portion, each of which I treat as an entity — Iliuk Arm, 

 South Bay, West End, North Arm, and Northwest 

 Basin. Two small lakes at relatively high elevations, 

 Hammersly and Murray, receive small numbers of 

 adult sockeye salmon, but were not part of this study. 

 The basic bathymetry and limnology of the lakes of 

 the Naknek system have been determined. The total 

 surface area and the areas within the 5-m contour, 

 selected as the arbitrary limit of the pelagic area, for 

 each lake or basin and the sampling units within each 

 lake or basin are itemized in Table 1 . The limnology of 

 these lakes was intensively studied in 1961 and 1962, 

 and details of the chemistry and productivity were 

 summarized and compared with other western Alaska 

 lakes (Burgneretal., 1969). In general, the lakes of the 

 Naknek system are deep and oligotrophic and have a 

 pH of about 7.2 and alkalinity of about 26 ppm. Max- 

 imum summer surface temperatures reach 12° to 16°C. 



and although thermoclines occasionally occur, they 

 usually last only a few days. 



Each lake of the Naknek system has several spawn- 

 ing grounds that are used by sockeye salmon, but 

 neither the extent of the spawning grounds nor the 

 numbers of spawners in the escapements (the adult 

 salmon that escape the fishery and enter fresh water to 

 spawn) are uniformly proportional to the size of the 

 lakes (Table 2). In Table 2 the various types of stream 

 spawning grounds have been combined for each lake 

 (the few known beach spawning areas are not signifi- 

 cant). The distribution of spawners among the several 

 lakes each year is variable and only occasionally pro- 

 portional to the amount of spawning ground contigu- 

 ous to each lake. For example, American Creek 

 (Coville Lake) has about one-third of the system's 

 spawning ground, but from 1959 to 1963 it received 

 from 10% to 60% of the escapement. 



Table 1. --Total surface area, area within 5-m contour, percent of each lake deeper than 5 m, and 

 percent of system total deeper than 5 m for lakes of the Naknek River system. 



Lake and 

 sampling area 



Total surface 

 area (km 2 ) 



Area within 



5-m contour 



(birj 



Percent of each lake 



deeper than 5-m 

 Contribution Total 

 of each area lake 



Percent of 



system total 



deeper than 



5 m 



Coville Lake 1 

 C-l 

 C-2 

 Total 

 Grosvenor Lake 

 G-l and 2 

 G-3 and 4 

 Total 

 Iliuk Arm 

 .VI 5 

 N-14 

 N-13 

 Total 

 Sou tli Bay 

 N-ll 

 N-9 

 N-6 

 Total 

 West End 

 N-4 

 N-2 

 N-l 

 Total 

 North Arm (all 

 units combined) 

 Nor times t Basin 



N-3 

 Brooks Lake 

 B-l and 2 

 System total 



181.5 



40.8 



74.9 



162.1 



74.6 



89. 



70. 



99.6 



4.5 



11.1 



790.2 



670.0 



84. S 



! In 1963 and 1964 Coville Lake was divided into more sample areas; the percent of the surface 

 area in water deeper than 5 m in each sampling area was: 1965--C-1 = 5.50, C-2U = 55.86, C-2M = 

 28.58, C-2L = 10.26; 1964--C-1 = 10.67, C-2 = 51.50, C-5 = 55.57, C-4 = 11.77, C-5 = 10.66. 



