limits, may permit a decrease in theannual cycling time between spawns making more than one
spawn per year possible.
Once the temperature and photoperiod for a species have been
determined, spawning may be delayed or prolonged by changing
the water temperature a few degrees up or down from the optimum. This technique prolongs the spawning season and produces
eggs on demand. Care must be exercised with the rate and timingof water temperature changes to prevent resorption of eggs.
Egg and milt production may be maximized with continuous
spawners by "holding" the temperature and photoperiod constantwhen a species has started spawning. A species may be spawned
more than 12 consecutive months when spawning temperatureand photoperiod are set in this manner (Ani.old et al. 1976).

Laboratory maintenance and spawning of important marine
fish species has been necessary to gather life history andreproductive information. Species whose native stocks have been
depleted by natural and/or man-made changes in the environmentor those species that have a potential for mariculture (Johnson etal. 1977) have been among those maintained in a laboratory situation to obtain this information.
The bulk of early information on reproduction has been attained from gravid fish collected and brought to laboratories during
the spawning season. For example, salmon and striped bass havebeen kept in tanks and manually stripped of eggs and milt
(Stevens 1966; Bardach et al. 1972). More recently, gonadal
and/or pituitary hormone injections have been used in conjunction with stripping. Howe,ver, with this technique many of theeggs were voided as immature oocytes in various stages ofdevelopment. Hormonal injections are valuable in inducing
spawning for those species which release all their eggs in a single
spawn (one time spawners). However, if the fish is a continuous
spawner (spawns over a long time period with many separate
spawns) the use of hormone injections usually causes all the eggs
to be released, only a small percentage of which are at a stage
which can be fertilized. Often the brood fish die or gonadal tissue
is permanently damaged from these hormone and stripping procedures. Variations in this basic technique in which the stripping
process is eliminated have also been reported; and gravid fish injected with hormones have been induced to spawn naturally in alaboratory situation (Kuo et al. 1974; Hoff et al. 1977; Garza et al.
1978).
Research on the life history of fish depends on a continuous andpredictable supply of eggs and milt. Methods involving hormone
injections do not always ensure an adequate supply of gametes.
But, this earlier research with salmon, striped bass, and otherspecies provided a number of techniques to collect fish, treat
diseases, control water quality, and feed fish in open and closed
systems (Lasker and Vlymen 1969; Spotte 1970; Bardach et al.
1972).
Pickford and Atz (1957) and Hoar (1959) recognized thattemperature and photoperiod were two of the most important
spawning stimuli in temperate and subtemperate fish species.
Temperature changes are most important for maturation in sometemperate species while in other species photoperiod plays the
major role (Kuo et al. 1974). Generally, in spring spawners, a risein temperature and an increase in photoperiod induces maturationand the inverse is true for the fall spawners. These increases ordecreases in temperature and photoperiod must be determinedwith each species before laboratory spawning can occur.
Another critical limit in spring or fall spawners is an obligatoryrefractory (winter) period that must be met and passed through

METHODS AND MATERIALSFish utilized for spawning experiments were taken near Port
Aransas, Tex., from estuarine and gulf populations of each species.
Red drum, Sciaenops ocellata, were taken by hook-and-line andbeach seine. Spotted seatrout, Cynoscion nebulosus, and red snapper, Lutjanus campechanus, were collected by hook-and-line.
Southern flounder, Paralichthys lethostigma, were taken by hookand-line and trammel net. Red drum and southern flounder weretaken during their fall spawning period and spotted seatrout in theearly spring season. Immature red snappers taken in early fall
were placed in the spawning tank. The snapper tank was covered
with nylon netting to prevent fish from jumping out of the tank.
Red drum (750 mm TL), spotted trout (356 mm TL), andsouthern flounder (males 254 mm TL, females 305 mm TL) were
kept as brood fish. Fish were transferred to the laboratory in fiber
glass tanks (300-1,900 I) and placed into 1,000-30,000 I fiber
glass spawning tanks. Fish were handled carefully to avoid surface
abrasions which could result in infections. External parasites were
removed with a 25-50 ppm bath of malachite green andFormalin. 3 After this treatment the fish were placed in spawningtanks. Details of the seawater holding facilities are described by
Arnold et al. (1976).
Photoperiod and temperature data were gathered from U.S.
Coast Guard and U.S. Weather Service records for Port Aransas,
Tex. By comparing larval collections or adult spawning records of'Contribution No, 631 of The University of Texas Marine Science Institute,'The University of Texas Marine Science Institute, Port Aransas Marine Laboratory, Port Aransas. TX 78373.

'Reference to trade names does not imply endorsement by the National Marine
Fisheries Service, NOAA.

25

redfish (Simons and Breuer 1962), southern flounder (Stokes
1975), spotted trout (Miles 1950), and red snapper (Mosely1966), the photoperiods and temperatures for the natural spawning seasons were determined. The laboratory photoperiod andtemperature regimes for induced spawning of these four species
were based on these meteorological and hydrological records.
Adults of the three species collected began feeding from 1 to 14
d after introduction to the spawning tank. Frozen penaeid shrimp
and mullet were fed ad libitum at 1.6% of the adult body weight
during 1973-76; but, after 1976 only shrimp was fed and mullet
was discontinued because a suspected bacteria carried by mullet
caused mortality in redfish. Immature red snapper fed almost immediately after collection on frozen penaeid shrimp and sciaenid
fish at 5% body weight. Red snapper diets were reduced proportionately over the 12-mo period to ad libitum feedings of about
1.6% of the adult body weight.
Loadings of adult fish per volume filter box have not exceeded
60 kg (0.137 g/cm 3 ), except 6 adult redfish (70 kg) were maintained successfully by the addition of a second filter box and air
lift. The mean loadings of filters and number of fish for red drum
was 0.080 g/cm 3 (6 fish), spotted seatrout 0.044 g/cm 3 (12 fish),flounder 0.025 g/cm 3 (12 fish), and red snapper 0.037 g/cm 3 (12fish). The ratio of males to females was 1:1 in most of our experiments. Flow per unit weight ranged from 1.5 to 2.3 Vkg fish
per min which was much lower than reported for freshwater trout
in closed systems (Fyock 1977).
Eggs of the four species were buoyant and were collected fromthe filter box surface (Arnold et al. 1976). Mean egg size and larval hatching times were similar for the three pelagic species, but
the flounder had a much longer larval developmental period withmuch lower hatch success (Table 1). Larval total length at hatch
was similar for all species.
Until 1974, water quality was maintained by weekly flushings
with fresh seawater and weekly vacuuming of the tanks. In 1974,
a program of daily sampling for ammonia, nitrite, and nitrate wasinitiated to match feeding rates with these water quality
parameters. When 0.5 mg/I NH 3 , 0.9 mg/I N0 2 , or 30.0 mg/I N0 3
was reached, ad libitum feeding rates were reduced for a few days
or fresh seawater was added. But, if 3% body weight feeding rates
were not exceeded and tanks vacuumed weekly, these concentrations were not exceeded. Uneaten food was immediately removed
from spawning tanks.

Laboratory temperatures and photoperiods were set to approximate those at collection near Port Aransas. Depending upon theacclimation process and weight regaining process, a period of
15-40 d was spent in this first laboratory regime before fish werechanged into a laboratory season. Once fish had been moved to alaboratory season, independence from the natural environment
was completed.

RESULTS
The initial spawning experiments on these four species were
patterned on the natural water temperature and photoperiods during each of the four seasons; however it can be noted that spawning started at < 365 d in the red drum (317 d) and spotted seatrout(253 d). Southern flounder were in the primary stages of gonad
maturation at capture and laboratory cycling was set to lead these
12 fish into their natural spawning season over a 131-d period.
Juvenile red snapper were maintained for 2 yr from capture tomaturity. Nine spawns were recorded over a 45-d period.
Red snapper are regarded as an offshore Gulf species that frequents reef structures, unlike the other three euryhaline species.
Two hundred and thirty-one days after being placed in the broodtank the first of seven spawns over a 40-d period occurred (Arnold
et al. 1978). Spawning was observed only one time. Egg releaseoccurred (during this observation) at the tank surface in the evening and involved one female and three males. No bodily contact or
butting by males was observed. A total of 2.8 x 104 eggs were
produced with an average of 1.5-2.0 x 103 eggs/kg in these firstyear spawning fish. It is believed that this Lutjanus species may be
a multiple or a continuous spawner but a malfunction in the environmental control system of 4 d interrupted the laboratory spawning regime.
Red drum were maintained for 268 d when the first spawning
behavior was noted and 49 d later, the first spawning occurred(Arnold et al. 1977). Sexual dimorphism in this species is notdistinct, but initial spawning behavior and drumming and buttingby males permitted sexual identification of the three males. At
spawning, males took on a dorsal blue-black and ventral silverywhite coloration. Females were butted and pushed to the water
surface where eggs were released. Spawning was a social behavior
with males and females participating en toto; only at the egg
release near laboratory dusk did spawning become a sole female

Table I.-Spawning experiment data and relationships for spotted seatrout, red drum, southern flounder, andred snapper induced to spawn by temperature and photoperiod cycling.
Item

Spotted seatrout

Red drum

Southern flounderRed snapper

Date test started
Date of first spawn
Date of final spawn
Number of spawns
Number of eggslspawn
Photoperiod (h L·h D)
Temperature range (0C)
Salinity range (°/ 00 )Mean egg size (mm)Number of oil droplets

8/6/73
4/18/74
7/30/7682
5.8 x 10·
15·9
23-26
25-30
0.77 mm1
99
15h@27°C
21 h @ 23°C
95-99
1.3-1.6

10/1/74
8/14/75
11/3/75
52
1.5 X 10·
12-12
22-26
26-30
0.95

8/13/76
12121/76
113/7713
5.0 X 10'9-15
16.5-17.5
25-30
0.93

Percent fertiHzation rate

Hours to hatch
Percent hatch rate
Total length larvae @hatch (mm)

I

I

> 99
19-20 h @ 24°C

30-50
61-71 h @! 24°C

9/16/77
5/7/78
6/12/787
2.5 X 10'
15-9
23-25
31-34
0.80
1
> 90.020 h @! 24°C

94-99
1.7-1.9

6-35
1.3-1.5> 95
1.7-1.926

and multiple male activity. No aggressive behavior by either sex
was noted. A total of 52 spawns over 76 d produced 60 x 10 6 eggs
(Table 1). From spawn 41 to the end, egg number decreased fromabout 1.5 x 10 6 to 5.0 X 104 eggs per spawn delineating the endof the spawning season. The average per female was 1.8 x 106
eggs/kg. Whether spawning ceased as a response to a lack of eggs
in the ovaries, or some endogenous rhythm, was not ascertained.
Red drum are classified as multiple spawners within their spawning season.
Southern flounder were collected at the beginning of the winterspawning run to the Gulf. Males were distinguished easily fromlarge females by their smaller size and their movement to Gulfwaters before females. Six females placed in the spawning tankbegan to hydrate 21-28 d prior to spawning. At this time, males
began to follow the females around the perimeter of the tanks.
Several days before spawning, males positioned their heads near
the females vent. Spawning at midday occurred at the surface between one pair of fish. No aggression or competition for a female,or between any fish, was noted. A total of 13 spawns by the threelargest females produced a total of 1.2 x lOs eggs. The average
varied from 1.0 to 1.5 x 10 3 eggs/kg. At the end of spawning, allfemales were hydrated indicating the presence of eggs in theovaries. No explanation for this cessation of spawning was found.
Southern flounder are multiple spawners within a set spawningseason, but to a lesser degree than red drum.
Spotted seatrout placed in brood tanks spawned 30 d after thelaboratory spawning period was initiated and spawned 82 times
over the next 380 d. Sexual dimorphism in this species is not pronounced but generally females tend to be larger. Sexual identification of the six males was made at spawning time by the presenceof a dark black stripe 1-3 cm wide which was superimposed upon
the lateral line system. At laboratory spawning time (dusk) as thesocial courtship intensified, the coloration of the male stripe also
intensified. Spawning occurred at the surface with a female andseveral males. Eighty-two spawns over a 380-d period at
23°-26°C produced approximately 7.1 x 101 eggs. Our experiment ceased because laboratory conditions were changed.
Whether spawning would have continued is unknown.
These initial results suggest that natural spawning of marine
fish is indeed possible and that prolonged spawning of somespecies may provide a continuous supply of eggs and larvae foraquaculture.

ARNOLD, C. R., J. L. LASSWELL, W. H. BAILEY, T. D. WILLIAMS, and W. A.
FABLE, Jr.
1976. Methods and techniques for spawning and rearing spOiled seatrout inthe laboratory. Proc. Annu. Conf. Southeast. Assoc. Fish Wild!. Agency 30:
167-178.
ARNOLD, C. R., J. M. WAKEMAN, T. D. WILLIAMS, and G. D. TREECE.
1978. Spawning of red snapper (Lutjanus campechanus) in captivity. Aquaculture 15:301-302.
BARDACH, J. E., J. H. RYTHER, and W. O. McLARNEY.
1972. Culture of miscellaneous brackish water and inshore marine fishes.
Culture of marine flatfishes. In Aquaculture, the farming and husbandry offreshwater and marine organisms, p. 541-556; 575-586. Wiley-Interscience, N.Y.
FYOCK,O.L.
1977. Nitrification requirements of water re-use systems for rainbow trout.
Colorado Div. Wild!., Spec. Rep. 41, 31 p.
GARZA, G., W. H. BAILEY, and J. L. LASSWELL.
1978. Rearing of black drum in fresh water. Prog. Fish-Cult. 40:170.
HOAR, W. S.
1959. Endocrine factors in the ecological adaptation of fishes. In A. Gorbman(editor), Comparative endocrinology, p. 1-23. Wiley, N.Y.
HOFF, F., Jr., J. A. MOUNTAIN, T. A. FRAKES, T. R. PULVER, and R. B. FUTCH.
1977. Controlled conditioning and spawning of the Florida pompano, Trachinorus carolinus, and southern sea bass, Cen/roprisris melano. IAbstr.) Fla.
Mar. Res. Pub!., Fla. Board Conserv., Tallahassee, Fla.
JOHNSON, A. G., T. D. WILLIAMS, and C. R. ARNOLD.
1977. Chlorine-induced mortality of eggs and larva of spOiled seatrout(Cynoscion nebulosus). Trans. Am. Fish. Soc. 106:466-469.
KUO, C. M., C. E. NASH, and Z. H. SHEHADEH.
1974. The effects of temperature and photoperiod on ovarian development in
captive grey mullet (Mugil cephalus L.). Aquaculture 3:25-43.
LASKER, R., and L. L. VLYMEN.
1969. Experimental sea-water aquarium. Bureau of Commercial Fisheries
Fishery-Oceanography Center, La Jolla, California. U.S. Fish Wild!. Serv.,
Circ. 334, 14 p.
MILES, D. W.
1950. The life histories of the spOiled seatrout, Cynoscion nebulosus, and theredfish, Sciaenops ocellatus. Tex. Game Fish Mar. Lab., Annu. Rep. 194950,38 p.
MOSELY, F. N.
1966. Biology of the red snapper, Lutjanus aya Bloch, of the northwestern
Gulf of Mexico. M.S. Thesis, Univ. Texas, Austin, 53 p.
PICKFORD, G. E., and J. W. ATZ.
1957. The physiology of the pituitary gland of fishes. New York Zoo!. Soc.,
N.Y., 613 p.
SIMONS, E. G., and J. P. BREUER.
1962. A study of redfish, Sciaenops ocellarus Linneaus. Pub!. Inst. Mar. Sci.,
Univ. Tex. 8(1962):184-211.
SPOTTE, S. H.
1970. Fish and invertebrate culture. Water management in closed systems.
Wiley-Interscience, N.Y., 145 p.
STEVENS, R.
1966. Hormone-induced spawning of striped bass for reservoir stocking.
Prog. Fish-Cult. 28:19-28.
STOKES, G. M.
1975. Li fe history studies of southern flounder (Paralichrhys lerhasrigma) andgulf flounder (P. albigulla) in the Aransas Bay area of Texas. Tex. Comm.
Fish. Res. Dev. Proj. Final Rep. 2-22I-R. Tex. Parks Wild!. Dep., Austin, 60
p.

LITERATURE CITEDARNOLD, C. R., W. H. BAILEY, T. D. WILLIAMS, A. JOHNSON, and J. L.
LASSWELL.
1977. Laboratory spawning and larval rearing of red drum and southern
flounder. Proc. Annu. Conf. Southeast. Assoc. Fish Wild!. Agency 31:
437-440.

27

Striped Bass Culture in the United States
BOB STEVENS!

ABSTRACT
Striped bass, Morone saxatilis, is native to the Atlantic and gulf coasts of the United States but its popularity
as a sport and a commercial fish has led to its establishment on the Pacific Coast and in inland reservoirs in 17
states.
Over 15 million fingerling striped bass are annuaUy produced by state and federal hatcheries for stocking inreservoirs and estuaries. Advances in striped bass culture within the past 15 yr have made the program possible.

Wildlife Service. A prototype hatchery was operated by S. G.
Worth beginning about 1881. The hatchery is located on the
spawning grounds of the Albemarle Sound population of stripedbass and is unique in that fish of both sexes can be taken in large
dip nets in the act of spawning. The ripe eggs are fertilized andplaced in hatching jars, the larvae hatch around 36 h later,
depending on the water temperature, into aquaria from which they
are stocked into rivers and streams. In recent years, the hatcheryhas been operated by the North Carolina Wildlife Resource
Department.
In 1961, the Moncks Corner Striped Bass Hatchery was built
on the tailrace below the Santee Cooper Reservoir by the South
Carolina Wildlife Department. The hatchery was built for the purpose of supplying the demand for larvae which had been createdby the successful establishment of striped bass within the reservoir and the excellent sport fishing which it produced. In otherwords, fish biologists and sport fishermen were interested inestablishing such populations in other reservoirs throughout theSouthern United States.
The Moncks Corner Hatchery was patterned after the Weldon
hatchery but, despite a major fishing effort, no ripe females were
captured in the tailrace in 1961 and no eggs were taken.
In 1962, hormones were injected into 162 female striped bassin order to induce ovulation. Due to inadequate facilities andignorance of the phenomenon of overripeness, only 2.64 million
fry were produced (Stevens and Fuller 1965).
In 1963,429 female striped bass were injected with hormonesand 13.8 million fry were produced. It was concluded that new
holding facilities for the adult fish would have to be constructed toobserve and frequently capture female striped bass in order to better define the role of overripe eggs as a source of egg mortality(Stevens et aI. 1965).
In 1964 new holding facilities were available, the negative roleof overripe eggs was defined, and 100 million larvae were produced from 337 females which has spawned 372 million eggs
(Stevens 1965, 1967a).
The percent hatch of eggs produced in 1962, 1963, and 1964
was 7.3, 17.0, and 31.0, respectively. Although it was suspected as
early as 1962 that ovulated ovarian eggs rapidly deteriorate inquality due to hypoxia, the phenomenon was demonstrated conclusively only in 1964. Also a technique of intra-ovarian samplingof ova from the ovary of living fish with a small glass catheter was
perfected. This enabled the prevention of the overripe statebecause eggs from the female could be periodically examined
microscopically in order to predict tne time of ovulation.

INTRODUCTION
The striped bass is of major importance as a food fish and agame fish in the United States. Its original range was on the Atlantic coast from the St. Lawrence River to the St. John's River innorthern Florida and in the Gulf of Mexico from western Florida
to Louisiana (Raney et aI. 1952). In 1879 and 1881, yearling
striped bass were seined from the Navesink River, N.J., andliberated in San Francisco Bay from whence they populated thewest coast of the United States.
The striped bass thrives in fresh, brackish, and saltwaters, in thejuvenile and adult stages, but it must spawn in freshwater streams.
While some populations such as those in the Chesapeake Bay andHudson River make inshore, coast-wide migrations beginning atage 2, the species is by no means as strongly anadromous as Atlantic and Pacific salmon or the shad and herring of the Atlantic
coast.
In 1941, the Santee Cooper Reservoir was created by the construction of a hydroelectric dam on the Cooper River, S.C. The
dam served to impound 160,000 acres of water and to inundate
portions of the Cooper and Santee Rivers which had historicallysupported large populations of striped bass. By 1949, a large
population of small striped bass was present and by 1952, a sport
fishery for the species existed with the reservoir. It was determined by Scruggs and Fuller (1955) that the population was landlocked, i.e., that the Wateree and Congaree Rivers above the reservoir
were providing the spawning grounds for the species and that conditions within the reservoir were suitable for the growth and survival of the species. During the next 5 yr, the population increased
dramatically and produced one of the largest populations ofstriped bass per volume of water ever to be observed (Stevens
1958). The species thrives to this day within the reservoir.

ARTIFICIAL PROPAGATION
Spawning
The first striped bass hatchery was established in 1906 on the
Roanoke River at Weldon, N.C., by the Bureau of Biological Services, which was the predecessor agency of the U.S. Fish and'Chief of Fishery Research. U.S. Fish and Wildlife Service. Department of the Interior. Washington, DC 20242.

29

The protocol for successful hormone-induced ovulation to be
described below launched striped bass culture in the United States(Stevens 1966).

tain water temperature at 21 °C or less because fry younger than 9d old are intolerant of higher water temperature (Stevens 1967b).
Between 25,000 and 100,000 larvae can be transported to therearing site in this manner in time periods up to about 12 h.
Longer trips require less density.

Protocol for Hormone Induced Ovulation of Striped Bass
1) Adult male and female striped bass are captured during thespring spawning season on or near their natural spawningarea and immediately injected with at least 127 I.U. ofchorionic gonadotropin per pound (0.45 kg).
2) Twenty-two hours after injection an intra-ovarian sampleof eggs is taken and examined microscopically in order topredict the time when the eggs will reach Stage VI.
3) Females are segregated according to estimated time ofovulation.
4) After reaching Stage VI, the stomach of the female ispalpated every 30 to 60 min in order to determine whether
ovulation has taken place. Eggs remaining in the ovary
more than 30-60 min become overripe and will not hatch.
5) Ripe females are manually stripped of their eggs. Spermfrom one or more males are stripped upon the eggs and thesex products are mixed by hand.
6) Water is then added and the fertilized eggs are placed inhatchery jars at the rate of 100,000/jar.
7) The eggs hatch in about 36 h, depending upon the watertemperature, and are shipped to rearing stations between
day 1 and day 5.

Rearing
Earthen ponds, which have previously been dewatered for 2 to
16 wk, are filled several days prior to stocking the fry. Organic
fertilizer is placed in the pond prior to and during the 40-50 dgrowing phase. Hay at 900-1,100 kg/ha or cotton seed or soybean
meal at 170-225 kg/ha has succeeded in producing 1.6 to 2.3 kgof fingerlings per hectare per day over a 40-d growing period(Stevens 1975).
In 1975, the Hudson River larval striped bass were reared inearthern ponds at the Edenton National Fish Hatchery in North
Carolina (Baker 1976). This rearing effort employed the use ofdried fish food which was fed daily during the latter part of therearing period. Average production in 18 ponds was 3.1 kg/ha perd in a 47-d growing season.
In 1974, the federal hatchery system averaged about 74,000
fingerlings per surface hectare weighing 39 kg in a 39-d growing
season (BrashIer 1975). Wide variation in production was the rule
between hatcheries and between individual ponds. For example,
at the Edenton National Fish Hatchery in 1974, an average production of 160,000 fish weighing 100 kg was achieved per hectare in a total of 2.4 ha (Ware 1975). The above mentioned rearing experiment by Baker at Edenton in 1975 produced an average
94,000 fingerlings per hectare in 5.7 ha.
Fingerlings are removed from the rearing ponds after 40-50 dbecause the natural food becomes depleted. If large fingerlings aredesired, the same ponds can be refilled and stocked at the rate of
62,000, 5 cm fingerlings per ha. Artificial diet~ provide the food.
Baker (1976), reared 273,00012 cm fingerlings in an average of
76 d after restocking in 16 ponds at Edenton. Survival was 82% of
the Phase I fingerlings stocked.
The current annual production of striped bass fingerlings in the
United States is over 15 million. These fingerlings are produced inabout 200 ha of rearing ponds located at state and federal fish
hatcheries throughout the Southern United States.
The fingerlings are stocked in reservoirs and estuaries in orderto establish, reestablish, or enhance striped bass populations. Most
reservoirs do not have suitable spawning grounds and so the
population must be maintained by annual or periodic stocking.

At the present time, approximately 12 striped bass spawning
hatcheries exist in the United States. Several are located far inland
and they depend upon spawning stock which were originallyintroduced into inland reservoirs as fingerlings.
In 1974, Bishop (1975), of the Tennessee Wildlife Resource
Agency, developed a new technique for spawning and hatching
striped bass which has been adopted by several of the abovementioned hatcheries. The new technique involves the use of circular tanks into which hormone-injected, wild, gravid females andmales are placed. In most cases the fish spawn, whereupon, they
are removed from the tank. The fertilized eggs hatch in the tank,and 4 or 5 d later the fry become concentrated around the edge ofthe tank and are dipped out for distribution to rearing facilities.
This technique has several advantage as follows. 1) The labor andequipment involved in handling, ova-sampling, spawning, andhatching are reduced or eliminated. 2) The hatchery manager does
not have to be experienced in predicting the time of ovulation andegg overripeness. In fact, overripeness is avoided. 3) The hatch isequal or superior to the Stevens method. 4) The adult fish can bereleased in much better condition, perhaps to spawn again. This
technique is highly recommended.

Intensive Rearing
Larvae.-Many attempts to rear larval striped bass intensively
have been made in recent years with rather limited success. Verylittle survival has been possible when attempting to feed prepared
diets to post-larvae. The feeding of brine shrimp and zooplankton
followed by prepared diet has met with greater success (McIlwain
1976 2 ). At this writing, however, pond culture is the only feasible
way of rearing striped bass in large quantities.

Care and Feeding of Larval Striped Bass
Striped bass larvae begin feeding 5 d after hatching and on thatday they must be offered brine shrimp or rooplankton or bereleased in earthen ponds where they find naturally produced
rooplankton and insect life. (Experiments concerning the releaseof fry into the wild demonstrated a low survival rate and it was
concluded in the early 1960's that the rearing of larvae to fingerlings before release into the wild was the most efficient way to
produce striped bass populations in reservoirs.)
The larvae are usually transported to the pond site in sealed,plastic bags containing 15 I of water and 0.014 m 3 of gaseous oxygen. The bag is placed in a styrofoam container in order to main-

Fingerlings.-Contrary to the results with larvae, fingerlings
can easily be trained to take dried diets and have been reared in'Mcilwain, T. D. 1976. Annual progress report on striped bass rearing and stock:ing program - Mississippi. Unpubl. rep., 33 p. Gulf Coast Research Laboratory,
Ocean Springs, Miss.

30

Much needs to be learned concerning the optimum number offingerlings which should be introduced into a given body of waterand there is no doubt that culture techniques can be made more
efficient with additional research (Bonn et al. 1976). Commercial
aquaculture of striped bass, which failed in the mid-1970's, may
be tried again in the near future because of more favorable
markets and better techniques. The inland reservoir striped bass
program will continue to grow and to benefit the sport fishermen.
The estuarine striped bass enhancement program will benefit bothsport and commercial fishermen.

large quantities in raceways. In Florida, a now defunct commercial enterprise (Marine Protein Corp.) reared large numbers offingerlings and sub-adults in raceways and silos. The author was
the manager in charge of a pond rearing facility in North Florida(Palatka) where striped bass larvae were reared to fingerlings anda raceway-silo facility in south Florida (Homestead) where thefingerlings were reared and sold as advanced fingerlings or reared
as food fish. While most of the information engendered is proprietary, the following statements can be made. 1) Over 300,000
fingerlings were reared in 208 I drums or 1,100-1,900 I horizontal
raceways. 2) Sixty thousand fingerlings were sold for stocking in
ponds and lakes in the United States, and, on 2 July 1974, 3,000
fingerlings were successfully shipped by air to the University ofTokyo. 3) Two hundred forty-four thousand fingerlings were
stocked into six silos at lengths varying between 5.3 and 18.5 cm.
The silos were of different heights and contained between 70,400
and 136,600 I of water. 4) Four thousand five hundred kilogramsof advanced fingerlings (25-28 cm) and over 9,000 kg of food fish(35-46 cm) were produced in six silos in 1973 and 1974.5) Major
problems included pesticide poisoning (heptachlor epoxide) fromsurrounding truck farms, bacterial diseases (Flexibacter columaris,
Aeromonas sp.), cannibalism, and the "oil crunch" which increased pumping costs beyond feasibility.

LITERATURE CITED
BAKER, J. E.
1976. The rearing of Hudson River striped bass at the Edenton National Fish
Hatchery, 1975. Final report prepared for Consolidated Edison Company
of New York, Inc., 16 p.
BAYLESS, J. D.
1972. Artificial propagation and hybridization of striped bass, Morone
saxalilis (Walbaum). S.c. Wildt. Mar. Res. Dep., 135 p.
BISHOP, R. D.
1975. The use of tanks for spawning striped bass (Morone saxalitis). Proc.
28th Annu. Conf. Southeast. Assoc. Game Fish Comm. 1974, p. 35-44.
BONN, E. w., w. M. BAILEY, J. D. BAYLESS, K. E. ERICKSON, and R. E.
STEVENS (editors).
1976. Guidelines for striped bass culture. Am. Fish. Soc., Bethesda, Md.,
103 p.
BRASCHLER, E. W.
1975. Development of pond culture techniques for striped bass Morone saxalitis (Walbaum). Proc. 28th Annu. Conf. Southeast. Assoc. Game Fish
Comm. 1974, p. 44-48.

Hybridization
Between 31 March and 18 April 1965, the author, while serving as manager of the Moncks Corner Striped Bass Hatchery,fertilized three different groups of striped bass eggs with spermfrom white bass, Morone chrysops. The cross was succe§sful andthe hybrid has proven itself to be a valuable addition to the overall
striped bass program in the United States because it almost invariably survives better than striped bass in the larval, fingerling,and sub-adult stages. In addition, it grows as well or better thanstriped bass for the first 5 yr. It does not successfully reproduce
itself in the wild and does not live as long as striped bass, andtherefore, produces few fish over 6.8 kg. Because of its high survivability, a hybrid fishery can be produced and maintained atmuch less cost and effort than is possible with striped bass (Ware1975).
Two other species, M. americana and M. interupta, have also
been crossed with striped bass but none have proven to be as
vigorous and as successful as the original cross, striped bass
female vs. white bass male (Bayless 1972). Bishop (1975) pointed
out that the tank culture method is not effective for hybrid fry production because female striped bass will not release their eggs in
the presence of white bass males.

MASSMANN, W. H.
1975. Twenty five years of federal-state cooperation for improving sport
fishing: accomplishments under the federal aid in fish restoration program,
1950-1975. U.S. Dep. Inter., Fish Wildt. Serv., Wash., D.C., 37 p.
RANEY, E. C., E. F. TRESSELT, E. H. HOLLIS, V. D. VLADYKOV, and D. H.
WALLACE.
1952. The striped bass (Roccus saxalilis). Bull. Bingham Oceanogr. Collect.
Yale Univ. 14,177 p.
SCRUGGS, G. D., Jr., and J. C. FULLER, Jr.
1955. Indication of a fresh water population of striped bass, "Roccus saxalilis" (Walbaum), in Santee-Cooper Reservoir. Proc. Southeast. Assoc.
Game Fish Comm. 1954, p. 64-70.
STEVENS, R. E.
1958. The striped bass of the Santee-Cooper Reservoir. Proc. 11th Annu.
Conf. Southeast. Assoc. Game Fish Comm. 1957, p. 253-264.
1965. A report on the operation of the Moncks Corner Striped Bass Hatchery.
S.C. Wildt. Resour. Dep., 25 p.
1966. Hormone-induced spawning of striped bass for reservoir stocking.
Prog. Fish-Cult. 28:19-28.
1967a. A final report on the use of hormones to ovulate striped bass, Roccus
saxalitis (Walbaum). Proc. 18th Annu. Conf. Southeast. Assoc. Game Fish
Comm. 1964, p. 525-538.
1967b. Striped bass rearing. North Carolina Cooperative Sport Fishing
Unit, North Carolina State University, Raleigh, 14 p.
1975. Current and future considerations concerning striped bass culture andmanagement. Proc. 28th Annu. Conf. Southeast. Assoc. Game Fish Comm.
1974, p. 69-73.
STEVENS, R. E., and J. C. FULLER, Jr.
1965. A preliminary report on the use of hormones to ovulate striped bass,
Roccus saxalilis (Wa1baum). Proc. 16th Annu. Conf. Southeast. Assoc.
Game Fish Comm. 1962, p. 222-235.
STEVENS, R.. E., O. D. MAY, Jr., and H. J. LOGAN.
1965. An interim report on the use of hormones to ovulate striped bass,
Roccus saxalitis (Walbaum). S.C. Wildt. Resour. Dep., Mimeogr. Rep., 17 p.
WARE, F. J.
1975. Progress with Morone hybrids in fresh water. Proc. 28th Annu. Conf.
Southeast. Assoc. Game Fish Comm. 1974, p. 48-54.

CONCLUSIONSThe striped bass has found favor with fisheries managers since
the end of the last century. The early work of S. G. Worth at
Weldon, N.C., around the turn of the century has been amplified
by modern workers over the past 15 yr and, as a result, inland
fisheries occur in 30 reservoirs in 17 different states (Massmann1975). Enhancement efforts in estuaries in Florida, Alabama,
Mississippi, Louisiana, California, Texas, and New York are being carried out with promising results. The Soviet Union has succeeded in establishing one or more wild populations from larvaeshipped from the Moncks Corner Hatchery in 1965.

31