Challenge of restocking in Japan with special reference to larviculture

Hiroshi FUSHIMI

Fukuyama University, Faculty of Life Science & BiotechnologyDepartment of Marine Biotechnology

Laboratory of Aquaculture & Stock EnhancementOhama, Innoshima, Hiroshima 722-2101, Japan

E-mail: hfushimi@ma.fuma.fukuyama-u.ac.jp

Scope

• Progress of production of hatchery-raised juveniles and restocking

1. Brief history of stock enhancement in Japan2. Challenge of restocking in Japan with special reference to larviculture

I. The System and Roles of Stock Enhancement

II. Procedure and technology needed for restocking

III. Progress in Production of Hatchery-raised Finfish Juveniles for Stock Enhancement

IV. Scale of Hatchery-raised Seed for Stock enhancement in Japan

• New Challenge for the Resource Restoration Plan in Japan

Progress of production of hatchery-raised juveniles and restocking in Japan

Brief History of Stock Enhancement in Japan

1961 The Japan Fisheries Agency established a plan to promote coastalfisheries by stock enhancement.

1962 The Seto Inland Sea was selected as a model littoral zone for stock enhancement.

1963 The Seto Inland Sea Fish Farming Association (SISFA) was established as the base of operation for intended technological development by commission from the government.

1979 SISFA was reorganized and renamed the Japan Sea-Farming Association (JASFA).

2003 JASFA was united to Fisheries Research Agency, and renamed National Center for Stock Enhancement (NCSE).

2006 6 NCSE were united to 4 Regional Fisheries Research Institutes of FRA.

Brief History of Stock Enhancement in Japan (2)

By the late 1970s The technology of artificial seed production of finfish had been established in Japan.

Hatchery-raised seed play an important role in supplying seedlings to aquaculture. Hatchery-raised seed supply most of the demands of aquaculture;

Red sea bream Pagrus major, Ocellate puffer Takifugu rubripes,striped jack Pseudocaranx dentex, Japanese flounder Paralichtys olivaceus, and Kuruma prawn Penaeus japonicus

Challenge of restocking in Japan with special reference to larviculture

I. The System and Roles of Stock EnhancementII. Procedure and technology needed for restockingIII. Progress in Production of Hatchery-raised Finfish Juveniles for

Stock EnhancementIV. Scale of Hatchery-raised Seed for Stock enhancement in Japan

I. The System and Roles of Stock Enhancement

Schematic explanation of roles in farming fisheries in Japan (after Japan Fisheries Agency). JASFA denote Japan Sea-Farming Association

National Centers for Stock Enhancement (NCSE)

1. Akkeshi Stn. 2. Miyako Stn. 3. Notojima Stn.4. Obama Stn. 5. Miyazu Stn. 6. Minami-Izu Stn. 7. Tamano Stn. 8. Yashima Stn. 9. Hakatajima

10. Momoshima11. Komame Stn.12. Kamiura Stn. 13. Shibushi Stn.14. Goto Stn.15. Yaeyama Stn.16. Amami Stn.

Locations of Prefectural Stock Enhancement centers

II. Procedure and technology needed for restocking

A case study on the Kuruma Prawn

Objective of Stock-enhancement of Kuruma prawn in Japan

• Recovering of the decreasing of catch

• To maintain a suitable catch level for fishermen

• The decreasing of catch in the 1960s were caused by land reclamations for development of industries.

• Necessarity of socio-economic analysis of the area

• We have realized to improve the minimum annual catch level to maintain the mean annual catch level by restocking (Lake Hamana-ko)

Objective-Recovering of the decreasing of catch

• Importance of clarifying causes the decreasing of catch

• Is it able to recover the stock by restocking?

- It should be dependent on the cause of the decreasing of catch

• The life cycle study of black tiger prawn in the target area is essential.

• In Japan, the catch decreasing of Kruma prawn were caused by land reclamation. It means that land reclamation destroy the nursery ground, and cut off the habitat sequence of Kuruma prawn.

Objective - To maintain a suitable catch level for fishermen

• To clarify the socio-economic role of the target species in the area

• It should be essential to establish the ideal annual catch level

• I analyzed the economic role of the Kuruma prawn in the Hamana-ko district.

• I determined the suitable annual catch level as 67t, and 47t as minimum annual catch level, depending on the protocol with the Hamana Fishermen's Cooperation Association. It was necessary to introduce 20 million hatchery-raised Kuruma prawn juvenile with BL 15mm per year.

2 - 3 Age, AdultSpawning Area( Open Sea )

Settlement; Nursery Ground

Adolescent

( Immediate Coastal Zones of Estuary, Shallows )

1 Age, Adult

Spawning Area ( Shallow Open Sea )

Plamktonic Life; Transportation

by Current

Born in early spawning Season

Born in Late Spawning Season

August to November June to July

iMigrationMigration

Schema of the Life Cycle of Kuruma PrawnAfter Kurata (1986), modified.

The environmental condition as key issue for stock enhancement (2)

Key issue 1 Habitat sequence corresponding to the life cycle

Kuruma prawnSettlement; 7-10mm Immediate coastal

zone of estuarineAdolescent; 30-50mm

Shallows Migration after Mating;

Shallow open sea connecting toshallows

2-3 age adult;Open sea connecting to shallowopen sea

Hatchery Nursery Fishing ground

Mortality 1 Mortality 2

Transportation

Acclimation

When, Where, and How to introduce the hatchery-raised juvenile to the nursery ground for acclimation rearing to

improve the effectiveness of restocking

To improve the health and quality

To improve adaptability for the natural environmental condition at releasing area

Releasing/Recruitment

To eliminate the mortality

Mortality 1 1. To improve the quality

2. To develop the transportation technique

Mortality 2 1. To clarify the causes of mortality

2. To improve the acclimation rearing technique

Scheme of Survival Curve of Accumulation Rearing

t 0 t a t r

N0

N

aN r

T i m e

t 0 ; Time of introducing

t a ; End point of mortality of introducing

t r ; Time of release

N0 ; Individual Number at time t0

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Nr ; Ind. N. at time t rIn

divi

dua l

Num

ber

Introducing Mortality in Acclimation

• Severe Mortality occurred at post-introducing to the nursery for acclimation - occurring in 24hours after introducing

• Caused by;1. Low quality of hatchery-raised

juvenile 2. Low transportation technique3. Tidal condition at introducing4. Predation

Mortality in Acclimation Procedure

• Usually, mortality in acclimation procedure is lower than Introducing mortality

• Survival rate is depending on the period of acclimation rearing

• To improve acclimation rearing technique; presence of the density dependent effect on growth and mortality

• To evaluate the effect by predation

• To determine the releasing size depending on the ecology of juvenile

Factors for success of stock enhancement

• (1) Releasing technique as an issue of man,

• (2) Quality of fish as an issue of seedlings, and

• (3) The environmental condition as an issue of the field for stock enhancement.

• (1) Development of transportation, acclimation, and releasing technique

• (2) Development of technology on improvement of the fish health and the fish quality

• (3) Improvement of knowledge of fishery biology and ecology

(1) Releasing technique as an issue of man

Development of transportation, acclimation, and releasing technique

Mainly depending on the quality of hatchery-raised seed

Improvement of physiological and ecological characteristics of hatchery-raised seed

(2) Quality of fish as an issue of seedlings

Development of technology on improvement of the fish health and the fish quality

Essential: Standardization of rearing technique under laboratory condition, i.e.,

Growth and survival rates were affected by density dependent effect;Presence of optimum introducing density at mouth opening for red sea bream, Japanese flounder, and etc.

Physiological and ecological characteristics of hatchery-raised juveniles

• Fish health is defined physiological wellness of hatchery-raised juveniles, and

• fish quality is defined ecological robustness of them such as behavioral and feeding activity.

• The fish quality means ability to adapt to natural conditions inreleased environments.

• Fish health must be the prerequisite of the hatchery-raised seed for release. It is measured by physiological and morphological characteristics of fish, i.e. biochemical compositions of body, tolerance of stress in handling and environmental change and morphological normality.

• Fish quality is concerning an aptitude for release. It is the key factor of survival in the field after release and stocking effectiveness.

Fish health and quality as key issue for improvement stocking effectiveness

• The morphological and physiological attributes of the cultured fish together constitute a measure of health and that health combined with behavior represents fish quality.

Fish quality or ecological robustness, is defined as the ability to adapt to natural conditions at release sites.

(3) The environmental condition as key issue for stock enhancement.

Improvement of knowledge of fishery biology and ecology

Relation between Life cycle and environmental conditions;

Planktonic life Settlement;Presence of transitional period

from planktonic to benthic life (Kuruma prawn, Mud crabs, Swimming crab, Japanese flounder)

Presence of drastic change of feeding habits; to omnivorous (red sea bream),fishvorous (Japanese flounder)

Factors affecting the result of acclimation - 1

Effect of size at introduction for acclimation rearing

the relation between mean body length and weight and survival rate during acclimation rearing carried out in the Lake Hamana (Fushimi 1986). Both plots are dome-shaped. The maximum survival rate was attained at a mean body weight of 30-50mg and a mean body length of 14-15 mm. Postlarvae with a BL of 14-15 mm had a body weight of 28.5-32.7mg.

Factors affecting the result of acclimation - 2

Density dependent effect on survival and growth in acclimation procedure

The natural mortality coefficient per 5 days, M5 rose linearly when the density was increased from 100 to 400 individuals per m2, but became asymptotic above 400 individuals per m2. The plot of daily growth rate on rearing density was dome-shaped, with a peak of 1.5 mm per day at 200 to 300 individuals per m2 . Therefore, the optimum density for introduction of seeds to the acclimatization enclosure was determined as 200 to 300 individuals per m2(Fushimi 1983).

Factors affecting the result of acclimation - 3

Effect of predation in acclimation procedure

The mortality due to predation (Mg) was determined using the relationship (M’=M+Mg). M and Mg have the same value when the stocking density is about 170 individuals per m2. Predation by gobies has a more severe effect on survival than density-dependent natural mortality at densities below 170 individuals per m2 .

Release after Acclimation Procedure - 1

• The body size and time of release affected to the recovery rate of released hatchery-raised seeds.

• Conditions affected to establish the strategy of release

• The body size is closely related to development of behavioral characteristics.

• Ability of hatchery, transportation apparatus, environmental conditions of releasing area, acclimation procedure, releasing technique, etc.

• Timing of release –important issue for stocking effectiveness

• The technological development of bloodstock management, especially induced spawning technique. Manipulating temperature and photoperiod for induced spawning.

Release after Acclimation Procedure - 2

How to detect the restocking effectiveness -1

• Restocking effectiveness improve fisheries productivity

• Fundamental information should be fisheries statistics

• It should be essential to develop the fisheries management for improvement of the restocking effectiveness

• Collaboration of fishermen

How to detect the restocking effectiveness -2• Importance of planning

for research on restocking effectiveness – arrow diagram of research should be essential

• Basic research should composed by fishery biology and population dynamics on natural and released populations.

• Components of research; Fisheries statistics, composition of catch, distinguish of cohort, dispersal and migration, growth, natural and fishery mortality, and socio-economics

III. Progress in Production of Hatchery-raised Finfish Juveniles for Stock Enhancement

Hatchery technology in Japan

• Development of larviculture were mainly supported by progress in

• Biological studies on finfish and shellfish nutrition

• Rotifer production technique• Aquaculture industries, such

as plastic equipment, freshwater Chlorella.

• Logistics in keeping refrigerated.

Key Issue for Intensive Larviculture

• Hatchery Mechanization • Marino-Forum 21(MF21) provides major support for the mechanization larviculture

- Micro-formulated feed for fry

- Mechanized closed continuous culture system of rotifer (Harvests of three billion S-type rotifer/ m3/ day)

- Continuous culture system of L-type rotifer (1000 rotifers/mL, 60% harvesting/day

IV. Scale of Hatchery-raised Juveniles for Stock Enhancement in Japan

Species NumberFinfishShellfish

Species Number of Larviculture and Release for Stock Enhancement in Japan

Pisces; Individual Number of Larviculture and Release in Japan

Red sea bream: Annual change of individual number of hatchery-raised seed production and release

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Red sea bream: Annual change of individual number of hatchery-raised seed production and release

Changes in Catch and the Number of Red Sea Bream Released in Kagoshima Bay

Japanese flounder: Annual change of individual number of hatchery-raised seed production and release

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Japanese flounder: Annual change of individual number of hatchery-raised seed production and release

Restocking Effectiveness of Japanese Flounder in Ibaraki Prefecture

Size Frequency Distribution and Released Fish Mixing Rate of Japanese Flounder in Ibaraki Prefecture

Released hatchery-raised flounder were definite easily by color abnormality of blind side.

Mixing rate was attained almost 10-15%.

Catch recovery caused by releasing hatchery-raised juveniles.

Crustacea; Individual Number of Larviculture and Release in Japan

Annual Catch Fluctuation of Kuruma Prawn, Penaeus japonicus, in Japan

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Kuruma prawn: Annual change of catch and individual number of hatchery-raised seed production and release (2)

New Challenge for the Resource Restoration Plan in Japan

Annual Catch and Production of Japanese Fisheries

200119941985197519651960

Catch in 10thousand t

Far seas fishery

Offshore fishery

Coastal fishery

Marine Aquaculture

Inland fishery& Aquaculture

Production in trillion Yen

Fisheries Measures for FY2006

I. Measures for Securing Stable Supply of Fishery Products1.Securing stable supply of fishery products for people’s diet.2. Appropriately preserving and managing fishery resources in the exclusive economic zone (EEZ)

3. Appropriate preserving and managing fishery resources outside EEZ4. Conducting surveys and research on fishery resources5. Promoting multiplication and aquaculture of aquatic animals and plants6. Preserving and improving the living environment of aquatic animals andplants

7. Maintaining and developing fishing grounds outside the EEZ8. Taking measures on fishery product imports and exports9. Promoting international cooperation

Fisheries Measures for FY2006, contn’d

II. Measures for Sound development of Fisheries Industry1. Fostering efficient and stable fishery business management2. Promoting more efficient use of fishing ground.3. Developing and securing human resources.4. Compensation for damages caused by fishery disasters.5. Achieving sound development of fishery processing industry and fishery distribution industry.

6. developing the infrastructure of fisheries industry7. Developing and diffusing technology8. Promoting participation of women9. Promoting activities of the elderly10.Achieving comprehensive development of fishing ground11.Making exchanges between cities and fishing villages12.Increasing measures for optimizing the multiple functions

We have almost 40 years history, experiences on stock enhancement and fruitful results of stocking effectiveness.However, we have to consider possible unfavorable biological effects of large numbers of release hatchery-raised juveniles.

We have to establish the more sufficient way to recover the status of fisheries resources or stocks.

We have to pass on to coming generations the abundant fisheries resources or stocks.

Thank you for your kind attention!!

Pacific herring: Annual changes of Production and release ofHatchery-raised juvenile and catch

Black sea bream: Annual change of individual number of hatchery-raised seed production and release

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Black sea bream: Annual change of individual number of hatchery-raised seed production and release

Pacific herring: Annual change of individual number of hatchery-raised seed production and release

Pacific cod: Annual changes of Production and release ofHatchery-raised juvenile and catch

Sea bass: Annual change of individual number of hatchery-raised seed production and release

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Annual change of catch (kg ) and release (inds.) of Kurumaprawn,Penaeus japonicus, in the Hamana-ko

Problems and Prospects

Possible unfavorable biological effects of large numbers ofrelease hatchery-raised seed

• The spread of pathogens,

• Competition for foods and cannibalism,

• Genetic deterioration of wild stock

Prospects

• Improvement of fish quality would enable us to reduce the number of hatchery-raised seed

and• This minimize negative

impacts of release on the environment.

Problems and Prospects (2)

(1) The spread of pathogens Important issue;Development of prevention technology of the spread ofPathogens.

JASFA has been engaged in this issue to take preventive measures against epidemicdiseases of finfish (Arimoto, 1999)

Fluctuation of annual catch of Japanese swimmingCrab, Portunus trituberculatus,in Japan

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Swimming crab: Annual change of catch and individual number of hatchery-raised seed production and release

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Swimming crab: Annual change of catch and individual number of hatchery-raised seed production and release

Problems and Prospects (3)

(2) Competition forfoods andcannibalism,

Establishment of fish quality improvement technology

However, some trials conducted to establish fish quality improvementtechnology of larviculture, we could not establish effective larviculturesystem improving fish quality.

Application of biocontrol method, which developed in swimming crablarviculture, should encourage developing future larviculture systemimproving fish quality.

Problems and Prospects (4)

(3) Genetic deterioration ofwild stock

•WWe have to encourage to conduct studies on this field, because we have little information on this issue (Harada, 1999).

•WWe have to use the wild organisms as bloodstock, and to improve the quality of hatchery-raised juveniles