208 



Fishery Bulletin 103(1) 



165'OOTM 160°0'OW 155'0'OW ISO'O'CTW 145 J 0'0W 



Alaska /' _■ ,. V /" 



57.8 



57.6 - 



57.4 - 



57 2 



NE shelf 



Vkv> 



152.8 152 4 152.0 



Longitude (°W) 



151.6 



151 2 



Figure 1 



Location of sampling operations (CTD, plankton, and trawl) conducted 

 during 5-18 September 1993, Kodiak Island, Alaska, to examine geo- 

 graphic variation among age-0 walleye pollock I Theragra chalcogramma I. 

 The ocean currents, shown as arrows on upper map, are adapted from 

 Reed and Schumacher (1986). 



Kodiak vicinity was related to the recruitment of pollock 

 to the GOA fishery (Wilson, 20001. Furthermore, age-0 

 juveniles in this vicinity were large in comparison to 

 those collected elsewhere (Wilson, 2000). The large size 

 of the "Kodiak" juveniles may reflect faster growth (Bai- 

 ley et al., 1996) due to a rich diet of euphausiids (Me- 

 rati and Brodeur, 1996). In contrast, the diet of age-0 

 pollock along the Lower Peninsula was dominated by 

 larvaceans (Merati and Brodeur, 1996). Interestingly, 

 high densities of age-0 pollock were closer to shore in 

 the Kodiak vicinity than along the Lower Peninsula 

 where the shelf is relatively broad. 



The apparent richness of the Kodiak Island vicinity 

 may reflect its relative upstream position in the Alaska 

 Coastal Current (ACC) (Fig. 1). Stabeno et al. (2004) 

 integrated much research on the ACC to provide a com- 

 prehensive view of its importance in circulation over 

 the GOA shelf. The ACC is wind driven and structured 

 by seasonal influxes of fresh water. Flow is generally 



southwestward over the shelf but there is considerable 

 topographic influence. For example, landmasses at the 

 northern entrance to Shelikof Strait (Kennedy-Steven- 

 son Entrance) allow only about 70% of the ACC water 

 to enter the Strait. The remaining 30% of the water 

 flows south around the northeastern end of the Kodiak 

 Archipelago. This bifurcation of flow occurs in an area 

 of vigorous tidal mixing and localized upwelling, both 

 of which contribute to increased biological productiv- 

 ity. Off the northeastern Archipelago, Stabeno et al. 

 (2004) have shown that the ACC follows bathymetric 

 contours into and out of sea valleys, thus, providing 

 some across-shelf movement of water. Advection of wa- 

 ter was found by Coyle et al. (1990) to be important in 

 the enhancement of zooplankton in Auke Bay, which is 

 in the eastern GOA. Less is known about the exchange 

 of water and zooplankton between the bays and fjords 

 of the western GOA and the adjacent shelf. Thus, the 

 ACC probably helps enrich the waters off northeastern 



