PRESENT STATUS OF MAJOR MARINE CULTIVATION AND 



PROPAGATION IN HOKKAIDO AND 



SOME PROBLEMS OF THE RESEARCH ACTIVITIES 



YOSHIO HASEGAWA and YUKIMASA KUWATANI' 



GENERAL FEATURES OF THE 

 WATERS AROUND HOKKAIDO 



Hokkaido is the northernmost island of Japanese 

 archipelago. It has a long shoreline extending about 

 2.700 km, which corresponds to about 10% of the 

 Japanese coastline. The island is surrounded by 

 three different seas— the Japan Sea, the Pacific 

 Ocean, and the Okhotsk Sea. The coastline of Hok- 

 kaido is influenced by two warm currents, the 

 Tsushima and the Kuroshio, and one cold current, 

 the Oyashio (Fig. 1). The seasonal fluctuations of 

 these warm and cold currents considerably influence 

 the oceanographic conditions in each local region. 

 Therefore, Hokkaido has many specific ecological 

 features as a result of these oceanographic, as well as 

 topographic, conditions. 



Japan Sea Region 



The Japan Sea coast of Hokkaido can be divided 

 into two regions by the Shakotan Peninsula: The 

 northern region is characterized by simple sandy 

 beaches, while the southern region, including the 

 Shakotan Peninsula, is characterized by a rough, 

 rocky shoreline. Along this coast, the warm 

 Tsushima Current Hows northward. In addition, 

 some upweliing of cold water-masses from the lower 

 layers of the Japan Sea occurs both in the offshore 

 waters and the inshore area of the Tsushima Cur- 

 rent. This intermingling of warm and cold water- 

 masses complicates the oceanographic conditions of 

 the area. Moreover, strong northwest winds bring 

 stormy weather conditions to this region during the 

 winter. Therefore, because of the oceanographic 

 conditions, stormy winters, and open topography, it 



is very difficult to establish and maintain artificial 

 equipment (rafts, longlines, etc.) for marine cultiva- 

 tion. 



Pacific Region 



The Pacific coast can also be divided into two 

 regions by Cape Erimo. In the eastern region, there 

 are many small bays or inlets in the Akkeshi area, 

 but the largest embayment, Uchiura Bay, is found in 



' Hokkaido Regional Fisheries Research Laboratory. Yoichi. 

 Hokkaido. Japan. 



Figure I . — Sea currents and isothermal lines in Japanese waters 

 during .August. 



