of the three categories are discussed for all of 

 the systems because for some systems the data 

 are too few. 



PHYSICAL DESCRIPTION OF 

 THE LAKES 



A substantial portion of this study was de- 

 voted to obtaining physical data on the lakes of 

 sockeye salmon systems in southwestern Alaska. 

 All of these lakes were either formed or modified 

 by glaciation during the Pleistocene (Mertie, 

 1938; Keller and Reiser, 1959). Except for the 

 Alagnak system, the lakes lie at elevations less 

 than 100 m. above sea level (table 1). In some 

 systems tidal influence extends to or almost to 

 the outlet of the lowest lake. 



On the basis of geological and biological as- 

 pects, the systems studied fall into two general 

 groups — "Mainland" and "Peninsula." The 

 Mainland Systems drain into Bristol Bay along 

 the west and north shores and include the Igu- 

 shik. Snake, Wood, Nuyakuk, and Kvichak. Sev- 

 eral of the Peninsula Systems enter Bristol Bay 

 from the northeast and east — the Alagnak, Nak- 

 nek, Egegik, and Ugashik. Two other systems 

 that we place in the peninsula category enter the 



Table 1. — Morphometry and altitudes of major sockeye salm- 

 on lakes of southwestern Alaska 



Depth 



System and lake 



Lake 

 area 



Maxi- 

 mum 



Develop- 

 ment 

 Volume of 

 shore- 

 line ' 



Alti- 

 tude 



MAINLAND 



SYSTEMS Km.' 



Igushik system 



Amanka Lake 35 



Ualik Lake 39 



Total 74 



Snake system 

 Lake Nuna- 



vaugaluk 89 



Total 89 



Wood system 



Lake Aleknagik.. 83 



Lake Norka 201 



Lake Beverley 90 



Lake Kulik 45 



Little Togiak 



Lake 6 



Total 425 



Nuyakuk (Tikchik) 

 system 



Tikchik Lake 53 



Nuyakuk Lake,, 144 



Lake Chauekuk- 



tuli 



Total. -- 



M. 



65 

 72 



23 

 28 



0.80 

 1.10 



3.94 

 1.78 



9 



15 



162 



110 

 164 

 188 

 160 



43 

 39 

 55 



77 



30 



3.57 

 7.84 

 4.95 

 3.47 



.18 



4.22 

 5.70 

 3.46 

 2.80 



3.50 



10 

 21 

 30 

 43 



45 

 283 



15 

 113 



.80 

 16.27 



2.44 

 2.92 



95 

 95 



Table 1. — Morphometry and altitudes of major sockeye salm- 

 on lakes of southwestern Alaska — Continued 



Ugaahik system 

 Upper Ugaahik 



Lake 



Lower Ugashik 



Lake 



Total 



1.70 



Chignik system 

 Chignik Lake- 

 Black Lake 



Total - 



Karluk system 

 Karluk Lake. 



40 



' Ratio of the length of the shoreline to the length of the circumference 

 of a circle of area equal to that of the lake. 



Pacific Ocean — the Chignik on the east coast of 

 the Alaska Peninsula and the Karluk on the 

 northwest shore of Kodiak Island. 



The geology of each general area is believed 

 to be at least partly responsible for differences 

 in water quality. Drainage areas of the Mainland 

 Systems consist primarily of sedimentary rocks, 

 which occasionally include local deposits of lime- 

 stone. Minor bodies of igneous rocks and other 

 products of volcanism also occur. In contrast, 

 the drainage areas of the Peninsula Systems, 



SOCKEYE SALMON IN MAJOR RIVER SYSTEMS IN SOUTHWESTERN ALASKA 



409 



