tant northern forms. The species listed in this article 

 are presently being cultivated in Hokkaido. 



The present status of some important inverte- 

 brates and seaweeds is as follows: 



Scallop (Patinopecten yesoenssis) 



Sea scallops are distributed along the whole coast 

 of Hokkaido. However, in recent years, the major 

 areas of production have been limited to the Okhotsk 

 Sea region, especially in the southern half of the 

 northern region and the Nemuro Strait area in the 

 southern region. Scallop production in Hokkaido 

 reached its peak in 1934, when 78,674 tons were 

 harvested. Since then, production has been declin- 

 ing, with accompanying wide annual fluctuations. A 

 low of 3,843 tons was recorded in 1968. However, in 

 1969, production rose to 8,618 tons. This increase 

 may be due to the gradual development of the artifi- 

 cial cultivation and the use of underwater off-bottom 

 techniques in Lake Saloma and Uchiura Bay, and 

 the stocking of seed scallops along the Okhotsk Sea 

 coast. It is not clear whether the remarkable reduc- 

 tion in production was caused by overfishing or by a 

 decrease in the amount of scallop setting as a result 

 of some adverse oceanographic conditions. 



Japanese surf clam (Mactra sachaHensis) 



This clam is found along the entire Hokkaido 

 coast. Major areas of production are the Pacific 

 coast region and the Nemuro Strait. In Hokkaido, 

 the annual production of surf clams is nearly 5.000 

 tons. Commercial-sized clams range in age composi- 

 tion from 4 to 10 yr old, and it is doubtful that the 

 resource would recover if overfished. At present, 

 the clam resource is being carefully managed by 

 regulating the size of the catch, fishing seasons, fish- 

 ing grounds, and minimum shell size. Transplanting 

 of juvenile clams has been attempted for the purpose 

 of preserving this resource. 



Abalone (Haliotis discus) 



Abaione are limited to the Japan Sea coast, the 

 Tsugaru Strait, and Uchiura Bay: it has never been 

 found in other areas. This restriction in its geo- 

 graphical range may be attributed mainly to the low 

 seawater temperatures during the winter season. 

 The number of abalone per unit of area is considera- 

 ble in Hokkaido. Because of cold waters, the growth 

 rate is slower than in the southern part of Japan. 



Accordingly, Hokkaido has played an important 

 role as a source of seed abalone for southern Japan. 

 Growth rates vary considerably along the Hokkaido 

 coast and successful transplants have been made 

 from poor growing grounds to good growing 

 grounds. 



Sea urchin (Strongylocentrotus intermedius and 

 S. nudus) 



Hokkaido's species of the sea urchins differ from 

 those of the southern part of Japan. They are of 

 commercial importance in Hokkaido and are found 

 along all coasts. Recently, effective management of 

 sea urchin populations has been carried out and. as a 

 result, the annual catch has shown a rising tendency. 

 In managing the populations, severe regulations 

 have been established on the fishing grounds, desig- 

 nated fishing seasons, and minimum carapace size. 

 Also, young individuals (those with immature 

 ovaries) have been transplanted to productive 

 grounds rich in seaweeds. 



Kelp (Laminaria spp.) 



Laminaria growing along the coast of Hokkaido 

 are classified into several species, namely L. 

 japonica, L. religiosa, L. ochotensis, L. diaboUca, 

 L. angustata, andL. angustata var. longissima. The 

 classification is based on their morphological 

 characters. However, from the taxonomical as well 

 as distributional viewpoints, it is appropriate to di- 

 vide the above-mentioned Luminaiia into two major 

 groups — Laminaria japonica group (including L. 

 japonica. L. ochotensis, and L. diaboUca) and 

 Laminaria angustata group (including L. angustata 

 andL. angustata var. longissinui)- The former group 

 is found in Uchiura Bay, the Tsugaru Strait, the 

 Japan Sea, the northern part of Okhotsk Sea region, 

 and along the coast of Shiretoko Peninsula. The 

 latter group grows along the coast of the Pacific 

 Ocean. Since 1955, the annual production of 

 Laminaria in Hokkaido has fluctuated between 

 100,000 and 150,000 tons in fresh weight. The most 

 abundant harvests were recorded, based on a 5-yr 

 cycle, in 1957, 1962, and 1967. Since the 19th cen- 

 tury, various attempts have been made to increase 

 Laminaria production. These include the planting of 

 stones and rocks and the blasting of rocky reefs. In 

 the recent years, cultivation of Laminaria, 

 especially forced cultivation, by a longline type or 



