that recruitment is presently less than in previous 

 years. The total tonnage landed by the commercial 

 shrimp fleet is also down. Therefore, the concept of 

 seeding the system with (1.2 x 10") 20-day-old post- 

 larval shrimp is being tested to see if the system is 

 still a suitable environment, if production of shrimp 

 can be stimulated and ifnew areas can be used. Some 

 shrimp are released directly into the nursery 

 grounds, while others are placed in a pen (30 x 10 x 

 10 m) for 2 to 4 wk to acclimate them to estuarine 

 waters. 



M. Fujiya, also of the Nansei Laboratory, began 

 physiological studies to measure the ""quality'" of 

 shrimp larvae reared in different ways, by observing 

 their reaction to anesthetics. His approach is to in- 

 sert electrodes into the brain of the shrimp and re- 

 cord their brain waves on an oscelloscope. 



H. Hirata, at Kagoshima University, has begun 

 work on the production of single-species mass cul- 

 tures of diatoms and their preservation. At present, 

 diatoms are concentrated and later frozen at 0°C. 

 They can be held successfully for periods of 30 days 

 or less. Various other techniques are now being 

 tested. 



Table 1 is part of a statistical report, translated by 

 Jiro Tanaka. Of particular interest is the number of 

 tons of P. Jiiponiciis cultured. Since 1967, annual 

 production has been about 300 tons. Although some 

 live shrimp are imported, the tonnage is far below the 

 market demand. The importation of frozen shrimp 

 has no direct bearing on the live shrimp market. 



CRABS, PORTUNUS TRIBERCULATUS 



Crabs, primarily Poriuniis trihcniiluins. have 

 been reared successfully to the 5th generation at the 

 Yamaguchi Fisheries Experimental Station. P. 

 trihcrciiUitiis is similar to the American blue crab. 

 Ccillinectes sapidus. Larval crabs in the zoea I-IIl 

 stages are fed rotifers, Brdchioniis plicatilis. which 

 are maintained on freshwater cultures oiClilorclla. 



Older stages are fed Anemia, chopped tlsh, and 

 crushed clams. Since crabs are active and ditTicult to 

 maintain in a barren enclosure, a series of vertical 

 netlike structures were placed in the rearing pond. 

 The growth of natural filamentous algae upon these 

 structures serves as a hiding place for the crabs. 



Unfortunately, fighting over territories and food 

 results in a high rate of mortality in the pond. Har- 

 vesting is accomplished by draining the pond and 

 raking the crabs, a process which is time consuming. 

 Although the price of these live crabs in United 

 States is$l. 10 each, their culture is not yet economi- 

 cally profitable in Japan. 



A number of prefectural laboratories rear crabs to 

 the megalops stage and release them into estuaries. 



FRESHWATER SHRIMP, MACROBRACHWM SP. 



At the Tokyo University of Fisheries, Ogasawara 

 and T. Sano discussed the culture of freshwater 

 shrimp of the species Macrohrachiiim. Eleven dif- 

 ferent species were being studied. To rear the larval 

 stages, they indicated that a medium of 50^ fresh 

 water and 50% seawater was necessary. A diet of 

 Arteiniii. reared on a freshwater culture of 

 Chlorella. is fed during the larval stages along with 

 ground clam (Tapes sp.) meat. When the shrimp are 

 older, pieces of chicken egg shells are added to sup- 

 plement the calcium in their diets. 



Juveniles of Macrohrachiiim rosenheri^i have 

 been reared on commercial trout pellets to market 

 size in 6 mo at the Izu Branch Laboratory. Although 

 results have been satisfactory, production costs 

 were not made available. 



SPINY LOBSTER, PANULIRUS JAPOMCUS 



At Kanagawa Prefectural Laboratory, research 

 on the spiny lobster, Panulirits japonicus, is being 

 conducted. Of particular interest is the work of 

 Inoue who has found that the phyllosoma larvae will 



Table 1. — ."XRHual production (in metric tons) of cultured, naturally 

 caught, and \mipov\ed Penaeus japonicus. 1965-69. 



112 



