Figure 1. — Bristol Bay, showing locations of principal river systems. 



Dodimead et al. (1963) depicted the pattern of the 

 nontidal currents in a review of the general 

 oceanographic conditions in Bristol Bay from May 

 through August in 1938 and 1939. Dodimead et al. (1963) 

 inferred from salinity and sigma-t distributions that 

 water in the bay moved counterclockwise. Hebard (1959) 

 determined that the average velocity of this current near 

 Port Moller (Fig. 1) on the Alaska Peninsula was slightly 

 less than 0.1 knot, or about 2 n.mi./day. 



In spring (May and June) a temperature front occurs 

 in the seawater across the bay and separates waters of 

 the inner bay from those of the outer bay. In 1939 this 

 front occurred along a line from Port Heiden to Cape 

 Pierce; surface temperatures and salinities indicated the 

 presence of counterclockwise gyres both shoreward and 

 seaward of this front (Dodimead et al. 1963). The in- 

 shore gyre was apparently confined to the surface, and 

 warm dilute river runoff was contained eastward of Cape 

 Pierce and forced to recirculate shoreward of this front. 

 By August the temperature front had disappeared, and a 

 peripheral counterclockwise flow was evident throughout 

 the bay.' These descriptions of water movement apply to 

 the area seaward of a line between Cape Constantine and 

 Rgegik Bay (Fig. 1). 



DISTRIBUTION OF RIVER WATERS 



Three methods were used to determine the dis- 

 tribution of waters from individual river systems in inner 



Recent data collected by the National Marine Fisheries Service, which 

 are on file at the Aukc Bay Laboratory. Alike Bay. Alaska, suggest that a 

 temperature front occurs annually, hut its location may van,- from year to 

 year. 



Bristol Bay: 1) measuring vertical and horizontal dis- 

 tributions of salinity, 2) tracking river waters tagged with 

 a fluorescent dye, and 3) tracking drift cards released at 

 strategic locations in the bay. 



Four Bristol Bay river systems were studied — Naknek, 

 Kvichak, Egegik, and Ugashik (Fig. 1). These systems 

 were chosen because their average combined production 

 of sockeye salmon is more than 70% of the total annual 

 Bristol Bay run. Moreover, a considerable amount of in- 

 shore mark-and-recovery data were available for adult 

 salmon of stocks occurring along the southeast side of the 

 inner bay where these rivers enter. 



Determining Salinity Distribution 



Salinity was measured in 1966 at stations along six 

 parallel transect lines across inner Bristol Bay. The 

 stations were located at 8-km intervals along the off- 

 shore transect lines, which were 16 km apart, and at 1.6- 

 and 3.2-km intervals along inshore transect lines, which 

 were 8 km apart. Salinity was measured with a Beck- 

 man Model RS5-3 electrodeless induction salinometer at 

 the surface and at 1- and 2-m intervals thereafter to the 

 bottom at low tide and usually during the following high 

 tide. 



Data were collected on consecutive days in late July 

 and August during periods when tidal conditions were as 

 nearly similar as possible. Although transects could not 

 always be run on the desired tide because of inclement 

 weather and darkness, they could usually be run on the 

 lowest and highest tides of the day. Coverage of a 

 transect line usually began between 1 and l'/2 h before 

 low or high tide. The tracking vessel was kept on a con- 

 stant compass course along a given transect line as it 



