CURRENTS IN SOUTHEASTERN BERING SEA AND POSSIBLE 

 EFFECTS UPON KING CRAB LARVAE 



by 



James F. Hebaxd 



U. S. Fish and Wildlife Service 



Seattle, Washington 



ABSTRACT 



During an investigation of the tidal and average currents in 

 southeastern Bering Sea, carried out in June 1957, the currents were 

 observed at four anchor stations by means of an Ekman current meter. 

 Dextrally rotating tidal currents occurred on the two offshore sta- 

 tions, and greatly compressed rotary tidal currents varying in direc- 

 tion of rotation occurred on the two inshore stations. The flow of 

 the average current indicated a counterclockwise circulation. 



These currents may affect the movement of king crabs in the 

 planktonic stage. 



INTRODUCTION 



The movements and physical characteris- 

 tics of the water in the king crab fishery 

 of southeastern Bering Sea (figure 1), were 

 investigated in June 1957 to determine the 

 tidal and average currents in an effort to 

 assess the possible effects they may have 

 on the king crab ( Paralithodes camtschatica 

 Tilesius). This investigation was under- 

 taken as part of the program of the King 

 Crab Investigations, United States Fish and 

 Wildlife Service. The results contribute 

 primarily to the knowledge of the currents 

 observed in southeastern Bering Sea and 

 also to the determination of the effects of 

 the currents on the king crab in the plank- 

 tonic stage. Future investigations will 

 attempt to relate the water movement to 

 other stages in the life cycle of the crab. 



The area under investigation is trian- 

 gular in shape, with an apex in the Bristol 

 Bay region. The land adds freshwater run- 

 off through many streams, among the largest 

 being the Ugashik, Egegik, Naknek, Kvichak, 

 and Nushagak Rivers, all of which empty 

 into the Bristol Bay region. The bottom 

 topography is one of gradually increasing 

 depth from Bristol Bay toward the southwest 

 (figure 1). 



The positions of the four current 

 stations are shown in figure 1. The maxi- 

 mum depths at the sampling stations A, B, 

 C, and D are 66, 40, 60, and 71 meters, 

 respectively. 



Previous current studies covering part 

 of the same area (surrounding and between 

 stations C and D) were made by scientific 

 personnel aboard the Japanese king crab 

 raothership, Tokei Maru, during the crabbing 

 seasons of 1955 and 1956 (International 

 North Pacific Fisheries Commission, 1957). 

 The 1955 data show that the tidal current 

 flowed west-southwest during the ebb-tide 

 hours and east-northeast during the flood- 

 tide hours. In 1956, this general pattern 

 sometimes became obscure. The recorded 

 tidal current velocities did not exceed 1.5 

 knots in either year. 



Past studies contributing to the knowl- 

 edge of water circulation in and around 

 southeastern Bering Sea include those by 

 the U. S. Coast Guard (1936), Thompson and 

 Van Cleve (1936), and the several mapping, 

 tide, and current surveys made by the U. S. 

 Coast and Geodetic Survey for the Tide and 

 Current Tables for the Pacific Coast of 

 North America. 



