16NOAA Technical Report NMFS 16

Proceedings of the Ninth andTenth U.S.-Japan Meetings
on Aquaculture
Carl J. Sindermann (Editor)

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

Panel Chairmen:
NINTH MEETING: AKIRA SUDA - JapanWILLIAM N. SHAW - United States
TENTH MEETING: CONRAD MAHNKEN - United States
TAKESHI NOSE-Japan

November 1984

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

NOAA TECHNICAL REPORTS NMFS
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copies may be obtained from: U.S. Department of Commerce, National Technical Information Service, 5285 Port Royal Road,
Springfield, VA 22161.

NOAA Technical Report NMFS 16

Proceedings of the Ninth andTenth U.S.-Japan Meetings
on Aquaculture
Carl J. Sindermann (Editor)

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

November 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 to aquaculture which could be of benefit to both countries.
The UJNR was started by a proposal made during the Third Cabinet-Level Meeting of the Joint 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.

Akira Suda - Japan
William N. Shaw - United Statesii

CONTENTS

NINTH MEETING
Papers presented by Japanese panel members:
KANAZA WA, A. Nutritional requirements and artificial diets of Kuruma shrimp, Penaeus japonicus . . . .. . . . . . . . . . . . . . . .
KURATA, H., K. SHIGUENO, and K. YATSUYANAGI. Kuruma shrimp culture in Japan. . . . . . . . . . . . . . . . . . . . . . . . . . . .
NOMA, T. Structure of a Kuruma shrimp culture pond. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Papers presented by U.S. panel members:
LIGHTNER, D. Y., R. M. REDMAN, D. A. DANALD, R. R. WILLIAMS, and L. A. PEREZ. Major diseases encountered incontrolled environment culture of penaeid shrimp at Puerto Penasco, Sonora, Mexico. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
MALECHA, S. Research and development in freshwater prawn, Macrobrachium rosenbergii, culture in the United States:
Current status and biological constraints with emphasis on breeding and domestication
SHLESER, R. A., and L. F. FOLLETT. Research and development in maturation and production of penaeid shrimp in the.. .. .. .. .. .. .. . ..
. . .. . .. .. .. .. . .. .. .. .. ..
. .. . .. ..
.
.. .. .
Western Hemisphere... . . .. .. .
SPARKS, A. K. An invasive fungus disease of the Tanner crab and its aquacultural connotations

3
9
17

25
35
57
61

TENTH MEETING
Papers presented by Japanese panel members:
KANAZAWA, A., S. TESHIMA, M. SAKAMOTO, H. MATSUBARA, and T. ABE. An attempt to culture the noble scallop,
Mimachlamys nobilis Reeve, using a microparticulate diet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
NOGAMI, K., O. FUKUHARA, and S. UMEZAWA. Recent developments in shellfish culture in southern Japan. . . . . . . . . .
UKI, N. Abalone culture in Japan. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
WADA, K. Osmoregulation in marine bivalves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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

71
73
83
89

Statement of Ninth Joint Meeting of the UJNR
Aquaculture Panel, Crustacean Culture,
Kyoto, Japan, May 26-27, 1980

The Ninth Joint Meeting of the UJNR Aquaculture Panel was held on May 26-27, 1980, at the
Kyoto International Conference Hall, in Kyoto, Japan. On the first day of the meeting, Dr. S. Satoannounced a change of officers for the Japanese delegation. Dr. A. Suda is the new Chairman, andDr. M. Fujiya the new Vice-Chairman. Dr. T. Nose is the new Secretary General. Mr. W. Shaw, theU.S. Chairman, announced that Dr. C. Mahnken will take over the chairmanship of UJNR for theAmerican side at the conclusion of the 9th session; however, due to Mr. Shaw's accident, Dr.
Mahnken chaired the session on the second day.
The business meeting was held on the second day. The morning session was chaired by Dr. Suda
and afternoon session by Dr. Mahnken. Dr. Mahnken introduced Dr. Banerjee as the new ViceChairman of the U.S.lUJNR panel.
I. Scientist Exchange
Panel concluded that the scientist exchange program sponsored by UJNR has been an effectivemeans of advancing aquaculture science and the exchange of information between the two countries. An extended study visit by one U.S. scientist (Mr. McCormick) is in progress and the visit ofanother U.S. scientist (Dr. Murchelano) may occur in September 1980 or March 1981.
Dr. Shleser will visit Japanese aquaculture industries in the near future. Four U.S.. scientists
visited Japan to participate in the 9th UJNR Conference (Drs. Shleser, Clark, Lightner, andMalecha). It was suggested by the Japanese that a detail travel plan and coordination be affected
previous to arrival of exchange scientists. Dr. Arai will be the next Japanese scientist to visit the
U.S. during 1980. He will conduct cooperative research on fish nutrition with Dr. Mahnken at theNorthwest and Alaska Fisheries Center (NW AFC), National Marine Fisheries Service, at Seattle,
Washington.
It was agreed to exchange information relative to the location and activities of aquaculture scientists in both countries. It was also agreed that a continuous exchange of information on relevant
issues be affected by the two chairmen.
2. Literature Exchange
The U.S. and Japan will continue literature exchange as done in the past. The U.S. chairman suggested that aquaculture literature search can be obtained from NW AFC computer facilities.
One translation (Eel culture) was given to the Japanese panel this year. The U.S. also elected tosend the national aquaculture plan to the Japanese chairman. The Japanese requested literature on
the culture of seaweed.
3. Cooperative Studies
An up-date of ongoing programs was presented. These included:a) Mass mortality of oysters.
b) Disease resistance of U.S. oysters in Japan (project needs re-evaluation).
c) Register of marine pathology (under consideration).
d) Cooperative studies on abalone (under consideration).
4. Second Five-Year Plans
The Japanese panel proposed two projects.
a) Large scale propagation of salmon.
b) Marine ranching.
The U.S. panel proposed four projects.
a) Salmon farming with emphasis on evaluation of ocean stocking, seeding technique, carrying
capacity, and smolt physiology.
b) Aquaculture engineering with emphasis on structures and new automated husbandry techniques.
c) Reproductive physiology, genetics, breeding of aquaculture species.
d) Environmental quality standards in aquaculture systems with emphasis on control of
metabolic by-products (self pollution).

5. Next Joint Meeting
The theme of the meeting will be "Molluscan Aquaculture," the site, the University of Delaware,and the date, September 1981.
It was agreed that UJNR will jointly sponsor a cructacean and molluscan nutrition symposiumwith the World Mariculture Society and the University of Delaware. The symposium will be heldclose to the scheduled time of the UJNR meeting. Japanese participants will include Dr. Koji Wada.
6. Field Trip
U.S. chairman thanked Dr. Matsusato for extensive activities on behalf of the panel.
7. Publication
An editorial policy will be developed at a later date by the U.S. panel and will be forwarded to
the Japanese panel for review.

Akira Suda - Japan
William N. Shaw - United States2

Nutritional Requirements and Artificial Dietsof Kuruma Shrimp, Penaeus japonicus
AKIO KANAZAW AIINTRODUCTION

52.4

Since Hudinaga (1942) succeeded in the artificial hatching andsubsequent culture of larvae of Kuruma shrimp, Penaeus
japonicus, techniques in these fields have developed remarkably.
Now, in Japan, Kuruma shrimp have been produced in commercial shrimp farms under artificially controlled conditions fromhatching to market size. However, problems still remain to besolved concerning disease and the quality and cost of diets. Nearly
half of the reasons for shrimp disease seem to be directly or indirectly attributable to nutritionally deficient diets.
Like other animals, shrimp require proteins, lipids, carbohydrates, minerals, and vitamins. Lack of even one nutrient resultsin deficiency disease, poor growth, and mortality during rearing.
In this presentation, I will discuss my investigation on the nutritional requirements for proteins, lipids, minerals, carbohydrates,and vitamins in Kuruma shrimp.

57.0

1.5

47.8
38.7
20.3

-Ol

61.6

~

29.5

.r:.

.....ClJ

Ol

::;c

~1.0
o
ro

66.2
11.2

PROTEINS AND ESSENTIAL
AMINO ACIDS
The dietary protein requirement of Kuruma shrimp was
estimated to be 52% when casein was used as a protein source(Deshimaru and Yone 1978) (Fig. 1). This value was higher than
the requirement for proteins in the eel (45%) and the carp (39%).
Next, I tried to culture Kuruma shrimp using a diet containing a
mixture of amino acids, instead of casein, to determine the essential amino acid requirements. However, the above amino acid diet
did not support the growth of Kuruma shrimp. Therefore, theessential amino acids were evaluated by tracer experiments inwhich the incorporation of PH] acetate into each amino acid was
examined after injection (Kanazawa and Teshima 1981) (Table
1). On the basis of the results of these tracer experiments,
arginine, methionine, valine, threonine, isoleucine, leucine, lysine,
histidine, phenylalanine, and tryptophan were found to be essential for Kuruma shrimp (Table 2).

0.7

r ----r---~

2.0

r,

o

2

4 Weeks

Figure I.-Growth curves of Kuruma shrimp fed on diets containing different
protein levels (percent).

Table I.-Incorporation of radioactivity Into the Individual amino acidsof protein fraction In shrimps 6 d after Injection of ['HI acetate.

LIPIDS
Amino acids

Feeding trials showed that lipids were important nutrients for
Kuruma shrimp, not only as an energy source, but also as a sourceof indispensable substances such as essential fatty acids andsterols.

Aspartic acid
SerineGlutamic acid
ProlineGlycine
AlanineCystineTyrosine
I Faculty of Fisheries, University of Kagoshima, 4-50-20 Shimoarata, Kagoshima
890, Japan.

Threonine3

Specific
activity(cpm!" mole)
203
102
196
138
132
187
159
1.2
1.9

Amino acids

ValineMethionine
Isoleucine
LeucinePhenylalanine
LysineHistidine
Arginine
Tryptophan

Specific
activity(cpm! " mole)
0.1
2.5
0.7
0.1
0.1
0.2
0.7
1.2
0.4

Table 2.-Essential amino acid requirements of Kuruma shrimp. +- = nonessential.
Amino acid

Penaeus japonicus

Aspartic acid
Cystine
AlanineGlutamic acid
SerineGlycineProlineTyrosine=essential;

Amino acid

Penaeus japonicus

Methionine
ValineThreonine
Isoleucine

+
+
+
+
+

Leucine20

Growth rate (%)
40
60

80

o
0.05
0.1

+

LysineHistidine
Phenylalanine
Tryptophan+

Arginine

Cholesterol adde
(9/1009 diet)

0.5

+
+
+

1.0

5.0

Requirements for Sterols
Figure 2.-Effect of cholesterol levels on growth of Kuruma shrimp.

Although animals generally synthesize cholesterol from lower
units, such as acetate and mevalonate, Kuruma shrimp and othercrustaceans lack this sterol-synthesizing ability (Zandee 1962,
1964,1966,1967; Van den Oord 1964; Gosselin 1965; Whitney
1969,1970; Teshima and Kanazawa 1971; Walton and Pennock
1972; O'Rouke and Monroe 1976; Teshima et al. 1976) (Table 3).
However, cholesterol was shown to be the precursor of steroid
hormones (Kanazawa and Teshima 1971) and molting hormones(Spaziani and Kater 1973; Gagosian et al. 1974) in crustaceans.
These results indicated that cholesterol is an essential substancefor normal growth in crustaceans. My feeding experiments revealed that the dietary cholesterol requirement in Kuruma shrimp was
about 0.5% (Kanazawa et al. 1971) (Fig. 2).

4% 18:1w9140

4% 18:1w9

incorporation--....
N

Cancer pagrus
Homarus gammarus
As/aeus fluviatilis
Rhithropanopus harrissii
Libinia emerginata
Callinecles sapidus
Balanus nubilus
A rternia salina
Penaeus japonicus
Panulirus japonica
Portunus trituberculatus
Carcinus maenas
Eupagurus bernhardus
Annadilidium unlgare
Cirolana lu1/fordi
Ligia occidentalis
Helice (ridens tridens
Seaarma dehaani+ 1% 18:3w3",C)

4% 18:1w9~80
C)+ 1% 18:Zw6

....
~

~

References

60

coZandee (1962, 1964, 1966)
Van den Oord (1964)
Zandee (1964, 1967)
Gosselin (1965)]=}4% 18:1w9c100oAs/aeus astaeus+ 1% 22:6w3120

Table 3.-Biosynthesis of sterols in Crustacea.
Species+ 1% 20:5w3

5% 18:1w940

Lipid free

Whitney (1969)

20
Whitney (1970)~}

Teshima and Kanazawa (1971)=}

Walton and Pennock (1972)=}

O'Rouke and Monroe (1976)=}

Teshima et al. (1976)o
10 20 30 40

50 60 65 Days

Figure 3.-Growth of Kuruma shrimp fed diets containing several fatty acids.

containing vegetable oils such as soybean oil and corn oil, is probably attributable to the lack of highly polyunsaturated fatty
acids. Fish oil, such as cod liver oil rich in w3-polyunsaturated
fatty acids, produced a high growth rate for Kuruma shrimp.

Essential Fatty Acids
Growth-Promoting Factor in Short-Necked Clam Oil
In Kuruma shrimp, linolenic acid (18:3w3) was more effective
as an essential fatty acid than linoleic acid (18:2w6). However,
eicosapentaenoic acid (20:5w3) and docosahexaenoic acid
(22:6w3) exerted a higher essential fatty acid activity thanl8:3w3 for the shrimp (Kanazawa et al. 1977, 1978; Kanazawa,
Teshima, Tokiwa, Kayama, and Hirata 1979) (Fig. 3). The dietaryrequirements for either 20:5w3 or 22:6w3 in Kuruma shrimp
were estimated to be about 1% (Kanazawa, Teshima, and Endo
1979) (Fig. 4). Therefore, poor growth of Kuruma shrimp on diets

Feeding trials showed that short-necked clam oil produced thehighest growth rate for Kuruma shrimp among the several lipid
sources examined. These results suggested that short-necked clam
oil probably contained certain growth-promoting factors besides
essential fatty acids. The search for these factors demonstrated
that the growth-promoting effect of short-necked clam oil was
mainly due to lecithin and kephalin (Kanazawa, Teshima,
Tokiwa, Endo, and Abdel Razek 1979) (Fig. 5).
4

60

50
~ 40

..
c

'" 30

~

a:;

"" 20
10

10

30

20

40

Days

120
100

Ei cosapentaenoic acid
20:5r.G./M
J,-. --

~ 80

.'"
c

~ 60
Figure 4.-Dietary requirement of Kuruma shrimp for linoleic,
linolenic, eicosapentaenoic, and docosahexaenok acids.

~40
20.1. 0%.0.5%.'/~.~:----./:~:~~
:~:/

10

20

30

40

50

Days

_n. PRO+ U Lecithin

MINERALS......7% PRO+ U Kephalin

120

Although the shrimp absorb some minerals from seawater,
mineral supplementation is necessary for optimum growth. I
assume that Kuruma shrimp require a dietary source of minerals
because of the considerable loss of calcium and other minerals
contained in the exoskeletons during molting. Mineral requirements of Kuruma shrimp were estimated as follows (mg/g of diet):Ca, 10; P, 10; K, 9; Mg, 3; Cu, 0.06 (Fig. 6). The addition of Fe
and Mn to the diet resulted in a decrease in growth rate
(Kanazawa and Teshima in press).

'7% PRO+ 1% Polar lipids~8% PRO'"7% PRO+ l% Total lipids"-7% PRO+ 1% ·Neutral lipids

80

CARBOHYDRATES
co
n:I
Ol

Interestingly, disaccharides and polysaccharides were superior
to monosaccharides, such as glucose, as a carbohydrate source for
Kuruma shrimp. Diets containing disaccharides, such as maltose
and sucrose, produced high growth and survival rates (AbdelRahman et al. 1979) (Fig. 7). The addition of 0.8% glucosamine
improved the growth of Kuruma shrimp, whereas that of chitin
resulted in a decrease in growth rate.

.....
.s::.

Ol

';i; 40;3:

VITAMINS
10

20

30

Days

The requirements for vitamin C, choline, and inositol in
Kuruma shrimp were determined to be 1.0,0.06, and 0.2% of thediet (Figs. 8, 9, 10), respectively. Diets lacking in vitamin C
resulted in poor growth and high mortality (Kanazawa et al. 1976;

Figure 5.-Effect of short·necked clam lipids on growth of Kuruma shrimp(PRO = pollack liver oil).

5

140

140

140

120

l20

120

100

~100

~ lOC

~

i Be

1
"

I

40

2C

20

Diet N o . 1 '4
5
Co contont 0 5.' 10.6 21.1 41.8("61III drr 41et)

Effect of Ca leyels In dieton growth of Kur\ll1ll shrimp

~

1

60

4C

I.

i eo

i eo

6C

fl

60
40

12

14
15
2.7 50' 10.6 21.1
lJ

I

I

0
Dio~ 110.
X. content
0(q/Ill drr 41ot)

Effect of P leyels In dieton growth of Kuruma shrimp

I

III i I200ll1e~ 110.
11
P cOl1Wn~
0(q/Ill drr 41o~)

II
I

10
6
7
9
4.5 9.0 17.9 '5.9

Effect of K leyels In dieton growth of Kuruma shrimp

Figure 6.-Requirements for minerals in Kuruma shrimp.

1.6
1.4

-

Vitamin C added(mg/100g drydiet)(1)19.5% Glucose(2)19.5% Sucrose(3)19.5% Dextrin(4)19.5% Starch-potato(5)19.5% Glycogen(6)19.5% Maltose

20

Percent gain
40
60

80

100

6

o
20

2

en

-1.2

1000

+>
en

.s::

....

2000

3
5

CIJ

3

» 1.0

"'0

o

..c
Figure S.-Effect of vitamin C levels on growth of Kuruma shrimp.

CIJ

~0.8

SGJ

1

~

Cho 1ine added

0.6(mg/100g diet)

20

Percent gain
40
60

80

100

o
10

Days

20

30

2.4
12
60

Figure 7.-Effect of dietary carbohydrates on growth of Kuruma shrimp.

300

Guary et aI. 1976). Dietary requirements of Kuruma shrimp forthiamine and pyridoxine were found to be approximately 6-12
and 12 mg%, respectively (Deshimaru and Kuroki 1979).

Figure 9.-Effect of choline levels on growth of Kuruma shrimp.

COMMERCIAL DIETS FOR
KURUMA SHRIMP

MICROENCAPSULATED DIETS

On the basis of my results on the nutritional requirements ofKuruma shrimp, several types of diet for Kuruma shrimp werecommercially produced in Japan. Some diets resulted in a higher
growth rate than live feed. The annual production of commercial
diets for Kuruma shrimp is about 1,500 tons.

Live feed is used in the culture of larvae after hatching. My
laboratory has attempted to make an artificial diet for larval
Kuruma shrimp. Recently, the staff has succeeded in culturing
Kuruma shrimp larvae from zoea stage to postlarvae by feeding
only the microencapsulated diet (Jones et aI. 1979).
6

Inositol added(mg/100g diet)

JONES, D. A., A. KANAZAWA, and S. ABDEL RAHMAN.
1979. Studies on the presentation of artificial diets for rearing the larvae of
Penaeus japonicus Bate. Aquaculture 17:33-43.
KANAZAWA, A., N. TANAKA, S. TESHIMA, and K. KASHIWADA.
1971. Nutritional requirements of prawn-II. Requirement for sterols. Bull.
Jpn. Soc. Sci. Fish. 37:211-215.
KANAZA WA. A., and S. TESHIMA.
1971. In vivo conversion of cholesterol to steroid hormones in the spiny
lobster, Panulirus japonica. Bull. Jpn. Soc. Sci. Fish. 37:891-898.
1981. Essential amino acids of the prawn. Bull. Jpn. Soc. Sci. Fish. 47:
1375-1377.
In press. Requirements for minerals in prawn. Mem. Fac. Fish. Kagoshima
Univ.
KANAZAWA, A., S. TESHIMA, and M. ENDO.
1979. Requirements of prawn, Penaeus japonicus, for essential fatty acids.
Mem. Fac. Fish., Kagoshima Univ. 28:27-33.
KANAZA WA, A., S. TESHIMA, M. ENDO, and M. KAYAMA.
1978. Effects of eicosapentaenoic acid on growth and fatty acid compositionof the prawn, Penaeus japonicus. Mem. Fac. Fish., Kagoshima Univ. 27:
35-40.
KANAZAWA, A., S. TESHIMA. and N. TANAKA.
1976. Nutritional requirements of prawn - V. Requirements for choline andinositol. Mem. Fac. Fish .• Kagoshima Univ. 25:47-51.
KANAZA WA, A., S. TESHIMA, S. TOKIW A. M. ENDO, and F. A. ABDELRAZEK.
1979. Effects of short-necked clam phospholipids on the growth of prawn.
Bull. Jpn. Soc. Sci. Fish. 45:961-965.
KANAZAWA, A., S. TESHIMA, S. TOKIWA, M. KAYAMA, and M. HIRATA.
1979. Essential fatty acids in the diet of prawn-II Effect of docosahexaenoic
acid on growth. Bull. Jpn. Soc. Sci. Fish. 45:1151-1153.
KANAZAWA, A., S. TOKIWA, M. KAYAMA, and M. HIRATA.
1977. Essential fatty acids in the diet of prawn-I Effects of linoleic andlinolenic acids on growth. Bull. Jpn. Soc. Sci. Fish. 43:1111-1114.
O'ROUKE, L., and R. E. MONROE.
1976. Utilization of radiolabelled acetate by three isopods in lipid synthesis.
Compo Biochem. Physiol. 55B:553-557.
SPAZIANI, E., and S. B. KATER.
1973. Uptake and turnover of cholesterol- 14 C in V-organs of the crab Hemigrapsus as a function of the molt cycle. Gen. Compo Endocrinol. 20:534549.
TESHIMA. S., and A. KANAZAWA.
1971. Biosynthesis of sterols in the lobster, Panulirus japonica, the prawn,

Percent gain

o

40

60

80

100

o
40
100
200

400

Figure IO.-ElTect of inositol levels on growth of Kuruma shrimp.

CONCLUSION
My nutritional studies have made a contribution to the development of formula diets which are coming into the market.
Previously, live feed, such as the short-necked clam and themussel, was widely used for the culture of Kuruma shrimp andwas an excellent diet. However, such live feeds are too expensive
for use in shrimp culture and the supply is unstable. If one uses
materials lacking in some nutrients, careful attention should be
paid to adjust every nutrient, such as proteins, lipids, minerals,
carbohydrates, and vitamins, to adequate levels on the basis ofdata on the nutritional requirements of Kuruma shrimp.
It is necessary to devise a diet which accelerates ovary maturation in Kuruma shrimp. If this problem can be solved, the cultureof Kuruma shrimp can be performed completely under artificial
conditions.

Penaeus japon;cus, and the crab, Ponunus trituberculatus.

Compo Biochem.

Physiol. 38B:597-602.
TESHIMA, S., A. KANAZAWA, and H. OKAMOTO.
1976. Sterol biosynthesis from acetate and the fate of dietary cholesterol anddesmosterol in crabs. Bull. Jpn. Soc. Sci. Fish. 42:1273-1280.
VAN den OORD, A.
1964. The absence of cholestrol synthesis in crab. Cancer pagurus L. Compo
Biochem. Physiol. 13:461-467.
WALTON, M. J., and J. F. PENNOCK.
1972. Some studies on the biosynthesis of ubiquinone, isoprenoid alcohols.
squalene and sterols by marine invertebrates. Biochem. J. 127:471-479.
WHITNEY, J. O.
1969. Absence of sterol synthesis in larvae of the mud crab Rhithropanopeus
harrissii and of the spider crab Libinia emarginata. Mar. BioI. (Berl.) 3: 134135.
1970. Absence of sterol biosynthesis in the blue crab Callinectes sapidus
Rathbun and in the barnacle Balanus nubilis Darwin. J. Exp. Mar. BioI.
Ecol. 4:229-237.
ZANDEE, D.1.
1962. Lipid metabolism in ASlacus astacus L. Nature (Lond.) 195:814-815.
1964. Absence of sterol synthesis in some Arthropods. Nature (Lond.) 202:
1335-1336.
1966. Metabolism in the crayfish ASlacus astacus (L). I11.-Absence ofcholesterol synthesis. Arch. Int. Physiol. Biochim. 74:435-441.
1967. Absence of cholesterol synthesis as contrasted with the presence offatty acid synthesis in some Arthropods. Compo Biochem. Physiol. 20:81 1822.

LITERATURE CITEDABDEL-RAHMAN, S. H., A. KANAZAWA, and S. TESHlMA.
1979. Effects of dietary carbohydrate on the growth and the levels of thehepatopancreatic glycogen and serum glucose of prawn. Bull. Jpn. Soc. Sci.
Fish. 45:1491-1494.
DESHIMARU, 0., and K. KUROKI.
1979. Requirement of prawn for dietary thiamine, pyridoxine, and choline
chloride. Bull. Jpn. Soc. Sci. Fish. 45:363-367.
DESHIMARU, 0., and Y. YONE.
1978. Optimum level of dietary protein for prawn. Bull. Jpn. Soc. Sci. Fish.
44:1395-1397.
GAGOSIAN, R. B., R. A. BOURBONNIERE, W. B. SMITH, E. F. COUCH, C.
BLANTON, and W. NOVAK.
1974. Lobster moiling hormones: Isolation and biosynthesis of ecdyslerone.
Experientia 30:723-724.
GOSSELIN, L.
1965. L'utilisation de l'acide mevalonique-2- 14 C, in vivo, dans I'hepatopancreas de Astacus fluviatilis. Arch. Int. Physiol. Biochim. 73:543-544.
GUARY, M., A. KANAZAWA, N. TANAKA. and H. J. CECCALDI.
1976. Nutritional requirements of prawn - VI. Requirement for ascorbic acid.
Mem. Fac. Fish., Kagoshima Univ. 25:53-57.
HUDINAGA, M.
1942. Reproduction, development and rearing of Penaeus japonicus Bate.
Jpn. J. Sci. 10:305-393.

7

Kuruma Shrimp Culture in JapanHIROSHI KURATA,l KUNIHIKO SHIGUENO,2 and
KENRO YATSUYANAGP

Figure 2 shows that the domestic annual catch of wild Kuruma
shrimp by fisheries in Japan has, for the most part, fluctuated between 2,000 and 3,000 t over the past 30 yr. The drastic fall in thelate 1960's recovered in the early 1970's owing to concentrated
efforts in releasing artificial fry in coastal nursery grounds.
Culture production, on the other hand, has followed a more or lesssteady increase since its beginning. Figure 2 also illustrates thatthe area of production is concentrated in the southern part ofJapan. The major limiting factors in the abundance and distribu-

INTRODUCTION
Live Kuruma shrimp is one of the most esteemed seafood
delicacies in Japan. Its maximum price may exceed ;fl0,OOO(about US$45)/kg at the wholesale market in large cities. Japan's
fishery and transport industries exercise special care in handling
this product to assure its freshness because of its prime importance in determining its market price. Most Kuruma shrimp are
kept alive throughout the entire process of catching or harvesting,and packing and shipping to urban consumption centers.
Kuruma shrimp culture in Japan began in the early 1960's andhas developed to a ;f9 billion business within 20 yr. Culture
techniques practiced today in Japan may be divided into two major types according to the kind of facilities used for growing. One
is an extensive type using tidal ponds of 0.5-5.0 ha in area
pioneered by the late M. Hujinaga; the other is an intensive typeusing concrete tanks with a dual bottom system developed by K.
Shigueno. There are considerable variations in detail within each
type.
Culture techniques of Kuruma shrimp have been reported indetail, along with experimental data, by Shigueno (1975) and Hujinaga et al. (1977). Commercial aspects of Kuruma shrimp
culture have been analyzed economically by Hirasawa andWalford (1979). This report briefly summarizes the present status
and problems of the Kuruma shrimp culture industry in Japan
from a technical and, to some extent, economic point of view.

400

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CONSUMPTION AND PRODUCTION OFSHRIMP IN JAPAN

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The Japanese nominal annual consumption of all kinds ofshrimp, as defined by domestic production plus imports, has
climbed steadily during the last 20 yr from about 0.6 kg per capita
in 1960 to 3.3 kg per capita in 1979 on a fresh head-on basis.
Over the same period, domestic production has remained relatively stable at 60-70 thousand t (metric tons) a year. The increased
consumption is associated with increased imports of penaeid
shrimp from Asia and South America. Figure 1 shows that inJapan shrimp of all kinds combined have supported a ;f 300-400
billion business in recent years.
Japan's demand for shrimp as a whole has leveled off recently.
However, the situation is quite different for live Kuruma shrimp.
Hirasawa and Walford (1979) estimated, based on income elasticity analysis, that a 10% increase in per capita income will
enhance the demand for live Kuruma shrimp by 22%.

o

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100

1975

1976

1977

1978

1979

Figure I.-Japan's nominal annual consumption of all kinds ofshrimp. Amountof import may be doubled when converted into original fresh head-on weight.
1-4, domestic production In head-on weight; 1, cultured Kuruma shrimp; 2,
wild Kuruma shrimp; 3, other marine shrimps; 4, freshwater shrimps; S,
imported shrimps, heads-off, frozen, salted, or dried. Data from the Fisheries
Trade Statistics and the Annual Report of Catch Statistics on Fisheries andAquaculture, Japanese Government.

'Nansei Regional Fisheries Research Laboratory, Ohno-cho, Hiroshima 739-40,
Japan.
'Kagoshima Prefecture Fisheries Research Station, Kinko-cho, Kagoshima 892,
Japan.
'Yamaguchi Prefeclure Fisheries Seed Production Center, Aio-cho, Yamaguchi
754-11, Japan.

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Figure 2.-Domestic catch and harvest of Kuruma shrimp In Japan,
showing annual trend (upper) and production by prefecture In 1977
(lower). Data from the Annual Report of Catch Statistics on Fisheries and Aquaculture, Japanese Government.

00':

()

CULTURE TECHNIQUESlion of the wild population are Ihe temperature of coastal waters
and the lack of large expanses of intertidal flats in the immediateinshore areas. The centers of cullure produclion are shifted further
south and include Okinawa where there are no wild populations.
The data presented i~ Figure 3 show that wild Kuruma shrimp
are fished for the most part from May to October, with the busiest
season from June to September. Cultured Kuruma shrimp are
harvested during the rest of the year when the market price isrelatively high. The main localities of Kuruma shrimp cullure arein the Seto Inland Sea, Amakusa, and Kagoshima. They differ inthe period of peak shipment depending on the water temperature
in winter, thus minimizing competition in the common market.

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Fry Production
Spawners.-AII the spawners for fry production are separated
from ordinary commercial catches. Artificial spawner production
is not yet practiced in Japan on a commercial scale. Wild
spawners are available as early as mid-March in restricted oceanic
grounds and as late as early October in coastal grounds.
Spawners are introduced directly into the breeding tank upon
arrival in the required numbers. The percentage of accepted
spawners that successfully spawn in the tank range from 20 to
50% depending on their activity and size. Usually they are held in
the tank for 2 d and are removed on the third day before rapid
growth of diatoms begins.

8
6

Breeding tank.-A simple rectangular concrete tank, 100-250
m3 in volume, is used in commercial fry cullure. As long as a sufficient number of spawners is available, a large tank is preferred.
Figure 4 shows the layout of a common rearing tank. It is usually
covered by transparent materials to maximize the use of solar
energy. The agitation of rearing water is effected by aeration withblowers through air diffuser stones. A rotary blade may also be installed slightly above the tank bottom to ensure a homogeneous
distribution of larvae, feed, and organic wastes. The tank water isheated early in the breeding season when the water is not warm
enough for larval development. The optimum temperature range is
26°-28°C.
Coastal seawater is filtered through a sand layer before it is introduced to the rearing tank. Shrimp larvae require clean water forsurvival. The quality of the rearing water is controlled by the daily
addition of fresh seawater during the early phase of rearing. For
this purpose the tank is filled with seawater to less than one-halfof its actual depth when spawners are introduced. By the time theFisheries(live)/ - - -~..::=-~.--.•- --.---.

4

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Inland Sea

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Figure 3.-Monthly variation of the wholesale price in Tokyo market in 1974
(upper) and of shipment by localities (lower). (Hlrasawa and Walford 1979.)10

- - - - 1 Om -----~
Ai'
Difful'er

Stocking density and survival rate.-Suitable stocking density is about 30,000/m 3 for newly hatched nauplii, and10,000-15,000/m 3 at harvest of postlarva of 11-13 mm in bodylength and 0.01 g in wet weight. Larval development requires
10-12 d and another 20-25 d are required to reach 0.01 g postlarva. Survival rates throughout larval and postlarval development
may be as high as 50% or greater, but vary to a considerable extent depending upon several factors.

Air Pipe
Steam Pipe

Strainer
10m
SiphonHarvest and shipment.-In order to harvest, the fry are concentrated by draining the rearing water to one-half or one-third ofits depth. They may then be scooped out with a dip net or flushed
out along with the rearing water through the bottom drain andcaught with an appropriate net. They are counted by measuring
either wet weight or volume and shipped in plastic containers bycold storage trucks equipped with an aerating device. About
700,000 fry may be kept in a 1 m 3 container for 10-12 h without
serious ill effects.

Water
SupplyPipe

1

Problems.-Deterioration of the midgut gland may occur during the early postlarval stage. Once this is observed, all theanimals in the tank will perish within a week. This is the only
serious problem in fry production of Kuruma shrimp.

2ml

Stopper
Pipe
Motor

®

Growing Shrimp in Tidal Ponds
Facilities.-The tidal pond is the most commonly used facility
in Japan for growing Kuruma shrimp. About 400 ha of coastal
area, converted mostly from salt evaporation ponds, are now used
for shrimp ponds. The ponds are drained during the off season in
winter for 60-80 d to expose the bottom sand to the atmosphereand sunlight to ensure adequate oxidation. Predatory fishes are
eliminated by applying piscicides before the shrimp fry are
released.
The pond areas range from 0.5 to 5.0 ha. Small ponds are usedas nurseries. For growing, however, large ponds are preferable
because they can be managed at a lower cost per unit area thansmaller ponds. In large ponds, a canal system is constructed running from the periphery toward the sluice gate. The exchange ofpond water is effected by the movement of tides. Usually about
one-third of the pond water is changed daily either during the day
or night. The rate varies according to the ambient temperature,oxygen content, and concentration of diatoms in the pond water.
Exchange of pond water is limited during each neap tide for 3-4 d.
The sluice gate is accompanied outside by an iron lattice to keepout large seaweeds and other floating material; inside a fine meshscreen fence prevents loss of shrimp and intrusion of predatory
fishes.
An aeration system or mechanical agitation is used to mix surface water and to supply oxygen. The deterioration of the bottom
condition may be improved to some extent by stirring bottom
sand with a water jet or by treatment with iron oxide at a densityof 60-120 g/m 2 • Seaweed is controlled by maintaining diatom
populations at an appropriate level.

~~~~~©
Rotary Slade

Figure 4.-Layout of Kuruma shrimp fry production tank. A, noor plan; B,
cross section; C, tank with a rotary blade.

shrimp reach the postlarval stage, the water will almost fill thetank. Afterwards, one-third to one-fifth of the water is renewed
daily according to its degree of deterioration.
Foods and feeding.-Diatoms, such as Skeletonema costatum
or Chaetoceros simplex, are supplied to the protozoeae either bydirect enrichment of the rearing water with nutrient salts or by introduction from other culture tanks. The direct enrichment
method is not always reliable in summer when the temperature of
the rearing water may exceed 30°C and during the rainy season
when the available solar energy is limited. The optimum densityof the food diatoms is between 30,000 and 100,000 cells/ml.
Frozen algal feeds and trochophore larvae of oysters may also be
used successfully.
During mysis and early postlarval stages, a variety of animal
feeds are used in addition to diatoms. Artemia nauplii are the mostcommon feed for animals in these stages. About 5-8 kg of dry egg
are used in the production of 1 million fry. Rotifers or bacteria
may be substituted. Minced meat of bivalve mollusks and mysids
are the most popular feeds for postlarvae; 120-170 kg of these, in
addition to A rtemia nauplii, are used to produce 1 million fry. The
use of compound feeds for postlarvae has recently become
popular.

Growth management.-To maximize productivity per unit
area, several technical improvements have been made in recent
years, although no final answers are presented. At present, three
types of management plans are practiced among tidal pond
culturists in the Seto Inland Sea area. They may be called onecrop, two-crop, and multicrop plans according to the number ofcropping times per year as illustrated in Figure 5 A-C. In anyII-,,,,1)~

OUI-2 0 .-Figure S.-Kuruma shrimp culture plans in tidal ponds in the Seto Inland Sea area. F, fry production; N, nursery; G, growing; H, harvest.

method, however, the maximum carrying capacity is around200-250 g of shrimp/m 2 • It is a basic principle of growth management to keep the stocking density below the carrying capacity bythinning out the population at appropriate times.
One-crop culture is the original type of culture. Figure 5A
shows that in this plan 0.01 g fry are directly released into theculture pond in May (a'), or I g fry that have been precultured inother nursery ponds at a density of 150-200/m 2 , are stocked in theculture pond in June at 15-20/m 2 (a''). In both cases, fast-growing
shrimp may attain 12-13 g each by September with a survival rateof 70-80%, which approaches the maximum carrying capacity.
The large shrimp should be removed by installing pound nets
along the periphery of the pond to allow the remaining shrimp
further growth. By November, 20-30% of the population isremoved and sold. The rest of the surviving shrimp, now attaining
25-30 g each, are harvested in full scale from November until
February. Total annual productivity is 3 t or less per hectare.
In the two-crop plan (Fig. 5B), the culture process is carried out
in two series of four steps each-fry production, nursery, growing,
and harvest-in succession during alternate months of the yearwith the same set of facilities, thus maximizing annual productivity per unit area. Shrimp are cropped twice a year during JulyAugust and December-February.
In the multicrop plan (Fig. 5C), I g fry are released in theculture pond at a lower density (12-13/m 2 ) than usual to allow
them to grow as fast as possible. As soon as the fast-growing
shrimp attain 10 g in early August, the farmer begins harvestinglarge shrimp and subsequently releases additional juveniles fromthe nursery ponds. This procedure is repeated almost every day
until the end of October. From November to February, effort isconcentrated in the final growing and full-scale harvest of larger
shrimp without additional stocking. The total harvest may reach
3.0-4.5 t/ha per yr.

reasonable cost. They were originally developed as an integral
part of Shigueno's method. Recently, however, as much as
30-40% of the total feed consumption in tidal pond culture has
been supported by these pellets.
Daily food consumption varies greatly depending on the size ofthe shrimp. Smaller shrimp consume much more feed than larger
ones in relation to their own body weight. Figure 6 shows thestandard daily rations by shrimp size. When pellets are used, about
one-sixth of these amounts may be taken as standard allowing forthe moisture content.
Food conversion ratios range from 14 to 15 when frozen feeds
are used. A similar value can be expected with pellets whenmoisture content is taken into consideration. In tidal ponds,
natural benthic organisms may constitute supplementary feed for
Kuruma shrimp, but the quantity of benthic organisms is too low
to support the shrimp in any appreciable densities.

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Foods and feeding.-The short-necked clam and blue mussel
have been the main feeds used in Kuruma shrimp culture. Theiruse, however, has been seriously limited in recent years owing totheir short supply and enormous increase in price. A variety of
substitutes are used today including small-sized shrimp, mysids,
krill, squid, oysters, and several kinds of fish with white meat.
These are stored frozen and used in combination. In addition tothese, several kinds of compound diets are now available at

0

2

4

6

8

10 12 14 16 18 20

BODY WEIGHT OF SHRIMP IN G
Figure 6.-Daily rations of Kuruma shrimp In percentages of their own bodyweight.

12

20-30% to ensure further growth of the remaining shrimp and tomaintain the overall survival and food conversion ratio at
reasonable levels. Through proper management, almost 70% of
the original number of shrimp may be cultured up to 20-25 g eachby March with a maximum production of 2.7 kg/m 2 •Harvest.-Cultured shrimp are harvested by either of thefollowing two methods. During the warm season they are effectively captured at night by pound nets installed at right angles tothe dikes of the pond. After the water temperature falls below
15°C in early December, the shrimp become dormant and are
harvested with drag nets equipped with either a water jet or anelectric sh::>cker.

Foods and feeding.-In Shigueno's culture method, the shrimp
are fed pellets, which are produced and sold from several factories
in Japan. Not all the pellets now on sale are adequate for intensive
culture, but the best quality ones promote satisfactory growth, survival rates, and visual appearance of the final products at areasonable cost.
Figure 8 shows feeding and growth of shrimp in two of thetypical culture practices carried on after Shigueno's method in
1979 at a shrimp farm in Kagoshima. The shrimp are fed once a
day after dark when they actively search for food. fresh frozen
feeds, comprising about 2% of the total amount, are used justbefore harvest to produce a desirable color in the final product.
The overall food conversion ratio averaged approximately 2.5 dryweight of pellet to wet weight of shrimp.

Growing Shrimp in Concrete Tanks
Layout of tank.-A circular concrete tank. 36 m in diameterand 2.5 m in depth at the periphery, is recommended as a standard
unit. Figure 7 shows a culture tank in cross section. Seawater isconstantly circulated at a peripheral linear velocity of about 10
cm/s. Movement of water is effected by two or three 1 hp motor
driven wheels or a series of oblique water sprays from a pipe,
whose length equals the tank diameter, above the tank. Since it isa continuous flow-through system, it is desirable to have a pumpcapacity at least 5 times the holding capacity of the tank.
A layer of fine sand about 10 cm thick is held slightly above thebottom of the tank by plastic spacers and a sheet of synthetic fibernet. The tank floor ascends from the periphery toward the centerat a slope of 211 00 to minimize loss of sand from the central drain.
The central drain automatically removes any deposits and suspensions of organic detritus, food residues, feces, and molts. These arecarried toward the center of the tank by centripetal force createdby circular movement of the tank water. This system is mosteffectively operated at night when bottom sediments are stirred up
by active movement of shrimp. During the day when shrimp remain buried in the sand, the central drain is closed and the draining is effected through other routes which run from midway between the center and periphery and under the sand layer. This
allows a flow of seawater through the sand bed and keeps it
aerobic. The quality of water and sand beds is managed by manipulating the water supply and draining route. The general practiceis to exchange more water at night than during the day. The tankwater should mature for 4-5 d before releasing the fry. During thistime, the water turns light brown due to the growth of diatoms.

Harvest.-A drag net with an electric shocker is effectively
used to harvest the shrimp. However, approximately the last 5% of
the shrimp have to be picked up by hand, one by one, from thesand bed after draining the water from the tank.

SHIPMENT
The harvested shrimp are held in chilled seawater in a darkroom for a couple of hours before being packed. This processminimizes shrimp metabolism and enhances their hardiness forout-of-water viability. They are then sorted into size groups andpacked in a carton sandwiched in chilled sawdust. One package
contains 2 kg of live Kuruma shrimp and almost equal amounts ofsawdust. These are packed and sealed in a large carton and arethen ready for shipment. Kuruma shrimp are usually flown fromthe production sites to Tokyo, Osaka, and other urban consumption centers and brought to the consumers while still alive on the
day following harvest.

Culture management.-During the nursery stage, as many as
400-600 fry/m 2 are stocked and cultured for about 50 d until theyattain 0.7 g each with an average survival rate of 80%. The stocking density is then adjusted to about 160 juveniles/m 2 by transferring some shrimp to other tanks where they enter the growth stage.
By the end of October, the shrimp reach 109 each and the stocking density approaches the maximum carrying capacity of 1.5
kg/m 2 • It is essential at this stage to reduce the population by

MAJOR TECHNICAL PROBLEMS
A major technical problem in growing Kuruma shrimp in tidal
ponds or Shigueno's tanks is the occurrence of heavy mortality
during the summer due to disease among the growing animals. The
most common symptom, which is usually followed by serious
mortality, is the deterioration of gills by infection with fungi or----------------------38 m---------------------_I

II! II! ! I

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Figure 7.-Dlagram showing the structure of a Shigueno type concrete tank for growing Kuruma shrimp.

13

25

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Shrimp's Growth
Shrimp's Growth
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Fresh Frozen FeedS

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Figure 8.-Feeding and growth of Kuruma shrimp in the Shigueno type growing tank. Fresh frozen feeds are euphausiids and shrimps and are used to produce adesirable color in the final product.

bacteria. The major cause is believed to be the excess stocking
density combined with pollution of bottom sediments due toaccumulation and decomposition of organic wastes.

Table I.-Cost and productivity of Kuruma shrimp culture.

COST AND PRODUCTIVITY
It is somewhat difficult to analyze commercial cultivation froman economic viewpoint, since the availability of reliable financial
data is limited and, in addition, the economic situation is affectedby a number of variables. The data presented in Table I areapproximations estimated from various sources. Nevertheless,these data show that the production cost per kilogram of shrimp ischeaper, for the present at least, in tidal ponds than in Shigueno's
tanks owing to a smaller expense for power and fuel in the former.
Productivity, however, is greater in Shigueno's tanks than in any
tidal pond on both a per unit area and per man basis. Other advantages of Shigueno's method over the tidal pond method are: 1) The
ease of various aspects 'of culture management, thus saving on
wage costs, 2) the capability of shrimp cultivation in localities
where tidal and topographic conditions are not suitable for theconstruction of tidal ponds, 3) the applicability of maximum
utilization of warm water effluents from electric power plants orother sources, and 4) the potential of providing a strong impetus
toward the development and improvement of high quality pellet
feeds.

Type of culture
Total cost per kg

Shigueno type;f 5.000

Feeds
Power and fuelInterest
Wages
Shipment
Depreciation
Seedling
Management
Repairs
Prosperity
Trips
Public relations
OthersPart· timers wage
Commodities
Chemicals
Others

39.3%
14.0
14.0
9.3
7.1
6.6
0.4
3.2
1.5
0.9
0.4
0.4
6.0
2.6
1.5
0.9
1.0

29-35%
3
4-10
18-31
10-15
2-5
2-5
4-8

Annual productivity
per ha (t)per man (t)25-27
2.5-4.0

3-5
1.8-2.2

Present paper

Hirasawa andWalford (1979)

Source of data

14

Tidal pond type;f 2.900-4.600;f 2.930
41%
3
5
18
16
3
1
8

8-11

Shigueno(1975)

RECENT TRENDS AND FUTURE OUTLOOKpractices and enhancing the survival rate which, in turn, will require refinement in the quality of compound feeds and in thetechniques of bottom sediment management.
To meet the economic demands of commercial shrimp culture
under a controlled environment, another means of low cost shrimp
production has been explored. The most promising is the farmingof the edge of the sea by releasing a large number of artificiallyreared shrimp fry. The principles and techniques of this activity
have already been reviewed by Kurata :!nd Shigueno (1979) andKurata (1981). The amount of Kuruma shrimp fry production forthis purpose has rapidly increased in recent years attaining a totalof 450 million in 1978; it is still expected to increase as a result of
the construction of new marine fish and shellfish seed production
centers in the majority of prefectures throughout Japan.

From 1970 to 1979, the Kuruma shrimp culture industry inJapan achieved striking growth. The amount of production increased by a factor of 5 at an average annual rate of 18% from 295
t to 1,480 t and is still expected to increase; the number of farms
increased 1.6 times from 77 to 120, and the total pond area increased 1.9 times from 204 to 397 ha. A much greater rate of increase in the amount of production over that of pond area is due toimprovement of productivity per unit area. It has increased 2.6
times from 1.4 t/ha in 1970 to 3.7 t/ha in 1979.
Recent trends are reflected in the construction of new concretetanks by Shigueno's method. The tank area of this type has increased at an annual rate of 24% during these years attaining 12
ha in 1979, while tidal pond areas have leveled off lately at about
400 ha. Beginning a new venture in shrimp culture in tidal ponds
in Japan seems to be far from feasible today owing to the enormous rise in the cost of land coupled with the inherent low productivity. In addition, the limited availability of fresh feeds due totheir high purchase and handling costs puts another constraint on
the culture practice in tidal ponds, where the majority of feeds for
growing shrimp depend on fresh frozen feed.
The culture techniques of Kuruma shrimp on the whole are wellestablished and the commercial venture of shrimp culture has so
far been a more or less profitable business in Japan. Its economic
feasibility, however, is to a large extent supported by a highmarket price for live Kuruma shrimp. A growing menace to the
future of this industry is the hovering trend in the price of products on the one hand and a rapid rise in production costs on theother. Efforts must be concentrated to further improve productivity through the intensification and rationalization of culture

LITERATURE CITEDHIRASA W A, Y., and 1. WALFORD.
1979. The economics of Kuruma-Ebi (Penaeusjaponicus) shrimp farming. In
T. V. R. Pillay and W. A. Dill (editors), Advances in aquaculture, p. 288-298.
Fishing News Books Ltd., Farnham, Surrey, Engl.
HUJINAGA, M., H. KURATA, and J. KITTAKA.
1977. The evolution of prawn culture. In T. Imai (editor), Aquaculture inshallow seas: Progress in shallow sea culture, p. 411-56/. New Delhi,
Amerind Publ. Co. Pvt. Ltd.
KURATA, H.
1981. Shrimp fry releasing techniques in Japan with special reference to theartificial tideland. Kuwait Bull. Mar. Sci. 2:117-147.
KURATA, H., and K. SHiGUENO.
1979. Recent progress in the farming of Kuruma shrimp (Penaeus japonicus)
In T. V. R. Pillay and W. A. Dill (editors), Advances in aquaculture, p. 258268. Fishing News Books Ltd., Farnham, Surrey, Engl.
SHIGUENO, K.
1975. Shrimp culture in Japan. Assoc. tnt. Tech. Promot., Tokyo, 153 p.

15

Structure of a Kuruma Shrimp Culture Pond
TOSHIFUMI NOMA 1SHRIMP CULTURE IN JAPANthe late Dr. Hudinaga and his successors, as well as to shrimp
culturists who have perfected the technique of mass production of
shrimp seed.
Originally, shrimp culture was performed in net enclosure
ponds (Yamamoto et al. unpubl. data). These ponds had a 100 m 2
surface area and were enclosed by bamboo nets (Fig. 2). Shrimp
culture of this type expanded in the Amakusa district. Net
enclosure ponds were often damaged by storm surges; as acountermeasure, the bases of the poles that sustained the net were
strengthened by stones or concrete. Even with this improvement,
they were still damaged by storm surges. An embankment wasalso tested, but low water exchange caused high mortality of theshrimp. In addition, this type of construction was expensive.
In 1920, the semi-embankment type was designed (Fig. 3). Thistype, a combination of net enclosure and submerged dyke, wasless expensive compared with full embankment, had a greater
water exchange rate, and had a smaller wave force acting on thepoles. Today the semi-embankment type is dominant in Amakusa.
Thus, shrimp culture ponds can be classified as I) semiembankment type, 2) embankment type, which are converted
from obsolete salt pans or kantakued paddy fields, 3) inland pond
(shrimp culture tank), and 4) others. The first two use tidal energy
for water interchange and exchange; the third uses a mechanicalpump.
Figure 4 shows the relationship between yield and surface areaof pond in Amakusa in 1970 (Yamamoto et al. unpubl. data). The
yields varied from pond to pond and ranged from 100 to 300 g/m 2 •After 1970, the yield in the district gradually increased as shown

In Japan, seafood, especially live and fresh fish, is highly
valued. The Japanese prefer sea bream, lobster, and shrimp and it
is not surprising that some of these species have been cultured.
Culture of Kuruma shrimp, Penaeus japonicus, was initiated in
Amakusa, Kumamoto Prefecture in 1902 (Honma 1971). Today,
the shrimp are cultured in the warm districts of southwest Japan.
Yearly production has been increasing; in 1979, production was
about 1,500 tons (Japan, Ministry of Agriculture and Forestry1981) (Fig. I). The flourish of shrimp culture can be attributed toINational Research Institute of Fisheries Engineering, Ebidai, Hasaki-machi,
Kashima-gun, Ibaraki, Japan.

(X 1,000ton)

2.0

1.5

1.0

0.5

,

I

I

\

,,
I

•,

oL-_L-_L-_-'--------:~----:::!=--=-=------l-~
'71

72

73

74

75

76

77

78

79

Pier

I

,

I

I

80

I

I

pond

\

ha
600

\

I
I

\

I

\

I

\

\

total

98

-----"'_ __
~

---

98

\

,,
,,

I

,
' ..........

~-----------~

95
200

\

1
I

\

400

"

";",,,,/

96/"--<:.

----- ......... ~,Kumamoto"""'-0

OL-_ _---1..-_L------L_--'----_L----="=-----,:!c------='::----,J'71 72 73 74 75 76 77 78 79 80
Figure I.-Yearly changes 10 Kuruma shrimp culture. Top: Others =Kagoshlma, Ehlme, Ohlta, and Okinawa, Bottom: The numbers under the total
Une are the percentages of embankment type ponds.

Figure 2.-Net enclosure.

17

I

A-A

.
o·

-~l!'.T--1;f-;I----'H"'.W"-."'L_

!

!;
.z: .

:

,I
I

I
I

I
I

A

I

pond
A

L:-1
I

I

I
I

I
_ _ _ _ _ _ _ ...JI

L:""'net....B-B(\'II.'
5~!

-+

po~n=dFigure 3.-Seml-embankment pond.
atop loa

box culvert
4.0.~':.~.-.:-',' -".::.~.,..

0(0 L)

ton
go

•

8

•

1

-

Table
I.-Yearlychange In production In
Amakusa. Total pond
area = 159.5 ha .
Average annual production = 374 gim' .

&
5

~ ~

.~ 3
::3l

•

Z

Year

Tons

1974
1975
1976
1977
1978

510
513
517
573
596

I

Z

3

Table I.-Types of pond and yield.

4

Yield

area Of each pond
Figure 4.-Yield and area of ponds, Amakusa, 1970.

in Table 1, and production per unit area reached 400 g/m 2 • Production per unit area of each type is shown in Table 2. Production
per unit area in tank culture is the highest and can be attributed topond management.

Pond type(g/m')

Semi-embankment
Embankment
Tank culture

400
400
2.500

(dissolved oxygen), adequate water temperature, and a clean andsoft sand bed which allows easy burrowing.
Pond management activities are listed in Table 3. Before theshrimp fry are introduced into the pond, the substrate is ploughed
repeatedly to oxidize the bed materials; deteriorated sand may bereplaced; and predator fishes are eliminated. The facilities arerepaired and, on occasion, sand will be supplemented.
In embankment type ponds, water is let into the pond about 10
d before the fry are introduced. The water is controlled to allow
propagation of diatoms to an adequate density.

F ACTORS TO CONSIDERIn planning a shrimp culture pond, many factors need to beconsidered (Kurata and Shigueno 1976; Shigueno 1969) including
1) natural conditions such as climate, topography, tide, and risk ofstorm surges, and 2) socioeconomic conditions. The pond isdesigned to meet the requirements of the shrimp and to facilitate
pond management. The shrimp require food, living space, DO
18

Concerning the latter, a maximum flow velocity > 0.4 m/s isadopted in Himeshima.
Net screens consist of a net fence for protection against driftingmaterial and a fine net for protection against predator fishes. Fine
net of 2 mm mesh is used in nursery ponds and 3 mm mesh is usedin culture ponds.

Table 3.-Management activities.
Preparatory activities
Oxidation of sand bed (chemical sterilization in tank culture)
Substitution of bed materials
Repair of facilities
Predator control
Water· curing
Activities during the rearing period (include the prestocking rearing)
Feeding
Water quality control
Uiva (Viva lacluca) control
Predator control

WATER QUALITY CONTROLIn culturing shrimp, the water quality should be properly maintained. Dissolved substances affecting water quality include DO,
organic matter (metabolite and food residues), NH 4 , and HzS. It is
well known that DO should be maintained at more than 6 ppm:

Harvest (with pond net or dragnet with electric shocker)

DONH 4
water temp.

In April and May, the shrimp fry are introduced into the pond.
This period is also the spawning season of the predator fishes, sea
bream (Pagrus major and Acanthopagrus schiegelii) and goby
(Tridnetiger obscurus). Eggs, 0.8 mm in diameter, of predator
fishes enter the pond through the net screen. After hatching, thejuveniles of predators grow more quickly than shrimp fry. Whenthe juveniles become bigger than the fry, they start to devour thefry. To prevent egg intrusion, net screens with fine mesh evensmaller than the egg's diameter is sometimes used. The penetration of the noxious ulva (Uiva) and its subsequent decomposition
cause serious deterioration of the water and bottom soil. This ispartly inevitable.
Because of predation and ulva, shrimp culture in the same pondshould be as short as possible. Therefore, pre-stocking rearing, i.e.,
in nursery ponds, is adopted. The nursery pond occupies 10 to
20% of the whole pond area and can be easily managed. Swarming of ulva is now checked by inducing and maintaining a bloomof unicellular planktonic algae such as diatoms. Sometimes ulva
may be scooped out or eliminated by chemicals (RADA).
The fundamental requirements and engineering items for ashrimp culture pond are shown in Table 4. In Japan, the type of
enclosure is generally determined by the importance of disasterprevention. If storm surges occur, the embankment type isadopted. The embankment may, however, cause deformation of
the shoreline, erosion, or sand accumulation. Therefore, carefulconsideration is needed before adopting this type of enclosure.
Water depth can be maintained at about I m in the summer.
The bottom elevation is M.L.W.L. (mean low water level) andm.s.l. for tank culture. The minimum thickness of the sand bed is
10 cm.
The dimension of the water gates is determined from the exchange flow rate needed and the ability to flush out drifted sandaround the water gate (Gyoko-Senkai Kaihatsu Consultant Co.Z).

> 6 ppm< 0.1 ppm
< 30°C.

The water quality control method is essentially a promotion of
the water exchange rate. For DO control, however, aeration withmechanical power is usually adopted. For hydrogen sulfide control, iron oxide can be dispersed in the pond.
If the density of phytoplankton is properly maintained, DO is
supplied by the phytoplankton. Therefore, DO is controlled by thedensity of the plankton. In this case, the water exchange rate isdetermined by the coloration of the pond water.
In tank culture, flow velocity, in addition to the water exchange
rate, is important. An adequate velocity is 7 -15 cm/s. Less than 7
cm/s, the organic matter cannot be flushed out; beyond 15 cm/s,
bed sand is moved.
To increase the water exchange rate, shallow water is preferred;
nevertheless, the quality of shallow water is apt to change quickly
as a result of a heavy rain or a high ambient temperature in thesummer. Therefore, water depth should be properly maintained.
The water exchange flow rate should be determined so as to maintain the concentrations of the dissolved substances at adequate orallowable levels.
For the semi-embankment or embankment types, supposing
thorough mixing in the pond, the concentration of a dissolved
substance, M, changes(1)

where V = water volume of the pond, q = effective exchange flow
rateltidal period,3 Me = concentration in outer sea, A = supply
rate of the substance, and t = time. Equation (1) becomes

A

q

A

M ={Mo-(Me+-)}e-v'+(Me+-)qq'Gyoko-Senkai Kaihatsu Consultant Co. 1976. Consultant report on the planningof Himeshima Shrimp Culture Pond. Unpubl. rep.

(2)

Table 4.-Fundamentai requirements for a shrimp culture pond.
Requirement
To hold the animals
To have a high rate of seawaterexchange, and the ability toflush out organic matterTo be able to maintain adequate
water depth
To protect from predator fish
Other

Engineering item

Figure 5 shows the graph of Equation (2). At infinite time, M
becomes Me +if there is no pollution or supply, M approaches
Me as in the dotted line.

1-;

Enclosure, sand bed
Flow velocity

Gate and submerged dyke
Screen net
Access for bulldozers into the pond

'q is not interchange flow rate. That is expressed by q = ~ . S where ~ = tidal
range and S = surface area of the pond.

19

In this case also, at t = 00, DO can be given by Equation (5').

Determination of Flow Rate

_
A -~t
A
M- IM o - (Me+-)e V + (M e +-)qq

Concerning the dissolved substance, M, the concentration at infinite time, M t = 00, should be the allowable one. When we know
A, the exchange flow rate can be given by

MI
M()-______

Me..LA=O--- --------

(6)

q

(Ma

~t

= Mt =

00).

In the same manner, for DO,
Figure 5.-Change of dissolved substances curve of Equation (2).

{3 - K(cs - ca)

q

=

(7)

DO Change
Supposing there is no 02 supply by phytoplankton, DO change
can be expressed by Equation (3),dc

V dt = K(cs - c) + q(ce + c) - {3Inversely, when q is given by the tidal condition, for example, we
can calculate the required rate of 02 supply, K, by(3)K{3 - q(ce - ca)
Cs - Ca

where c = DO, Cs = saturation concentration of DO, {3=02 consumption rate, K = coefficient of O 2 supply.

Methods
where K 2 = reaeration coefficient by flow velocity, in case of Air
Bubble Curtain (A.B.C.)

In considering the exchange flow rate using a mathematicalmodel, there is the supposition of thorough mixing in the pond.
Therefore, there should not be stagnation in the pond. Countermeasures for such stagnation include gate operation or tidal current control with a training dyke (Nakamura et al. 1975).
The training dyke, as shown in Figures 7 and 8, is located inreciprocal tidal currents. Downward stream flow is easy; however,
upward stream flow is difficult.
The coefficients of discharge of the inlet, which is constructedwith a training dyke, are changed by flow condition. Tidal residual
is induced in a reciprocal flow.

(4 )where D m = molecular diffusion coefficient of O 2 into water, U m= maximum velocity by A.B.C., hf = frictional depth, 0 = coefficient of flow velocity attenuation (0 = Hf (1 {2Hf)2~), L =

length of pond perpendicular to flow and K s = coefficient of O 2
dissolution from bubbles (Fig. 6). Integrating Equation (3) with c= Co at t = 0,c = {co -Kcs + qCe - {3

K +q

K+q

} e- v' +Kcs + qCe - {3K + q'(5)

We can estimate the DO at t = 00 by Equation (5),

Ct

= 00

Kcs

+ qCe - {3
K +q

(5')

Figure 7.-Tidal current control by training dyke.

Figure '.-Definltlon sketch of aeration by A.B.C.

20

EXAMPLESjl}! inverse

mE
,

A ,,,

\

I

flow

Embankment Type: Himeshima Shrimp Culture Pond,
• \ I i'-~
I.... ~ I

Figure 9 shows an embankment type culture pond converted
from a kantakued paddy field. There are four ponds, each with a 2
to 2.3 ha surface area and two gates. When the tide is rising, theupper side gates are opened to let water into the pond; when thetide is falling, the lower gates are opened. Thus pond water
generally flows one way. Bottom elevation is indicated as +0.0,+0.7, etc. Each pond can be drained at mean spring low waterlevel and is accessible to ploughs and cultivators.
Figure 10 illustrates the structure of a gate. The pond is on theleft side. A fine mesh (0.6 mm) net screen, smaller than the egg
size of predator fishes, is set in this portion. It is well brushed in
the ebb of spring tides.

I

I

,
,,
I

1

asymptote!iDl normal
flow
it

Figure 8.-Configuratlon of a training dyke.

+0.7m

+0.7

+0.7

+0.7

H.H.W.L+3.208M.S.H.W.L +2.713

2ha

2.3ha

2.3ha

2.3ha

~

~

~
provisional~

M.N.H.W.L. + 1.957

M. S. L+1.460

M.N.L.W.L +0.963

Closing
M.S.L.W.L +0.208
DoL.
_0.0
/A>~

21

Figure 9.-Plan view of Hlmeshlma shrimp culture pond.

v+~l;:r

~b~,
I
I

§

Figure lO.-Structure of gate.

I

L.-.(D

Shrimp Culture Tank: Mitsui-Nohrin Inc.

22

ACKNOWLEDGMENTS

LITERATURE CITED

Many people have helped in various ways during the preparation of this paper. I am grateful to Mr. Nakamura, Kumamoto
Prefecture Fisheries Experiment Station and to Mr. Fujita,
Tarumizu Aquaculture Center of Kagoshima Prefecture Fisheries
Experiment Station who sent me reprints and references.
I am indebted to Mitsui-Nohrin Co. and Himeshima Kuruma
Shrimp Culture Co. who have permitted the reproduction of theirphotographs and figures.

HONMA, A.
J 971. Aquiculture in Japan. Japan FAO Association.
JAPAN, MINISTRY of AGRICULTURE and FORESTRY.
1981. Statistical yearbook of fisheries and aquaculture for the year 1979.
Ministry of Agriculture and Forestry, Tokyo.
KURATA, H., and K. SHIGUENO.
1976. Recent progress in the farming of Kuruma shrimp (Penaeusjapanicus).
In T. V. R. Pillay and W. A. Dill (editors), Advances in aquaculture, p. 258268. FAO Technical Conference on Aquaculture, Kyoto, Japan, 26 May - 2June 1976.
NAKAMURA, M., S. HAGlNO, and T. NOMA.
1975. A proposal of pollution control by training dike. UMI to SORA, vol.
50.
SHIGUENO, K.
1969. On Kuruma shrimp culture technique.

23

Major Diseases Encountered inControlled Environment Culture of Penaeid Shrimp at
Puerto Penasco, Sonora, Mexico
D. V. LIGHTNER, R. M. REDMAN, D. A. DANALD, R. R. WILLIAMS,I
and L. A. PEREZ2

ABSTRACTA number of diseases have played a significant part in the evolvement of controlled environment culture ofpenaeid shrimp, as developed by the Universities of Arizona and Sonora at their research facility in Puerto
Penasco, Sonora, Mexico. Among the etiologies of those diseases are viruses, bacteria, fungi, algal toxins, andnutritional imbalances. Of the 20 or so diseases or conditions observed at the facility, 11 (filamentous gill disease,ciliate gill disease, Fusarium disease, black death, three forms of bacterial disease, larval mycosis, blue syndrome
X, hemocytic enteritis, and MBV disease) are discussed here in terms of their etiology, epizootiology, and thepreferred methods of treatment and prevention.

INTRODUCTION

The first research aquacells were remodeled greenhouses. These
structures were 7 m wide x 30 m long with a 0.9 m center concrete walkway. Polyvinyl liners were installed to create two 3 x
23 m raceways of approximately 0.3 m depth, in each inflated
plastic structure. The structures were covered with an ultravioletstabilized 10 mil polyethylene film which was inflated to form a 7
x 30 m half cylinder. From these evolved the "pilot-plant"
growout raceways now in use which are 0.61 x 3.4 x 62 m indimension. In these raceways, harvest densities of commercialsize (average tail size at harvest was 31-35 count) P. stylirostris
have exceeded 5 kg/m 2 of bottom area and have consistently
averaged over 3 kg/m 2 . Total production of the 18 raceways (or0.4 ha of water surface) in the commercial prototype was 80,000
Ib or about 45,000 Ib of tails for the first year of operation. Tail

Controlled environment aquaculture (CEAq) of penaeid shrimp
by the Environmental Research Laboratory of the University of
Arizona began in 1972 as an evolutionary product of the controlled environment agriculture technology developed by the
Laboratory. The research facility, located on the northern Gulf ofCalifornia near Puerto Penasco, Sonora, Mexico, is a cooperative
project of the En vironmental Research Laboratory and The Center
for Scientific Investigations and Technology (CICTUS), at the
University of Sonora (Fig. 1). As a result of progress within thepast several years (Salser et al. 1978), the project is now movingfrom the "pilot-plant" phase to a fully commercial phase. A 10 ha
CEAq facility is planned for Hawaii, with construction to begin in
1981.

CULTURE METHODS
Broodstock, consisting of populations of laboratory-reared F ,or F 2 generation Penaeus stylirostris or captive wild shrimp, areheld in special raceways for maturation. Diet, water, temperature,and photoperiod are all controlled and monitored. Fertilized
females are collected as needed and transferred to the hatchery for
spawning. Egg hatching and larval culture is accomplished bymodifications of the procedures described by Mock and Murphy(1970) and Mock et al. (1980).
The postlarvae are transferred to a fiber glass flow-throughnursery system until they reach 10 to 50 mg. From the nursery,
postlarvae are transferred to a postnursery system, a miniature
raceway, where they are stocked at 500 to 1,000/m 2 and remain
until they have reached 0.5 to 2 g. Finally, they are transferred to a
growout raceway system where they are stocked at a density of
150 to 250/m 2 • They will spend 20 to 25 wk in this growout
system and are usually harvested at approximately 21 g (35count).
Figure I.-Aerial view of the Universities' of ArIzona and Sonora shrimp
culture research facility at Puerto Penasco. The locations of the seawater wells,
the broodstock raceways, the hatchery, nursery/postnursery, and the growout
raceways are Indicated.

'University of Arizona. Environmental Research Laboratory, Tucson, AZ 85706.
'University of Sonora, CICTUS, Hermosillo, Sonora, Mexico.

25

production for the second year of operation (1979-80) will exceed
60,000 lb.
Seawater supplying the Puerto Penasco facility is pumped froma series of seawater wells that are placed in the sand dunes above
the high tide mark on the beach to provide filtered seawater ofnearly uniform quality and temperature, regardless of season.

algaelike organism that is very similar or identical to Leucothrix
mucor (Fig. 2). All four species of penaeid shrimp (Penaeus
stylirostris, P. californiensis, P. vannamei, and P. monodon) reared
at Penasco are affected by this disease. Penaeus californiensis is
the most severely affected by the disease, while P. stylirostris, P.
vannamei, and P. monodon are more resistant.
Leucothrix mucor is a common ubiquitous estuarine and marine
microorganism of uncertain taxonomic position (Brock 1974). It
attaches to living and nonliving solid substrates (Sieburth 1975)
and in shrimp culture systems it readily attaches to the surfaces of
the gills and accessory gill structures. It is not invasive and causes
no demonstratable pathology to these surfaces (Lightner 1975,1978b). When present on the gills in large amounts, it can impede
water flow across the gills and reduce oxygen exchange. Debris,
uneaten food material, algae, and fecal material may become trapped by the Leucothrix filaments on the gills and complicate thecondition. Mortalities due to Leucothrix infestation of the gills arethought to occur from hypoxia. Under conditions of stress due to
crowding, molting, or low oxygen levels, Leucothrix may cause
severe losses overnight. If left untreated, FGD can cause a continuous steady, low level mortality.
FGD may be managed by the use of a copper compound applied
on a scheduled, or on an "as needed," basis. A seawater-soluble

DISEASE AND CONDITIONSENCOUNTERED
Nearly 20 diseases or disease1ike conditions have been observed at Puerto Penasco in CEAq systems. Many of these diseases
were reviewed by Lightner (1975, 1977), but others have since
been recognized. Listed in Table 1 are the most important diseases
encountered at Puerto Penasco in CEAq-reared shrimp that haveresulted in the loss of significant numbers of shrimp.

Filamentous Gill Disease
One of the main problems which has received a major researchemphasis at Puerto Penasco has been filamentous gill disease(FGD). This disease is caused by a filamentous blue-green

Table I.-Major diseases encountered at Puerto Penasco and present control methods.'
Etiology

Control Measure

Leucothrix mucor and various
other filamentous forms including
Cytoph<lga sp., and Flexibacter sp.
Coloni 11 peritrich protozoans(Zo{)/hamnium, Epi,ryli" andVorticella)

Cutrine (at 0.1 mg Cu for 24 h or 0.25
to 0.5 mg Cull for 4 to 8 h).

DiseaseGill disease
I) Filamentous gill disease2) Ciliate gill disease3) Fusarium disease

Fusari!Jm solani

4) Black death

Dietary deficiency of ascorbic
acidI) Formalin (at 25 to 75 mg/l for 4 to

8 h).
2) Glutaraldehyde (at 2.5 mg/l for 6 to
8 h).
No control methods other than use ofresistant species.
Supplement diet with I to 2g/kg of
diet, or provide fresh algae.

5) Juvenile and adult bacterial
diseasesI) Septicemias2) Shell disease and infected
wounds6) Larval and postlarval bacterial
diseases
7) Larval mycosis8) Blue Syndrome X (BSX)

9) Blue-green algae poisoning(Hemocytic enteritis)10) MBVD Disease

Vibrio alginvlyticu~'.
V. Gnguillarum,
V. parahaemolyticus.
Psrudomonas spp., andAeromonas spp.

Same as above
Laxenidium

Unknown. but suspect
chloricated hydrocarbon
contamination of feed ingredients
Ingestion of:
Schizothrix ca/ciocola,
Spiruli.,a subsal;a, and possibly
Microcoleus lyngbyaceu5

A baculovirus'Summarized from Lightner (1977).

26

Antibiotics mix.ed with feed and fed

for 14 d.
I) Terramycin at 500 to 1,000 mg/kg
feed.
2) Furacin or Furanace at 100 to 500
mg/kg fced.
3) Mixture of Terramycin (500mg/kg) and Furacin, Furanace(100 mg/kg).
Sanitation, disinfection, and drying oflarval rearing tanks between uses.
I) Malachite green at 0.006 mg/l
continuous.
2) Trenan at 0.01 mgil continuous.
3) Sanitation.
Avoid use of feed components
containing PCB's, DDT, DDE, etc.
I) Medicated feeds to control
secondary bacterial infections.
2) Reduce light to prevent algal
growth.
3) Control algae growth with
algicides.
I) None known except sanitation.
2) Medicated feeds to control
secondary bacterial infections.

cause no appreciable internal damage to the gills (Lightner et aI.
1975,1977).
Formalin 3 is reported to be effective in controlling theseorganisms in all forms of shrimp and crustacean culture (Johnson
et aI. 1974; Schnick et aI. 1979). In CEAq systems both Formalin
and glutaraldehyde (Table 1) have been found to be effective incontrolling this form of gill disease,. but because of the relatively
high cost of glutaraldehyde, Formalin is the preferred therapeutant(Lightner 1977).

Fusarium Disease
An important disease of adult and subadult penaeid shrimp isdue to Fusarium solani, an imperfect fungus of world-wide distribution. Severe losses due to F. solani have occurred in raceway
populations of P. californiensis and P. stylirostris at Puerto
Penasco. Spores of F. solani are present in water from the seawater wells at Penasco, apparently being derived from organic
material in the beach sands through which the station's water ispumped. In raceway populations of subadult P. californiensis, theslightest wound or abrasion is sufficient to establish a fusarium infection; hence, at Penasco, most fusarium lesions occur on the appendages, or as ulcerative lesions on the carapace, or on thepleural plates on the abdomen (Fig. 4a). "Black gills" is the mosttypical lesion seen in Japan in cultured shrimp infected by F.
solani (Egusa and Veda 1972), and this form of fusarium diseasehas been observed at Penasco.
Diagnosis of fusarium disease is made by the use of a wet
mount of material scraped from a suspect lesion. Demonstrationof the "boat-shaped" macroconidia (Fig. 4b), which is thecharacteristic spore for members of the genus Fusarium, confirms
the diagnosis.
The histopathology accompanying a fusarium infection is
striking. A typical reaction to the fungus is an intense cellularinflammatory response, with the shrimp hemocytes forming large
encapsulations around invading hyphae (Fig. 4c). Often, theinflammatory tissues become melanized, giving the lesion abrownish to black pigmentation.
No effective chemotherapy or preventive measures are known
for fusarium disease (Hatai et aI. 1974; Lightner, Moore, andDanald 1979), and mortalities due to fusarium disease in highly
susceptible species such as P. californiensis may approach 100%
(Fig. 4d). Fortunately, some penaeid species are relatively resistant to F. solani infections. Penaeus californiensis is the mostsusceptible to F. solani of the penaeid species tested so far at
Penasco. Penaeus vannamei and P. stylirostris are more resistant toinfection, and are not highly susceptible to infection by F. solani
at sizes below 20 to 25 g (Table 2). Rearing Fusarium-resistantspecies of penaeid shrimp in CEAq systems is, at the present time,
the only known method of preventing fusarium disease (Lightner,
Moore, and Danald 1979).

Figure 2.-Scannlng electron micrograph of the gill lamellae of a blue shrimp,
Penaeus stylirostris. The abundant long tortous filaments present on the surfacesof the lamellae are Leucothrix mucor. The smaller rod.shaped organisms lying
lengthwise on the gill surfaces are bacteria, probably mostly Vibrio and Pseudomonas spp. x 3,192.

copper compound, available commercially as Cutrine-Plus (TableI) has been an effective management tool for FGD (Lightner and
Supplee 1976), but even better methods of preventing or controlling FGD are needed.

Ciliate Gill Disease
Another form of gill disease that may occur alone or with
Leucothrix is due to one or more species of the colonial peritrich
protozoans Zoothamnium sp., Epistylis sp., and Vorticella sp.
(Overstreet 1973; Lightner 1975,1977; Couch 1978). As was thecase with Leucothrix-caused gill disease, these organisms, whenabundant on the surface of the gills, cause hypoxia and shrimp
deaths by impeding respiration (Fig. 3). Like Leucothrix, theyBlack Death
Black death is the name given to a nutritional disease ofpenaeid shrimp caused by a dietary deficiency of ascorbic acid
(Lightner et aI. 1977). Shrimp having black death (Fig. 5a)typically display blackened (melanized) lesions in the stomach
wall, the hindgut wall, in the gills, and in the subcuticular tissues
Figure 3.-Scanning electron micrograph of a secondary gill rachis of a blue
shrimp, P. stylirostris, that is heavily infested with colonies of the colonial peri.
trich Zoothamnium sp. Also present are filaments of Leucothrix mucor and a few
diatoms. x 199.

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

27

,q1OO

100

~0 eo

eo

E 70

70

;t. 80

80

80

80

90

90

~

::J 4040

11I 30

30

20

20

10

10

U
U

0

rrar

time (1M<S, MaS)~

Figure 4.-a. California brown shrimp, Penaeus californiensis, with lesions due to Fusarium so/ani on its head appendages (arrows). Only Fusarium-infected stumps
remain of the antennae, the antennules, and the antennal scales. b. Phase contrast photomicrograph of micro- (the short elliptical one- or two-celled spores) andmacroconidia (the longer boat-shaped multicelled spores) of Fusarium so/ani. The presence of these spores in material scraped from suspect lesions is pathognomonic for
infection due to F. so/ani. No stain. x 665. c. Photomicrograph tbrough a Fusarium so/ani-caused cuticular lesion on a Penaeus californiensis. Present in the proximal
portion of the lesion (left) are degenerating muscle fibers. Centrally and distally in the lesion are masses of infiltrating hemocytes, some of which have encapsulated
hyphae (H) of F. so/ani. Masses of necrotic and melanized hemocytes are represented as darkened areas. Hematoxylin and eosin. x 93. d. Plots of time versus accumulated mortality in an epizootic in a raceway population of California hrown shrimp, Penaeus californiensis.

at various locations in the shrimp. To date, black death has been
experimentally induced in P. californiensis and P. stylirostris byfeeding diets devoid of added ascorbic acid (Magarelli et al. 1979;
Lightner, Hunter, Magarelli, and Colvin 1979). Deshimaru andKuroki (1976) have probably observed the same syndrome in P.
japonicus.
Histologically, black death lesions may be distinguished fromshell disease lesions, which they superficially resemble, by thelack of erosion or damage to the cuticle in the former disease (Fig.
5b). Instead, black death lesions are melanized, hemocytic lesions
present in the epithelial and subepithelial connective tissues of thestomach, hindgut, gill, and general cuticle, and in the loose connecti ve tissues in such organs as the hepatopancreas, the nerve
cord, etc. (Lightner, Hunter, Magarelli, and Colvin 1979; Hunter
et al. 1979).

Table 2.-Susceptibility and incidence of Fusarium so/ani infections in threespecles of Penaeus at Puerto Penasco.

Species

Relative
susceptibility

Earliest
susceptible age(wk)

Incidence'

Penaeus californiensis

high

30-40

'55

moderate

40-50

'6.5

low

68

'3.5

(Calif. brown)
P. stylirostris(Blue)
P. vanname;(White)'Incidence per thousand of population for time period January to March 1977.
'Born 4/2/76.
'Born 5/1/76.
'Born 9/4/75.

28

cessfully resolved by the host's inflammatory response, septicemia
and death will result. In CEAq of penaeid shrimp, most bacterial
diseases seem to be of a secondary nature, resulting from someprimary lesion due to another infectious organism, a parasite, towounds, or to nutritional, mechanical, chemical, or physical stress(Lightner 1977).
Diagnosis of bacterial infections is made by the demonstrationof gram-negative motile rods in the hemolymph or tissues ofshrimp with advanced shell disease or with septicemias. Successful therapy of bacterial infections in penaeid shrimp (Table 1) has
been reported by the direct addition of certain antibiotics to theculture tank water (Aquacop 1977; Delves-Broughton andPoupard 1976) which is practical only in shrimp hatching, larvalrearing, and nursery tanks, or by the use of medicated feeds (Table
1) in larger shrimp.

Larval Mycosis
The phycomycetous fungus Lagenidium callinectes has been
observed and has caused significant epizootics in the larval stagesof P. stylirostris and P. californiensis at Puerto Penasco. Losses approaching 100% (Fig. 6) have been observed in our Galvestonstyle larval-rearing tanks (Lightner 1976; Salser et al. 1978). In
these larval-rearing tanks, L. callinectes has been observed to infect fertilized and unfertilized eggs, all of the larval stages, and up
to 2-d-old postlarvae. The naupuliar and early protozoeal stages
are those stages that are typically the most severely affected.
The source of the fungus infecting larval shrimp in larvalrearing tanks has been shown to be the gravid female shrimp fromwhich the spawn was obtained. Lagenidium callinectes is apparently a normal epiphytic saprophyte on adult wild andhatchery-reared penaeid shrimp. An infection is established whena zoospore attaches to, and encysts upon, the cuticle of an egg orlarval shrimp. The encysted spore then germinates, with the germtube penetrating the cuticle. The mycelium gradually expands andappears to replace most of the striated-muscle tissues until the larva is literally filled with hyphae. Infected individuals become immobile and settle to the bottom of the tank. Sporogenesis thenbegins with formation of discharge tubes, terminal vesicles, andrelease of zoospores (Lightner and Fontaine 1973).
Several methods of chemotherapy for Lagenidium have beenreported (Armslrong et al. 1976; Bland et al. 1976; Aquacop1977), and two chemicals have shown promise in controlling thefungus. Bland et al. (1976) and Lightner (1977) reported
malachite green oxylate at 0.006 ppm (static) as effective inarresting Lagenidium epizootics in larval rearing tanks or inpreventing epizootics, if added prior to the time the epizootics
become established (Fig. 6). Armstrong et al. (1976) and Aquacop(1977) found trifuralin (Treflan) to be effective in preventing
Lagenidium epizootics in the culture of larval crabs and shrimp.
For Lagenidium control in shrimp, Aquacop (1977) found that asingle application of 0.01 ppm Treflan was enough to kill
Lagenidium zoospores, but such applications had no effect on thethalli which continued to grow and reproduce. Aquacop (1977)
further reported that multiple 6-h duration applications of Treflan
in the parts-per-billion range are effective in preventing thedisease.

Figure 5.-0. Gross photograph of juvenile California brown shrimp, Penaeus
californiensis, with the disease black death, which Is due to a dietary deftclencyof ascorbic acid. b. Photomicrograph of a section through one of the blackened
cuticular lesions like those shown in Fig. Sa. This section was made through thejunction of two adjacent abdominal pleural plates, hence two sections of cuticle
are present. Melanized accumulations of hemocytes are present In the hypodermis and especially In the subhypodermal connective tissues. Hematoxylin
and eosin. x 170.

Bacterial Diseases
Diseases due to bacterial infections in captive wild and incultured shrimp are well known (Lewis 1973a, b; Cook and Lofton 1973; Delves-Broughton and Poupard 1976; Lightner andLewis 1975; Aquacop 1977; Lightner 1977). In every reported
case of bacterial infections in penaeid shrimp, motile gramnegative, oxidase positive, fermentative rods have been isolated.
So far, most isolates have been Vibrio alginolyticus, V.
parahaemolyticus, or V. anguillarum. Certain other species ofVibrio, Pseudomonas, and Aeromonas may occasionally be involved in this disease syndrome (Lewis 1973b; Lightner 1977).
Bacterial infections in shrimp may take two forms, localized
pits in the cuticle (shell disease) or generalized septicemias. In
shell disease (Cook and Lofton 1973), the causative organisms
cause erosions of the cuticle. However, if such lesions are not suc-Blue-Green Algae Poisoning (Hemocytic Enteritis)
Blooms of certain marine filamentous blue-green algae, allbelonging to the family Oscillatoriaceae have been implicated as
29

100

~

90

80

183

43

u

:J

'"

60

..

§~

~

~

~ 50
~

11l
L

~

''0""

"':5
122

0

01

c

<xl

"-

L

ell

57

Oil

I

ni
> 70
.s;
:J

244

';
~ agmd'.m diagnosad. malachitq g-qqn

cC
28

.Q

~

40
30

61

~ 20

14

a.8.

10

o 1

, ,

3
PlI-Plll

"'"

t·

14

16

-MI MJ-MIIMIl-. day

Iml2. life cycle stage

Figure 6.-Survival plots of larval blue shrimp, Penoeus stylirostris, populations in which disease due toLagenidium collinectes was epizootic. The population designated as "hatch 27" was treated with malachite green
upon detection of the presence of Lagenidium, while the population labeled "hatch 28" was not. The epizootic in
hatch 27 was arrested with nearly a 50% survival rate, while the untreated hatch 28 had nearly 100% mortality.

causative agents in a disease syndrome of primarily young
juvenile P. stylirostris of 0.1 to 5 g average weight. However, thedisease has been observed in 12 to 20 g P. stylirostris. The disease,called hemocytic enteritis (HE), apparently results from the effectof toxins released in the gut from ingested algae (Lightner 1978a;
Lightner et al. 1978). The principal lesion observed in this diseaseis necrosis and hemocytic inflammation of the mucosa (Fig. 7) of
those portions of the shrimp gastrointestinal tract that lack achitinous lining (the midgut, the epigastric caecum, and the hindgut caecum).
The cause of death in shrimp with HE may be due to osmotic
imbalances or to poor absorption of nutrients from the midgut due
to the destruction of the midgut mucosa but, in most instances,death appears to be due to secondary bacterial septicemias. Vibriosp., principally V. alginolyticus, is the organism most commonly
isolated from the hemolymph of shrimp with septic HE (Lightner
1978a; Lightner et al. 1978). Mortality rates in populations of P.
stylirostris with HE have reached 85% but, typically, have been <50% of the affected population (Table 3).
At Puerto Penasco, three species of the Oscillatoriaceae,
because of their relative abundance in shrimp tanks during HE
epizootics, have been suspect as probable causative algae. Of
these three species, two (Schizothrix calcicola (Agardh) Gamontand Spirulina subsalsa Oersted), have been shown to induce thedisease experimentally when fed as unialgal cultures to susceptible
juvenile P. stylirostris. A third species, Microcoleus lyngbyaceus(Kutzing) Crouan, while suspected as being a cause of HE in
shrimp tanks, has not been shown to induce the disease in experi-

Figure 7.-a. A sagittal section of the normal anterior midgut of a juvenile blue
shrimp, Penaeus stylirostris. Hematoxylin and eosin. x 186. b. A sagittal sectionof the anterior midgut of a juvenile blue shrimp with hemocytic enteritis. Remnants of the gut mucosal epithelium (E) are present, but In many areas only
masses of hemocytes (H) line the gut lumen. Hematoxylin and eosin. x 83.

30

Table 3.-Summary of bemocytic enteritis epizootics in blue shrimp, Penaeus slyUroslris,
which occurred during blooms of certain blue-green algae in raceways at Puerto Penasco.
Approximate datesof epizootic
July-Sept. 1975
July-Aug. 1976
Oct.-Dec. 1976
Oct. 1976
Nov. 1976
Jan.-Mar. 1977
Oct.-Nuv. 1977
Apr. 1978
Mar.-Apr. 1979
May 1979
July-Aug. 1979
Sept.-Nov. 1979
Sept.-Nov. 1979
Nov. 1979
Feb. 1980
Feb. 1980
Apr. 1980
Apr. 1980

Population

Tank orSize range

raceway no.

wt. (g)

InitialFinal% loss4
95
60.05-4.0
0.62-2.4
0.54-2.6
0.24-1.0
2.9-5.0
12.3-19.8
0.01-0.5
0.5
0.01-0.5
0.01-0.1
0.01-0.1
0.01-0.1
0.01-0.6
0.1-0.5
0.1-2.1
0.5-1.0
0.01-0.5
1.0-1.5

17 .700
21.00021,70019,600
11,20012,70026,000105,000
68.000120,000
506.000
849,000
563.000
450,000
208,000
123,000
310,000
275,000

2,700
4,000
8,700
10,5006,900
11,10010,000102,000
60,000

85
81
60
46
38
13
61
3
12
10-20
10
40
15
20
5
2
20
5

II

12
7
II

P2
PI & 2
P4 & 5P3
P4 & 5
PI & 2
G7

08
PI010,11,12

461,000
497,000
486,000
358,000
197,000
121,000
250,000

Approximate

ments in which unialgal cultures were fed to susceptible P.
stylirostris.
Because HE typically has a septic phase that is the usual causeof death, antibiotic therapy is often useful. Medicated feeds containing Terramycin (oxytetracycline hydrochloride) and/or
Furacin (nitrofurazone) have been used with mixed success in
reducing mortality rates due to HE at Puerto Penasco (Lightner etal. 1978). The use of algaecides also appears promising in preventing this disease by reducing the amount of blue-green algae present in shrimp rearing tanks.

Blue Syndrome X
Since the shrimp project was started at Puerto Penasco, apeculiar disease syndrome, that we call blue syndrome X (BSX),
has occurred twice. On both occasions, BSX caused extremely
heavy mortalities of juvenile and subadult shrimp. The disease
was named blue syndrome X because it was first recognized as a
distinct (but of unknown etiology) disease syndrome in populations of the blue shrimp, P, stylirostris (Salser et al. 1978).
However, the disease is not confined to the blue shrimp, and it isthought to also have occurred in the California brown shrimp, P.
californiensis, at Puerto Penasco.
BSX is a difficult disease to diagnose because no consistent,
distinctive, or unique lesions are present grossly or histologically.
However, blue shrimp popl,llations in which BSX is enzootic doshow some characteristic behavior patterns and occasional
physical changes that are characteristic of this disease. The firstcharacteristic of BSX is that shrimp, within a population having
BSX, die during molting or following handling stress. Secondly, up
to 50% of the shrimp within BSX affected populations have been
observed to develop "blunted heads" (Fig. 8) within a few weeks
after BSX mortalities have begun in the affected population. Thiserosion of the head appendages is apparently due to abnormal
trauma to those appendages by repeated collisions with the wallsof the culture tank, or to poor calcification of the new exoskeleton
in those regions.

Figure 8.-Photograph of subadult blue shrlmp,Penaeus slyUroslris. The bottom
shrimp has normal head appendages, while the two above have "blunted" oreroded away the antennae, antennules, rostrum, antennal blades, and portionsof their compound eyes. Such erosions of the head appendages are typical of
shrimp having blue syndrome X (BSX) disease.

The etiology of BSX is uncertain,4 but circumstantial evidence
suggests that the most recent occurrence of BSX at Puerto Penasco
was due to a batch of cod-liver oil (which is included in the
shrimp's ration to supply essential fatty acids and certain
vitamins) that was contaminated with up to 25 ppm PCB and up
to 5 ppm DDT and DOE. However, we have not yet proven therelationship of these contaminants to BSX disease.

'Tests run subsequently to submission of this manuscript indicated that the suspect
cod liver oil when added to the shrimp ration at 0, I x, and 4x of the normal levels
had no effect on the prevelance of BSX, nor on tissue levels of accumulated PCB,
DDT, and DOE in affected populations of blue shrimp. Hence, the etiology of BSX
remains unproven.

31

Death in shrimp with MBVD may be due to destruction of thehepatopancreatic tubule epithelium or to secondary bacterial septicemias (usually due to V. alginolyticus). Because of the secondary
bacterial septicemias, antibiotic therapy was useful in delaying,
but not stopping, mortalities due to MBVD in the population of P.
monodon.

Baculovirus Disease
A single population of adult Penaeus monodon was annihilated
by a disease called MBVD (monodon baculovirus disease). Adultand subadult P. stylirostris and P. californiensis directly exposed to
MBV-infected P. monodon for several months were apparently
resistant to infection by the virus and showed no mortalities orother signs of the disease.
In P. monodon, MBVD is diagnosed by demonstration of multiple nuclear polyhedral bodies (Fig. 9) within the hypertrophiednuclei of infected hepatopancreatic epithelial cells (Lightner andRedman 1981).
Virus particles, occurring both free in the nucleoplasm or
occluded within the inclusion bodies, displayed a morphology
typical of baculovirus occuring in other Arthropods and in otherspecies of penaeid shrimp (Summers 1977; Couch 1974).

LITERATURE CITED
AQUACOP.
1977. Observations on diseases of crustacean cultures in Polynesia. Proc.
World Maricult. Soc. 8:685-703.
ARMSTRONG, D. A., D. V. BUCHANAN, and R. S. CALDWELL.
1976. A mycosis caused by Lagenidium sp. in laboratory-reared larvae of thedungeness crab, Cancer magisler, and possible chemical treatments. J.
Invertebr. Pathol. 28:329-336.
BLAND, C. E., D. G. RUCH, B. R. SALSER, and D. V. LIGHTNER.
1976. Chemical control of Lagenidium, a fungal pathogen of marine crustacea. Univ. N. Carolina Sea Grant Program, Pub I. No. UNC-SG-76-02, 38 p.
BROCK, T. D.
1974. Family IV. Leucotrichaceae Buchanan 1957. In R. E. Buchanan and
N. E. Gibbons (editors), Bergey's manual of determinative bacteriology. 8thed., p. 118-119. The Williams & WilJ<ins Co., Baltimore, Md.
COOK, D. W., and S. R. LOFTON.
1973. Chitinoclastic bacteria associated with shell disease in Penaeus shrimp
and the blue crab (Callinecles sapidus). J. Wildl. Dis. 9:154-159.
COUCH, J. A.
1974. An enzootic nuclear polyhedrosis virus of pink shrimp: Ultrastructure,
prevalence, and enhancement. J. Invertebr. Pathol. 24:311-331.
1978. Diseases, parasites, and toxic responses of commercial penaeid shrimpsof the Gulf of Mexico and South Atlantic coasts of North America. Fish.
Bull., U.S. 76:1-44.
DELVES-BROUGHTON, J., and C. W. POUPARD.
1976. Disease problems of prawns in recirculation systems in the U.K.
Aquaculture 7:201-217.
DESHIMARU, 0., and K. KUROKI.
1976. Studies on a purified diet for prawn-VII. Adequate dietary levels of
ascorbic acid and inositol. Bull. Jpn. Soc. Sci. Fish. 42:571-576.
EGUSA, S., and T. UEDA.
1972. A Fusarium sp. associated with black gill disease of the Kuruma prawn,
Penaeusjapanicus Bate. Bull. Jpn. Soc,Sci. Fish. 38:1253-1260.
HATAI, K., K. NAKAJIMA, and S. EGUSA.
1974. Effects of various fungicides on the black gill disease of the Kuruma
prawn Penaeusjapanicus caused by Fusarium sp. Fish Pathol. 8:156-160.
HUNTER, B., P. C. MAGARELLI, Jr., D. V. LIGHTNER, and L. B. COLVIN.
1979. Ascorbic acid-dependent collagen formation in penaeid shrimp.
Compo Biochem. Physiol. 64B:381-385.
JOHNSON, S. K., J. C. PARKER, and H. w. HOLCOMB.
1974. Control of Zoolhamnium sp. on penaeid shrimp. Proc. World Maricult. Soc. 4:321-331.
LEWIS, D. H.
1973a. Predominant aerobic bacteria of fish and shellfish. Tex. A&M
Univ., Sea Grant Publ. 401, 102 p.
1973b. Response of brown shrimp to infection with Vibrio sp. Proc. World
Maricult. Soc. 4:333-338.
LIGHTNER, D. V.
1975. Some potentially serious disease problems in the culture of penaeid
shrimp in North America. Proc. U.S.-Japan Natural Resources Program,
Symposium of Aquaculture Disease, Tokyo, p. 75-97. Spec. Pub I. Fish.
Agency, Jpn. Govt. and Jpn. Sea Reg. Fish. Res. Lab., Niigata.
1976. Epizootiology of two mycotic diseases in the culture of penaeid shrimp.
Proceedings of the First International Colloquium on Invertebrate Pathology
and 9th Annual Meeting of the Society for Invertebrate Pathology, p. 179183. Queens Univ. Kingston, Ontario, Canada.
1977. Shrimp diseases. In C. J. Sindermann (editor), Disease diagnosis andcontrol in North American marine aquaculture. Developments in aquaculture
and fisheries science, Vol. 6, p. 10-77. Elsevier Sci. Publ. Co., N.Y.
1978a. Possible toxic effects of the marine blue-green alga, Spirulina subsalsa,
on the blue shrimp, Penaeus stylirostris. J. Invertebr. Pathol. 32:139-150.
1978b. Gill disease; a disease of wild and cultured penaeid shrimp. Proc.
66th Meeting International Council for the Exploration of the Sea. C.M.
1978/F:24.
LIGHTNER, D. V., L. B. COLVIN, C. BRAND, and D. A. DANALD.
1977. Black Death, a disease syndrome of penaeid shrimp related to a dietary
deficiency of ascorbic acid. Proc. World Maricult. Soc. 8:611-623.

Figure 9.-a. Photomicrograph of a section of the hepatopancreas of a Penuus
monodon with monodon baculovlrus disease (MBVD). The nuclei of many
hepatopancreatic epithelial cells are greatly hypertrophied and contain from one
to several rounded occlusion bodies. Wolback's g1emsa. x 379. b. Electron
micrograph of an hepatopancreatic epithelial cell that Is infected with MBV.
Numerous rod-shaped virions are present free In the karyoplasm and occluded
within the large spherical crystalline occlusion body. Lead citrate and uranyl
acetate. x 16,226.

32

LIGHTNER, D. V., D. A. DANALD, R. M. REDMAN, C. BRAND, B. R. SALSER,
and J. REPRJETA.
1978. Suspected blue-green algal poisoning in the blue shrimp. Proc. World
Maricull. Soc. 9:447-458.
LIGHTNER, D. V., and C. T. FONTAINE.
1973. A new fungus disease of the white shrimp Penaeus seli/erus. J. Invertebr. Pathol. 22:94-99.
LIGHTNER, D. V., C. T. FONTAINE, and K. HANKS.
1975. Some forms of gill disease in penaeid shrimp. Proc. World Maricult.
Soc. 6:347-365.
LIGHTNER, D. V., B. HUNTER, P. C. MAGARELLI, Jr., and L. B. COLVIN.
1979. Ascorbic acid: nutritional requirement and role in wound repair inpenaeid shrimp. Proc. World Maricult. Soc. 10:513-528.
LIGHTNER, D. V., and D. H. LEWIS.
1975. A septicemic bacterial disease syndrome of penaeid shrimp. Mar.
Fish. Rev. 37(5-6):25-28.
LIGHTNER, D. V., D. MOORE, and D. A. DANALD.
1979. A mycotic disease of cultured penaeid shrimp caused by the fungus
Fusarium solani. In D. H. Lewis and J. K. Leong (editors), Proc. Second
Biennial Crustacean Health Workshop. Texas A&M Univ. TAMU-SG-79
114:137-158.
LIGHTNER, D. V., and R. M. REDMAN.
1981. A baculovirus-caused disease of the penaeid shrimp, Penaeus monodon.
J. Invertebr. Pathol. 38:299-302.
LIGHTNER, D. V., and V. C. SUPPLEE.
1976. A possible chemical control method for filamentous gill disease. Proc.
World Maricull. Soc. 7:473-481.
MAGARELLI, P. C., Jr., B. HUNTER, D. V. LIGHTNER, and L. B. COLVIN.
1979. Black death: an ascorbic acid deficiency disease in penaeid shrimp.

Compo Biochem. Physiol. 63A:103-108.
MOCK, C. R., and M. A. MURPHY.
1970. Techniques for raising penaeid shrimp from the egg to post-larvae.
Proc. World Maricull. Soc. 1:143-156.
MOCK, C. R., D. B. REVERA, and C. T. FONTAINE.
1980. Preliminary observations on the larval culture of Penaeus sryliroslris
using modifications of the Galveston technique. Proc. World Maricull. Soc.
11:102-117.
OVERSTREET, R. M.
1973. Parasites of some penaeid shrimps with emphasis on reared hosts.
Aquaculture 2: 105-140.
SALSER, B., L. MAHLER, D. LIGHTNER, J. URE, D. DANALD, C. BRAND, N.
STAMP, D. MOORE, and B. COLVIN.
1978. Controlled environment aquaculture ofpenaeids. In P. N. Kaul and C. J.
Sindermann (editors), Drugs and food from the sea, myth or reality?, p. 345355. Univ. Oklahoma Press, Norman.
SCHNICK, R. A., F. P. MEYER, L. L. MARKING, T. D. BILLS, and J. H.
CHANDLER, Jr.
1979. Candidate chemicals for crustacean culture. In D. Lewis and J. Leong(editors), Proc. Second Biennial Crustacean Health Workshop. Texas A&M
Univ. TAMU-SG-79 114:245-294.
SIEBURTH, J. M.
1975. Microbial seascapes. A pictorial essay on marine microorganisms andtheir environments. Univ. Park Press, Baltimore, Md., 247 p.
SUMMERS, M. D.
1977. Baculoviruses (Baculoviridae). Chapter 1. In K. Maramorosch(editor), The atlas of insect and plant viruses. Ultrastructure in biologicalsystems, Vol. 8, p. 3-27. Acad. Press, N.Y.

33

Research and Development in Freshwater Prawn,
Macrobrachium rosenbergii, Culture in the
United States: Current Status and Biological
Constraints With Emphasis on
Breeding and Domestication
SPENCER MALECHN

life cycle, including maturation, courtship, mating, brooding,spawning, larval development, and juvenile to adult growth, may
be accomplished in tanks, ponds, or aquaria.
Figure I shows the overall life cycle of the prawn. Breeding
behavior has been described by Rao (1965) and Ling (1969a).
Mating occurs between hard-shelled males and newly molted
females. Adults form single pair bonds and undergo amplexus atwhich time a spermatophore (sperm packet) is deposited on thefemale's abdomen (Sandifer and Smith 1979; Sandifer and Lynn
1980). Eggs, extruded through the female's gonopores, passthrough this packet, are fertilized, and remain attached to thefemale's ventral abdomen ("tail") during incubation. This lasts forabout 15 d after which free swimming protozoea larvae are released ("hatched") into the water column. These undergo 11 larvalmolts followed by one molt into benthic crawling postlarvae (PL).
Since there is considerable variation in individual growth whichleads to a size frequency distribution with a large variance, growth

INTRODUCTION
In this paper I would like to briefly review the research anddevelopment (R & D) of prawn culture in the United States, including its current status in Hawaii, and mention some of the current
developments which show promise. I will then discuss a few major biological properties of the prawn or its culture system which,in my view, presently constrain optimal production. I will end mypaper with a review of some of the results I have obtained in mybreeding and domestication work and will point out what I feel tobe promising areas of future R&D.
The state of the art of Macrobrachium rosenbergii culture has
been reviewed elsewhere (Hanson and Goodwin 1977; Ling and
Costello 1976). In addition, the Proceedings of the World
Mariculture Society, from 1975 to the present, and the journal
Aquaculture, from 1970 to the present, contain most of the papers
that have been published regarding M. rosenbergii research. It is
not my intent to provide a comprehensive review of all this work
but only to point out what I feel are the highlights in prawn R&D
in the United States. For greater accuracy in technical data thereader is referred to the professional published literature.

ZOEA LARVAE
O.5mm '(;1~~11.0" 15

LIFE CYCLE

j;Y

(>"

}'

35
DAYS

DAYS

.,'"

Macrobrachium rosenbergii is a large 2 freshwater decapod caridean crustacean distributed throughout areas of Southeast Asia,
India, Australia, and areas around the South China Sea (see Fig.
13). Reviews of its biology can be found in Ling (1969a), Miyajima (1977), and Wickins (1976). The genus Macrobrachium contains hundreds of species which have been monographed forSoutheast Asia (Holthuis 1950) and the Americas (Holthuis
1952). Macrobrachium rosenbergii apparently is a species that is
evolving "out of the sea" (Johnson 1960a) in that its larvae require brackish water for their development. In fact, the "breakthrough" in closing the life cycle of M. rosenbergii came when
Ling (1969b) raised the salinity in his larval culture aquaria to
16% 0 (Goodwin 1977). Previous attempts to rear larvae tometamorphosis failed because only freshwater was used.
There are constraints in prawn aquaculture (see later) but these
do not involve life cycle factors. The various stages in the prawn's

lorval5 toges

12 molts

Macrobrachiumrosenberg II
1I FE
CYCLE

ADULT
Figure I.-Life cycle of the freshwater prawn, Macrobrachium rosenbergii.
Figures represent average values for stages in Hawaii. Larval and pond growout
stages can vary considerably in individual circumstances depending upon environmental conditIons. Adult prawn drawn to represent a 45.6 g individual(I011b, 22/kg), an average market weigbt. Mating, Including amplexus, is ofvariable lengtb over a 48-b period during wbicb tbe female is receptIve. Spawning usually occurs witbin 24 b of successful matIng.

'Prawn Aquaculture Research Program, Department of Animal Sciences, University of Hawaii, Honolulu, HI 96844.
'My field studies have measured a 654 g male in New Guinea. Reports of a 1,000
g animal come from Taiwan.

35

Like most of the other aquaculture organisms, the freshwater
prawn is relatively biologically unexplored. Consequently, almost
anything we learn from using it in experimental research could
have impact on optimizing its culture. However, almost all of theresearch projects listed in Table I are applied, i.e., directed toward
the prawn's aquaculture potential.

to sexual maturity is variable (6-9 mo) and harvestable (> 35 g)
prawns are available in 9-11 mo.

EXPERIMENTAL RESEARCH
Naturally, the growing interest in freshwater prawn culture has
generated experimental research efforts designed to answer someof the fundamental questions which could lead to better production. By experimental research we mean research conducted
where there is some degree of control over variables whose effects
are under study and also where controls and replications of treatments are possible. This is in contrast to research in newtechnology development where efforts are made to achieve a certain result and not necessarily to understand the underlying causesof these results or the relationship of the variables which affect theoutcome.
A number of groups around the United States have concentrated
on research into the different aspects of prawn culture andbiology. Table I provides a list of these and Figure 2 shows theareas in the United States where the activities are located. This expands the list given in Hanson and Goodwin (1977) but is notmeant to be exhaustive. Figure 3 shows the number of research
papers that have appeared in the journal Aquaculture and in theProceedings of the World Mariculture Society.

RESEARCH AND DEVELOPMENT PROGRAMSIN THE UNITED STATESThe modern history of the culture of the freshwater prawn,
Macrobrachium rosenbergii, is short although the prawn has been
cultured for centuries in ponds using captured seedstock (Bardach
et al. 1972; Ling 1969a). It was not until recently that Ling
(1969b) succeeded in closing its life cycle. This was followed by
the development, in the late 1960's in Hawaii, of mass rearing
techniques by Fujimura and his colleagues who also began thedevelopment of pond rearing techniques (Fujimura and Okamoto1970). The first successful commercial pond, built exclusively for
prawns stocked from hatchery reared seed-stock, was started in
the early 1970's in Hawaii and is still in production.
Following the successes of Fujimura in developing mass larvalrearing and pond culture techniques, Hawaii became the initialleader in the culture of the freshwater prawn. Several agencies inTable I.-Research programs in universities and government agencies in the United States.
Organization
Universities
Texas A&M U.
U. of Miami

Florida Atlantic U.
Clemson U.
Rutgers U.

U. of Nevada, Reno

Oregon Inst. Technology
Louisiana StateSouthern U.
U. of Hawaii
Honolulu. HI 96822

Government Agencies\llinois Natural History
SurveyNational Marine FisheriesServiceMarine Resources ResearchInst.

Anuenue Fisheries ResearchCenterPrincipal contact

Address

Research activities

Dep. Wildlife & Fisheries Sci.
College Station, TX 77843
School of Marine &Atmospheric Science
4600 Rickenbacker Causeway
Miami, FL 33149
Boca Raton. FL 33431
Clemson, SC 29631
Dep. Physiology
P.O. Box 231
New Brunswick, NJ 08903
School of Veterinary Medicine
5305 Mill Street
Reno, NV 8950 I
OreTech Post Office
Klamath Falls, OR 9670 I
School of Forestry & Wildlife
Management
Baton Rouge, LA 70802
Dep. BioI. Sciences
Baton Rouge, LA 70813
Dep. Animal Sciences

Robert Brick

Polyculture, nutritional physiology

Peter Lutz

Metabolism, stress physiology

Sheldon Dobkin
Larry Bauer
A. Farmafarmian

Pond culture
Pond production economics l
Nutrition binders, physiology

Robert Taylor

Hatchery, thermal effluent pond
culture, geothermal

William Johnson

Hatchery, geothermal pond culture

Robert Avault

Pond culture, polyculture'

Jay Huner

Pond culture, polyculture'

Spenccr Malecha

Dep. Oceanography
Dep. Agric. Engineering

Edward Laws
J. K. Wang

Domestication, breeding, growth
biology, polyculture'
Pond ecology
Nursery systems

Kinmundy, IL 62854

Homer Buck

Polyculture with manure lCharleston Laboratc,ry
P.O. Box 12607
Charleston, SC 29412
South Carolina Wildlife &Marine Res. Dep.
P.O. Box 12559
Charleston, SC 24912
Area 4, Sand Island
Honolulu, HI 96819

L. V. Sick

Nutritional requirements

Paul Sandifer
T. I. J. Smith

Pond culture.' nursery systems,
economics. reproductive biology

Michael Fujimoto

Extension, hatchery

ICooperative programs.

36

/

THER'ALfNEH

NUTRITION~•(RUTGERS)POLYCULTURE(ILL, NAT, HIST,SURVEY)JERSEY~.....t>HAWAIIDEVELOPING
INDUSTRY,

Figure Z.-Locatlons for prawn R&D activities in the UnitedStates, 1980.

BREEDING
POND

ECOSYSTE~lS

GROWTH BID,
(U, OF HAWAJ I)

EXTi~~~~~UE FIsHER I ES)

other states soon began R&D programs. South Carolina became aleader in this regard as researchers began the preliminary hatcheryand field trials needed to establish the feasibility of growing the
freshwater prawn in temperate North America (Sandifer andSmith 1978; Smith and Sandifer 1980; Smith et al. 1977, 1978).
The basic constraint to profitable culture seems to be the shortgrowing season which requires a separate nursery phase (Fig. 4;
Sandifer and Smith 1978). The great variability in individual
growth is also a constraint because it leads to populations withhighly skewed size frequency distributions with large variance(Smith et al. 1978) necessitating markets for many size classes.
The production economics for pond culture in South Carolina
have been completed (Roberts and Bauer 1978) and feed remains
the highest fixed cost.
Field trials in 1978 (Smith and Sandifer 1980) have indicatedthat stocking juvenile prawns as a mixed population of PL's andjuveniles was better for seasonal production than stocking PL'salone. This is because the large prawns can be marketed whole asa specialty product and the remaining smaller individuals as
shrimp tails. Field trials in 1979 (Smith et al. 1981) show an improvement of the gross feed conversion ratio (from 2: I in previous
years to 1.2:1 in 1979). Additionally, the 1979 field trials indicatethat a stocking density of 0.4/ft 2 (4.3/m 2 ) was the most attractive

30

25

20

Proceedings
AnnualMeetingWorld-...;;/
Mariculture
Society

15

%
10

I

....,

5

I

'70

'71

'72

'73

'74

'75

,

,1\'

\

Aquaculture' .... /"',~""'- -...

76

'77

'78

'79

'80

YEAR
Figure 3.-Percent total papers devoted to research on Macrobrachium
rostnbtrgii that have appeared In the journal Aquaculture and the Proceedings ofthe World Mariculture Society, 1970-80.

A

M

HATCHER' ----]

POl'l'O CUL TURf

PRODUCTION

ANNUAL

Figure 4.-Productlon and annual cycles for freshwater prawns in South Carolina (from Sandifer and Smith 1978). The components ofthese cycles can be considered typical for the continental United States although the duration of each will vary from area to area.

37

economically, i.e., overall mean size was greater despite lower
production; seed costs for this density were lower than the otherdensity.
Research and development activity has also occurred in Florida
under the aegis of the Florida Department of Natural Resources.
Hatchery (Dugan et al. 1975; Hagood and Willis 1976) and fieldtrials (Willis and Berrigan 1977, 1978) have been completed.
Texas A&M University began a program to study the natural
history of native species of Macrobrachium in Texas in the early
1970's. From this the present study of practical farm management
techniques for Macrobrachium production and of their basic
biology was begun in 1975. 3 Currently, emphasis is placed upon
production of M. rosenbergii in small ponds (0.1-1.0 ha) althoughnative species are still studied.
The growing season for M. rosenbergii in Texas ranges from 4.5
to 6 mo, depending primarily upon latitude. Stocking of ponds
usually involves PL's directly from a hatchery. A few private producers have designed warmed nurseries for stocking PL's ahead of
the outdoor growing season. These nurseries are indoor, closed
systems equipped with biological filters. The first stock of"advanced juveniles" (approximately 2 cm in length) were placed
into ponds in 1980.
About a dozen private cooperating farmers are working with
Texas A&M's Department of Wildlife and Fisheries this year in
their research program across the state. Earthen ponds stocked at alow density (35-40,000/ha) are used for current studies. The
ponds are well fertilized and are usually fed sinking catfish pellets
as the most readily available feed.
Macrobrachium studies are also supported by the Texas
Agricultural Experiment Station. Studies over the last 3 yr have
involved polyculture of M. rosenbergii with Tilapia aurea.
The Texas Agricultural Extension Service is involved in promoting the culture of M. rosenbergii in Texas through the networksof County Extension Agents and County Fisheries Extension
Agents. Farming freshwater shrimp is promoted as an element ofintegrated agriculture.
The Arkansas Game and Fish Department" has recently begun
pond growth trials with M. rosenbergii and has expressed an interest in aiding small-scale commercial development.
From these studies production of between 1,550 and 2,000
kg/ha seems to be possible in one season's growth during theNorth American summer.

During the second year of the project, 264 Ib (120 kg) ofprawns were produced in a 0.25-acre (0.10 ha) pond at the power
plant in a 6-mo growout period during the winter, Cold watertemperatures hampered the growth of prawns but results were encouraging enough to expand the project. During the third year, 10
ponds totalling 3 acres (1.21 ha) were operated on a production
and research basis.
A I-acre (0.41 ha) pond was stocked in April 1979 and harvesting was initiated in the pond in mid-September. From midSeptember 1979 through mid-January 1980, approximately 1,000
Ib (455 kg) of prawns were harvested. Present efforts at the powercompany are directed at culturing the prawns in floating net structures in the company's main cooling ponds.
The future of prawn raising in Nevada may center around theuse of low temperature « 300°F) geothermal water which willprobably be cascaded throug!l a series of uses. Such water isrelatively common because of the widespread drilling of geothermal wells which are intended for power production. However,prawn raising in Nevada is still in the pilot stage with no large
scale commercial production.
A thermal effluent project has been carried out in New Jersey(Eble et al. 1975, 1977). Although initially promising (Godfriaux
et al. 1977), the feasibility of economic culture was deemed slightmainly due to the inability to raise prawns at high densities insmall cooling ponds. This points up the importance of the constraint of Macrobrachium rosenbergii's growth pattern, discussed
later, to high density culture.
Another project under the lead of the Oregon Institute ofTechnology7 seeks to develop M. rosenbergii culture using
geothermal water. The initial phase of the program began during
the 1975 -76 academic year and was primarily concerned withdetermining the feasibility of rearing M. rosenbergii in geothermal
waters. Success on a small scale prompted an expansion to a larger
operation concerned with an attempt at hatching larvae and rearing them to a reproductive stage in geothermal water. This second
phase of the operation also proved to be successful and harvests ofa few crops were made of marketable size in less than averagetime due to the constant water temperature.
The program is in the process of expanding to include two
0.5-acre (0.20 ha) ponds for the purpose of conducting a density
and growout period study utilizing different subsurface strata.
Also included in the development will be a larger hatcherybuilding which will enable improvement of hatching techniques.

Thermal Emuent and Geothermal
Extensive, Low Input Culture
Two recent projects have emphasized the culture of prawns inthermal effluent. A prawn raising project has been underway at
the University of Nevada, Reno, since October 1976. 5 The project
has been funded by the Electrical Power Research Institute. The
objective of the project is to determine the feasibility of raising
prawns in power plant effluent and/or geothermal water in
Nevada.
The first year of the project was spent in developing techniques
for raising larval prawns to the postlarval stage using Instant
Ocean 6 sea and a recirculating system.

Inasmuch as M. rosenbergii is a benthic omnivore, it is capableof utilizing the natural productivity (microbes, insects, microfauna) from shallow ponds and flood plains. This makes it a goodcandidate for culture patterned after the extensive "culture" ofcrawfish in Louisiana and Arkansas.
Small-scale stocking of diked, flooded areas in Louisiana has
been tried and has yielded promising results. Production of between 400 and 600 kg/ha seems a reasonable goal. In one trial,Spostlarvae were stocked at very low density (2 m 2 ) in early spring,left to survive and grow on the natural productivity that developedin an ecosystem that was dominated by native aquatic macrophytes, and harvested in the fall by slowly draining the area into acatch basin. Total production was 26 kg/ha of tails with only 11 %'Roben w. Brick, Depanment of Wildlife & Fisheries Sciences, Texas A&M
University, College Station, TX 77843, pers. commun. 1975.
'Mike Freeze, Arkansas Game and Fish Commission, No.2 Natural Resources Dr.,
Little Rock, AR 72205, pers. commun.
'Roben Taylor, Project Manager, University of Nevada, Reno, Veterinary Medical
Center, 5304 Mill Street, Reno, NV 89502, pers. commun. May 1980.
'Reference to trade names does not imply endorsement by the National Marine
Fisheries Service, NOAA.

'William Johnson, Project Director, Aquaculture, Oregon Institute of Technology,
Klamath Falls, OR 97601, pers. commun. May 1980.
'Jnformation provided by J. Boulet, P.O. Box 267, Larose, La.

38

survival. However, costs of input were very low: Labor at stocking
and harvesting, costs of postlarvae, and some pumping costs. Net
profit was $225/acre (~ 131,216/ha).9 This sort of extensive
culture seems most promising on marginal areas of land alreadydevoted to other agriculture commodities. If production could be
improved to 500 kg/ha, extensive prawn culture could add a valueof over $1,500 (~ 354,000)/ha to the operation.
As with the other single single season crops, there would haveto be markets for all the size classes if the large variance in thesize frequency distribution develops. The following table shows
the various size classes that were marketed in the Boulet trial.
Production(tails)States on a large scale. From time to time, a small operation will
begin but no significant commercial culture is presently being
conducted in the continental United States and prawn culture is,by and large, still in the formative stages. Despite this, interest in
freshwater prawn culture remains quite high, and two mainland
based U.S. companies remain in freshwater prawn aquaculture.
The Weyerhaeuser Corporation maintains a hatchery and R &D facility in Homestead, Fla. 1o (Note added in proof: This company is no longer in business.) Research at this facility is directedin the areas of pond management, population manipulation, andfeed formulation. In the area of pond management, the operating
assumption is that large pond acreages (as might be expected infuture expansion) will have to be self-managing so that "crises ofscale" will not develop (more will be said about this later).
Weyerhaeuser's efforts in population manipulation involve working on strategies to maximize yield within the existing limitationsof the organism. In the area of feed management, means ofsupplying critical nutritional elements through pond food webs
are being investigated.
The other large U.S. company is Red Lobster Inns, with corporate headquarters in the United States l l and a freshwater
shrimp farm in Central America. 12 The pond facility is locatednear San Pedro Sula, Honduras, and consists of 54 ponds (67acres; 27.13 ha) ranging from 10 acres (14.1 ha) to 3.0 acres (1.21ha). A coastal hatchery is near Puerto Cortes and consists of 25
4,000-gal (15,160 I) tanks. An inland hatchery at pond site has 3
4,OOO-gal (15,160 1) and 38,000-gal (144,020 I) tanks. Bothhatcheries average 90-140 PUgal (24-37/1) at 8-9 cycles/yr. R &D efforts concentrate on increasing pond production, nutrition,and feed efficiency. No hatchery R&D is being conducted. Current pond production is averaging 2,500 Ib/acre per yr (2,806
kg/ha per yr) with up to 3,500 lb/acre per yr (3,930 kg/ha per yr)
in some ponds. Aqua Finca de Camerones concentrates on harvesting 8-16 animals/lb (18-35/kg) in order to supply 20-35 tails/lb(44-77 /kg) to its parent chain's Red Lobster Restaurants. They
receive $1.90-$2.00/lb (~ 986-1,038/kg). For this market it
appears that at least 500 acres (202 ha) of growout ponds will be
required to provide a return commensurate with an overseas investment risk for a U.S. corporation. In this regard, Aqua Finca deCamerones plans an extension to 700 acres (283 ha) beginning inearly 1981. This will entail a hatchery expansion to a 300,OOO-gal(1,137,000 I) recirculating water reuse system. Aqua Finca deCamerones plans call for cooperative ventures with local Hondurans whereby the former will provide postlarvae, technology,
food, and guaranteed production purchase. The ponds will be built
by the local entrepreneurs who then grow the prawns.

Selling price% of total

Lb
285
530
50
30
60
20

kg
129.4
241.0
22.7
13.6
27.2
9.1

No.llh
15-20
24-30
36-42
43-50
51-60
> 81

No/kg
33-44
53-66
79-92
95-110112-132> 178$USIlb
5.50
4.90
3.75
3.25
2.70
1.25

¥flcg
2,856
2,543
1,947
1,687
1,401
649

harvested
30
54
5
3
6
2

The low stocking density seems to reduce the intrapopulationcompetition possibly due to the fact that animal to animal encounters may be infrequent. The net result is that a highly skewed
depensated population may not develop. Such a population is amajor constraint to more intensive culture (see later).

Polyculture
The benthic omnivorous feeding niche which Macrobrachiumrosenbergii occupies makes it a good candidate for polyculture
with fishes, especially with low cost organic inputs like manure.
Malecha, Buck, Baur, and Onizuka (1981) have demonstrated thepotential of the polyculture of prawns and a complete complementof fishes occupying various feeding niches. They raised pigs along
the pond banks to provide manure and obtained good growth, but
their prawn production was low (322.3 kg/ha) in their first trial
due to the fact that their system was probably understocked(6.2/m 2 ). Nevertheless, these results clearly demonstrate that M.
rosenbergii can derive a significant, if not complete, portion of its
nutritional requirements from heterotrophic productivity
stimulated by low cost organic inputs. Moreover, the cost savings
from no supplemental prawn feeding complemented by the increased revenue possible from fish and agricultural livestock givepolyculture a high potential for use in economical prawn culture.
Other studies have emphasized the use of polyculture in prawn
pond culture. Huner et al. (1980) polycultured M. rosenbergii with
catfish, Ictalurus punctatus, fingerlings and obtained 449 kg/ha ofprawns. Similarly, Brick and Stickney (1979) have reared M.
rosenbergii and Tilapia aurea in Texas.

The Hawaiian Industry
Prawn culture in Hawaii is economically viable (Shang andFujimura 1977; Lee 1979). The present industry was built upon
the development of mass rearing techniques (Fujimura andOkamoto 1970) and under the guidance of the Anuenue Fisheries
Research Center which provides seedstock to aquafarmers and

INDUSTRY OPERATIONSContinental United States
To date private operations using extensive pond culture of
Macrobrachium rosenbergii have not been developed in the United

IOInfonnation provided by Ed McSweeney, Prawn Research Director, Weyerhaeuser Corporation, Research and Engineering Aquaculture. P.O. Box I ~84. Homeslead,
FL 33030.
"Red Lobster Inns of America, Inc., P.O. Box 13330, Orlando, FL 32809.
I2Infonnation provided by Ronald E. Wulff, Technical Director for Aquaculture.
Aqua Finca de Camerones, Aquaculture Fann Ltd., Apartado 677, San Pedro Sula.
Honduras, C.A.

•¥ 236 = $1.00.

39engages in a major extension program involving pond site selection, construction, management, and product handling. The extension services are available to all prawn operators and seedstock isprovided free for a 3-yr period under a contractual arrangement.
The following is taken from Lee (1979).13"Production for 1979 is estimated to be 257,000 pounds(116,818 kg). This is much lower than was expected at the start of1979 due to unusually cold weather during the first months of
1979, limited supplies of juveniles for stocking, construction
delays, and the generally optimistic expectations of farmers ....""In 1970, Hawaii had 1.5 acres (.61 ha) of prawn ponds. The
industry has since expanded to a total of 275 acres (Ill ha).
Growth is expected to reach an additional 900 acres (364 ha) in
the next four years.
"The industry consists of 13 part-time and eight full-time
operations. These range in size from .25 acres (.103 ha) to about
100 acres (41 ha). Sixteen farms are located on Oahu, two are on
Kauai, and three are on the Island of Hawaii.

Table 2 and Figure 5 show the growth of the Hawaiian industry
for the last 7 yr or so. Table 3 gives production (kg/ha) for selected
ponds located on aquafarms that are under the cooperative agreement with Anuenue Fisheries Research Center. Table 3 provides amore accurate picture of production in kg/ha per yr than does
Table 2 which does not reflect the fact that some ponds, although
under culture in that calendar year, have not contributed a full
year's production data. Consequently, industry-wide average production appears much lower in Table 2 than the actual production
based on producing ponds.
The Hawaiian industry is a young one and, despite its success, itdoes have a long way to go before it develops into a vertical integraded food production sector analogous to other agricultural sectors. The biological problems and unanswered questions that
presently constrain the Hawaiian industry are discussed later.
They stem from close examination of the properties andunknowns that are characteristic of the present stocking, growout,
and harvesting system.

Table 1. Average size of freshwater prawn farms (modified from Lee 1979).
Average
Number of farms

Acres

Hectares

10
4
2
3
2

.5
2.5
6.4
19.3
95

.2
1.03
2.62
7.9
38.5

"From 1972 to 1977, prawn production increased annuallyfrom 4,000 (1,818 kg) to 55,000 (25,000 kg) pounds. From 1977
to 1978, production doubled. As of October, 1979, 176,400
pounds (80,182 kg) have been produced. This rapidly increasing
supply of prawns will soon require a coordinated market development program. Promising areas for future market expansions are
the tourist and resident sectors of the local market and export
markets in Japan and the U.S. Mainland. This expansion will
necessitate further research into product processing and handling,
and promotional and advertising campaigns.
"The wholesale price to the farmer for freshwater prawns was
at a constant $3.50 per pound from 1972 to 1976 (Table 2). The
price rose to $3.75 per pound (~ 1947 kg-I) in 1977 and reacheda weighted average of $3.82 (~ 1983 kg-I) per pound in 1978. In
1979, the wholesale price was approximately $4.00 (¥ 2077 kg-I)
per pound. The forecast for 1980 suggests that prices will remain
at around $4.00 per pound (¥ 2077 kg-I).

700

INDUSTRY GROWTH
600

500

400

300

200
100

78

"Pounds and U.S. dollars are convened to kg and ;I and insened parenthenticallyby the author for the purpose of discussion.

80

Figure S.-Growth of the freshwater prawn industry in Hawaii, 1971-81 (fromLee 1979).

Tahle 2.-Size, production, and value offreshwater prawns in Hawaii, 1972-79 (1 US = 236!l!:). Modified from Lee (1979).

Acres

Hectares

1972

1973

1974

1975

1976

1977

1978

(As of
Oct.)
1979

1.5
0.61

1.5
0.61

5
2.02

26
10.53

26
10.53

33
13.36

107
43.32

275
111.34340
137.65

4,277
1,944

4,378
1,990

10,960
4,982

40,25918,30043,30019,68254,937
24,971

110,159
50,072

176,400
80,182257,900
117,227

14,9703,532

15,323
3,616

38,3609,052

140,907
33,251

151,550
35,762206,014
48,619420,000
99,293705,600
166,538

1,031,600
243,480

3.50
1,817

3.50
1,817

3.50
1,817

3.50
1,817

3.50
1,817

3.75
1,947

3.82
1,983

4.00
2,077

4.00
2,077

Total
expected
1979

Production

Ib
kg
Value
U.S. $¥'

Wholsale
Pricellb (U .S. $)/kg (¥)

81'x 1,000.

40

Table 3.-Productlon data by pond size for selected ponds under cooperative agreement with Anuenue
Fisheries Research Center extensIon program. Ponds were selected on the basis of providing a full year
(12 mol of monthly production data regardless of the starting calendar date. Data for second and thirdyears should be considered in light of the small number of ponds in the data set for those years.
Pond size< 1 acreProduction year
No. of ponds
Production (kg)Hectares
Production(kg/ha)~ 2 acre(0.82 hal

1-2 acre(0.40-0.82 hal(0.40 hal
First
15
5.721
3.13

Second
5
2.458
0.80

Third
2
632
0.23

First Second
19516.403 7,038
9.63
2.67

Third
1
2,546
0.730

First Second
5
4
10,663 8,550
6.40
5.30

Third
3
11,954
4.25

1,830

3,097

2.789

1,704

3,495

1,660

2,812

Hatchery

2,634

1,612

phosis. At this time PL's are about 1 cm and are stocked at a rateof about 1.5 animals/ft2 (16.14 animals/m 2) of pond bottom.
Pond sizes vary from 0.25 to 4.0 acres (0.10 -1.64 ha) and they
are of all shapes from nearly square to those with length-to-width
ratio exceeding 3 to 1. Embankment slopes vary from 1.5:1 to
2.5: 1 depending on soil types. The total land area required for a
I-acre pond is 1.20 ha or 112.4% of the actual pond area in order
to allow for 15-ft (4.6 m) wide berms and access roads surrounding the ponds.
Grass is planted on road banks for bank stabilization and toprovide shelter for young and molting prawns and to foster natural
productivity to supplement the prawn's diet.
Ponds are usually supplied with water from wells or stream
diversions which flow continuously at rates varying from 15 to 25
gpm/acre. Discharge rates are usually 5-15 gpm/acre (18.9556.85 I/min per ha), taking into account natural evaporation andseepage. The water delivery system consists of pipes running fromthe main line to the "head" of the pond. An outlet is located at the
opposite end. Farmers try to maintain a rich bloom of green algae(500,000 to 2,000,000 cells/ml) in each pond. Feeding is usually
done once in the evening by means of broadcasting from the pondbanks. Prawn farmers are currently using a ration of broiler starter
which costs about 14¢lIb (~ 73/kg). The current average conversion ratio is about 3.3: I (exact information is not available).
Growth and production vary from pond to pond. Figure 6 showsa typical growth curve of a population of prawns in Hawaiian
ponds. The two most important characteristics of this curve,
which are typical of those in other studies (Smith et al. 1978), aresexually dimorphic growth and heterogeneous individual growth.
The latter was first noticed by Fujimura and his colleagues during
the early pond growth trials and was a major deciding factor in the
choice of the harvesting method known as the "Continuous
Harvest System," whereby "new growth," i.e., market size
animals, are supposedly culled by periodic seining from the rest of
the undersized animals, called "runts," which would remain in thepond and grow to replace the previously culled "bulls." In theory,
this harvest system would provide a constant production supply
needed in a fledgling industry where postharvest storage capacity
was not developed and consistent market consignments had to be
met. There are several drawbacks to the Continuous System, as
discussed in Malecha, Polovina, and Moav (1981). Figure 7 showsa typical length-frequency distribution of prawn sizes in ponds

The first step in the Hawaiian production cycle involves
obtaining gravid females from commercial ponds. No separate
broodstock ponds are maintained by hatcheries. A strain called
the "Anuenue" strain is presently utilized in all hatchery and pond
production although other strains are under evaluation (Malecha
1977). Prawns mate in commercial ponds and females brood theireggs. Embryological development in Macrobrachium rosenbergii
takes about 15 d and experienced hatchery operators can tell by
the egg color about when hatching will occur and thereby capture
only females that will hatch in keeping with a predetermined
starting time for the first hatching cycle.
At the Anuenue Fisheries Research Center (AFRC) hatchery,females are brooded in 300-gal tanks. Eggs hatched into freeswimming larvae are then transferred down into the larval rearing
tanks. Initially about 1 x 10 6 (::::: 130/1) larvae are kept in one tank.
This is split into 300,000 larvae (:::::43/1) during the 3-wk or so
development cycle. On the average 150,000 PL's/tank (:::::15-20
larvaelI) are produced. Larvae are fed newly hatched Artemia
nauplii and strained fish flesh. The latter is made up in three particle sizes by means of forcing fillets of tuna through screens withthe pressure from a stream of water. Larvae are reared in watercontaining about 5 x lOs to I x 10 6 cells/ml of unicellular phytoplankton, usually Chore/lao This "greenwater" is cultured in large
5,000-gal (18,950 I) circular tanks and pumped into the rectangular larvae rearing tanks. The latter are flushed every 2 dafter
the first 12 d. The phytoplankton-rich "greenwater" increases
survivability by maintaining good water quality through waste
removal. In essence, the "greenwater" is a biological filter. Larvae
may passively ingest the phytoplankton cells but they do notassimilate them into their tissue as shown by Cohen et al. (1976).
Other Macrobrachium rosenbergii hatcheries have raised larvae to
PL with good success using other biological filtration besides"greenwater" for water quality maintenance.

Ponds
The AFRC has developed a pond management strategy thatconsists of regular stockings of earthen ponds with hatcheryreared juveniles and regular, selective harvesting of marketable
prawns. PL's are stocked as soon as possible following metamor41

15
10

undergoing harvesting in which prawns from the previous stocking are selectively removed first.
Approximately 7 to 9 mo after the initial stocking, selective
harvesting begins. A seine net with a bag attached to the trailingend is used to cull large prawns. A team of three or more workers
enters the pond at one point and pulls the leading edge of the seine
net around the perimeter. After the pond, or a portion of it, hasbeen completely encircled and the leading edge of the net returnedto the point of entry, the net is then pulled in and the bag closed
off. A three-man crew can harvest approximately three 0.5-acre(0.20 hal ponds per day.
After the entire net is pulled in and only the bag remains in thewater, the prawns are scooped out of the bag, sorted, and loadedby hand into transportation tanks. The harvesting efficiency, or
percent of desirable prawns caught, depends on the workers' skill
and pond bottom and bank conditions. Generally the method captures only 50 to 75% of the marketable prawns in the pond, with
only a few undersized ones.
Harvesting continues at a nearly constant rate with decreases inyield during various periods. The reason for the fluctuations in the
production is not known. All in all, stocking and harvesting
management strategies do not appear to be optimum so there is
ample room for experimentation and improvement.

DEC. 1967

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Almost all prawns grown in Hawaii are marketed either alive or
chilled on ice. Some farmers blanch whole prawns for 20 s at
150°F (65.6°C) at the pond site and then pack the animals in ice
for delivery. This procedure only safely extends shelf life by about
4 d, even though local market outlets prefer a longer shelf life
rather than have high inventory turnover. Of course exploiting export markets will demand a long shelf life.
There seems to be little need for R&D in the food science andtechnology areas regarding postharvest handling and processing.
Any new materials and procedures that may be needed can be
developed from modifications of the "off-the-shelf" procedures
and technologies readily available in the seafood and marine
shrimp processing industries.

17

16

LENGTH (eM)
Figure 6.-Length frequency distribution for males and females sampled froman earthen pond In Hawaii. Distributions show sexual dimorphic growth (fromFujlmura and Okamoto 1972).

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Marketing

technology, despite some design limitations, is adequate for good
production (Sandifer et al. 1977).

Markets for freshwater prawns seem to be little different fromthose of other crustaceans of similar size and price. Demand forcrustacea 1S (and all aquatic foods) can be expected to rise in the
coming years so that emphasis in the area of marketing should be
to provide a consistent high quality supply.
In Hawaii, prawns are marketed between 6 and 10 count (6 to
10 animalsllb, :::::13-22 animals/kg) with the heaviest emphasis
between 8 and 10 count. The harvest seining captures only thesesizes. However, pending the demonstration of its economic feasibility, many more size classes can be marketed ranging from the"cocktail shrimp" or "bait" category to the lobster size (lIb or
0.45 kg). In our search for new genetic stocks (see later) we haveroutinely encountered animals> 500 g in markets in Indonesia
and New Guinea. It is possible that large animals can be marketedat premium prices and the smaller animals marketed at costeffective prices. It is foreseeable that operating costs would belower for the "cocktail" size prawns as a result of high turnoverand low biomass of these small animals. In addition, less applied
feeds are needed by animals of this size and the natural productivity in the pond is probably sufficient to provide their nutritional
requirements.

Aquaculture and Agriculture
Before discussing specific biological constraints to prawn production, I would like to mention what I believe could be a type ofgeneral constraint to the progressive development of prawn
aquaculture specifically and aquaculture in general. This is theconscious or unconscious attempt to force our R&D efforts intomodels developed for land-based agriculture. Table 4 gives acomparison of land-based plant and animal agriculture andaquaculture.
The obvious differences in habitat (water vs. air and soil) actually belie more fundamental differences which, in my opinion,must be recognized in R&D planning. The three most important
are the: 1) Nature of the husbandry environment, 2) domestic
history, and 3) indeterminate growth of the prawn.
In aquaculture systems, especially those that are pond-based,
the production of the husbandry environment (i.e., the pond
ecosystem) is as important to the production of the cash crop as
the nature of the inputs which, as it turns out, are inputs to the entire pond ecosystem. As I discuss in a later section, pond-based
aquaculture utilizes a "food web" not a "food chain." There is nobona fide analogue to this situation in terrestrial agriculture. The
closest may be range management in beef cattle. Because of this
we must be very careful not to use an inappropriate R&D model.
A case in point is in the area of nutritional requirement research.
Notwithstanding the need for complete diets in intensive systems,
we must take into account the contribution of the pond
ecosystem's natural productivity nutrient delivery systems andprawn feeding anatomy and behavior in designing our nutritional
research. These are every bit as important to production optimization as having a thorough knowledge of the prawn's nutritional requirements and efficiencies. We do not want to be in the positionof knowing the latter and not being able to do much about it
because of the nature of the husbandry environment.

BIOLOGICAL CONSTRAINTSIn Hawaii there appears to be no major biological constraint toprofitable culture of Macrobrachium rosenbergii where appropriate climatic conditions, starting capital, economical feed, andgood quality land and water are available. However, the acquisition of additional knowledge of existing management practices
and/or the development of alternative ones is needed to improve
production and/or profitability in order to induce additional investment and to insure the success of the industry presently being
developed. I believe focus is needed on the pond growout system
in all temperate, semitropical, and tropical cultures. Nursery
technology R&D is important in temperate culture. Hatchery

Table 4.-Comparison or aquaculture and agriculture organisms. See text for discussion. -indicates

categories specifically discussed in text as the most important in distinguishing between land and water based
agriculture.
Organisms
Category
3. Growth medium• b. Domestic history
c. Fecundity
d. Juvenile mortality

e. Regeneration of tissues• f. Competition
g. Body T"
h. Mobility
i. Visibility of individuals
j. Mating potential
k. Genetic engineering* 1. Growth characteristics• m. Mixed culture?
• n. Diversity of husbandry systems• o. Relations in the wild

Aquatic

Livestock

Plant

H2O

air
long
v.low-med
5-20%
0
O-Iow
warm
low
high
l/2 sibs. full sibs
noair/groundlong
low-highlowmediummedium but?
cold

0
v. high90%
mediumv. intense
cold
high
v. low"diallel"difficultindeterminantYes: polyculture
v. high
traceable,
strong43

determinantnone
v. narrowweak inmost cases

none

high
selfing
possibleindeterminant
v. little
medium to narrow
traceable
in most cases

Another major difference between aquaculture and land-based
agriculture is the greater variety of husbandry environments andmultispecies culture available in aquaculture. I think we must notallow single species characteristics of our land-based animal
systems to restrict us from developing, as thoroughly as possible,
the polyculture systems peculiar to pond aquaculture.
The lack of domestic history in prawns like most other aquaculture organisms means that our breeding and selection programsmust be designed accordingly. For one thing, the technology ofexperimentation has yet to be worked out so that the prawn can be
genetically optimized. I discuss this at the end of this paper. This
problem is true of other aquatic species. For example, the Israeli
carp breeding group (Moav and Wohlfarth 1973) spent years
developing experimental technology. In fact it was almost a
decade between the time they began their work and their publications in referenced journals (Moav et aI. 1975; Moav andWohlfarth 1974; Wohlfarth and Moav 1972; Wohlfarth et al.
1975). These publications, as well as others, demonstrated thatmethodologies peculiar to carp breeding had to be developed
along with the breeding work per se. In particular, specialized
statistical manipulations were needed to deal with the effects ofcompetition in a species with indeterminate growth (Moav andWohlfarth 1974).
Prawns also have indeterminate growth. This means an individual can be almost any size at a given age depending upon theenvironmental conditions. Because of this, intrapopulation competition causes heterogeneous individual growth making production a function of the population size frequency distribution as
well as inherent physiological capacity. There is no analogous
situation to this in animal agriculture; we cannot expect toestablish a crustacean analogue to weaning weight or 205-d
weight gain as done in beef cattle breeding.

applied to the pond must really be considered an energy input toan ecosystem and not "feed" in the traditional agricultural sense.
With the exceptions of systems like heavily manured polyculture
ponds in Israel (Moav et al. 1977), no other ecosystem, production
or otherwise, is characterized by such large energy inputs asprawn ponds and other semi-intensive and intensive warm wateraquaculture ponds.
Little is known about how much of the applied feed is utilized
directly by the prawn, how much is lost, or how much is cycled tothe prawn through other components of the pond ecosystem.
The prawn, like other caridean shrimp, is relatively inefficientat food ingestion. It does not possess a gastric mill like somepenaeids, but rather manipulates and masticulates its food outside
its buccal cavity with its anterior appendages (Patwardhan 1935a,b). Unless food is well bound, particles become dislodged and areswept away by the prawn's exhalent gill current. Moreover, unless
prawns are maintained in a hungry state, they are slow to react toand ingest their food. This is unlike some other fish species whichswallow whole, floating pellets and consume almost all applied
food with little wastage.
Even if prawns were capable of consuming most of their foodwithout waste, feed applied to the pond would have to be bound ina water-stable form in order to minimize its disintegration on thepond bottom. Feed binding agents have been identified but seemtoo costly to be utilized on a large scale (Forster 1972).
Dispersed particles of feed pellets provide attachment sites foraquatic microbes in a way that is analogous to situations in otherecosystems where allochthonous organic plant matter (leaf fall,macrophytic particles) sinks to the pond bottom and then is immediately colonized by microbes to form detritus (Olah 1972).
Following attachment, microbes utilize dissolved organic and inorganic nutrients for growth. Saprophytic functions proceed whensufficient microbial populations become established on the particles (Dickenson and Fugh 1974; Hargrave 1972).
Another important result of current feed application practices
may be the leaching of dissolved organic matter into the water
which may provide: 1) Nutrients for primary production (Cowan
and Lee 1973; Turner 1978), 2) dissolved organic matter for
heterotrophic metabolism and growth (Hall 1975; Iverson 1973;
Paerl 1974), and 3) dissolved organic matter for the formation ofparticulate organic matter which can be used as a substrate forfurther microbial growth (Lush and Hynes 1974; Floodgate 1972;
Paerl 1974, 1978). All three of these processes result in the production of particulate organic matter which represents a potential
food source for prawns.
Although no leaching data are available for the various feedpellets, most are largely composed of water-soluble plant material(soy bean meal, cereal, bran, etc.). In other ecosystems studied,especially estuarine and stream systems, allochthonous organic
plant matter begins leaching dissolved organics almost immediately upon contact with water (Lock and Hynes 1976).
Most of the currently used prawn feeds disintegrate within a
few minutes after being placed in water. Probably a significant
amount of inorganic nitrogen and phosphate, as well as dissolved
organic matter, leach out from these pellets within 30 min.
Therefore, prawn feed pellets probably contribute substantially tothe nutrition of nonprawn organisms in the pond ecosystem.
Macrobrachium rosenbergii, like other caridean crustaceans, is a
crawler and lives in the epibenthos of a pond. In many ecosystems
where the major food chains are detrital, the benthic sediments
are the major source of nutrients for the biota in the ecosystem. In
these cases, epibenthic and infaunal invertebrates, including
decapod crustacea, derive their entire nutritional benefit from

Nursery and Intensive Systems
In temperate climates, the development of nursery technology
to "extend" the pond growing season is needed (Sandifer andSmith 1978). A number of studies (Eble et aI. 1977; Forster andBeard 1974; Kneale and Wang 1979; Mancebo 1978; Sandiferand Smith 1975, 1977, 1978; Smith and Sandifer 1975; Wickens
and Beard 1974; Willis et aI. 1976) have shown the production
potential of nursery systems but they, like other intensive culture
systems, are constrained by the inability of the prawn to achieve
high enough production under crowding to offset operating costs.
As clearly seen in the size frequency graphs of Sandifer and Smith(1975), part of this is due to the heterogeneous individual growthrate. However the costs of early growth under intensive culture
can be offset by the profits of a pond culture phase (Fig. 4; Sandifer and Smith 1978).
Nursery system development mandates ancillary studies onbasic nutritional requirements of the prawn since complete diets
will have to be developed to sustain prawns at optimal growth inintensive rearing systems which have essentially no "naturz.l productivity." Several groups are engaged in this work (Table I).

Consequences of Feed Application in Culture Ponds
The development of an optimum pond production system will
involve an increased capability to efficiently and confidently
manage the pond as an aquatic ecosystem which provides prawns
with shelter, food, waste removal, and living space. In this regard,
prawn production is the same as the production of trophic levels
in other aquatic ecosystems (Ivlev 1945). Consequently "feed"44degree. In the short term, "prophylactic" management practices
must be designed to minimize "crises." In the long term, however,
we must increase our knowledge of the pond as an ecosystem inorder to insure the success of larger prawn farms and an expanded
industry.
Since the respiratory activities of the phytoplankton andbacteria undoubtedly contribute substantially to the oxygen demand of the water column and sediments, a logical first step in the
direction of achieving pond "self-management" will be to reduceor in other ways more effectively manage the biomass of theseorganisms. However, in the long term, the effective managementof pond culture will be predicated upon sound ecological knowledge of the pond ecosystem. We will have to apply skills of theaquatic ecologists and approach the pond culture system as ahighly eutrophic aquatic ecosystem. I make a point of this because
pond aquaculture in general and prawn pond aquaculture in particular, with the notable exception of Boyd (1979), suffers fromapplication of traditional land-based agricultural models whereinthe "ecology" of the husbandry environment is rarely, if ever, asubject of consideration. Indeed, it does not have to be. No one
would consider a chicken house or feedlot as an "ecosystem." It
would be a mistake if we apply the typological thinking of terrestrial animal agriculture to prawn ponds and consider the latter assome kind of "aquatic cage." As I discussed in the previous section, unless we change the prawn's "sloppy" eating habits and its
masticatory anatomy, there is little chance that a pond will simply
be an aquatic cage in an efficient food "chain." In my opinion,
prawn pond aquaculturists should not force the pond into thismold but rather should utilize its inherent production properties
and capabilities through the greater stimulation and use of its
natural productivity.

their proximate environment through various forms of detrital ingestion (Darnell 1964; Fenchel and Jorgensen 1977; Odum and dela Cruz 1963, 1967).
Johannes and Satomi (1966) demonstrated that the marine
shrimp Palomonetes pujio can utilize its own feces for its mainfood source; assimilation efficiencies of fecal pellets were as highas 70%. Frankenberg and Smith (1967) showed that seven speciesof crustacea, including two decapods, ingested and utilized feces
produced from fishes and other invertebrates to meet a significant
portion of their metabolic need.
All in all, I think it is safe to conclude that, unless a stable foodpellet is developed which can pass largely intact into the cardiac
stomach of the prawn, the feeds applied to ponds in the mannercurrently practiced primarily serve to nourish animals and plants
in the pond ecosystem other than the prawns. To what extent thisoccurs is uncertain but almost any optimum feed management
strategy will have to be predicated upon the fact that there are
more than two steps in the transfer of the energy within a prawn
production pond, i.e., prawn production is not a function of a foodchain:(input)--applied feed--prawn--prawn production--(output)
but a food web:0rawn_prawn production_ (output)-f.
app1 i ed( lnput)_ feed

+I I
I

L ~ (prawn waste),t - - - - - - - - - - -,prlmary production~Im; crob; a1 heterotrophs

Sexual Dimorphic Growth

The consequences of the feed application, especially as it applies to the nutrient loading of the pond and the relative roles it
plays, along with natural pond productivity are important areas ofresearch that need to be addressed in an effort to design a maximum feed and feeding management system.

Figure 8 shows an interpretation of growth curves for male andfemale prawns. Sexual dimorphic growth can also be seen in
Figures 6 and 7. Female growth begins to sharply level off muchearlier than male growth. Consequently the former should be
harvested and marketed at an earlier age and at a smaller size thanmales. This strategy has been an economically sound practice inthe meat poultry industry (Soller and Moav 1973). The current
continuous stocking and harvesting system practiced in Hawaii
works in the opposite direction: Males are harvested first andfemales are allowed to grow until they finally make it to the"Crises of Scale" and Self-Management in
Pond Ecosystems
Shang and Fujimura (1977) showed that monoculture ofprawns benefits from an economy of scale, i.e., larger farms canbe expected to be more efficient and more economical. Not surprisingly, farms in the 300 to 1,000-acre (123-410 ha) range arebeing developed in Hawaii and elsewhere. However, it is notknown to what degree the advantages of the economy of scale will
be offset by the disadvantages of "crises of scale." There have notbeen sufficient data to perform an accurate actuarial analysis ofproduction losses which would allow an assessment of themagnitude of these crises and an optimum risk management
strategy designed to cope with them. Until recently, prawn aquaculture has consisted of small-scale operations in which individualaquafarmers managed a few acres of ponds. For example, the industry has expanded since 1976 in Hawaii from a few acres to thepresent size of 275 acres (113 ha).
There is no doubt that large prawn farms will present management problems which cannot be solved by techniques developed
for smaller operations. For example, it will be difficult and expensive for the owner of a large aqua farm to frequently police his
ponds in order to prevent anoxia. Therefore ponds in large-scale
operations will have to, in effect, "manage themselves" to a great

MEAN
SIZE

TIM E
Figure 8.-Growth curve for mean size of males and females of a hypothetical
population. Sexual dimorphism should be managed by harvesting females
earlier at a lower weight.

45

desirable market weights. In batch harvest there is a significant
difference in male and female production. Figure 9 shows that theshape of the size frequency distribution does not change forfemales at different culture densities, whereas the male distribution becomes more skewed. This may mean that 1) there is muchless competition between females, 2) male-female competition is
low or even absent, and 3) male-male competition is very strong.
All in all, it seems that the prawn's sexually dimorphic growth
pattern should be either managed more effectively or changed.

one season growth trials, Le., single batch harvests contain an array of sizes, all of which must be marketed (Smith et aI. 1978).
The size frequency distribution in Macrobrachium rosenbergii"depensates" (i.e., the variance increases as the mean increases)
as it does in fishes (Ricker 1958). However, M. rosenbergii
populations heavily depensate and skew to the right (Fujimura
and Okamoto 1970; Smith et aI. 1978). "Typical" size frequency
distributions are shown in Figure 9. Similar depensation patterns
occur in carp and have been shown to entice group competition
which magnifies slight initial size differences into large ones as
the population grows (Moav and Wohlfarth 1974). Larger animals
called "shoot carp" (Nakamura and Kasahara 1955) or "jumpers"(Moav and Wohlfarth 1973) continue to maintain the large size
disparity between themselves and smaller animals by depressing
the growth rate of the latter below optimum levels. These large
carp seem to be equivalent to "bull" prawns (Fujimura andOkamoto 1970).
The bull growth suppression may not be permanent. Malecha(1977) demonstrated that if a population of juvenile prawns witha large size variance is graded into size classes, the largest animals
in each size class attain approximately the same final size in thesame time despite very different initial sizes. Similarly Nakamura
and Kasahara (1957) found that runted fish are capable of increasing their growth rate when they are removed from thedepressive effects of larger individuals. If the highly skewed
depensated populations of M. rosenbergii are largely a result of
intrapopulation competition, growth rates of smaller animals
could be increased by grading them out of a depensated population into one composed of similar sized individuals.
I have obtained some preliminary results on heterogeneous
individual growth. Figure 10 shows the result of an experiment inwhich skewed size frequency distributions developed in Macrobrachium populations whose individuals were reared in separate
compartments but communal water and given ad libitum food aswell as a comparable population where individuals were notseparated from one another. Both populations depensate at thesame rate (Fig. 11). If the heterogeneous growth was due mainly
to competition for food, then the individually reared animals
should not have shown the highly depensated pattern. Figure 12
shows the preliminary results of another experiment where
animals reared individually in aquaria do not depensate but

Heterogeneous Individual Growth
Mention was made above of the fact that the heterogeneous individual growth is a major constraint to optimum production in

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~

:~~'\

...
5

-MALAYSIAN

6 o..:...~===~--------~==::::::==--­

\

1\
\

i=
~

---ANUENUE
-

- --

~

16

COMMUNAL

\

\

/

~,

8

I

_/

\_
~.
:10
40
50
60

10

~

SIZE CL.ASS(Q)

I

80

90

160

1.6

2.4

3.2

4.0

4.6

S.6

6.7

7. 2

8.0

9.0

WEIGH T INTERVA L- G.

Figure 10.-Slze (In grams) frequency distribution oflndlvlduaUy 5egretated andcommunaUy boused animals from two stralns. Sexes are mixed. Populations
bave depensated under botb bouslng condItions.

Figure 9.-Populatlon structure of prawns reared In eartben ponds In Soutb
CaroUna at tbree stockIng densitieS. Mean stocklng welgbt was 0.3 g and mean
growing season was 162 d (from Smltb et al. 1981).

46

40

A = ANUENUE
M MALAYSIAN

small population size to produce evolutionary changes in species.
The anthropological aspects of this are well documented (Zeuner1963) but not much scientific scrutiny has been directed at thedomestication process because the opportunity to study, document, and control the phenotypic and genotypic changes that occur in the domestication of livestock, poultry, and companion
animals is limited. The opposite is true in aquaculture.
With the exception of some carp (Balon 1974) and trout (Hines
1976), cultured aquatic species are relatively undomesticated and,at first glance, indistinguishable from wild stock. Consequently, acultured aquatic species can be traced back to its origin thereby
aiding in assessing the domestication process. Such is the casewith the cultured freshwater prawn, Macrobrachium rosenbergii.
The prawns propagated and grown commercially in many
countries throughout the world (known as the "Anuenue" strain)came from a small founder stock collected near Penang, Malaysia,
and shipped to Hawaii in the mid-1960's (Malecha 1977). Obviously the gene pool that gave rise to the Anuenue stock cultured
in Hawaii and elsewhere has proven sufficient for profitable production. However, this may not be the only gene pool available tothe aquaculturist for domestication considering the large distribution of M. rosenbergii (Fig. 13) which may be composed of intraspecific races differing from one another in various aquaculturally
important parameters (Johnson 1960a, b).
We are attempting to use M. rosenbergii's wide native distribution to uncover intraspecific variation available for domestication
and assessing the degree to which it has progressed so far. This involves the development and characterization of genetic stocks andtheir hybrids developed from newly imported founders collectedfrom throughout the species range (Tables 5, 6; Fig. 13). Ourcharacterization is based on a widely diverse array of tests designed to uncover behavioral, physiological, developmental, morphometric, and electrophoretic variations. By emphasizing a wide
range of different tests, we hoped to develop a priori reasons forfurther and more extensive testing in one area. The characterizations of the Anuenue stock, which has been under culture forabout 15 generations and one recently developed from founders
from the same geographic location (called "Malaysian"), allow
one to assess the degree of incipient domestication which has
occurred in Macrobrachium rosenbergii. Our objective was to investigate whether current culture practices should be changed inan effort to accelerate the domestication process toward anorganism with more favorable characteristics.

=

o
o

30

_---:2 AJCOMMUNAL_____-

X~]IND---====i=-~M.nUX 20

10

20

60

40

80

DAYS
Figure n.-Coefficlent of variation (standard deviation/mean )( 100) for communally and Individually segregated populations from two strains.

30

~

~
~CONTROLS

20

~X100
X
10

2'1

3·4
SAMPLING DATE

4'15

Figure 12.-Coefficlent of variation for Individual animals reared in separate
aquaria. Runts were obtained from another system and were extremely small
for their age (::: 13 mol. Controls were size matched to runts and were the proper size for their age.

undergo reverse depensation. Other results of this experimentshow that animals which are runted (small for their age) growfaster than comparably sized control animals (normal size for
their age). All in all, my work in aquaria and tank systems suggeststhat the greater part of prawn heterogeneous individual growth isdue to suppressive effects exerted by large animals on small ones
and that this effect may be mediated by a water borne crowding
factor. Of course much more work is needed in this area before
heterogeneous individual growth can be eliminated as a biologicalconstraint in prawn culture.

Genetic Diversity
We performed electrophoretic analysis of gene-enzyme variation in Macrobrachium rosenbergii for the purpose of quantifying
the amount of racial divergence among geographically separated
natural populations. A total of 440 individuals from 11 localities
spread from Sri Lanka to New Guinea, Palau, and the Hawaiian
cultured stocks have been analyzed for genetic variation in 31
electrophoretically detectable proteins using techniques describedby Tracey et al. (1975). Nei's (1972) measure of genetic distancewas employed to calculate genetic similarity among the geographic populations as well as the cultured Anuenue stock in orderto help me assess any differences seen between the Malaysian andAnuenue stocks.
Table 7 (originally developed in Stelmach 1980) shows thegenetic distance among geographic populations and the cultured
Anuenue stock. Genetic distances were calculated according to
Nei (1972). The table shows that M. rosenbergii can be divided in-

CONTROLLED DOMESTICATION,GENETIC ASSESSMENT, AND
SELECTIVE BREEDING
GeneralDomestication is a genetic selection process which works
through geographic and reproductive isolation, inbreeding, and
47

+-

30'

~IST°"-'----------:.:.:r;,-

9T-o'

IS'

0' ------......:::.t--:-"--------',:-4::--~~___jq~~____::;=;:;_-~
"-

IS'

•

o

"-

"-

"-

"-

SURVIVING LIVE STOCK 1'75-'781'""- ......

BIOCHEMICAL DATA. IW1LD CAUGHT,

o M~:P~~~::~IC......

'-'-,DATA {WILD CAUGHT,'77 OR '781

• Biochemical and morphometric

AUSTRALIA

di!u 0" hetcherv reared
progeny

30' - - - - - - - - - , - - - - - - - - - + - t - - - - - - - - - - t - - - ' - - - - - - - -Figure 13.-Native distribution of Macrobrachium rosenbergii showing geographic origin of the Anuenue stock and areas
visited in a field survey. Small closed circles refer to areas from which imported founders have been used to develop
parental and hybrid progeny. Large open circles represent populations which were analyzed electrophoretically (i.e.,biochemically). Diamond symbols represent areas visited from which morphometric data was obtained.

If inbreeding has a profound effect on the gene pool of theAnuenue stock it would display increased homozygosity anddecreased heterozygosity. Table 7 shows, however, that theAnuenue and Malaysian stocks, as well as the other stocks in theWestern group, have very similar heterozygosity values. Overall
intrapopulation variability is low: About 28% of the loci in an
individual is heterozygous while the average percentage of polymorphic loci in each population is about 14%.
Our electrophoretic results support the conclusion that Macrobrachium rosenbergii has undergone substantial racial divergenceover its natural range and that geographic populations represent adiverse genetic resource for prawn domestication (Hedgecock et
al. 1979). Other work assessing various physiological performance characters (Sarver et al. 1979) also supports thiscontention.

Table 5.-Parental and hybrid broodstock currently maintained at the Anuenue
Fisheries Research Center in Honolulu for evaluation. Parental stock represent
decendants of live-caught founder collected from M. rosenbergii's native range(Fig. 13).
Parental broodstock

Hybrid broodstock

Stock

Generation

Paternal

Anuenue

Control
F,
F,
F,
F,
F,
(FI' F,)
F,
Founders on ly
Founders only
Founders only

Anuenue x Sri Lanka

Palauan
Malaysian
Ceylonese'
SarawakThai (Thailand)
Australian "A," "8'"Philippine
Australian (Darwin)'
Sri Lanka'
TaiwanMaternal

Anuenue x

MalaysianAnuenue
Anuenue
Anuenue
Anuenue
Ceylonese
Anuenue

x
x
x
x
x
x
x

Anuenue x

PalauanAnuenue
Australian (Darwin)
Australian 8
Thai
Ceylonese
Anuenue
Philippine
Sarawak

Ceylonese x Sri Lanka
Ceylonese x Australian 8

Morphometric Conservatism'Ceylonese received in 1977; Sri Lanka received in 1976.
'Australian "A" and "8" traceable to orange egg and yellow egg hatches from a
1976 shipment.
'Shipment received 1977.

Changes in size and body proportions characterize domestication. Since the carcus quality of prawns is important in marketing
it is important to know the relationship of hard nonedible exoskeleton parts to the soft edible parts ("the tail"); prawns aremarketed by the pound whole and as "tails" with carapace, walking legs, and claws removed.
We compared allometric growth patterns between cultured andwild stocks and their hybrids in an effort to assess any favorable
morphometric variation present throughout the species range
which would be available for domestication and the degree towhich the culture environment and hybridization affect these patterns. To do this we determined the growth and size relationships
between several body characteristics (Fig. 14, Table 8) using theallometric equation Y = aXb and regression analysis. The

to a Western and Eastern group as has been pointed out byHedgecock et al. (1979) in a preliminary report. This dichotomyin M. rosenbergii's gene pool corresponds well to the zoogeographic boundary known as Wallace's Line.
Special note is taken of the genetic distance between theAnuenue and the other stocks. As shown in Table 7, the Anuenue
stock has developed very little from its wild relative in theWestern group. It must be pointed out that little divergence would
be expected in alleles at allozyme loci.
48

Table 6.-Breedlng results for parental and hybrid matings (Table 5) compared with totalmatings conducted at the Anuenue Fisheries Research Center. Approximately 50% of all matings
result In live hatches of larvae while a much lower percentage of those matings between ecotype
stocks result in live hatches. This Indicates a bottleneck In obtaining successful live hatches fromnewly Imported founders probably due to lack of acclimatization to the hatchery environment.

successful% ofsuccessful

PeriodTotal
attempted

berriedattempts

live hatch

Live hatches
as % ofberried10/78-9/79
10/77-7/79

507
1,068

251
464

40
43

148
212

59
46

10/78-9/79
10/77-9/79

Matings ofdifferent stocks
attempted
21
66

13
38

62
58

I

8

14

37

No.

No.

Table 7.-Nel's (1972) genetic similarity values for geographic populations of M. rosenbergii. Data
based on electrophoretic analysis of an average of 26 loci (from Stelmach 1980).
Western
Sri
Sri Lanka

Eastern

Cal

Thai

Jak

Anue 1 Sar

Phi

NG

Aust

Pal

.9669

.9668

.9633

.9590

.9598

.7355

.7327

.7088

.7339

.9998

.9996

.9978

.9979

.7347

.7318

.7070

.7325

.9999

.9964

.9984

.7329

.7283

.7058

.7308

Calcutta
Thailand.9961

JakartaAnuenue

.9980

.7310

.7270

.7063

.7291

.9951

.7373

.7325

.7157

.7352

.7268

.7225

.6983

.7239

.9958

.9526

.9990

.9487

.9955

Sarawak------------

Philippines
New Guinea.9543

Australia
Palau

.018

.029

1.32

1.24±

.32

.16

Average heterozygosity levels per locus
.008
.027
.020
.021
.026
Average number of alleles per locus
1.16
1.14
1.19
1.11
1.20
1.25
Porportion of polymorphic locus
.11
.15
.12
.07
.10
.13

.012

0
1.25

1.00

.11

0

28

28

Average num ber of loci

28

25

25

28

27

28

20

24

1Anuenue stock: Cultured stock derived from imported founders from Malaysia. No additional Malaysian sample analyzed electrophoretically.

reference dimension, X, was orbit length except in two cases. In
one case both the dependent and reference dimensions were two
separate segments on the same chela. This corrected for regenerating chelae which would be expected to display lower relative
growth to orbit length. In the case of tail width comparisons, twoseparate tail dimensions were used as the X and Y variables. Ourdata was from three sets (Fig. 13): One from growing populationsof cultured stocks developed from founders imported from
Malaysia, Sri Lanka, Palau, and Australia prior to 1977, as well as
control Anuenue stock; another from dead specimens from 10
geographic locations in New Guinea, Sarawak, Sri Lanka, India,
Thailand, Malaysia, Indonesia, Taiwan, the Philippines, and Palau
measured in a field survey conducted during 1977-7 8; and thethird set from cultured hybrid groups bred from imported founderparents. Linear regression was performed on the paired comparisons divided by sex, geographic location, and culture conditions;
95% confidence intervals were determined for each analysis as

well as R2 values. Based upon the overlap of these intervals, thesubgroups were pooled first by sex, the location, then culture
history. We could find no major differences in relative size or
growth between sexes and geographic location in either thecultured stocks or wild stocks. Although there were statisticallysignificant differences between some groups we were able to combine all the data from the various groups for each variable becauseof the overlapping confidence intervals. Table 8 shows preliminary results comparing cultured and wild populations for six
variables including orbit length (OL), carapace width (CW),
posterior tail width (T t), and anterior tail width (T 3)'
Table 8 also shows results of the allometric analysis in hybridgroups. We did find statistically significant differences amongsome hybrid groups but we do not interpret these as predictive
biological differences which give evidence of heterosis. The
slopes of the regression lines did not differ by whole integer values
which would have indicated such a major effect.

49

tMEROPOOITE LENGTH (Ml)t_~((

CARAPACE
WIDTH leW)..- CARAPACE lENGTH (CL)-",~~~-----ORBIT lENGTH (Ol)-----4~~1~~

kg= WErGNT(wt)

Figure 14.-Dorsal view of prawn showing variables used in allometric analysis. See text and Table 8.

represent co-adapted genetic combinations which are disrupted byoutcrossing. Morton et aJ. (1967) have made similar conclusions
in their study of outcrossing among human races. Because of this,intraspecific crosses of ecotypes will not be expected to produce
the phenodeviants (Spurway 1955) or "hopeful masters" thatwould greatly improve on M. rosenbergii's conservative allometricpatterns.
I conclude that if changes are required in the prawn's morphometric and growth patterns, rapid domestication of the prawn will
have to turn to more radical, direct, genetic intervention to disrupt
and change the genetic systems which control the body proportions and growth such as use of radiation mutagenesis, interspecific hybridization, and sex reversal.

Table 8.-Coefficlents for the allometric equation Y = aJ(b cultured and wild
populations. R' measures the closeness of fit of the regression line to experimental data. Variables are as described in Figure 2. Four comparisons showedisometry indicating that the rate of growth of the variables is the same in all
sizes and ages. See Figure 14 for key to variables.
Variables

Y

X

Data Setab

Sample
size

R'

Wt

OL

CW

OL

CL

OL

T,

OL

T,

T,

.018
.009
.149
.127
.271
.187
.158
.141
.797

3.151
3.396
1.152
1.188
'1.144'1.232'1.080'1.075'1.008

988
890
988
892
988
895
370
895
370

.902
.962
.864
.968
.880
.980
.973
.962
.837

T,

T,

Cultured
Wild
Cultured
Wild
Cultured
Wild
Cultured
Wild
Cultured
Wild
Cultured
Wild

.464
.315

I

370
895

.946
.939

.949
'1.082Degree of Domestication
Recently we have compared the degree of incipient domestication that has occurred in the Anuenue strain. To do this I conducted a series of growth and tolerance tests on the Anuenue strain
and a one-generation descendent stock (called "Malaysian")developed from founders from the same geographic location as thefounders of the Anuenue stock. The former is assumed to be theputative domesticate and the Malaysian stock its wild, undomesticated relative. A detailed account can be found in Malecha et al.
(1980). Only a brief review will be presented here. Table 9 summarizes the results.
In two cases, the temperature tolerance and the communal versus individual growth study, the Malaysian stock displayed asuperior performance over the Anuenue stock. It is difficult to attribute these results to artifacts of the experiment. There is apossibility that the superior temperature tolerance of the Malaysian stock reflects an environmental effect and not a bona fide effect of the genetic background of the Malaysian stock.
It is unlikely that the difference could be attributed to a maternal x brood effect since the prawns were several months old whenthe experiment was started. Moreover, maternal and brood effects
should diminish through time. This is not the case; the Malaysian'Isometry.

Based on my preliminary failure to uncover economically important allometric size differences among stocks, we feel that
there is little hope of finding, outright, one displaying a morefavorable morphometric pattern than the presently cultured
Anuenue stock. Furthermore, the lack of differences between
cultured and wild populations indicates that Macrobrachiumrosenbergii does not display ecophenic variation: New phenotypic
expressions of the same genotype as a result of being brought froma wild to controlled husbandry environment (Spurway 1955; Hale
1962). "Ecophenes" are habitat forms which reflect a species'
potential for phenotypic variation in the absence of genetic
changes during domestication.
The lack of major differences between hybrid and parentalgroups for the allometric comparisons suggests no large positive or
negative heterosis. I conclude that the parental populations do not50

LARVAL

Table 9.-Summary of results assessing the degree of domestication In Macrobrachium rosenbergii. Tests evaluated the Anuenue (putative domesticate) andthe undomesticated Malaysian relative. For further details see Malecha et al.
(1980).

Treatments

Environment

Size
Duration I

range 2Treatment
effectDEVElOPMENT
x

Tolerance:
Temperature

IX

~\>-~

Genetic
effectReplicated, Experimental
Growth:Communal/lndiv.
housing
Crowding levels
Density levels
TemperaturelevelsSalinity levels

1.3-5.7 g
PL-O.IO g
1.4-4.8 g

Yes
Yes
Yes

M>A
M=A
M=A

Aquaria
Aquaria30 d
30 d

PL-O.IO g
PL-O.IO g

Yes
Yes

M=A
M=A

Aquaria

24 h

PL's

Yes

----- - - - -- ---- ---------

VIII

"

---------------------------

VII_------------------------------------------_- - - - - - - - - -

IV
85 d
30 d
85 d

•

Pl -------------------------------------,,\>-~./~
V VI

Tanks
Aquaria
Tanks

XI

_

III

_

-----MAlAYSIAN---ANUENUE

II ------i "I i i ' Iii I iii i' J i
5
10
15
20
DAYS POST HATCH

iii i , iIi" , I "
25
30
35

i

I
40

1:--FIRST- - -- -' -- -- iPl

M>AFigure IS.-The first day (represented as a range) at which a particular larvalstage appeared In larval rearing tanks containing either Malaysian or Anuenue
stocks.

Unreplicated, Observational
Pond growth

2 ponds

91 d

PL-O.lO g

M~ALarval growth

Tanks

40 d

LarvaeM<A

Larval developmentTanks

29-39 dLarvaeM<A

inferior, but net-wise, animals are reproducing more often
perhaps because they have longer residence time which may maximize chances of mating with females. The question is to what
degree these animals contribute to the broodstock for PL production for restocking ponds.
Female broodstock are obtained from commercial harvests sothey are large but whether they represent genetically superior
animals is not known. Figure 16 portrays three possibilities that
could occur in selecting female broodstock under a system of continuous harvesting as practiced in Hawaii. Females being used forbroodstock could represent the full spectrum of genetically controlled growth rates. In some circumstances the worse casescenario shown in Figure 16 could prevail, i.e., the largest animals
could represent the older but slowest growers. Depending upon
how much of the variance in growth rate is genetically controlled,
the present practice of broodstock selection could be directly
counterproductive to progressive domestication of M. rosenbergii.
Therefore some changes may have occurred in broodstock selection in order to improve stock rather than just propagating it.
However the management for most farms involves seine harvests
and multiple stocking so there is no way to establish the age of any
prawn collected from the pond and no way to control the matingof the broodstock females. Because of this there is no control overparental breeding value, i.e., the genetic worth of an animal's
genotype. No other modern agricultural system relies on such"natural service" in this manner. Batch harvesting systems (Fig.
4) can be used to establish breeding values for broodstock.
Since the cultured environment is much different than what
Macrobrachium rosenbergii is exposed to in the wild, one would
expect that the Anuenue genotype diverged f:om its founder stockeven without conscious selection. There are several possible explanations why this does not appear to have occurred. One is thatthe selective pressures relevant to the characters I examined are
the same in the natural and cultured environments. This seems
very unlikely. Another possibility is that there is not enoughgenetic variability within the Anuenue stock upon which selection
could act. This again seems unlikely since there is a lot of variation in M. rosenbergii in growth rate, tolerance to low temperature,and various other parameters (Hedgecock et al. 1979; Sarver et al.
1979).

I Duration

is given as the longest interval of anyone trial.
'Upper size range reported as the largest value in anyone trial.

group was growing fast in one trial at both 57 and 85 d. It is important to note that there were 17 other trials which compared thetwo strains for growth and no differences were seen. Since the
Malaysian-Anuenue comparisons involved offspring from single
families, individual variation may be confounding our results.
The general tendency for the Malaysian group to have a longer
larval development time (Fig. 15) than the Anuenue may perhaps
reflect incipient domestication in the latter in larval development.
It is normal hatchery practice to discard slow developing larvae
which may have served to genetically change the larval development pattern of the Anuenue stock in the direction of faster larval
development. However, I cannot be sure of this from my results
since they were merely observational. More rigorous experimentson larval development between the two groups will have to be
conducted.
I feel that if further testing reveals a bona fide genetic superiority of the Malaysian stock over the Anuenue stock a "reverse"
domestication process could be occurring for some characters as
the result of the current management practice.
The culture environment itself (McCauley 1978; Doyle andHunte 1981) imposes selection pressures which cause an evolutionary change in the population's capacity to survive; this is collectively known as "fitness." Unless man controls every aspect of
this capacity (i.e., its life history), then changes can be expected in
an organism which benefit it and not necessarily the economics ofman,
It is not certain just how Macrobrachium rosenbergii has maximized its fitness in the culture environment, but it is possible thatthe current practices in Hawaii actually may be directly selecting
genetically inferior organisms (in terms of human criteria). For
example, one scenario could involve the avoidance of genetic
death imposed by the pond harvest, i.e., if males who avoid theharvest cull are able to reproduce more often than others andavoidance is related to slow growth rate, it follows that genetically51

YOUNGGOOD-

Domestication seeks to change, not tolerate, undesirable performances. Of course, during the formative years of the development of
a Macrobrachium rosenbergii industry in Hawaii (and elsewhere)
the natural biological patterns of the organism had to be accommodated. But culture technology has progressed sufficiently sothat intervention to change certain biological species
characteristics is not only possible but necessary. Passively allowing M. rosenbergii to display natural, but unfavorable, patterns
and/or adopt survival mechanisms in culture systems is extremely
counterproductive. The time has come to "winnow" M.
rosen bergii' s gene pool now that it has been successfully"flushed."

OLD

C

B

BAD

C

A

B

WORSE

C

B

A

A

THE FUTURE: CHANGING
M. ROSENBERGII'S GENE POOL
In my opinion two approaches hold promise for winnowing theprawn's gene pool: I) sexual reversal and 2) hybridization. Both ofthese approaches can be brought to bear on the two most important characteristics of the prawn's growth pattern: Sexually dimorphic growth and heterogeneous individual growth.

Figure 16.-Three possible interpretations of a pond size frequency distribution
offemales cultured In ponds with continual harvest by seining some ofwhlcb are
removed for broodstock. Underlying distributions A, B, C represent different
age classes as shown In the table. GeneticaDy Inferior broodstock could beselected If cuDed females represent older, slower growlnglndlvlduals.

Sex Reversal
Other factors may be swamping out evolution within thecultured environment. Since larval survival is nearly 50% in many
hatcheries (Sandifer and Smith 1977), compared with much lessthan I % in the wild, it is possible that the development of successful mass rearing techniques served to "flush" the M.
rosenbergii gene pool in a manner similar to that described by
Carson (1968,1975) for the genetic events which accompany certain types of speciation. "Flushes" are numerical increases in
numbers that accompany population growth during periods ofrelaxed selection. "Flushes" are thought to foster genetic events
which "open up" a species' genotype by causing the appearanceof new genetic combinations which may be selected for (or notselected against) under the new selection regimes. These genetic
events could occur rapidly if a species is removed abruptly fromthe ecological niche in which it has evolved and placed in a different environment such as during colonization of a new habitat orbringing an organism under culture. Both processes would be expected to lead to selection for a new adaptive optima (Wright1963). The new environment could be a major factor in speciation
following colonization and severe selection pressure can be imposed by a domestication husbandry regime. Spurway (1955) has
illustrated the latter by describing the practice of "winnowing"whereby cereal crop seeds are passed through screen mesh. Thoseseeds that fall through are used, those left out are not. This leads to100% selection against certain size groups. It seems there is noquestion that the Macrobrachium rosenbergii gene pool has been
"flushed," but it seems not to have been "winnowed" such thatdifferences appear between the cultured and wild stocks.
One final note. Changes during domestication can be expected
to occur but they may not always be favorable, Le., wild relatives
or incipient domesticates are actually genetically superior to thecultured stock. Under culture man is the predator since the outcome of culture is death-killing the organism for food. It is obvious then that organisms, unless managed not to do so, will
evolve adaptations to survive this outcome. Consequently
management practices must be designed to directly manipulate
the variables considered important and avoid unfavorable adaptations. In addition one must not fall into the trap of designing
management systems around undesirable characteristics likeheterogeneous individual growth rate. This is not domestication.

Sexually dimorphic growth could be manipulated by thegeneration of single sex broodstock. This could be accomplishedby a mechanism shown in Figure 17. All females should result
from such a mating as shown in Figure 17. If males are heterogametic, XY, generation of all male progeny by means of mating
is more difficult since a feminized male mated to a normal malewould give three possible genetic combinations. It is not known
whether the YY geneotypes would be viable; they are not inhigher organisms. Even if they were, the YY condition would
have to be identified without killing the animal and the mating
and spawning of a normal female and a "viralized" female.
Viralization of females and sexually indifferent prawns has beenaccomplished to a point in Macrobrachium rosenbergii (Nagamine1979). It is possible that future work may be able to virilize
genetic females such that they are reproductively capable ofmating with a normal female.
Another route to take may be the affect of hormones on sexual
development. Perhaps androgens and estrogens can be used toreverse sex as has been done in some fishes (Johnstone et al. 1978;
Yamazaki 1976).
All of this is very speculative and the effective incorporation ofsex reversal in monosex prawn culture will require a lot of work.
Despite this, sex reversal holds promise for removing a major
biological constraint in prawn culture.

Hybridization
In my opinion hybridization may hold high potential for
genetically changing the heterogeneous individual growth pattern.
If the latter is a species characteristic then hybrids between two
species may exhibit a "hybrid breakdown" in the behavioral
mechanisms which characterize their parental species. Of course
this is only speculation at this point. There is no evidence that it
will occur but I think it's worth a try. Hybridization can also be
useful for combining favorable geneotypes such as from a species
which gives good growth and one that is more cold tolerant andover-winters well.
Before one can proceed with successful hybridization, regardless of how productive it may be, one must first perfect methods of52

CARSON,H.L.
1968. The population flush and its genetic consequences. In R. C. Lewontin(editor), Population biology and evolution, p. 123-137. Syracuse Univ.
Press, Syracuse, N.Y.
1975. The genetics of speciation at the diploid level. Am. Nat. 109:83-92.
COHEN, D., A. FINKEL, and M. SUSSMAN.
J 976. On the role of algae in larviculture of Macrobrachium rosenbergii.
Aquaculture 8: 199-207.
COWAN, W. F., and G. F. LEE.
1973. Leaves as a source of phosphorous. Environ. Sci. Technol. 7:853-854.
DARNELL, R. M.
1964. Organic detritus in relation to secondary production in aquatic communities. Int. Ver. Theor. Agnew. Limnol. Verh. 15:462-470.
DICKENSON, C. H., and G. F. F. FUGH.
1974. Biology of plant liller decomposition. Vols. I, II. Acad. Press, N.Y.
DOYLE, R. W., and W. HUNTE.
1981. Genetic changes in "fitness" and yield of a crustacean population in acontrolled environment. J. Exp. Mar. BioI. Ecol. 52:147-156.
DUGAN, C. C., R. W. HAGOOD, and T. A. FRAKES.
1975. Development of spawning and mass larval rearing techniques forbrackish-freshwater shrimps of the genus Macrobrachium (Decapoda palaemonidae). Fla. Mar. Res. Publ. 12, 28 p.

IF:
genic

chromosomal

HH

or

Hh

or

XX
Xy

~

c!

homogametic
heterogametic

THEN:

~
HH

"c! "

cI'

"7

HH

x

Hh"~

Hh

x

c!

"¥-"

~

HH - all HH females
Hh

HH

r/'

~

:ag

Hh)
rI'

?

all Hh - HH x
males
Figure 17.-Hypothetical scenario for the creation of monosex broods using sex
reversal. Scenario is predicated upon a simple heterogametic/homogenetic
mechanism for sex determination, either a single dialleUc locus or sex chromosome.

EBLE, A. F., M. C. EVANS, N. DeBLOIS, and N. E. STOLPE.
1977. Maintenance of broodstock, larval rearing and nursery techniques used
to grow Macrobrachium rosenbergii in waste-heat discharge waters of an elec·
tric generating station in New Jersey (U.S.A.). Actes de Colloques du
C.N.EXO.4:233-245.
EBLE, A. F., N. E. STOLPE, M. C. EVANS, and N. F. DeBLOIS.
1975. The use of thermal effluents of an electric generating station in New
Jersey in the culture of the tropical prawn, Macrobrachium rosenbergii, andthe rainbow trout Sa/mo gairdneri. fn C. R. Guerra, B. L. Godfriaux, and A. F.
Eble (editors), Power plant waste heat utilization in aquaculture - Workshop I
papers, p. 234. Public Servo Elec. and Gas Co., Newark, N.J.
FENCHEL, T. M., and B. B. JORGENSEN.
1977. Detritus foodchains of aquatic ecosystems. Adv. Microb. Ecol.
1:1-58.
FLOODGATE, G. D.
1972. The mechanism of bacterial allachment to detritus in aquatic systems
in detritus and its role in aquatic ecosystems. Mem. Inst. Ital. Idrobiol.
29(suppl.): 105-127.
FORSTER, J. R. M.
1972. Some methods of binding prawn diets and their effects on growth andassimilation. J. Cons. Int. Explor. Mer 34:200-216.
FORSTER, J. R. M., and T. W. BEARD.
1974. Experiments to assess the suitability of nine species of prawns forintensive cultivation. Aquaculture 3:355-368.
FRANKENBERG, D., and K. L. SMITH, Jr.
1967. Coprophagy in marine animals. Limnol. Oceanogr. 12:443-450.
FUJIMURA, T.
1974. Development of a prawn culture industry in Hawaii. Job completion
report: July I, 1969 to June 30, 1972. U.S. Dep. Commer., NOAA, NMFS,
21 p.
FUJIMURA, T., and H. OKAMOTO.
1972. Notes on progress made in developing a mass culturing technique for
Macrobrachium rosenbergii in Hawaii. fn T. V. R. Pillay (editor), Coastal
aquaculture in the Indo-Pacific region, p. 313-327. Fishing News (Books)
Ltd., Surrey, Engl.

artificial insemination and in vitro development. Sandifer and hiscolleagues are conducting important studies in this area (Sandiferand Smith 1979; Sandifer and Lynn 1980).

ACKNOWLEDGMENTS
The assistance and professionalism of Jacqueline Glipa, Amy
Dicksion, and Scott Masuno in preparing, and working under thedeadline for, this manuscript are gratefully appreciated.
Thanks also go to the following who kindly provided information for this review: Jim Boulet, Larose, La.; Robert Brick, Texas
A&M University, College Station, Tex.; A. Farmanfarmaian,
Rutgers University, N.J.; William Johnson and Kenan Smith,Oregon Institute of Technology, Klamath Falls, Oreg.; George
Lewis, University of Georgia, College of Agriculture, Athens, Ga.;
Peter Lutz, University of Miami, Miami, Fla.; Ed McSweeny,
Weyerhaeuser Corporation, Homestead, Fla.; Paul Sandifer, South
Carolina Wildlife & Marine Resources Department, Charleston,
S.c.; Robert Taylor, University of Nevada, Reno, Nev.; Thomas
Wellborn, Jr., Cooperative Extension Service, Mississippi State,Miss.; Jack Whetstone, Sea Grant Advisory Program, Clemson
University, Georgetown, S.C.; and Ronald Wulff, Aqua Finca deCamerones, Honduras, C.A.

GODFRIAUX, B. L., C. R. GUERRA, and R. E. RESH.
1977. Venture analyses for intensive waste heat aquaculture. Proc. World
Maricult. Soc. 8:707-722.
GOODWIN, H.
1977. Of prawns, people, and soy sauce.fn J. A. Hanson and H. L. Goodwin(editors), Shrimp and prawn farming in the Western Hemisphere, p. 197200. Dowden, Hutchinson & Ross, Inc., Stroudsburg, Pa.

LITERATURE CITEDHAGOOD, R. W., and S. A. WILLIS.
1976. Cost comparisons of rearing larvae of freshwater shrimp, Macrobrachium acan/hurus and M. rosenbergii, to juveniles. Aquaculture 7:55-74.
HALE, E. B.
1962. Domestication and the evolution of behavior. fn E. S. E Hafez (editor),
The behavior of domestic animals. Bailliere Tindall & Cox, Lond.
HALL, K. J.
1975. Effect of nutrient enrichment on the heterotrophic uptake of organic
solutes by micro-organisms. Verh. Int. Verein. Limnol. 19:280-285.
HANSON, J. A., and H. L. GOODWIN.
1977. Shrimp and prawn farming in the Western Hemisphere. Dowden,
Hutchinson & Ross, Inc., Stroudsburg, Pa., 439 p.

BALON, E. K.
1974. Domestication of the carp, Cyprinus carpio L. R. Ont. Mus. Life. Sci.
Misc. Publ., April 29, 1974.
BARDACH, J. E., 1. H. RYTHER. and W. O. McLARNEY.
1972. Aquaculture: The farming and husbandry of freshwater organisms.
John Wiley & Sons, N.Y.
BOYD, C. E.
1979. Water quality in warm water fish ponds. Auburn Univ. Press, VII,359 p.
BRICK, R. W., and R. R. STICKNEY.
1979. Polyculture of Tilapia aurea and Macrobrachium rosenbergii in Texas.
Proc. World Maricult. Soc. 10:222-228.

53

HARGRAVE, B. T.
1972. Aerobic decomposition of sediment and detritus as a function of particle surface area and organic content. Limnol. Oceanogr. 17:583-596.
HEDGECOCK, D., D. J. STELMACH, K. NELSON, M. E. LINDENFELSER, and
S. R. MALECHA.
1979. Genetic divergence and biogeography of natural populations of Macro. brachium rosenbergii. Proc. World Maricult. Soc. 10:873-879.
HINES, N. O.
1976. Fish of rare breeding: salmon and trout of the Donaldsen strains.
Smithson. Inst. Press, Washington, D.C., 167 p.

MALECHA, S. R., D. SARVER, and D. R. ONIZUKA.
1980. Approaches to the study of domestication in the freshwater prawn,
Macrobrachium rosenbergii, with special emphasis on the Anuenue andMalaysian stocks. Proc. World Maricu1t. Soc. 11:500-528.
MANCEBO, V. J.
1978. Growth in tank-reared populations of the Malaysian prawn, Macrobrachium rosenbergii (de Man). Proc. World Maricult. Soc. 9:83-90.
McCAULEY, D. E.
1978. Demographic and genetic responses of two strains of Tribolium caslaneum to a novel environment. Evolution 32:398-415.
MIYAJIMA, L. S.
1977. About Macrobrachium species. In J. A. Hanson and H. L. Goodwin(editors), Shrimp and prawn farming in the Western Hemisphere, p. 201209. Dowden, Hutchinson & Ross, Inc., Stroudsburg, Pa.
MOAV, R., G. HULATA, and G. WOHLFARTH.
1975. Genetic differences between the Chinese and European races of thecommon carp: I. analysis of genotype-environment interactions. Heredity
34:323-340.
MOAV, R., and G. W. WOHLFARTH.
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NAGAMINE, C. M.
1979. The development of sexual dimorphism in the Malaysian prawn,
Macrobrachium rosenbergii (De Man), and the effects on the primary andsecondary sexual characteristics following androgenic gland ablation in themale and androgenic implantation in the female. Ph.D. Thesis, Univ.
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NAKAMURA, N., and S. KASAHARA.
1955. A study on the phenomenon on the Tobi-koi or shoot carp.-I. On theearliest stage at which the shoot carp appears. [In Jpn.) Bull. Jpn. Soc. Sci.
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NEI,M.
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1963. Detritus as a major component of ecosystems. Bull. Am. Inst. BioI.
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1967. Particulate organic detritus in a Georgia salt marsh-estuarine ecosystem.ln E. M. Lauff (editor), Estuaries, p. 383-389. AAAS Publ., Washington, D.C.
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1935a. On the structure and mechanism of the gastric mill in Decapoda. V.
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ROBERTS, K. J., and L. L. BAUER.
1978. Costs and returns for Macrobrachium grow-out in South Carolina,

HOLTHUIS, L. B.
1950. The Palaemonidae collected by the Siboga and Snellius expeditions
with remarks on the other species I. Subfamily Palaemoniae. Siboga Exped.
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1952. A general revision of the Palaemonidae (Crustacea Decapoda Natantia)of the Americas. II. The Subfamily Palaemonidae. Allan Hancock Found.
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IVERSON, T. M.
1973. Decomposition of autumn-shed beech leaves in a spring-brook and its
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region in zoogeography. Proc. Cent. Bicent. Congr. BioI. Singapore, 1958,
p.170-181.
1960b. Sub-specific and intra-specific variation in some freshwater prawnsof the Indo-Pacific region. Proc. Cent. Bicent. Congr. BioI. Singapore,
University of Malaya Press.
JOHNSTONE, R., T. H. SIMPSON, and A. F. YOUNGSON.
1978. Sex reversal in salmonid culture. Aquaculture 13:115-134.
KNEALE, D., and J. K. WANG.
1979.

A laboratory investigation of Macrohrachium rosenbergi; nursery pro-duction. Proc. World Maricult. Soc. 10:359-368.
LEE, S. R.
1979. The Hawaiian prawn industry: a profile. Aquaculture Development
Program, Department of Planning and Economic Development, State of
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1969a. The general biology and development of Macrobrachium rosenbergii(de Man). FAO Fish. Rep. 57:589-606.
1969b. Methods of rearing and culturing Macrobrachium rosenbergii (DeMan). FAO Fish. Rep. 57:607-619.
LING, S. W., and T. J. COSTELLO.
1976. The culture of freshwater prawns: A review. In T. V. R. Pillay and
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Limno!.

Oceanogr. 21 :436-443.
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54

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55Research and Development in Maturation and Productionof Penaeid Shrimp in the Western Hemisphere
ROBERT A. SHLESER and L. FRANK FOLLETT'INTRODUCTION

tion of penaeid shrimp has restricted shrimp aquaculture from expanding to new areas which have acceptable climatic and seawater conditions, but which lack suitable indigenous species. Until recently, such areas as Honduras, Panama, Ecuador, and Costa
Rica have seen expansion of shrimp farming. An important
pioneer in this area has been the Ralston Purina 2 Company, which
has an extensive development of shrimp farms in Panama. Ralston
Purina plans to complete 1,600 acres of new shrimp production
ponds before the end of 1980. In addition, Table 1 shows ourestimates of commercial shrimp ponds currently in production in
the Western Hemisphere.
It may provide a useful perspective to present a short review ofthe development of current shrimp farming techniques in Central
and South America. As mentioned above, the Ralston Purina
Company is responsible for most of the early pioneering work in
the industry, having refined the techniques for shrimp larval
culture which were developed by Mock of the National Marine
Fisheries Service Laboratory in Galveston, Tex. Additional information from experimental fishing documented the locations
where gravid females could be found in abundance throughout theyear. Using this informtion, industry is able to capture females
and spawn them aboard the fishing vessels. The resultant larvae
are then reared in culture tanks until they are 10 d beyond thepostlarval stage, with survival rates currently as high as 80%. The
shrimp are then grown in nursery ponds until they reach 1 g size;
feed conversion at this stage is 1.0: I to 1.2: I. Nurseries measuring
up to 2 acres have been successfully managed. The shrimp arethen stocked at a density of 30,000 to 40,000/acre in large growout ponds which measure 10 to 50 acres in size. At this stage, feed
conversion rates of 2.75:1 are the average, with feeds of about
25% protein, costing 12¢ to 15¢/lb in Central America. The
shrimp are harvested after approximately 120 d in the pond. Witha survival rate of 60%, and depending on season, it is possible toMarine shrimp occupy the largest section of the U.S. seafoodmarket. In terms of product value, in 1977, almost 25% of the seafood market in the United States was occupied by marine shrimp(Robinson 1977). Approximately 1.6 million pounds of shrimp
are consumed in the United States each day, 70% of this amountimported from outside our country. This totals more than $490
million worth of imported shrimp per year.
The ability of our domestic shrimp fleet to continue to supply
current levels of this product is now in question. The recently
established 200-mi economic zone has resulted in the exclusion of
U.S. boats from many regions where they previously had access tofertile areas for catching shrimp. With the increased recognitionof the value of shrimp, it is likely that in the near future U.S. boats
may also be excluded from other regions where U.S. fishing rights
had previously been established.
The shrimp fishery within the United States' own 200-mi zone
is limited, so foreign restriction of the fishery is expected to placeincreased pressure on other stocks available in unrestricted international waters. This will have a "domino effect" of requiring
larger vessels to cover greater distances, in order to sustain theamount of catch that is needed to keep up with boat loan
payments, insurance, and other related costs. In turn, the increased
fishing pressure will require more fuel, which will significantly affect the cost of fishing and ultimately make the U.S. catch lesscompetitive with foreign products from areas such as Ecuador,
where petroleum fuel is still 18¢ per gallon.
Though it is too soon to reach a conclusion, there is also
speculation that oil spills in the Gulf of Mexico may have an
adverse impact on our domestic shrimp catch. Finally, the availability of the catch to the U.S. market may be confounded by thefact that other nations which value shrimp more than the UnitedStates can compete economically for the amount of product available when supplies are limited.
While the prognosis for the shrimp fishery appears poor,
especially for the United States, the demand for shrimp is increasing. We feel that a shrimp aquaculture industry in the UnitedStates could help supply our domestic demand for the product, andhave other advantages such as providing new economic opportunities for rural communities.

2Reference to trade names does not imply endorsement by the National Marine
Fisheries Service, NOAA.

Table I.-Estimated acreage orcommercial shrimp production
ponds in the Western Heml·
sphere.

PRELIMINARY WORK AND
COMMERCIAL PRODUCTION
Until recently, shrimp farming has been restricted to regions of
the world where gravid females of suitable species have been
available in abundance. Failure to achieve mastery over reproduc-

Country

Acres

BrazilColombia
Costa Rica
EcuadorHonduras

1.000
80
400
60.000
220
1,800
100
680

PanamaPeru
United States'The Oceanic Institute. Makapuu Point, Waimanalo, HI 96795.

57

obtain about 1,400 Ib/acre per crop. Shrimp tails of a size which
total between 30 to 40lIb are produced.
At the Oceanic Institute, we are evaluating the economic andtechnical potential of farming marine shrimp in Hawaii. We areconducting evaluations of four species of marine shrimp: Penaeus
vannamei and Penaeus stylirostris from Central and SouthAmerica, Penaeus monodon from Southeast Asia, and Penaeus
japonicus from Japan.
As part of this work, we have performed an economic analysisof the costs of production in Hawaii (Shleser 1979). In order tounderstand the potential of shrimp farming, we designed a conceptual 100-acre shrimp farm with facilities for a hatchery, anursery with 5 0.25-acre ponds, a grow-out capacity of 15 5-acre
ponds, and 3 0.25-acre ponds where shrimp are matured forbreeding purposes (Fig. 1, Table 2).

~

The completed economic analysis revealed several interesting
points which have played a major role in shaping our research at
the Oceanic Institute:1) At present market prices, shrimp farming in Hawaii could be
carried out profitably if suitable species were available, and if
shrimp could be bred in Hawaii.
2) The major cost in shrimp production is feed.
3) Increasing the number of pounds produced annually byincreasing production or growth rate is the only significant improvement to be made on the economics of production, besides
reducing feed costs.
Of major interest has been the possibility of reducing feed costs
by using cow manure to enrich ponds and establish food chainsthat will help sustain the shrimp. Preliminary observations weremade several years ago at the Oceanic Institute, which encouraged
us to conduct more formal experiments. We received 25,000
Penaeus japonicus postlarvae from Jiro Kittaka of Kitasato
University in Japan, grew the shrimp to 0.25 g size in round tanks,
then stocked them in an 1/8-acre, mud-bottom pond which had
been enriched with sun-dried cow manure. The shrimp were fed
approximately 1% body weight per day of a commercial feed containing 25% protein. After 6 wk, the pond was harvested. The
average weight of the shrimp was 17.2 g, with some shrimp
weighing as much as 30 g (Fig. 2). We are currently conducting an
extensive program to further evaluate the use of cow manure as ameans of reducing production costs in shrimp farming. We are
evaluating water quality, pond biota, microbiology, nutrition,
stocking density, maturation rate, and economics.

EGGS/NAUPLJ I

000

1

HATCHERY TANkS (1,000 lITERS):
100,000/TANk, 20-30 DAYS

MATURE SHRIMP

EJ,

MATURATION TANkS(20 FEET DIAMETER):
C.6/SQUARE FOCT, 100-200 DAYSMRKET-SIZE SHRIMPt
POSTlARVAE

NURSERY PONOS (1/4 - 1/2 ACRE):
1,OOC,OCO/ACRE, 30-50 OAYS

r---

r--

60

JUVfNILE SHRIMP

50
~

40

j

PRODUCTION PONDS (1+5 ACkES):
1.000 - 2.000 POUNDS/ACRE/CROP AT 20 SHRIMP/?OUN::l. 90-100 c-AY$

I

-

30

Mean we; ght. 17.2 grams

Figure I.-Steps in the shrimp productinn cycle,
20,--I---I--

Tahle 2.-Summary of annual operating costs for a lOO-acre shrimp farm in
Hawaii.
Item

AmountPucentHatchery and brood stock operating costs
Amortization of capital costs(10 yr at 17% interest)
Taxes
Salaries
Security
Feed
Operaling supplies
Utilities
Mileage
Legal and auditing services
Contingent costs (10% of total costs)$ 72,825(I

147,450
9,600
93,1501,000
225,475
10,00012.1845,200
6,500
58,33823

Total$641,722

-

10

I

·10

10

12

14

16

18

20

22

24

26

rlh

28

30

32

>32

Weight (grams)

Figure 2,-Frequency distribution of weights of 298 Penaeusjaponicus harvested
from P_I, 2 (JP-I), 21 September 1978.

1
15

o
35

MATURATION WORK

1
2
I
1
10

As mentioned previously, until recently shrimp farming has
been restricted to regions with natural populations of a suitablespecies of shrimp. Hawaii has no species of indigenous shrimpthat are known to be suitable for aquaculture, so if an industry is

100

58

only the source of the gonad-inhibiting hormone, but also thesource of a number of other metabolic hormones which may play
an important part in reproduction. These results and possibilities
emphasize the need for a more basic understanding of both thefactors and mechanisms that control reproduction, as well as theprocesses involved in formation and maturation of eggs in theovary.
Continuing research has just begun to be effective in solving
some of these problems. Emphasis has been placed on nutrition,using live or freshly killed "natural foods," and on fortuitous setsof physical rearing conditions (MacGrath footnote 3; Yap footnote 5), since studies over the past 20 yr have verified that nutrition, salinity, temperature, and photoperiod affect reproduction(Caubere et al. 1976; Cheung 1969; Giese 1959; LaubierBonichon and Laubier 1976).
Three present research programs at Texas A&M University are
relevant to this approach. Addison Lawrence is currently investigating the relationship between the process of reproduction andthe concentration of protein, lipid, and carbohydrate in major
tissues (such as the hepatopancreas, gonads, and muscles) in comparisons between wild-caught shrimp and those cultivated undervarious environmental conditions. Robert Brick pursues a similar
approach with the histology and histochemistry of these organs.
Brian Middleditch focuses on determining dietary deficiencies by
examining the lipid components of various tissues and of eggs
from wild stock, compared with patterns obtained from shrimp
reared in captivity.
Related studies are also in progress at the Environmental
Research Laboratory of the University of Arizona, and by
Aquacop6 at the CNEXO Laboratory in Tahiti, where changes in
dietary components are being evaluated with respect to reproduction. The Galveston Laboratory of the National Marine FisheriesService has made great progress in this area using the ablation
technique. They have been spawning several females per week ofthe species Penaeus stylirostris, using a modification of the technique developed by the Aquacop group in Tahiti.

to develop there, it will be essential to mature and spawn shrimp
in captivity. Thus, maturation and spawning are areas of great interest to us, as well as to other researchers around the world whoare involved in shrimp aquaculture. The Oceanic Institute isrelatively new in this field. Considerable work had been done byothers before the Oceanic Institute entered the field. This previous
work provides the basis for the development of our programs.

Induced Maturation
Following the rediscovery of the Pan house effect, recent
research in Tahiti and the Philippines has shown that penaeid
shrimp can be induced to mature, mate, and produce offspring in
captivity (Pan house 1943). This has been accomplished by pinching off one eyestalk (ablation) of female shrimp grown to maturesize in captivity or obtained from the wild. Male shrimp appear tomature normally in captivity, and achieve reproductive capability
without such treatment. Such ablation studies have been repeatedin other parts of the world, and eight shrimp species are now
known to respond to this technique. These species are: Penaeus
monodon, P. aztecus, P. setiferus, P. stylirostris, P. merguiensis, P.
japonicus, P. vannamei, and Metapenaeus ensis (Aquacop 1979;
Caubere et al. 1976; Laubier-Bonichon and Laubier 1976;
McGrath;3 Primavera 1978a, b).
The success of the ablation technique in stimulating reproduction in penaeid shrimp is consistent with postulated mechanismsof reproductive control in other crustaceans (Adiyodi and Adiyodi
1970; Bliss 1966; Bomirski and Klek 1974; Cheung 1966, 1969;
Fyffe and O'Connor 1974; Gomez 1965; Kleinholz 1976; KlekKawinska and Bomirski 1975; Otsu 1963). It is suggested that thesequence of reproductive processes (gonad maturation, egg development, formation and release of mating hormone to initiate
mating behavior, and spawning) is blocked by the presence of an
inhibiting hormone which is synthesized in the eyestalks. Ablation reduces the concentration of inhibitory hormone circulating
within the shrimp's body. When the titer of inhibitory hormone islow, the thoracic ganglion or brain produces and releases a gonadstimulating hormone which begins the reproductive sequencedescribed above.
The results achieved with the ablation technique are considereda major breakthrough in penaeid shrimp aquaculture. However,attempts to apply the technique as a practical means of providing
the numbers of offspring required to stock large commercial
shrimp farms have not proven totally satisfactory. In some instances. ablated female shrimp showed mating behavior but failed
to spawn. The numbers of eggs spawned were often considerably
fewer than those from wild-caught spawners. Hatching rates were
frequently low, and at times the hatched larvae did not survive thelarval period (MacGrath footnote 3; Simon 4 ; YapS).
Such observations suggest that eyestalk ablation prior to thecompletion of other essential events such as yolk development or
DNA formation disrupts the timing and sequence required for successful reproduction. This comes as no surprise, since reviews by
Kleinholz and Adiyodi and Adiyodi describe numerous other endocrine functions found in the eyestalk (Adiyodi and Adiyodi
1970; Kleinholz 1976). Eyestalk ablation therefore removes not

Natural Maturation
To date, not enough information has been accumulated to completely elucidate all of the factors responsible for stimulating
reproductive behavior for anyone penaeid species. However, anumber of groups have periodically succeeded in achieving
maturation and spawning of nonablated female shrimp. The
Aquacop group in Tahiti has succeeded in spawning Penaeus vannamei, P. stylirostris, P. monodon, P. japonicus, P. merguensis, andMetapenaeus ensis without ablation (Aquacop 1979). The Ralston
Purina Company, at its experimental facility in Florida and its
production facility in Panama, has succeeded in spawning P. vannamei and P. stylirostris without ablation. Penaeus japonicus has
been spawned in France by Laubier-Bonichon and Laubier(1976).
The Oceanic Institute has achieved natural reproduction of
Penaeus japonicus in Hawaii. We held approximately 50 P.
japonicus in a 7.3 m diameter pool, designed according to thesystem devised by Shigueno (1975). The shrimp were fed at approximately 5% body weight per day using a mixture of freshly
thawed lobster, oysters, clams, and squid, which were minced to a'w. MacGrath, Director of Mariculture, Ralston Purina Company, St. Louis, Mo.,
pcrs. commL:.n.

'c. M. Simon, Laboratory Supervisor, Maricultura, S.A., Puntarenas. Costa Rica,
pers. commun.

6Aquacop is the aquaculture team of the Centre Oceanologique du Pacifique.
Located in Tahiti, the Centre is pan of the French Centre National pour I'Exploitation des Oceans (CNEXO).

'w. Yap, Aquaculture Research Coordinator, Southeast Asian Fisheries Development Centre (SEAFDEC), Iloilo, Philippines, pers. commun.

59

particle size of about I cm 2 • During January 1979, 10 females inthe tank were observed to carry spermatophores. Nauplii wereobserved in the tank, but no attempt was made to rear the larvae atthat time.

adult female shore crab, Carcinus maenas (L.). BioI. Bull. (Woods Hole)
130:59-66.
1969. The environmental and hormonal control of growth and reproductionin the adult female stone crabMenippemercenaria (Say). BioI. Bull. (Woods
Hole) 136:327-346.
FYFFE, W. E., and J. D. O'CONNOR.
1974. Characterization and quantification of a crustacean lipovitellin.
Compo Biochem. Physiol. 47B:851-867.
GIESE, A. C.
1959. Comparative physiology: Annual reproductive cycles of marine invertebrates.ln V. E. Hall (editor), Annual review of physiology, Vol. 21, p. 547576. Annual Reviews, Inc., Palo Alto, Calif.
GOMEZ, R.
1965. Acceleration of development of gonads by implantation of brain in the
crab Paratelphusa hydrodromous. Naturwissenschaften 52:216.
KLEINHOLZ, L. H.
1976. Crustacean neurosecretory hormones and physiological specificity.
Am. Zool. 16:151-166.
KLEK-KA WINSKA, E., and A. BOMIRSKI.
1975. Ovary-inhibiting hormone activity in shrimp (Cragnon cragnon) eyestalks during the annual reproductive cycle. Gen. Compo Endocrinol.
25:9-13.
LAUBIER-BONICHON, A., and L. LAUBIER.
1976. Reproduction controleo chex la crevelte Penaeus japonicus. In T. V. R.
Pillay and W. A. Dill (editors), Advances in aquaculture, p. 273-277. FAO
Tech. Conf. on Aquaculture, Kyoto, Japan.
OTSU, T.
1963. Bihormonal control of sexual cycle in the fresh water crab, Potamon
dehaani. Embryologica 8:1-20.
PANHOUSE, J.
1943. Influence de I'ablation du podoncule oculaire sur 1a croissance deI'ovaire chez la erevelte Leander serralus. C. R. Hebd. Seanc. Acad. Sci.,
Paris, 217:553-555.
PRIMA VERA, J. H.
1978a. Induced maturation and spawning in five-month-old Penaeus monodon Fabricius by eyestalk ablation. Aquaculture 13:355-359.
1978b. Annual Report. Aquaculture Department, Southeast Asian Fisheries
Development Center (SEAFDEC), Iloilo, Philippines, 37 p.
ROBINSON, L. A. (editor).
1977. Fisheries of the United States, 1976. U.S. Dep. Commer., NOAA,
Natl. Mar. Fish. Serv., Curro Fish. Stat. 7200, 96 p.
SHIGUENO, K.
1975. Shrimp farming in Japan. Association for International Technical
Promotion, Tokyo, Japan, 153 p.
SHLESER, R.
1979. Economic analysis of shrimp farming in Hawaii. Working Report of
the Oceanic Institute, Waimanalo, Hawaii.

FUTURE WORK
It is clear that much work remains to be done in shrimp culture
research. To this end, the National Marine Fisheries Service
Laboratory at Galveston, Tex.; the Port Aransas Laboratory ofTexas A&M University; and the Oceanic Institute have developed
a collaborative program. James McVey of the Galveston Laboratory is researching environmental factors that control reproduction, while Addison Lawrence of Texas A&M University is investigating nutritional factors affecting reproduction. The Oceanic
Institute is working in conjunction with Lewis Kleinholz of Reed
College in Portland, Oreg., to identify and isolate the hormones
controlling reproduction in penaeid shrimp.

LITERATURE CITED
AD/YOD/. K. G., and R. G. AD/YODI.
1970. Endocrine control of reproduction in decapod crustacea. BioI. Rev.
45:121-165.
AQUACOP.
1979. Penaeid reared broodstock: closing the cycle of P. monodon, P. styUroslris and P. vannamei. Proc. World Maricult. Soc. 10:445-452.
BLISS, D. E.
1966. Neurosecretion of invertebrates other than insects. Part IV. Physiological processes and neurosecretion as related to ecdysis and reproduction.
Introduction: Relation between reproduction and growth in decapod crustaceans. Am. Zool. 6:231-233.
BOMIRSKI, A., and E. KLEK.
1974. Action of eyestalks on the ovary in Rilhropanopeus harrisii and Cragnon
cragnon (Crustacea: Decapoda). Mar. BioI. (Berl.) 24:329-337.
CAUBERE, J.-L., R. LAFON, F. RENE, and C. SALES.
1976. Etude de la maturation et la ponte chez Penaeus japonicus en captivite.
In T. V. R. Pillay and W. A. Dill (editors), Advances in aquaculture, p. 277284. FAO Tech. Conf. on Aquaculture, Kyoto, Japan.
CHEUNG, T. S.
1966. The interrelations among three hormonal-controlled charac«rs in the60

An Invasive Fungus Disease of the Tanner Craband its Aquacultural Connotations
ALBERT K. SPARKS'INTRODUCTION

ther, the greater the number of internal organs infected, the more
pronounced is the differential shift.
Careful study has shown that the fungus is an undescribed genus
and species of Ascomycetes and a manuscript describing andnaming it is in the final stages of preparation. It is an unusuallyfastidious fungus; numerous attempts to culture it from internaland external hyphae and from spores on a wide variety of media
and a broad spectrum of environmental conditions have been, todate, uniformly unsuccessful.

The occurrence of an encrusting fungus on the exterior surfaceof the Tanner crab, Chionoecetes bairdi, has been recognized byfishermen, crab processors, and fishery biologists for many years.
Because of the black pigmentation of the hyphae and fruiting
bodies, it is known as "black mat disease" or "black mat syndrome." During the processing of crabs with the external encrustation, fragments of the pigmented fungus are frequently
broken off and contaminate the meat. Therefore, crab processors
are reluctant to buy heavily encrusted crabs and areas known tohave a high prevalence of the condition are often avoided byfishermen.
The fungus was long thought to be restricted to the external surface of the crab. In the first published report of the syndrome, Van
Hyning and Scarborough (1973) identified the fungus as Phoma
fimeti, a ubiquitous soil fungus, and stated that they never observed it in any internal tissues and that it apparently has nodeleterious effect on the crab. They also noted that the fungus appears to be both species specific and area specific, not occurring
on other crabs in localities of heavily infested C. bairdi or reported
in the Pacific Northwest of the United States, Japan, or the Canadian Atlantic.
In the summer of 1978, J. Hibbits of my staff collected anumber of C. bairdi, both with and without external encrustations,in the Kodiak area of Alaska. The crabs were necropsied aboard
ship, with small random portions of each major organ excised andfixed for histological processing. On arrival at the laboratory in
Mukilteo, Wash., the tissues were processed and examined
microscopically.
Our initial studies (Sparks and Hibbits 1979) revealed that thefungus readily penetrates the exoskeleton, proliferates within the
subepidermal tissues, and subsequently invades more internal
tissues. We stated that heavy infections probably prevent molting
and postulated that the disease is eventually fatal to the crab. We
also questioned the identification of P. fimeti as the causative
agent of the disease.
Through an arrangement with personnel of the Alaska Department of Fish and Game, I have continued the study with crabs
shipped alive by air from Cordova, Alaska. To date (May 1980), I
have thoroughly studied 50 crabs with external black mat encrustation and a like number without gross signs of the syndrome. I
feel that I now have enough data to understand the progression,
but not the rate, of internal infection. Mix and Sparks (1980) havealso determined that the infection causes a statistically significant
shift in the hemocyte differential count, with a marked increase in
the percentage of eosinophilic granulocytes in infected crabs. Fur-

PROGRESSION AND PATHOGENICITY
OF THE DISEASE
Normal, uninfested specimens of C. bairdi possess an orange,
somewhat iridescent exoskelton. The external manifestation of the
syndrome begins as small discrete black spots, usually on the dorsal cephalothorax, which enlarge and coalesce to cover much of
the dorsal aspect of the cephalothorax (Fig. 1). Eventually the entire cephalothorax is completely covered with a black tarry massof hyphae and fruiting bodies, which eventually spread to the appendages and ventral surface of the crab (Fig. 2). Less frequently,
the encrustations appear first on one or more of the walking legsor on the legs simultaneously with carapace involvement. Also,
encrustation of the eye stalk usually occurs early in the syndrome.
Removal of the carapace and examination of internal tissues forevidence of fungal invasion is unrevealing, except that the epidermis is more than normally adherent to the inner surface of theexoskeleton. There are no grossly evident, pigmented hyphae andno recognizable disturbance of the normal architecture.
Microscopic examination reveals that the surface encrustations
consist of a mass of thick-walled, pigmented hyphae and fruiting
bodies or perithecia (Fig. 3). Within each mature perithecium
numerous asci develop, each of which contains eight spores (Fig.
4). There is a long, thin filament tightly wound around each end of
the spore, which, when the spore is discharged, unwinds (Fig. 5)
and presumably aids in the attachment of the spore to a potential
host.
Examination of unstained squash preparations of the epidermis
of crabs with external encrustations clearly reveals that fungal
hyphae are present. Sections of carapace and underlying epidermis and subepidermal tissues stained with Grocott's Methenamine
Silver (GMS) demonstrate that the hyphae readily penetrate thethick chitinous carapace. Even in light-to-moderate infections, asmeasured by the extent of encrustation, random samples of thesubepidermal tissues are packed with proliferating bundles ofsparingly branched, sparingly septate hyphae (Fig. 6). As they
proliferate, the hyphae invade, destroy, and almost completely
replace all tissue components in the subepidermal layer.
As the intensity of the infection increases, tissues and organs
beneath the subepidermal layer are invaded, with the primaryroute of invasion via the connective tissue that supports the major

I Resource Assessment and Conservation Engineering Division Northwest andAlaska Fisheries Center, National Marine Fisheries Service, NOAA, 2725 Montlake
Boulevard East, Seanle, WA 98112.

61

1

Figure I.-A Tanner crab wilh black mat syndrome. Most of lhe dorsal cephalothorax is covered and the encrustalion is
spreading to the legs. Most of the round structures on the 3rd right walking leg are epibionts, not fruiting bodies.
Figure 2.-A heavily encrusted crab, almost coml,letely covered hy fungal hyphae and fruiting bodies.

62Figure 3.-Section of carapace and external mat of hyphae and fruiting bodies (Perlthecia). GMS XIOO.
Figure 4.-An ascus containing 8 spores of the fungus. Phase contrast, fresh mount of unstained ascus. XISSO.

63

Figure 5.-A free spore with polar filaments with filaments extended. Phase contrast, unstained. X620.
Figure 6.-Subepidermal tissue containing nllmer<lUS sparingly branched, sparingly septate hyphae. GMS X620.

64

Figure 7.-A deep muscle of the cephalothorax invaded at the periphery and in the interior by hyphae (h). Hematoxylin & Eosin
X250.
Figure S.-Eye muscles invaded by hyphae. Note the swelling in the infected portion of the muscle in the center of thephotomicrograph and the loss of architectural integrity of the muscle at the upper right. GMS X620.

65

Figure 9.-Destruction of retinular ceUs of the rhabdomes In the retina by invading hyphae (h). GMS X620.
Figure to.-Complete destruction of retina by invading hyphae. Note the numerous bundles of hyphae, infiltrating hemocytes andextensive melanization. GMS X2S0.

66

fected crabs. Further evidence for this assumption is the apparent
inability of infected crabs to mount a successful defense
mechanism. To date, almost all the infected crabs examined havebeen collected by crab pot, an unlikely source for moribund
animals. Also, crabs near death are more susceptible to predation
and are probably quickly removed from the population. However,the lethality and the time required for the disease to kill crabs requires laboratory confirmation. If the disease is proven to terminate fatally, it may, at least partially, explain recent population
declines (up to 50%) in C. bairdi stocks in Alaska.
Sparks and Hibbits (1979) believed that the mycosis begins on
the surface and then penetrates the chitinous exoskeleton to invade internal tissues, rather than, as many fungal parasites ofarthropods do, becoming established internally before developing
reproductive structures externally. This assumption is based on thefact that internal invasion ·has been present in every crab withexternal fungi examined but none of the many crabs lacking theexternal encrustations contained internal hyphae. There is noquestion, however, that the internal hyphae provide the nutrient
for the external hyphae and fruiting body growth.
The mycosis presents a potential problem in the event that the
Tanner crab becomes a cultivated species. Of more immediate importance, however, the information needed on the mechanism of
infection, progression of the disease, effect on molting, andlethality, can be effectively obtained only under controlled
aquaculture conditions. Thus, aquaculture can provide data ofvalue for the management of wild populations.

organs. However, deep muscles are frequently involved, with thehyphae first invading the periphery of a muscle then growing inward along the edges of muscle bundles (Fig. 7). Frequently, theconnective tissue and muscles adjacent to the hematopoietic organ
contain numerous hyphae and occasionally the interlobular connective tissue and the hemopoietic tissue proper is invaded anddestroyed.
The walls of deep blood vessels, as well as those in the subepidermal layer, are invaded and occasionally even in nonmoribund crabs, the fibrous connective tissue comprising the wall of
the heart contains masses of hyphae. Sometimes the wall of theesophagus, cardiac stomach, and hindgut are invaded.
Hyphae and perithecia are frequently present on the externalsurface of the eyestalk and virtually all infected crabs haveeyestalk invasion. The epidermis and subepidermal layer, as in the
cephalothorax, are first invaded, then hyphae extend into themuscles of the eyestalk, disrupting the normal architecture anddestroying the muscles (Fig. 8). Somewhat later, hyphae growalong the retinal basement membrane and subsequently invade theretina, where they proliferate between the rhabdomes and invade
and destroy the retinular cells of the rhabdomes (Fig. 9). Eventually, many crystalline cones of the retina are invaded and disrupted.
Although host defense mechanisms are usually minimal, marked
hemocytic infiltration sometimes occurs and melanization of thedestroyed retina follows (Fig. 10).
Fruiting bodies and external hyphae may occur on the externalsurface of gill lamellae with the underlying lamellar tissue invaded
and replaced by a solid mass of proliferating hyphae. The base of
the gill may also be involved, with invasion of connective tissue
and podocytes.

ACKNOWLEDGMENTS
The highly skilled technical assistance provided by Jolly Hibbits is gratefully acknowledged. She necropsied and processed all
the crabs, studied the spore morphology and did the taxonomic
work required to determine that the fungus was an undescribedgenus and species of Ascomycetes. The cooperation of AI Kimker,
Alaska Department of Fish and Game, in collecting and shipping
live crabs from Alaska is also greatly appreciated.

DISCUSSION
It is probable, from the massive destruction of the epidermis
and subepidermal tissues, that crabs infected with the fungus areunable to molt. However, I have not been able to verify this experimentally because of lack of a laboratory seawater system withfacilities to sterilize the effluent water and destroy infective
spores. There is circumstantial evidence that infection prevents
molting, in that areas of known high incidences of the black mat
syndrome are also areas of high percentages of skip-molt crabs.
Further support is provided by the fact that I have never foundinternal hyphae in a crab lacking external encrustation. If I am
correct in my assumption that infected crabs are unable to molt,
infected sublegal crabs will never enter the fishery.
Because of the obvious ease with which the hyphae invade
tissues and the massive proliferation and destruction accompanying the invasion, it also seems likely that the disease is lethal to in-

LITERATURE CITED
MIX, M. C., and A. K. SPARKS.
1980. Tanner crab Chionoecetes bairdi Rathbun haemocyte classification andan evaluation of using differential counts to measure infection with a fungal
disease. J. Fish Dis. 3:285-293.
SPARKS, A. K., and J. HIBBITS.
1979. Black mat syndrome, an invasive mycotic disease of the Tanner Crab,
Chionoecetes bairdi. J. In vertebr. Pathol. 34: 184-1 91.
Van HYNING, 1. M., and A. M. SCARBOROUGH.
1973. Identification of fungal encrustation on the shell of the snow crab
(Chionoecetes bairdi). J. Fish. Res. Board Can. 30: 1738-1739.

67

Statement of Tenth Joint Meeting of the UJNR
Aquaculture Panel, Molluscan Culture,
Lewes, Delaware, October 27, 1981

The Tenth Joint Meeting of the UJNR Aquaculture Panel was held on October 27, 1981, at the
Marine Science Center, University of Delaware, Lewes, Delaware.
Dr. Takeshi Nose, Secretary General of the UJNR Aquaculture Panel, acted as chairman for theJapanese Panel because Dr. Hanamura could not attend. Mr. Conrad Mahnken was chairman for
the United State Panel. Dr. Nose announced a change of officers for the Japanese delegation. Dr.
Akira Suda, former chairman, has accepted a new position as Executive Director of Japan Sea
Farming Fisheries Association. In his place, Dr. Nobuhiko Hanamura has been appointed as the
new chairman, Japanese Panel. Rapporteurs for the tenth meeting were Dr. Kouichi Ohwada and
Mr. Ben Drucker.
Mr. Robert Wildman was appointed as the new Vice-Chairman of the U.S. Panel to replace Dr.
Tapan Banerjee, who has accepted a position with the U.S. Agency for International Development
in Indonesia.
I. Scientist Exchange
The scientist exchange program sponsored by UJNR is an effective means of exchanging information on aquaculture between the two countries and was continued between the Ninth and TenthUJNR meetings. During this period:-Dr. Arai and Dr. Wada visited the NMFS, Seattle, Washington, Laboratory and the Universityof South Carolina, respectively.
-Graduate students from the University of California and Western Washington University visited
the Tohoku Regional Fisheries Laboratory and the Oyster Research Institute.
-Three members of the Japanese Panel of the UJNR and three scientists as observers, attended
the Tenth Joint UJNR Meeting and the Second International Conference on Aquaculture Nutrition.
-In 1982, Dr. Nagahisa Uki will visit the United States to do research on abalone aquaculture.
2. Literature Exchange
For the period 1980-1981, the Japanese Panel sent to the U.S. Panel 120 scientific papers. During the same period, the U.S. Panel sent to Japan 78 scientific papers. At the Tenth UJNR Meeting,
the Japanese delegation presented to the U.S. Panel five copies of a publication entitled "Review on
Aquaculture Research in Japan."
A computerized data base for literature surveys in the field of aquaculture is currently available
to Japanese UJNR members.
3. Cooperative Studies
An up-date of ongoing programs was presented. These included:
1) Registry of Marine Pathology
This program has been most successful and will be continued in the future. It is hoped thata publication will result in a photographic atlas of diseases of marine and freshwater fishes.
2) Mass Mortality of Oysters
This program has been ongoing for a number of years and the principal investigators will
decide whether or not to continue the study.
3) Disease Resistance of U.S. Oysters in Japan
Strains of disease resistant oysters have been sent to Dr. Kan-no by Dr. Chew, and comparisons have been made with wild populations. This program should be completed.
4) Cooperative Studies on Abalone
Dr. Uki will be visiting the United States in 1982, and he will discuss with U.S. investigators the potential for a cooperative program beneficial to both countries.
At this time, the U.S. Panel has no new cooperative projects to propose. However, during thecoming year they will look into the potential for establishing cooperative programs such as:-Smoltification-Reproductive physiology-Comparative nutrition69

-Water re-use systems-Pond dynamics
The Japanese Panel also has no new proposals to suggest at this time.
Any proposals developed during the coming year will be sent to the Chairmen of the Japaneseand U.S. Panels prior to the next meeting in adequate time for review.
4. Second Five- Year Plan
The following schedule was agreed upon as the second five-year plan for UJNR activiiies:
Salmon Enhancement (ocean ranching, salmon farming, public hatchery
YEAR I (Japan)
systems, carrying capacity, smoltification, seeding, nutrition, evaluation of
stream stocking, etc.)
YEAR 2 (USA)Aquaculture Engineering (emphasis on structures and new automated technology in aquaculture systems)
YEAR 3 (Japan) - Environmental Quality in Aquaculture Systems (water quality, self-pollution, water re-use systems, and animal health)Reproductive Physiology (genetics and breeding of aquaculture species)
YEAR4 (USA)YEAR 5 (Japan) - Marine Ranching
5. Publications
An editorial policy was agreed on by both Panel Chairmen. This accepted policy includes:-Papers are to be written in English-All papers will be published by the U.S. side with one Japanese and one U.S. scientist as coeditors-For maximum coverage, the papers will be published as an official publication-Papers will be summarized at meetings-Papers will be distributed to members and observers prior to presentation at the annual meeting-Publications consist of three types of papers:-Overview papers-Status of research papers, and-Technical papers
The 1978 and 1979 papers are currently being prepared for publication by Dr. Sindermann. The
1980 and 1981 papers will appear as a single publication.
6. Next Joint Meeting
The next meeting of the UJNR Panel is scheduled for Tokyo, Japan, in mid-October 1982. The
meeting theme will be "Salmon Enhancement." A field trip to northern Japan will follow thebusiness meeting.

Conrad Mahnken - United States
Takeshi Nose - Japan70

An Attempt to Culture the Noble Scallop,
Mimachlamys nobilis Reeve,
Using a Microparticulate Diet
AKIO KANAZAW A, SHIN-ICHI TESHIMA, MINESHI SAKAMOTO,
HIKARU MATSUBARA,l and TAKEMITSU ABE2

ABSTRACTThis paper deals with the attempt to culture the noble scallop, Mimachlamys nobilis Reeve, using two typesof micro particulate diets. Carrageenan-micro bound diet (MHO) or nylon-protein microencapsulated diet (MEO)
was fed together with marine Chlorella. As a control, marine Chlorella-Chaetoceros were fed following themethods of the Fisheries Experimental Station of Oita Prefecture. Higher growth and survival rates of thescallop larvae were attained in the group fed marine Chlorella-carrageenan MHO (1: I). The shell length ofscallops fed this diet reached 995 I'm average, with 19.2% survival over 47 d. The shell length of the control
scallops fed marine Chlorella-Chaetoceros was 875 I'm average, with 4.8% survival over 49 d. Scallops fed marine
Chlorella-nylon protein MEO (1:1) showed similar growth and survival to scallops fed only marineChlorella anddied in about 23 d without reaching the sessile stage. The results of the present study indicate the possibilities ofrearing larval scallops and other pelecypods on microparticulate diets composed of ingredients which satisfy thenutritional requirements of these animals.

Feeding Experiments

INTRODUCTION
During the past 4 yr, we have tried to make a microparticulate
diet for larval fish and crustaceans as substitutes for live food,such as Chaeloceros and the rotifer Brachionus plicalilis. We havesucceeded in rearing the larval prawn Penaeusjaponicus from zoea
to postlarvae on an artificial diet alone, and have demonstrated
that the growth and survival rate of prawn fed artificial diets were
almost comparable with those of prawn fed live food.
The noble scallop, Mimachlamys nobilis Reeve, is one of several
promising species for aquaculture in Japan. Seedling productionof this scallop has been carried out using marine Chlorella,
Chaetoceros, Monochrysis, Phaeodactylum, and rotifers as dietaryorganisms (Yamada 1980; Nanba 1980). However, it requires
excessive manpower and expensive facilities to culture theseplanktonic organisms. In the present study, an attempt was madeto culture the larvae of the noble scallop using microparticulate
diets.

Four experimental groups were chosen: Group I received amarine Chlorella sp.-carrageenan microbound diet (MBD), 1:1.
Group 2 received a marine Chlorella sp.-nylon protein microencapsulated diet (MED), 1:1. Group 3 (control) was reared on
marine Chlorella-Chaeloceros calcilrans by the method employedat the Fisheries Experimental Station of Oita Prefecture (Shiihara
and Takeda 1978). Group 4 was maintained on marine Chlorellaalone. The nylon-protein MED was prepared as described
previously (Jones et al. 1976). The method for preparation of the
carrageenan-MBD will be reported elsewhere. The diets were supplied to larvae on the basis of the following formula during theperiod of hatching to 400 !lm length:

MATERIALS AND METHODS

The diet supplied was expressed as the number of diet particles/mlof medium. For the larvae (shell length ~ 400 !lm), 65,000 cells or
granules/ml were supplied. Tables I and 2 show the compositionof carrageenan MBD and nylon-protein MED. The composition ofnylon-protein MED was the same as that of the purified diet for P.
japonicus (Kanazawa et al. 1977) except for trace amounts of
Na 2 SiO J .

Diet supplied (particles/ml) = ISO x shell length (flm)- 7,500 cells or granules/ml
water.

Noble Scallop Larvae and Culture Methods
Spawning was induced by stimulating mature females by both
exposure to air and temperature control as described by Shiihara
and Takeda (1978). After hatching, the D-type larvae (population
density, I larva/ml) were reared until the sessile stage in an
aerated 100 I round tank with its sides covered with a black
plastic sheet. Thirty percent of the water was renewed every 3 d
by filtration through a fine net (mesh size, 25 !lm). Larvae at thesessile stage were reared by hanging the oyster shells as a culch inrunning water with a flow rate of 100 lid.

RESULTS AND DISCUSSION
The results of the feeding experiments are shown in Table 3 andFigure I. Noble scallop larvae fed Chlorella-carrageenan MBD
showed superior growth and survival to those fed control diets(Chaeloceros-Chlorella). A marked difference was seen in the survival rates between the Chlorella-carrageenan (19.2%) and control(4.8%) groups, although the scallop larvae in both dietary groups
attained the size utilized for raft culture at almost the same time.

'Faculty of Fisheries. Universily of Kagoshima. 4-50-20 Shimoarata. Kagoshima
890. Japan.
'Oita Prefecture Fish Fanning Center. Oita. Kyushu. Japan.

71

Table I.-Composition of the carrageenan microbound diet (MBD). Diet particulate size: 5-8 I'm
diameter.

1200

Ingredient1000

gil OOg dry diet

Skim milk'
Chicken egg yolk 2
Chicken egg albumin

37
10

Tapes extract powder2
Yeast extract powder2

10
10

Pollack liver oil
Oleic acid 08:!w9)

6~ Chlorella

10

Amino acid mixture}
Mineral mixture)

Vitamin mixture)o• Ch1ore11a + Chaetoceros

o Chlore11a + Carrageenan MBD+ Nylon-protein MED.. Chlorella

800
E

6
5

3-

I

en

:5 600<:5

OJ'Morinaga Milk Company Co., Ltd.
2Riken Vitamin Co.
'Kanazawa, Teshima. and Tokiwa (977) andKanazawa, Teshima, Inamori, (washita, and Nagao(1981 ).

1!
400
VJ

200
Table 2,-Composition of the nylon-protein
microencapsulated diet (MED). Diet particulate
size: 5-8 I'm.

ogil OOg dry diet

Ingredient

10

20

3D

40

50

Feeding period (days)
50.0
4.0
5.5
0.8
0.3
0.3
0.5
6.0
6.0
8.54
6.0
0.5
0.5
1.65

CaseinStarch soluble
GlucoseGlucosamine HCI
Na-citrateNa-succinate

Cholesterol
Pollack Ii ver oi I
Soybean lecithin'
Mineral mixture
Vitamin mixture

I-Methionine
1- Tryptophan

Cellulose

Figure I.-Growth of larvae of the noble scallop during the feeding period.

two dietary groups reached the sessile stage in about 12 d, whereas
those of the former two dietary groups did not attain the sessile
stage even after 23 d, when mortality was complete. In addition,
larvae of the noble scallop reared on Chiarella-carrageenan MBD
showed a higher survival rate than those fed live food andChlarella-Chaetaceras 1 mo after being transplanted to the sea.
The present study shows the possibility of using the carrageenan MBD as a substitute for Chaetaceras for rearing larvalstages of the noble scallop. Also, this study indicates the possibility of rearing the larval scallop and other pelecypods with microparticulate diets as long as they are composed of ingredients
which satisfy the nutritional requirements of these animals.

'Nakarai Chemicals, Ltd.

Table 3,-Results of the feeding experiment.

Dietary group

Feeding
periodGrowthshell
length(d)(I'm)

Survival(%)

Survival (%)
of raft cultured

LITERATURE CITED

specimens'
JONES. D. A., T. H. MOLLER, R. J. CAMBELL, J. C. MUNFORD, and P. A.
GABBOT.
1976. Crustacea. In G. Personne and E. Jaspers (editors). Prne. 10th European
Symp. Mar. BioI., Oostend, Belgium. 1975. p. 229-239. Universa Press,
Wetteren, Belgium.
KANAZAWA, A., S. TESHlMA, S. INAMORI, T. IWASHlTA, and A. NAGAO.
1981. Effects of phospholipids on growth, survival rate, and incidence of malformation in the larval ayu. Mem. Fac. Fish., Kagoshima Univ. 30:
301-309.
KANAZAWA, A., S. TESHIMA, and S. TOKIWA.
1977. Nutritional requirements of prawn-VII. Effect of dietary lipids on
growth. Bull. Jpn. Soc. Sci. Fish. 43:849-856.
NANBA, T.
1980. Seed production of Chlamys (Mimachlamys) nobilis. Rep. Fish. Exp.
Stn. Wakayama Pref. 6:112-119.
SHIlHARA, H., and T. TAKEDA.
1978. Studies on the artificial seed production of Chlamys (Mimachlamys)
nobilis - I. Rep. Fish. Exp. Stn. Oita Pref. 10:59-65.
YAMADA, O.
1980. Seed production of Chlamys (Mimachlamys) nobilis. Rep. Oita Fish.
Corp., p. 19-25.

I Chlorella +Carrageenan MBD
2 Chlorella +Nylon protein MED
3 Chlorella +Chaetoceros
4 Chlorella

47

995

4.7 (4,725)2

0.0

22
49
24

19.2

874

4.8
0.0

0.8 (759)2'One month after being transplanted to sea.
2Number of live specimens.

The difference in survival rates between both experimental groups
seemed to be attributable to mortality at the beginning of umboperiod and at the pigment-cell stage.
Larvae maintained on the nylon-protein MED showed similar
growth and survival rates to those fed Chiarella alone, but their
growth and survival rates were lower than those maintained on the
Chiarella-carrageenan MBD and control diets. Larvae of the latter
72

Recent Developments in Shellfish Culture in
Southern Japan
GENERAL REMARKSKAZUHIKO NOGAMPWest Islands: The giant wing oyster, Pteria penguis, in bays of theAmami Islands, the black lip pearl shell, Pinetada magaritifera, in
lagoons of the Yaeyama Islands, and the noble scallop, Chlamys
nobilis, in the Okinawa Islands and in other coastal areas facing
the Pacific Ocean.
The Seto Inland Sea is the most representative enclosed area inJapan. Oceanic waters come in and flow out only through twochannels at the southeastern and southwestern ends. A number ofrivers and streams flow into the shallow sea with an average depthof 31 m. These factors cause wide variation of temperature andsalinity in the sea. Tidal range averages 3.5 m in the central portion. The maximum velocity of tidal current is recorded to be as
fast as 10 kn. These remarkable variations in the environment
favor ~he propagation and farming of diverse bivalves and othermollusca. Besides the famous oyster culture, farming grounds ofthe short-necked clam, Ruditapes philippinarum, and the hardclam, Meretrix lusoria, have developed in the sandy littoral
beaches around river estuaries. Pilot programs are also being conducted for other species in the tidal beach areas. Young of thebivalve of the ark shell, Scapharca suberenata, collected fromnatural beds are transplanted into muddy coastal waters of 4-5 m
depth. Hatchery-reared ark shells are cultivated in cages or released on the bottom in coastal areas of 10-30 m depth.

There are a number of species of molluscan shellfish whichhave long been exploited by fisheries in southern Japan. At present about 30 bivalves and 10 snails are of particular importancefor commercial exploitation. Cultivation and farming are alsocommercially important. Seven bivalves, including black lip pearl
shell, giant wing oyster, noble scallop, oyster, pecten, ark shell,
and pearl oyster, are actively cultivated. Furthermore, releases andtransplantations on commercial and semicommercial scales incoastal areas are conducted for ark shells, clams, hard clams, noble
scallops, round clams, and short-necked clams among bivalves,
and abalone and snails among gastropods. Figure 1 schematicallyshows the major localities of these species.
Coastal waters in southern Japan provide suitable environments
for the culture and farming of these species. Figure 2 shows thepaths of the Kuroshio and Tsushima Currents that flow along the
Pacific and Japan Sea sides of the area. It also gives distribution ofisothermal profiles in the summer and winter. It is obvious thatthe dominating warm currents result in a moderate sea climate
along the coast facing the open sea, ranging between 15 ° and
17 °C in winter, and averaging about 27°C in summer. The
seasonal change of climate is more extensive in the bays and in
the inland sea.
Rocky shores prevail along the open coast, providing profitablezones for releasing and harvesting abalone. In 1979,2.18 million
abalone seeds were produced and released in the rocky zones. Efforts have been made to transplant young shells of hard clams on
sandy bottoms: A Veneridae (Meretrix lamarekii) along Hiuchi
Nada of the Seto Inland Sea, and another Veneridae (Gomphina(Macriduseus) melanaegis) along the Sea of Japan. Recently seedsof the ivory shell, Barylonia japoniea, have been produced by alaboratory and then released in coastal waters with sandy or muddy bottoms along Tottori Prefecture. The scallop, Pecten albieans,is actively cultured in the eastern part of Shimane Prefecture.
These two prefectures are in the Chugoku Region and face the Sea
of Japan (Fig. 2). Subtropical species are cultured in the SouthI

Hiroshima Bay and adjacent waters have long been utilized forthe culture of edible and pearl oysters. Abalone have been released
along the rocky shores receiving the influence of warm, swift currents. Pectens are reared by the hanging method during the coldseason. Hard clams are often cultivated or released, on an experimental scale, in sandy bottom areas.
The Ariake Sea, western Kyushu, is characterized by wide expanses of tidal flats, an extensive tidal range of 6 m, and wide
ranges in temperature and salinity. Significant natural production
by young shellfish provides seeds for "intermediate breeding"(rearing from spat to any size).

Nansei Regional Fisheries Research Laboratory, Ohno-Cho. Hiroshima, Japan.

73

o

r.~

(}V;fj-Jr,Y Scallop

oyster(Ark shell-lHar;d cl am \ \Noble scallop

SOUTH WEST ISLANDS

a~sC2110po

50I

4~ IT[~ Giant wing oyster()

100 KmIo.,oBlack lip pearl

she~:~

a

G/:J

50

100 KmI:0oFigure I.-Distribution of the major molluscan shellfishes for cultivation and farming in southern Japan. Shadow drawings represent species for release and transplan.
tation. Blank drawings represent species for cultivation. Scientific names of the species in the map are: Abalone, Halio/is discus and H. gigan/ea; Ark shell· I ,Scapharcabrough/onii; Ark shell-2, S. subcrena/a; Black lip pearl shell, Pine/ada margari/ifera; Clam.l, Gomphia melanaegis; Clam.2, Mere/rix lamarckii; Giant wing oyster, P/eria
penguin; Hard clam, Mere/rix lusoria; Noble scallop, Chlamys (Mimachlamys) nobilis; Oyster, Crassos/rea gigas; Peelen, Pee/en (N%vola) albicans; Pearl oyster, Pine/ada
furcata martensii; Round clam, Mac/ra mac/ra chinensis; Snail, Babylonia japonica; Short-necked clam, Rudi/apes philippinarum.

74

26
0

130

36

12

0

CIiUGOKU~---j----27

17

2~

18

20.

..

26

0

- 21

•22

~tb

YAEY~c;
:

.

29

29

o

L---123':"0-------------126°"----------------129°~-----------__1

Figure 2.-Major ocean currents and surface isothermal contours in southern Japan. Arrows denote the Kuroshio and Tsushima Currents. Closed and broken lines
denote average isothermal contours in August and in February, respectively.

75

OYSTER CULTURE IN HIROSHIMA PREFECTURE
OSAMU FUKUHARAI

level of about 20,000 t or slightly above. This can be attributed to
the recovery of a number of rafts, even though the number offarms decreased continuously until the mid-1970's.
The incident in 1969 suggested that the recent crowding of rafts
caused various ill effects upon the oysters, and eventually resulted
in a decrease in productivity in the oyster ground. In this regard, it
is noted that the yield per raft averaged around 2.5 t during theearly years, but declined to around 2.0 t after 1972.

Hiroshima Bay and adjacent waters are well known for theirlong history of advanced oyster culture (Fujiya 1970; Furukama1971). This industry has spread over Japan in the last 100 yr.
Oyster culture in Hiroshima has been a fairly stable industry
both in amount of yield and in operation of the farms until the late1960's. Since then, adverse problems have emerged, mostly due todeterioration of the environmental conditions of the oyster
grounds and to a rise in operating costs. From a technical standpoint, the intention is to stabilize the harvest at an optimum level
and to maintain the oyster grounds in suitable condition for thisspecies, rather than to increase total production.

OYSTER FARMS
Oyster culture represents a typical coastal fishery in Japan.
Usually members of a family work jointly. An oyster farm, or aunit of management of cultivation, is operated by a group offishermen. About 50% of the units have 10 to 20 rafts each, but
the largest farms use 100 rafts or more. The majority of farms
employ 10 to 12 workers. Almost 80% of the employees arefemale part-time workers who shuck the shells during the harvest
season, from November to April. The wage of these part-timeworkers constitutes about 50% of the total operating cost. Each ofthem shucks almost 40 to 50 kg of oyster meat per day, or about 4t of oysters cultured on 1,000 to 1,200 strings during one season.
The number of oyster culture farms increased from 550 in 1959
to 920 in 1967, and then decreased until 1975, especially
immediately after the serious damage to the industry in 1969. For
the last 5 yr until 1979, the number of cultivation farms stabilizedaround 600 to 650 units (Fig. 1).

AMOUNT OF PRODUCTIONIn Figure I, the yield of oysters harvested from farms, the yield
per raft, the number of rafts, and number of farms during 21 yr
from 1959 to 1979 in Hiroshima Prefecture are given. During theapproximately 20 yr, the annual production of oyster meat ranged
from 10,000 to 30,000 t (metric tons), constituting about 50 to 70% of Japan's total. Before 1969, the yield increased, together withan increase in the number of rafts and cultivation units. But a
notable decrease in the yield occurred in 1969 and 1970. The
decline in 1969 was attributed to mass mortalities of oysters due
to adhesion of the shell of the annelid, Hydroides elegans. Furthermore, a strong typhoon hit the area during the summer, destroying
many rafts and other facilities. This damage left its effect onoyster culture until 1970 and 1971, resulting in a decline in thenumber of rafts by nearly a quarter of that of the previous years.
Since then, oyster production has been maintained at a moderate

CULTIVATION PROCEDURES
Figure 2 schematically represents the current standard procedures used in oyster culture. The culture period lasts 2 yr.

'Nansei Regional Fisheries Research Laboratory, Ohno-Cho, Hiroshima. Japan .

30
z

"

~

~

co

::

20

"- '

. \. . /:<1'",-1'...
("'_._~J'/~.•.•....•• / / /of.""'..---:;:.•......

. .•..

'72, 76'.. ····.•i

10

12
~

~

~ 10

Figure I.-Yield of oyster meat and number of facilities in Hiroshima Prefecture, 1959-79. Top: Closed and broken Unes denotetotal yield and yield per raft, respectively. Bottom: Closed and broken lines denole number of rafts and number of farms, respectively.
'60

'62

'66

'68

'70
YEAR

76

, 78

>-

g w

~

~

:>

«

~

~

"~

<'5

u

w

c

~

.,

w
"-

~ ~ ~

w

z

u

I

.,

~ j ~ ,<=> ~ cw -'l "-w >=" «
~

:>

~

,;

u

z

~

~
~

I

SPAT

TVPE

GROWl NGCOLLECTION

HARDENING

Figure 2.-Schematlc representation of oyster culture. Asterisks
denote a handling to keep the strings at deep layers of 2·5 m toprevent adhesion of fouling animals to the oysters.

TYPE

B

SPAT
'"
COLLECT ION ' "HARDENING\GROWIN.!

\GROWING\HARVEST\

Each raft carries 650 to 780 strings just below it. In the summer
an additional string of 2 to 5 m is inserted between the raft and therearing strings in order to prevent adhesion of barnacles, mussels,
and other fouling animals that prevent growth of the oysters. Also
harmful factors such as a decline of oxygen content, rise of
temperature over an optimum level, or blooming of red tide areliable to occur in the warmer months. Fishermen shift the fattening rafts from coastal waters to the calm offshore waters aroundislands, until the autumn when the chance of encountering such
harmful factors is reduced.

Previously a short-period culture of 1 yr was used, but it was nolonger used after 1964, possibly due to the rise in density ofoysters that apparently resulted in the decline of food organisms
and in the desolation of the sea bottom.

COLLECTION OF SPAT
Usually scallop shells are used to collect oyster spat. A collector
is made of 70 scallop shells spaced from each other by a plastic
tube, at intervals of about 2 cm, that is run through a semisteel
wire of 1.6 m in length. The collectors are put on a rack installedin the littoral zones or hung from rafts in the oyster grounds. The
fishermen collect a suitable number of spat, 40 to 50 animals pershell, by carefully regulating the duration of collection whichranges over several days. The chance to achieve such successful
seeding occurs only one or twice every summer. In order to obtainreliable information for determining the optimum period for seedcollection, the prefectural and municipal research organizations
investigate the density of spat in the seawater, growth of the oyster
spat, and density of such fouling animals as barnacles and mussels.
This information is made available to the fishermen. In addition,
the fishermen themselves and their cooperatives conduct similar
surveys in the seeding areas, including counting spat on themonitoring collectors and swimming larvae in samples of plankton net collections.

HARVEST FOR MARKET
Usually the harvest of marketable oysters starts in late Octoberor early November. Almost all the oysters shucked by the end ofJanuary go to the markets for fresh consumption. From February
to April, the percentage of oysters used in processing, including
canning, freezing, and smoking, rises gradually at first and thenmore rapidly. Processing consumes about 30 to 50% of the total
annual production in Hiroshima Prefecture.

PROBLEMS AND PERSPECTIVESIn Hiroshima Prefecture, approximately 10,000 rafts are used
for oyster culture in an area of about 160 km 2 . Thus the density is
as high as 62.5 rafts/km 2 or 156 g of harvestable oyster meat or
780 g of living animals/m 2 • Such overcrowding of the animals is
the most probable cause of the decreased production of oysters perraft from 2.5 t in the 1960's to 1.0 t in the 1970's. Moreover, thehigh density of the oysters makes them vulnerable to environmental changes and contaminated farming grounds. This often resultsin tremendous fluctuation, causing a disastrous decline in production. Recently it was noted that the oyster grounds are beginningto display a symptom of "senescence." The Hiroshima Prefectural
Fisheries Cooperative Associations and other organizations haveinitiated research to find a means to recover the oyster grounds.
In the past, a sufficient number of spat were collected by simple
racks installed on the littoral zone in early summer. However, recent changes in both the topography of the coast and the techniques of oyster culture have required the introduction of seedcollection with rafts. Reclamation of the littoral zone has progressed and has destroyed ma'ny spat areas therein. The transfer ofoyster rafts to the island in summer reduces the number ofspawners in the coastal area. Therefore, the role of rafts has
become more important for the production of seed oysters than
before. This requires a reliable and detailed forecast of the distribution and abundance of spat in order to assure efficient utilization of the rafts. In order to supplement the natural seeds, theHiroshima Prefectural Fisheries Experimental Station is studying
a practical production system of oyster spat based on artificial fertilization (Kusuki 1976).

HARDENING
Seed oysters collected on the rafts stay in the water for thewhole day. These animals are less tolerant to exposure to air andother environmental changes, and must be hardened after growing
below the raft for several days. This procedure is usually not required for spat collected on the racks in the littoral zone, whichhave already been exposed to air.
The seed oysters are transferred to hardening racks installed on
the beach, and exposed for 6 to 10 h a day. This procedure retards
growth of the spat but provides them the adaptability against environmental changes, and controls weak members among the spat.
Hardening commences in September and is then divided into
two types of culture: "A" and "B". In type "A" culture, hardening
ends in late autumn. Type "B" culture needs a longer hardening
period of 7 mo, lasting through the following spring. Figure 2
schematically compares these types of oyster cultivations.

FATTENING
The seed oysters, hardened if necessary, are then transferred tofattening rafts. Scallop shells with seed oysters are hung on asemisteel wire of about 10m in length, and set at an interval of 15
cm spaced by plastic tubes. The rafts are 165 to 190 m 2 on thesurface, ranging between 8 and 9 m in width and 18 and 22 m inlength.
77

Production of 20,000 to 30,000 t of oyster meat per year resultsin more than 120,000 t _of oyster shells piled up from the oyster
factories every year. Unpleasant odors and flies from the wasted
shells create serious social problems. Unfortunately, only a small
portion of the waste is used in forage and fertilizer. The bamboo
poles of the oyster rafts last for 3 yr. In other words, the fishermenmust replace 30% of the raft materials every year. At present, thebamboo is burned on the beach, creating other problems, such aspollution of seawater, obstruction of ships, and so on.
In addition, rising wages may affect management of oyster
farms. It will be difficult to retain sufficient labor, especially forshucking the shells. Automation is rarely introduced to this part ofthe oyster cultivation procedure.
"Senescence" of the sea, in my opinion, is the most essential
constraint in operating oyster farms in Hiroshima Prefecture. Thishas been caused by overutilization of the sea for a long period.
Therefore, some measures should be implemented to regulate thenumber of rafts at an optimum level and to conserve the fishinggrounds.

LITERATURE CITED
FUJIYA, M.
1970. Oyster farming in Japan. Helgol. wiss. Meeresunters. 20:464-479.
FURUKAMA. A.
1971. Outline of the Japanese marine aquaculture. Jpn. Fish. Resour.
Conserv. Assoc., June 1971, Tokyo, Japan, 39 p.
KUSUKI, Y.
1976. Rearing larvae of Japanese oyster, Crassostrea gigas (Thunberg). Bull.
Hiroshima Fish. Exp. Stn. 617:27-36.

CULTURE AND PROPAGATION OF BLOOD ARK SHELLSKAZUHIKO NOGAMJI

and the next years. In the Center, the spawners are selected fromthe commercial catch taken by small coastal trawlers in lateMarch and early April. Specimens used for seedlings exceed aminimum 90 mm in shell length and average 115 mm in lengthand 380 g in body weight. They are reared, without feeding, inplastic baskets hung in running filtered seawater. Under such conditions, 2 to 8% of the animals die by mid-June, but all the survivors mature when the water temperature rises to 20°C. For
spawning induction, the animals are transferred to standing water
heated to around 25°C and then to running water of around 28 °C.
The procedure lasts for about 7 hid. Up to 80% of the spawners
discharge eggs or sperm after repeating the temperature stimulation for 2 or 3 d.
Fertilized eggs are washed and then left for one day and night.
Newly hatched larvae are reared in a I-ton FRP (fiberglassreinforced plastic) tank painted black at a density of 1.5 individuals/ml. The tank contains seawater leached with a 5 flm filter
and aerated gently. The larvae are fed with a mixture of Pavlova
lutheri and Chiarella sp. at a ratio of I :8, spread in the water at adensity of 10,000 individuals/ml.
Eighty collectors made of oyster shells are hung for each tankon the 20th day after fertilization. The seeds are harvested when
they grow to I mm in shell length by early or mid-September. The
survival rate is almost 88% from hatch out to the seed stage. The
spat are then kept in lantern nets originally developed for pearl
oysters for intermediate breeding until they reach 20 to 40 mm inlength in the following March to July. During intermediate breeding, fishermen change the lantern nets several times, and replace
one net with another of larger mesh. The survival rate during thisperiod is about 30% (Ohashi and Koumoto 1980).
Thirty to fifty young of 20 to 40 mm just after intermediate
breeding are kept in a 45 x 30 x 15 cm plastic cage, which issunk to the bottom of the sea. The fattening continues until thefollowing May when the shells grow over 70 mm in length and
100 g in weight.

The blood ark shell, Scapharca broughtonii, is a relatively largesized species among the edible mollusca, often reaching 15 cm inshell length. Its major habitat is in shallow bays and gulfs, 5 to 30
m in depth, with a flat muddy bottom. Their range extends fromsouthern Hokkaido to Kyushu. These shellfish grow faster in the
Seto Inland Sea and bays along Kyushu than in other localities.
Furthermore, people in these areas highly value blood ark shells
for their delicious taste in sushi and sashimi. Thus, this species is
one of the most important for coastal fisheries. Intense demands
for the blood ark shell have recently stimulated the initiation of
artificial propagation and other cultivation techniques.

CULTURE BASED ON NATURAL SEEDS
It is possible to collect seeds of blood ark shells in early Junewith cedar leaves attached to a plastic net hung in coastal watersof 20 to 30 m depth. However, this technique is now employed
only in a few prefectures of southern Japan, because the success ofseed collection depends upon unstable natural factors including
the abundance of spawners and environmental conditions.

ARTIFICIAL REARINGIn 1961 it became possible to induce spawning of blood ark
shells by temperature stimuli. The larvae were then fed with
Monas sp. until spat stage (Kan-no 1963). According to Itami etal. (1970), the Hyogo Prefectural Fisheries Experimental Station
produced I million spat in 1969. Later investigations made it
possible to conduct mass production in the order of I million spatin many prefectures.
The Yamaguchi Farming Fisheries Center commenced mass
production of seeds in 1976, and produced 10 million spat in that

'Nansei Regional Fisheries Research Laboratory, Ohno-Cho, Hiroshima, Japan.

78

ark shells. In the next experiment, 500 shells were released in a 10x 10m area. Five plastic traps were set and seized 20 to 94% of
the starfish. The results were encouraging-30% of the ark shells
remained alive during 100 d. If the starfish are intensively controlled at the beginning, one can expect to obtain efficient resultsin the seed release program.
Recovery rates of natural seeds also showed remarkable variation depending on time and other conditions of release. The mostsuccessful results so far obtained were harvests of 25 to 30% ofark shells I yr after seed release.

Most suitable cultivation grounds occur in the muddy bottom
sea of 10 to 25 m depth. The survival rate reaches 80 to 90% in
good culture grounds. Experimental rearing by the Nansei
Regional Fisheries Research Laboratory indicated possible occurrence of mass mortalities of the shells in the cage at high bottom
temperatures above 25°C and for wide diurnal changes intemperature exceeding 5°C. As a matter of fact, significant mortality was not reported in the cold summer of 1980.

RELEASEPROBLEMS AND PERSPECTIVES

There were several trials to release the 2 to 4 mm young after
intermediate rearing. In Yamaguchi Prefecture at the western endof Honshu Island, 15,000 seeds of 40 mm in length and 15 g inweight were scattered in a location with a muddy bottom of 23 m
in depth. One year later, trawlers harvested the ark shells whichgrew as large as 107 g in average weight. The recovery rate was
one-third. No other trials succeeded to produce marketable shells.
It is likely that starfish are significant predators of the ark shell(Takami et al. 1979). Once Yamaguchi Naikai Fisheries Experimental Station released seeds of blood ark shells of 37.8 mm inmean length and 14.4 g in mean weight in several lots at diverse
densities of 5 to 50 specimens/m 2 . The starfish, Asterias amurensis, aggregated in the experimental area on the second day of theexperiment, and their density reached 13 to 1,125 individuals/m 2
on the 18th day. The starfish dug out and fed on young ark shells.
Eventually they preyed on all the shell seeds by the 39th day. Control of starfish led to a significant increase in the survival rate of

Figure I schematically shows the life history of blood ark shellstocks under cultivation and farming, and under exploitation. In
both the cage culture and the releasing program, one can expect toharvest the shellfish 2 yr after birth. Because it takes 3 yr forblood ark shells to mature sexually, cultured individuals have nochance to contribute to reproduction.
Commercial trawlers exploit blood ark shells in five cold
months between December and April. Fishing operations at thepresent intensities remove part of the I-yr-olds, most of the 2-yrolds, and almost all of the 3-yr-olds and larger. The spawning
stocks comprise only a small fraction of 3-yr-olds which escaped
exploitation. Therefore, the natural spawning stocks are very
scarce and may not produce significant recruitment.
Figure 2 shows a plan to recover the ark shell stocks by protection of a portion of the fishing grounds as an artificial spawning

AGE>---- 0 - - - ; ' - 1 . . , - - -

--

JUNE

DEC.

JUNE

I _ _-<1
DEC.

JUNE

1

_

3

I

Ofc.

JUNE

DEC,

JUNE

4

AOULTS CATCH & BREEDING-EGG COLLECTIONREARING & SEED COLLECTiON
INTERMEDIATE BREEDING (SEA)_ _.:::::::_-_-_-_._-::::::_-:.-.-.-_-:_-~ HARVESTRELEASING (FARMING GROUNDS)-"''''''''''',,:-~~. HARVEST
CAGE CULTURE (SEA BOTTOM)•SPAWNER STOCK-0

1 MM LENGTH-SPAWNINGSPAWNING

PARTLY SPAWNINGTO RECRUIT-0-030 HM LENGTH

70 MM LENGTH, 100 G WE I GHT•- - _ ..... _._-SPAWNING& PELAGIC LIFE

PARTLY' SPAWNINGSPAWNINGSPAWNING

Figure I.-Annual operations of blood ark shell production in aquacnlture and fisheries.

-=:::::::-::::::::::::::::::=_:::::-:::::::_::::::-:::::::~:::::-PARTLY HARVESTSETTLEMENT

fI'oSTlY HARVEst

HARVEST

BURROWING

Intermediate
breeding

Fishing

Figure 2.-Schematic drawing of culture and aquaculture of theblood ark shell. Methodology of artificial spawner nest is studied
under research project of marine rancbing.

ARTIfICIAL SPAWNER NEST

79

nest. Five problems must be solved in order to implement thisplan.

stocks. Optimum size and density of spawners must be identified
for efficient seed collection. Also comprehensive investigationmust be conducted to relate biology of the blood ark shell withwater, bottom, and benthic fauna.

1) A mass production system must be used to increase the seedsupply beyond the present level of the order of 10 million 1 mm
spats.
2) Optimum size of seeds for release must be determined,
because there is no guarantee that the currently produced seeds ofabout 30 mm are of the optimum size.
3) Techniques for rearing the shells must be developed. The
plastic cage method in current use requires tedious operations including frequent cleaning and exchange.
4) Research must be conducted to clarify the major factors affecting growth and mortality of the shells in the cultivation
grounds. Emphasis must be put on clarification of lethal factors
including high temperature and predation by starfish, andestablishment of means to eliminate these factors.
5) Biological mechanisms for maturation and spawning must be
clarified for manifestation of means to establish the spawning

LITERATURE CITED!TAMI. K., K. TANGE, K. YAMAUCHI, B. TAKEDA, and A. HAMAGUCHI.
1970. Studies on the production of an ark shell, Anadara broughtonii - I.
Artificial breeding in lank. The Aquiculture 18(1 ):25-34.
KAN-NO. H.
1963. Breeding of the ark, Anadara broughtonii (Schrenk), in tank. Bull.
Tohoku Reg. Fish. Res. Lab. 23: I08-1 14.
OHASHI, H., and Y. KOUMOTO.
1980. Technical development for mass production of blood ark shell. Rep.
Tech. Dev. Farming Fish. 6:80-135.
TAKAMI, T., T. IWAMOTO, T. NAKAMURA, and H. INOUE.
1979. Studies on the aquaculture and production of the ark shell. Spec. Pub I.
of Yamaguchi Pref. Naikai Fish. Exp. Stn.

THE PRESENT AND FUTURE OF PECTEN CULTURESATOSHI UMEZAW A I

Pecten, Pecten (Notovola) albicans, is one of the warm-waterbivalves distributed in the coastal zones extending from southern
Hokkaido to Kyushu. Their habitat is a sandy bottom of 10 to 80
m in depth. Coastal trawlers have exploited this shellfish for many
years. Although production has remained at low levels in recent
years, a sudden increase in the stocks has been reported in at least
five prefectures of southern and central Japan between 1958 and1968 (Kobayashi 1978; Tanaka 1977; Tanaka 1980). In otherwords, the pecten stock is an unstable fishery resource. But the
species must be useful for utilizing sandy zones widely distributed
in southern Japan. These areas have a very low productivity with
only limited fishing activity, except for the culture of the seaweed
Undaria.
Seed collection first succeeded in 1977 in Okinoshima (anisland in the Sea of Japan), Shimane Prefecture. Since then, commercial cultivation of pecten has been practiced there. Productionin the whole prefecture reached 300,000 pecten of marketablesize in 1980, which were grown from 800,000 seeds collected in1979 (Ayama and Matoba 1980). It is likely that this commercial
cultivation will spread over other parts of the sandy coast along
southern Japan.
Figure 1 illustrates the current practice of pecten culture in
Shimane Prefecture, which is almost identical to techniques applied to related species of scallops in northern Japan. Table 1 lists
various management operations, as well as size and survival of the1

shells during the cultivation which lasts for 15 to 17 mo fromFebruary to July in the following year. At present, all the seeds arethose collected in the sea, and no artificial propagation is practiced yet. The collectors are fine-meshed bags holding old fishingnets or cedar leaves, and are hung at middle to bottom layers of thesea. Seeds are taken in sandy zones of 20-40 m depth with swift
water flow. It is known that the spat are abundant below 15 mfrom the sea surface. The collectors are set in Feburary and takenout in May and June. Average density exceeds 80 spat per collector. The newly collected spat, 1 to 2 mm in shell length, are reared
until September in lantern nets originally designed for pearl
oysters. Young of about 5 cm in length are transferred to cone nets
in September, and cultured there until they reach a marketablesize of 8 to 10 cm shell length and 80 to 90 g in weight in thefollowing May and June. The survival rate averages about 80%
from the seeds of 1 to 3 cm through marketable size. In the courseof fattening, fishermen remove fouling animals, select pecten bysize, and change the nets several times during the period from
October to December.
Pecten culture is very new, starting only in 1977. It is still
operating at a trial and error stage. It is not certain whether natural
seeds are sufficient to sustain possible expansion of the cultivations. Market demand for this species is still not well known.
Biological surveys are also not sufficient to understand thephysiology and ecology of this species, except for studies on thefluctuation in stock size and on the collection of seed.
The newly started Marine Ranching Project considers pecten to
be one of the most important molluscan shellfish. This is a good

Nansei Regional Fisheries Research Laboratory, Ohno-Cho, Hiroshima, Japan.

80Shallow

Offshore

shore

Buoy

Buoy

SINKER

Figure I.-Schematlc representation of pecten culture. See text andTable I for explanation.

CC»lE NET

LAtlTERNNETSPAWNER

Table I.-Major operations of pecten cullure.

MonthWork items

Fe1bruary
April
May

Prepare and hang seed collectors.
Take seeds and bring them into
lantern nets for fattening.

Type of net

Lantern net (30 x 30 cm withmesh aperture of 4.5-6 mm)

I

June

July
AugustOctoberI
DecemberJanuary
AJril
M?y
July

Fattening
Change to cone nets with 5 to 10
layers.
Size selection.
Remove the fouling animals andchange mesh size.

Stocking
density

Number per net
is 50 I cm seeds
402 cm seeds
303 cm seeds

Size ofshell(cm)

SurvivaJl

1-3

100

Cone net (0 50 cm with mesh
aperture of 9-15 mm)

20 indo per layer

4-5

90

Cone net (0 50 em with mesh
aperture of 15-21 mm)

15 indo per layer

5-6

80

8-10

70

Fattening
Harvest and market (size select andpackage)'Survival denotes percent after start of fattening.

LITERATURE CITED

opportunity for us to advance the life history of Ihis species. Currently, the major emphasis is laid on the clarification of
mechanisms to reduce stock size in the transition periods frompelagic life to settling life, and then to demersal habitat; formationof the aggregation vulnerable to exploitation; and mechanisms
underlying the outbreak of the stocks. The project also aims to obtain any measure required for conservation of natural stocks
which supply the seeds, and for establishment of stable andregulated stocks of spawners. The final purpose of the research activities is to find a means for utilizing the untamed sandy beaches
and then for increasing production of the coastal fishermen.

AYAMA, T., and M. MATOBA.
1980. On the cultivation of pecten. Ocean Age 12(3):53-59.
KOBA YASHI, K.
1971. On the pecten in the coastal waters of Tottori Prefecture - II. Outbreaks in the offsea of Tottori Beach. Bull. Tottori Pref. Fish. Exp. Stn.
8:13-24.
TANAKA, K.
1980. On the mass survivors of J.apanese scallop, Pecten (N%vola) albicans,in Tateyama Bay. Bull. Jpn. Sea Reg. Fish. Res. Lab. 31:165-168.
TANAKA, Y.
1977. Conditions to forming an enhancing ground of scallop. Pecten albicans.
Fish. Eng. 14(1): 19-24.

81

Abalone Culture in Japan
NAGAHISA UKP

INTRODUCTION

waters of Hokkaido there is the cold- water species, Haliotis discus
hannai. Along the southwestern coast of Honshu, in the coastal
waters of Kyushu, and in the sea of Japan there are three warmwater species: H. discus, H. gigantea, and H. sieboldii (Fig. 2).
Another warm-water species, H. diversicolor, is found in subtropical areas especially near the Izu-shichito Islands and southern
islands of Kyushu. Fifty percent of the total yield of abalone isfrom H. discus hannai and the remaining 50% is divided between
the warm-water species, with the production of H. diversicolor
making up only a few hundred tons of the total.
There are regulations protecting the abalone resource fromoverfishing in each prefecture. Figure 3 shows the closed season
and shell length limitations on harvest in the abalone producing
prefectures. The season is generally closed between August andOctober for the cold-water species and October to mid-December
for the warm-water species, primarily to protect the abalone during spawning. The legal harvest size differs among districts; it islimited to between 7.5 and 9.5 cm for H. discus hannai, 9 to 12 cm
for the three warm-water species, and 4.5 to 5.5 cm for H. diversicolor. Limitations on harvest methods, times of operation, andsometimes the total catch, are decided by the fisheries cooperatives themselves. Moreover, the harvest methods themselves often
serve to protect the resource. Harvesting according to local tradition, long poles with hooks in cold waters, and skin diving in

The production of abalone has become stable in Japan. The annual catch is approximately 5,000 tons with shell, and because of
the great demand for abalone, imports are increasing (Fig. 1).
Abalone, along with shrimp and sea urchins, command a highprice. Abalone are very valuable in the coastal fisheries economy
where the producers' price is about 5,000 yen/kg with shell. Suchsignificant resources, so to speak "sea treasures," have been traditionally managed by rigid limitations on fishing season, harvest
size, sometimes harvest methods, and limitations on total harvest,
at the local level.
On the other hand, seedling production techniques for abalone
are a recent advancement. An' artificial supplement of seedlings to
the natural resources is becoming a possibility on a commercial
scale. Moreover, developments in the techniques of seaweed
afforestation are improving the productivity of the fishinggrounds. The introduction of these modern techniques have hadmany positive effects on the abalone fishery. In this paper, recent
fisheries developments are discussed along with their future
prospects.

PRESENT ABALONE FISHERIES
There are five important commercial species of abalone inJapan. Along the northeastern coast of Honshu and in the coastal@ H • discus hannai'Division of Mariculture, The Ministry of Agriculture, Forestry and Fisheries,
Fisheries Agency, Tohoku Regional Fisheries Research Laboratory, Shiogama,
Miyagi 985, Japan,~ H.discus

CD H. gigantea
ton 1 - - - - - - - - - - - - - - - - - - - - - - - - - - - ,
3

• 10
6

•

•

~.---.," /.-.-.-'.-.-.

.

~OTHERS(J09)..............

4

/

3

0 - - - .....

H. sieboldii

/~

/

/

F..... . . . . . . . . cf /

I

/

?

/

O-_-<;8",..~~0-----8-.:-::-~--if
0------0-- _--0-----0-----0-----0
olL:-9::70:----::·7~1--::·7'::'"2-~.""':73:---.7~4--.7.....5--.~76--.7~7--.7-8-~'79.....;
Figure I.-Japanese total catcb (indicated by closed circles) aDd Imports of
abaloDe (OpeD circles indicate the amouDt of Un, fresb, cbllled aDd mUD abo
aloDe, aDd squares repreaeDt CaDDed abaloDe), (After JapaD Esport ... Import
MODtbly.)

Figure 1.-ADDuaJ catcb of abaloDe of eacb prefecture aDd tbelr species ratio In
tbe producta. Figures In pareDtbeaes after tbe prefectural Dame are tbe meaD
catcb from 1965 to 1971sbowD In tODS. (After IDoue 1976.)

83

PREFECTURE

JUt

AUG

SEP

OCT

NOV

DEC

JAN

FEB

MAR

APR

MAY

JUN

~

LIMITED

Prefectural Experimental Station had a section for seedling production. About 8 yr ago, the seedling production sections were expanded and gradually reorganized into the Fisheries Farming
Centers (F.F.C.). Seedling production has increased subsequent tothis reorganization.
The type of seedlings produced in each F.F.C. reflect the locallysignificant marine products, which are mainly red sea bream andkuruma-prawn in southern Japan, and salmon and abalone innorthern Japan. Iwate and Miyagi Prefectural F.F.C.'s, both
located on the northeastern Pacific coast, produce the most
abalone seedlings. Each F.F.C. annually produces about I million
abalone seedlings. There are about 33 F.F.C.'s and one Research
Foundation (Oyster Research Institute) producing abalone seedlings. Figure 5 depicts the annual production of seedlings in Japan
from 1970 to 1979; the number of seedlings reached 6 million in
1979.
Large scale abalone production is possible because of the development of several techniques based on an increased understandingof the abalone's biology. The conditioning of adults for spawning
was possible after the physiological mechanism of maturation(Kikuchi and Uki 1974a) became clear. Spawning techniques
using ultraviolet irradiation (Kikuchi and Uki 1974b) and handling procedures for the larvae followed clarification of the larvae's
development related to temperature (Seki and Kan-no 1977,1981) and after investigation of the phenomenon of larval settlement on adult mucus trails (Seki 1979). Details on the current
commercial processes have been introduced by Grant (1981).

t~~EgHHOKKAIDD

7.5

AOMORI

9

IWAlE

9
9

MIYAGI

9.5

FUKUSHIMA

12

CHIBA

II ;:
J:~

KANAGAWA
SHllUDKA
MIE
TOKUSHIMA
EHIME
OITA
KUMAMOTO

.;;;

1 0.6

'"

9

10

SAGA

I :~

NAGASAKIFUKUOKA10
I 0

YAMAGUCHISHIMAN[

Figure 3.-The ciosed seasons and shell length (em) limitations for harvesting in
the main ahalone producing prefectures.

warm waters, are techniques requiring skill and limit participationin the fishery.
The abalone population has carefully been preserved from excessive fishing by both law and traditional ways. The present
fishery is hedged with restrictions. These restrictions have beennecessary for the survival of the resource because the abalone is abenthic animal with a slow growth rate and is easily caught.

DEVELOPMENT SYSTEM OFABALONE FISHERIES

6,---------xlO

6

Although the restrictions on the harvest of abalone are necessary, they present problems for artificial propagation. These
restrictions are based on maintaining the natural stock and do nottake into account the increased potential for production. A
counter proposal, which does take into account the newcapabilities, has been suggested by the team at my laboratory(Kan-no 1975), and governmental policies on abalone are
gradually changing in recognition of the new potentials. Figure 4
outlines the technical system proposed by the team, and the important points of the system could be summarized as follows.
Spawning: conditioning of spawning
stock for spawning through·out the year

Techniques ofartificial seed·production

'72

'73

'74

'75

'76

77

'78

'79

{

Rearing:mass culture system ofjuveniles

Food:seaweed afforestation

Improvement of Nutritional Environment

Habitat:availability of food andprotection from predatorsand competitors forjuvenile and adult

Distribution of the genus Haliotis corresponds with the distribution of the order Laminariales except for the coldest districts ofeastern Hokkaido on the Okhotsk Sea. Abalone eat seaweed andespecially prefer the order Laminariales. Uki (1981) has shownthat the best growth of H. discus hannai is with the genus
Laminaria. The food value of marine algae in northeastern Japanfor the growth of H. discus hannai is shown in Figure 6. In cold
areas the main food for abalone are Laminaria spp. and Undaria
pinnatifida. Eisenia bicyclis, Ecklonia cava, and U. pinnatifida are
the important foods in warm areas.
Annual net production of these algae is about 10 kg wetweight/m 2 in a fertile bed and around 4 kg wet weight/m 2 in a

Figure S.-Annual production of artificially produced abalone seedlings inJapan.

Development of
abalone fisheries

Methods toimprove therocky coastal{

environment

Figure 4.-Technical system for developing abalone fisheries. (After Kan-no
1975.)

Techniques of Seedling Production of Abalone
Artificial seedling production of marine animals has beendeveloped at the national and prefectural levels in Japan. Each
84

80

1

7

30

04

2

/-----1.0 - - - - - - - - - - - o - 2 . ~-0-=----------1
14·
60

....
o

'+-

012

17••,6 013

.15

Q5
09

19••,8100.20'I-I

l66'13.2f
~.
24 22

-U5

~ 27

_'L..-Jo..--.........Jo..--J.-.L-"'----.l...-""'"----.......-.......-.......-....I..-....I..-....................I-.....I-.....I

0

U5
1.0
Eisenia equivalent for body weght

1.5

Figure 6.-Relative food values (Eisenia-equivalent) of seaweeds. Using the growth rate of Halio/is discus hannai fed
on a diet of Eisenia bicyclis as a standard. (After Kikuchi and Uki 1981.) 1: Laminariajaponica, 2: L. japanica f.
membranaeea, 3: L. religiosa, 4: L. diabolica, 5: L. angus/ala var. logissima, 6: Kjellmaniella gyrata, 7: Eisenia bicyclis,
8: Vndaria pinnatida, 9: Sargassum ringgoldianum, 10: Dic/yop/eris divaricata, 11: Pachydic/yon coriaceum, 12: Codiumsp., 13: Viva pertusa, 14: Porphyra yezoensis, 15: Solieria mo/lis, 16: Grateloupia sp., 17: Rhodymenia intricata, 18:tVeodiisea yendoana, 19: Gelidium amansii, 20: Acrosorium sp., 21: Grateloupia e/lip/ica, 22: Plocamium /el/airiae, 23:
Ch.rysymenia wright/ii, 24: Symphyocladia latiuscula, 25: Pikea cali/ornica, 26: Callophy/lis crispata, 27: Schizymenia
dubyi, 28: Corallinoideae. Open circle, square, and closed circle indicate Phaeophyta, Chlorophyta, and Rhodophyta,
respectively.

bottom by providing alternative food, and spreading spores on
denuded rock. Second, the grazers are regularly harvested to limit
their numbers. After afforestation, a L. religiosa community, 6 to 8
kg wet weight/m 2 in annual net production, will be produced thefollowing year in an area that was previously denuded. After thearea has been reforested, a calculated number of abalone seedlings
are introduced onto the fertile ground.
Results of this experiment substantiated the hypothesis that the
Isoyake areas are caused by the overgrazing of herbivores. Further
information on plant succession in shallow coastal areas has
resulted from this experiment and observations. Figure 7 shows
the resulting vegetative cover at different grazing pressures. For
example, since Laminariales is a favorite food for grazers it is thefirst to decrease when grazing pressure increases. Controllingherbivorous feeding pressure is the key to managing abalone
farming.
Arayabu Bay of Enoshima Island, located off Ojika Peninsulain Miyagi Prefecture, is one of the farms where experimental
afforestation was conducted from 1969 to 1974. Before the trials,
the bay area of 2.3 ha had no commerci'll value since it was a
typical Isoyake. However, the bay has continuously produced 3
tons of abalone per year since the afforestation experiment. Since
the experiment, the Enoshima Fishery Cooperative has taken overmanagement of the bay itself utilizing methods developed during
the experiment.

common bed. There are many herbivores besides abalone like sea
urchin, snail, limpet, sea hare, and others which depend on algae
as a main food source. The usual population density of theseherbivores is approximately 100 to 200 g wet weight/m 2 . The
dominant herbivore in a good abalone fishing ground is Haliotis
spp., which should occupy 60% of all herbivores. A poor groundwill be dominated by sea urchins and/or small snails.
An infralittoral area that is devoid of large kelp, such as that of
the order Laminariales, and is dominated by a dense mat ofcrustose coralline algae, is called an "Isoyake" in Japanese and"Pink Rock" in English. These areas are like deserts and theanimals that live in them have little commercial value because of
their lack of meat and poor gonadal condition. Fishermen cannot
catch and sell them because they have no commercial value. We
often have this phenomenon in the coastal waters inhabited by H.
discus hannai.
In recent years, this phenomenon of a sea desert has been
ascribed to an inordinately large population of grazers. There areover 300 g wet weight/m 2 in an Isoyake area and continuous grazing, especially by the dominant sea urchin, Strongylocentrotus
nudus, cuts the growing young fronds of seaweeds. In an Isoyake
area, the equilibrium between plants and grazers is not beneficial
to the fishermen. The cycle between the barer area of an Isoyake
and the poor harvest by fishermen will not change without intervention.
A marine afforestation technique has been developed to makeareas that have been overgrazed more productive (summarized by
Kito et al. 1979). The technique consists of two parts. First, theplanting of Laminaria religiosa, which has three main functions:
Supplying diet to grazers, reducing grazing pressure on the rocky

FARMING OF SEEDLINGS
Abalone seedling production remained on a small scale, both inquality and quantity, before the improvement of hatcheries. How8S

>

>
.~
.~

E

E

e

.!!!

ii

o

~

~

FEEDING PRESSURE OF BENTHIC HERBIVOROUS ANIMALSIMPROVEMENT OF HABITAT

ever, several important experiments were performed to examine
the possibility of abalone farming in this exploratory period. It has
gradually become clear that release of small size seedlings, under 3
cm, has a low recovery catch a few years later. It seems that alarger seedling around 4 to 6 cm must be used to increase abalone
population. For example, in Kanagawa Prefecture the H. gigantea
seedlings larger than 4 cm showed a good survival rate of 70 to
80% after a year release (Fig. 8). Funka Bay, which did notpreviously have an abalone fishery, has been converted into a new
fishing ground by the transplantation since 1950 of naturally produced large seedlings of 4 to 6 cm shell length. There is a clear
quantitative relationship between transplantation and catch (Saito
1979). It is our understanding that releasing 10,000 large seedlings will result in a 0.5 to 1 ton catch of abalone at harvest timein these successful trials.

The decrease of seedlings in the natural bed is mostly caused by
predation by carnivores. Some fish, octopus, sea stars, and crabs
are well known as predators of abalone. Concrete blocks engravedwith slits, and baskets filled with boulders, are designed to protect
the seedlings from attack in the juvenile nursery grounds (Fig. 9).
Some of these measures are reflected in the increased survivorshipfor the nursery bed population as shown in Figure 8. According to
the data collected by Inoue (1977), a seedling reared in thenursery ground will have the same survivorship as a seedling I cm
larger in a natural bed. Since it is possible to release a smaller
seedling and get a similar harvest, there is a saving for the system.

1. 0 ,--.,.---,-------r--,-------r--,-----.,.-------,

0.8

E
~

t'5<: ~

LE
Figure 7.-The relation between feeding pressure of benthic herbivorous animals and the covering of a shallow reef of the Sanrlku
Coast. (After Kikuchi and Uki 1981.)

.~

>

~
E
E 11 11e ~§ m:g~
g,
~~
e>

.~

~~

~~R

-l,. _ Q~~- =--~ OdD: :
°

/'

I

/

-::::::::::::0A

b 01---_--+_ _-+-_ _
,,

UB

[J

,.
I

B

n
~

1.0m

C:

::

I

II

~~

Ott - 1o

,

I

eI
..
U2 -,,
I
I
l

00 0

2

4

6

8

10 12

14 16

J.

SHELL LENGTH AT THE RELEASING TIME

1.5m

T

Figure 8.-The relation between the annual survival rate of seedlings ofthe abalone, Hatiotis gigantea, and shell size (em) at releasing time. Data
were obtained from tagging experiments at Kanagawa Prefecture after I
yr release. Open and closed circles Indicate data from natural bed' and thenursery beds made of boulders, respectively. (After Inoue 1977, fig. lOG.)

Figure 9.-Examples of block units for constructing abalone farming
grounds. (After Inoue 1980.)

86Figure lO.-Several examples of cold water marine beds and the practice of abalone seedling production. A: Typical Isoyake caused by continuous feeding of herbivores,
especially sea urchins (Strongylocentrotus nudus in this case) at Enoshima Island in Miyagi Prefecture. B: A view of the Laminaria afforestation system during summer
season at Arayabu Bay on Enoshima Island. C: Fertile bed of Laminaria religiosa community converted by the artificial afforestation technique. Thirty kg/m' ofstanding crop of L. religiosa In wet weight is recorded In the densest community. D: Young community of Eisenia bicyclis gradually occupying the hottom of Arayabu Bay
on Enoshimalsland instead of the usual L. religiosa community. E: The water way for abalone juvenile production at Iwate Prefectural Fisheries Farming Center. F: The
abalone seedlings of Haliotis discus hannai attached on polyvinylchloride plates.

FUTURE PROSPECT OF
ABALONE CULTURE

tives at the size of 2 to 3 cm after 1 yr of rearing. Cooperatives
usually rear the abalone in intermedi'ate culture for 1 yr until theseedlings are 4 to 6 cm. After intermediate culture, the seedlings
are released. Figure 10 illustrates the practice of abalone seedling
production and shows several examples of cold water marine beds.

The size of the seedlings is the key to getting a high rate ofrecovery. F.F.C.'s usually deliver their seedlings to the coopera87

The number of seedlings produced in F.F.C.'s is reaching a levelsufficient for abalone farming on an industrial scale. For example,
Miyagi and Iwate Prefectural F.F.C.'s have a target in the near
future of 4 and IO million abalone, respectively.
The next technical challenge for boosting abalone production
will be to get a larger seedling within a shorter period of time.
Hybridizing new varieties of abalone and the development ofartificial diets are considered to be the main subjects to solve.
Improving basal production in fishing grounds was attained by
the development of the genus Laminaria afforestation techniquein a cold-water area; however we also have Isoyake in warmwater areas. A new project, aimed at the development of Eisenia
bicyclis afforestation techniques, has been proposed as a part of
the Marine Ranching Project promoted by the Ministry of Agriculture, Forestry, and Fisheries.
The perennial E. bicyclis community, which is often associatedwith Eklonia cava, is superior to annual or biennial Laminaria
communities in terms of continuous productivity. Laminaria
religiosa distributed in the main abalone fishing grounds is nonproductive during the winter while an Eisenia and Eklonia community is able to give food in all seasons and these plants have arelatively long life of about 7 to 8 yr. Recently the bottom of
Arayabu Bay of Enoshima Island, where herbivorous feedingpressure has been artificially controlled, is gradually bemg occupied by an E. bicyclis community. It will probably give a hint on
developing Eisenia afforestation techniques in warm-water areas.
With the tools in hand to improve the abalone's habitat andproduce large numbers of seedlings, the main obstacles to increasing the harvest of abalone are overcome.

LITERATURE CITEDGRANT, 1. F.
1981. Abalone cuhure in Japan: Development and current commercial practice. Tasmanian Fish. Res. 23 :2- 17.
INOUE, M.
1976. Abalone. In Jpn. Fish. Coop. Assoc. (supervisor), Aquaculture handbook, Vol. I, p. 19-61.
1977. Propagation in the coast of Japan-On the propagation of the abalone.
Mar. Sci./Monthly 9: 18-25.
1980. Y. Oshima and T. Tamura (supervisors), Fisheries engineering handbook, p. 151-161. Midori Shobo, Tokyo.
KAN-NO, H.
1975. Recent advances in abalone culture in Japan. In Proc. First Inl. ConL
Aqua. Nutr., p. 195-211. Univ. Delaware, Lewes, U.S.A.
KIKUCHI, S., and N. UKI.
1974a. Technical study on artificial spawning of abalone, genus Halioris 1.
Relation between water temperature and advancing sexual maturity of Haliotis discus hannai Ino. Bull. Tohoku Reg. Fish. Res. Lab. 33:69-78.
1974b. Technical study on artificial spawning of abalone, genus Haliotis II.
Effect of irradiated sea water with ultraviolet rays on inducing to spawn.
Bull. Tohoku Reg. Fish. Res. Lab. 33:79-86.
1981. Productivity of benthic grazers, abalone and sea urchin in Laminaria
beds. Suisangaku Ser. No. 38, Seaweed Beds, p. 9-23. Koseisha Koseikaku,
Tokyo.
KITO, H., S. KIKUCHI, and N. UKI.
1979. Seaweed as nutrition for seabed marine life technology for artificial
marine forests. In Inl. Symp. Coasl. Pacific Mar. Life, p. 55-66. Western
Washington Univ., Bellingham, U.S.A.
SAITO, K.
1979. Studies on propagation of Ezo Abalone, Haliotus discus hannai Ino-I
Analysis of the relationship between transplantation and catch in Funka Bay
Coasl. Bull. Jpn. Soc. Sci. Fish. 45:695-704.
SEKI, T.
1979. An advanced biological engineering system for abalone seed production. In Inl. Symp. Coasl. Pacific Mar. Life, p. 45-54. Western Washington
Univ., Bellingham, U.S.A.
SEKI, T., and H. KAN-NO.
1977. Synchronized control of early life in the abalone, Haliotis discus hannai
Ino, Haliotidae, Gastropoda. Bull. Tohoku Reg. Fish. Res. Lab. 38: 142153.
1981. Observations on the settlement and metamorphosis of the veliger of theJapanese abalone, Haliotis discus hannai Ino, Haliotidae, Gastropoda. Bull.
Tohoku Reg. Fish. Res. Lab. 42:31-39.
UKI, N.
1981. Food value of marine algae of Order Laminariales for growth of theabalone, Haliotis discus han/wi. Bull. Tohoku Reg. Fish. Res. Lab.
42: 19-29.

ACKNOWLEDGMENTS
I wish to express my appreciation to Hisashi Kan-no, Directorof the Mariculture Division of the Tohoku Regional Fisheries
Research Laboratory, for his valuable suggestions and ::0 Shogo
Kikuchi, Chief of Fish and Shellfish Section of the Laboratory, for
discussions of the problems. I am also indebted to Brian Hovis, aresearcher at the Oyster Research Institute, for his kindness incorrecting the manuscript.

88

Osmoregulation in Marine Bivalves
KOJI WADAI

mined with an amino acid analyzer (Hitachi, KLA-5 2 ), and theamount of amino acids was calculated on the dialysate.

Marine culture of edible bivalves, as well as nonedible ones
such as the pearl oyster, has long been an important industry inthe coastal fisheries of Japan. An annual production of more than
200,000 tons (with shell) has been maintained for more than 10
yr. Most bivalves are cultured intensively by using hanging
methods. However, the recent trend of increasing production
within a limited area with high stocking density is accompanied
by an increase in the mortality of bivalves and lowered quality ofthe products. The widely adopted hanging method involves theconfinement of bivalves in a pocket or basket net, which forces
the bivalves to live quite differently from the environment of theirnatural habitat.
Some species, such as oysters, have developed physiologicaland metabolic functions to adapt themselves to severe changes,
such as in salinity and temperature, in their natural environment.
On the other hand, species such as scallops have not developed
such adaptations due to the more mild environmental conditionsof their habitat. This paper deals with the relationship between
habitat and the ability to osmoregulate in some species of bivalves
with special reference to free amino acids found in their body
fluids.

Determination of Osmotic Pressure
In order to compare the osmoregulatory ability in the marine
bivalves, the following experiment was conducted using saltwaterat six levels of salinity: 1) Normal seawater, 2) 75% seawater, 3)
50% seawater, 4) 25% seawater, 5) 150% seawater, and 6) 200%
seawater. The salinity level was adjusted by adding either salt- or
freshwater to normal seawater. A plug was inserted between shell
valves of each bivalve to help the experimental medium comefreely into the mantle cavity. They were placed in six plastic tanks
filled with the experimental seawater. The experimental seawater,
mantle cavity fluid, haemolymph, and extrapallial fluid were collected in centrifuge tubes at 3, 23, and 48 h after the bivalves were
immerged in the experimental medium, and centrifuged to remove
cells and debris. The osmotic pressure of the media and body
fluids was measured using an Advanced Model 3Cl1 Cryomatic
Osmometer.

RESULTS
MATERIALS AND METHODS
The composition of major elements in the extrapallial fluid of
Mytilus, shown in Table I, indicates that concentrations of
sodium, chlorine, and magnesium in the fluid were similar to
those of the environmental medium. They appear to be in an
ionized form. Similar results have been reported on extrapallial
fluid and haemolymph of marine bivalves (Schoffeniels and Gilles
1972; Wada and Fujinuki 1976).
The amino acid composition differed significantly between theuntreated extrapallial fluid and its dialysate (Table 2). All of thetaurine was able to pass through a cellophane membrane and appears to be in free and peptide forms. On the contrary, most of theother amino acids were found to be in forms of protein and complex: Mytilus (3.7 I-lmol/ml), Crassostrea (1.1 I-lmol/ml), Pinctada

The present study was carried out with clams (Saxidomus purpuratus), mussels (Mytilus edulis), oysters (Crassostrea gigas andPinctada jucata), and scallops (Chlamys nobilis). After being collected, the bivalves were kept in net baskets at Ago Bay, Mie
Prefecture, for at least 1 wk prior to the experiment.

Individual Ion Analysis
Major elements such as sodium, potassium, calcium, andmagnesium in the extrapallial fluid of Mytilus edulis and environmental seawater were determined using atomic absorption spectrometry. Concentrations of chloride and sulphate were measured
volumetrically and gravimetrically, respectively. Details of sampling methods and analytical techniques were described in aprevious paper (Wada and Fujinuki 1976).

2Reference to trade names or commercial firms does not imply endorsement by the

National Marine Fisheries Service, NOAA.

Amino Acid Analysis
Table I.-Comparison of main element content in
the untreated (A) extrapallial fluid and its dialysate(B) of Mytilus edulis (ppm).

Each of the extrapallial fluids collected from Saxidomus,
Mytilus, Crassostrea, Pinctada, and Chlamys was divided into two
equal portions. One was evaporated and then hydrolyzed in an
ampoule with 6N hydrochloric acid at 110°C for 22 h. The otherwas dialyzed by cellophane tube and the residue was hydrolyzed
under the same conditions. Amino acids in the hydrolysate of theuntreated extrapallial fluid and the residue of dialysis were deter-

Extrapallial fluid'Oumura Branch of Nalional Research Institute of Aquaculture, 19-2 Kushimagoo, Oumura City, Nagasaki-Ken, Japan.

89

Element

Seawater

A

B

Na
K
Ca
Mg
CI
SO.

8,980
291
327
1,120
17,230
2,402

9,060
388
334
1,070
17,090
2,856

9,060
388
334
1,070
17,0902,605·

Table 2.-Comparison of amino acids in the untreated (Aj extrapallial fluid and its dialysate (8) ofmarine bivalve molluscs (jJmoVIOO ml).

-----_._--_.

Saxidomus
purpuratus

Species
Amino acidA

8

Cysleic acid

9.2
43.6
2784
364
189.5
75.1
12.0
74.1
33.9

43.6
0.3
0.1
0.3
0.7
04
0.9
0.2

29.7

0.1

----_.Taurine

Asparlic acidThreonine
SerineGlutamic acid
ProlineGlycine
AlanineCystineValineMethionine+

Leucine22.0
30.9

Thyrosine
Phenylalanine
LysineHistidine
Arginine

16.6
35.2
526.8
49.6

Isoleucine

0.1
01

+
0.1
0.1
0.1
0.2

Pincrada

MytilusCrassostrea

fucow. _ -edulis_._-

gi!:osChlamysnobilis

A

B

A

B

A

B

A

20.7
1,486.1
795.0
439.0
396.1
750.1
152.6
561.7
559.8
53.9
429.2
123.6
398.3
491.4
147.7
252.0
880.3
227,8
3080

14.8
1,486.1
71.3
6.7
7.2
42.1
2.7
53.2
58.7

50.3
370.3
245.1
91.8
88.7
242.1
41.5
193.2
1584

94
370.3
15.5
6.9
12.1
21.7
24
50.6
24.3

80.7
105.0
436.8
160.5
117.3
305.2
64.1
288.1
226.5

2.3
105.0
4.6
1.0
1.1
44
1.8
6.2
74

8.2 0.2
8.6 8.6
195.7 0.2
56.0
55.8
131.6 04
224 0.8
305.1 11.9
73.8 0.1

16.8
1.8
64
9.0

138.3
24.8
94.3
I J 8.1
254
86.0
143,8
148.6
51.1

6.5

1384
45.8
160.2
239.7
54.1
100.6
42,6
300.9
115,4

+
+
13.0
724

2.6
3.1
4.1
1.1
23,0
2.9
2.2

5.0

+
3.5
4.7
1.7
3,3
1.4

47.7
10.9
44.5
47.5
14.9
14.9
67.0
185.8
39.7

B

0.2
0.1
0.1
0.2

1.0
0.3

._--

DISCUSSION(14.9 fimoIlml), and Chlamys (0.09IAmoIlml). This significant difference in taurine concentration seems to reflect the difference inhabitat of these bivalves. In another study (Wada 1982), taurine
was not found in the fluid of freshwater species.
Figure I shows the osmotic pressure of the mantle cavity fluid,
haemolymph, and extrapallial fluid collected at 2-5 h for Saxidomus and Chlamys, and at about 24 h for Mytilus after immersion
in the experimental medium. At those respective hours, Saxidomus
began to die in 200% (osmotic pressure = 2,000 mOsm/kg) and
150% (osmotic pressure = 1,480 mOsm/kg) seawater, Chlamys inany external medium except for normal (osmotic pressure = 940
mOsm/kg) and 75% (osmotic pressure = 710 mOsm/kg) seawater,and Mytilus in 200% seawater.
The body fluids of these bivalves remained isosmotic with 75%
seawater for a few hours after they were placed in the 75%
seawater medium. However, the body fluids of Saxidomus became
hyperosmotic in more diluted media (Fig. I), where the clam
could live for at least 24 h. In Mytilus, the body fluids were
isosmotic in the range of 150% (osmotic pressure = 490
mOsm/kg) seawater but became hyperosmotic in 25% (osmoticpressure = 240 mOsm/kg) seawater (Fig. I). The mussel tolerated
a wider range of external salinities down to 25% seawater during
the experiment. On the other hand, Chlamys could withstandsalinities only down to 75% seawater. When scallops became
unable to acclimate themselves to external media of high or low
salinity, the osmotic pressure of the haemolymph and extrapallial
fluid decreased in higher salinities and increased in diluted media,
as shown in Figure I, and they died.
When bivalves were put in the diluted media, Saxidomus expanded their volume and the edge of the mantle pulp of Mytilus
and Saxidomus closed to prevent the external medium from coming into the mantle cavity. Consequently, in spite of the valves being kept open in the experiment, the salinity inside the mantle
cavity of Saxidomus and Mytilus was maintained at values higher
than those measured in 50% and 25% seawater. Moreover, theyclosed their valves tightly and were able to temporarily isolatethemselves from the external medium. Chlamys did not close theirvalves and mantle edge tightly.

Understanding osmoregulatory mechanisms of marine molluscs
in relation to their habitat provides important knowledge fordevelopment of hanging culture techniques which confine theorganisms in baskets. Many studies have demonstrated thatmarine molluscs are osmoconformers and their body fluids areisosmotic under a wide range of external salinities. Bivalves appear to regulate the ionic and free amino acid concentrations of
their body fluids against changes in external salinities to a certain
extent; they also tolerate sudden changes in the salinity of theirenvironmental medium by closing their shell valves tightly (Carnien et al. 1951; Duchateau et al. 1952; Gilles 1972; Robertson
1964; Schoffeniels and Gilles 1972).
The clam, Saxidomus purpuratus, is a soft bottom burrower. It
burrows deeply in the mud and has well-developed siphons. In
natural conditions, deep burrowers such as Saxidomus andPanopea seldom encounter a shift in salinity and temperature.
However, when they are cultivated in a basket hanging from a raftthey die at temperatures higher than 20°C. Most of them can only
survive under 490 mOsm/kg at most for I d. They close theirvalves tightly and can tolerate salinity changes for a few days.
Attached surface dwellers such as Mytilus, Crassostrea, and Pinetada which live in an intertidal zone must endure a wide range ofexternal salinities and temperatures; for example, Mytilus edulis
and Crassostrea gigas can live even in environmental media of <240 mOsm/kg for a long period. Similarly, the attached surface
dwellers isolate themselves from the medium by closing their shell
valves. On the other hand, the scallop Chlamys nobilis, an unattached surface dweller, lives freely or attaches only weakly by a
byssal thread on the bottom surface. The swimming ability ofscallops such as Chlamys and Pecten makes it possible for them toescape and protect themselves from predators or sudden disturbances in environmental conditions. They can swim by clapping
their shell valves, but cannot close the valves tightly. Consequently. the unattached surface dwellers are the weakest among thebivalves in their ability to osmoregulate; for example. Chlamvs
nobilis cannot live in media < 710 mOsm/kg.
90

Mytilus edulis

Saxidomus purpuratus
I~
"-

2,000

E

~

E

~""
o

Q)

~
IJl

Cl
.::&.

"E
IJl

+ mantle cavity fluid0o haemolymph• extrapallial fluid..

~ 1,000'ym'd;"m

u
:;:

~'\

...c. 1,000

~

~

-#-

~l

IJl

0

oL-.....,-----r-------:,--o
100200Concentrationo haemolymph• extrapallial fluid

Q)

l!!

'~~ ()~+ mantle cavity fluid

1ij-

::::I
IJl
IJl

~

"5
E
CS

.~

E

ymedium

.!O!

2,000

0

"\

200

100

Concentrationof sea water (%)

of sea water0(%)

Chlamys nobilis:l 2,000
"E

-+It

• '\.

IJl

o

0

E

)
00

+ mantle cavity fluid
0 haemolymph• extrapallial fluid

'\.

-dJ)

Q)

5IJl

•

ymedium

IJl•~ 1,000

*'\

u

'g
E
IJl

W- ~ ~i'-tG-o'-it-+

oL........r--------...---"'-T---200

100

Concentrationof sea water

Figure I.-Osmotic equilibrium and disequilibrium between the body nuids andexternal media in the processes of acclimation and death.

0

(% )

ACKNOWLEDGMENTS

The amount of free amino acids in the extrapallial fluid appears
to differ significantly among soft bottom burrowers, attached surface dwellers, and unattached surface dwellers. It is noted that theattached surface dwellers have higher amounts of free amino acidsin their body fluids than the others, but have similar amounts ofthe main inorganic elements to those of the environmental
medium.
The above-mentioned consideration suggests that free aminoacids, especially taurine, may be involved in the osmoregulationof body fluids of marine bivalves. The ability to tolerate an
osmotic stress appears to depend on physiological and biochemical characteristics adapted to particular habitats. Free
amino acid analyses of the body fluids obtained from 13 species
of marine bivalves under various salinities are being conducted inorder to obtain further information on the role of free amino acids
in osmoregulation.

The author expresses his sincere thanks to S. Funakoshi and T.
Suzuki of the National Research Institute of Aquaculture for their
help in the measurement of osmotic pressure.

LITERATURE CITEDCAMIEN, M. N., H. SARLET, G. DUCHATEAU, and M. FLORKIN.
1951. Non-protein amino acids in muscle and blood of marine and fresh
water Crustacea. J. BioI. Chern. 193:881-885.
DUCHATEAU, G., H. SARLET, M. N. CAM lEN, and M. FLORKIN.
1952. Acides amines non proteiniques des tissus chez les Mollusques Lamellibranches et chez les Verso Comparaison des formes marins et des formes
duleioles. Arch. Int. Physiol. 60: 124-125.
GILLES, R.
1972. Osmoregulation in three molluscs: Acanthochitona discrepans (Brown),

91

WADA, K.
1982. Pearl-its formation and idenfication. Gem. Assoc., All Japan Press,
Tokyo.
WADA, K., and T. FUJINUKI.
1976. Biomineralization in bivalve molluscs with emphasis on the chemicalcomposition of the extrapallial fluid. In The mechanisms of mineralizationin the invertebrates and plants, p. 175- I 90. South Carolina Univ. Press,
Columbia.

Glycymeris glycymeris (L.) and My/itus edulis (L.). BioI. Bull. (Woods Hole)
142:25-35.
ROBERTSON, J. D.
1964. Osmotic and ionic regulation. In Physiology of mollusca I, p. 283-308.
Acad. Press, N.Y.
SCHOFFENIELS, E., and R. GILLES.
1972. Ionregulation and osmoregulation in mollusca. In Chemical zoology
VIII. Mollusca, p. 393-398. Acad. Press, N.Y.

92