THE PRESENT STATUS OF SHELLFISH CULTURE IN JAPAN 



HISASHI KAN-NO' and TOMOO HAYASHl- 



INTRODUCTION 



In 1969, shellfish production (including pearl oys- 

 ters) in Japan was 561,132 tons worth 58,444 million 

 yen (Table 1). Types of shellfish products landed 

 during the past decade have changed because of 

 certain effects on the environment and changes in 

 commercial demands. Shellfish, like Meretiix. 

 which live along the coastal area, have decreased 

 remarkably in production because of the loss of their 

 habitat from industrialization. In 1969, the oyster 

 industry in the Seto Inland Sea area was seriously 

 affected because the oysters were heavily fouled by 

 the calcareous tube worm. Hydioides nonegica. 

 For the past several years, production in the pearl 

 industry has declined because of reduced demand 

 for pearls. On the other hand, landings of scallops, 

 abalone, and top shell, so-called high grade prod- 

 ucts, have been increasing yearly both in tonnage 

 and value because of the demand by the consumer 

 for fresh marine products. Production through 

 aquaculture has remained commercially stable in 

 Japan. 



In the past, shellfish aquaculture in Japan was 

 limited, strictly speaking, to oysters and pearls. Re- 

 cently, both scallops and abalone are being grown 

 using aquaculture techniques. In general, aquacul- 

 ture requires three important techniques: 1 ) to catch 

 the juveniles in desirable places with collectors, 2) to 

 produce seed for culture using hatchery (artificial) 

 techniques, and 3) to cultivate the seed to market 

 size in the field. .Aquaculture techniques are being 

 utilized to grow oysters, pearls, and scallops, and it 

 is expected that abalone will also be produced in the 

 near future through aquaculture. 



In my presentation at the first UJNR (United 

 States-Japan Natural Resources) Aquaculture Panel 

 meeting. I would like to explain briefly about the 



Table 1. — Shellfish production in Japan, 1969. 



' Tohoku Regional Fisheries Research Laboratory. Shiogama. 

 Mi\agi-ken. Japan. 



- National Pearl Research Laboratory. Kashikojima. Mie-ken. 

 Japan. 



Shellfish 



Landings 

 in tons 



Value in 

 million 



of yen 



.Abalone iHaliotis discus luinai. 



H. discus, H. gijiantiea. H. 



sicholdi) 6.463 



Top shell ( Turhu corneliis) 8.459 



Hard clam (Merelrix meretrix. 



M. liisoriu) 7,081 



Short-necked clam (Venerupis 



semidccussala) 1 16,572 



Common scallop (Palinopeclen 



yessoensis) 14,644 



Surf clam (Spisula sachalinensis) . . . 4,050 

 Ark shell (Anadara suhcrenata) .... 38.289 



Other molluscs 114.281 



Oyster (Cnissosrrea gigas) 245,458 



Pearl 97 



Pearl molber sheW (PicUula fucalu) . 5,738 



Total 561.132 



5,692 



1,7L5 



966 



3.025 



1.833 

 948 

 1.918 

 9.920 

 8.149 

 22,600 

 1.678 



58.444 



present status of shellfish aquaculture in Japan and 

 its prospects for the future. 



OYSTER CULTURE 



Production of oysters (Crassostrea gii^cis) has 

 rapidly increased since the 1950"s because of the 

 development of hanging culture. Strings of oysters 

 are hung from racks, rafts, or longlines, depending 

 on water depth. Hanging culture makes good use of 

 the water column and is not limited by depth or 

 nature of bottom. In 1969, production was 245,458 

 tons (including shell) valued at 8.149 million 

 yen (Table 1). 



The first operation in oyster culture is to catch the 

 juveniles (seed). Strings of shells are suspended dur- 

 ing the summer spawning season from racks placed 

 in coastal areas such as bays and inlets. After set- 

 ting, the seed is hardened, a process of draping the 

 strings over racks so that they are out of water for a 



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