Naknek and Karlnk systeyns. — General ob- 

 servations had indicated that the space require- 

 ments for spawning female sockeye salmon vary 

 with differences in quality of the gravel and size 

 and stage of the stream and that the space used 

 by a spawning female is elastic — large when 

 escapements are low and small when they are 

 high. We estimated, therefore, the space require- 

 ment for a spawning female from maximum 

 observed densities of sp..\vners in measured sec- 

 tions of streams in the Naknek system. Average 

 densities for entire streams were used in the 

 Karluk system. 



Our studies confirmed the earlier general ob- 

 servations that space requirements vary among 

 different kinds of streams. For example, in the 

 lai-ge and relatively deep rivers between lakes 

 and the terminal rivers in the Naknek system, 

 the space requirements are between 4 and 9 m." 

 per female. In the smaller streams the require- 

 ments are much less — 2 to 3 m.- In the open- 

 water beach areas the requirements are probably 

 similar to or perhaps larger than those in the 

 large rivers. In the shallow torrential lateral 

 streams in the Karluk system, space require- 

 ments were often substantially less than 2 m.- 

 ( table 13) , but 2 m.- would appear typical for the 

 system as a whole on the basis of stream survey 

 data from many areas ( Richard Gard, personal 

 communication) . 



Our calculations of the potential capacity of 

 the streams in the Naknek and Karluk systems 

 to support spawning sockeye salmon are based 

 on the estimate of maximum density for each 

 type of stream. 



Estimates of Potential Spawning Capacity hy S\stem 



The potential capacity for the streams in each 

 system to support spawning adults was based on 

 the amount of potential spawning grounds and 

 the space required per spawning female. The 

 potential spawning capacities of the beach areas 

 were estimated from escapement surveys and 

 various other data. 



Wood system. — The potential spawning area 

 of rivers and streams (including connected 

 ponds) of the Wood system was estimated to be 

 241.4 hectai-es (table 12) , and the area required 

 per spawning female was estimated to be 2 m. ' 

 By dividing the spawning area by the area re- 

 quired per female and assuming a 1 : 1 sex ratio, 

 we calculate that the maximum spawning popu- 



Table 13. — Estimated numbers of potential redd sites in 

 various types of spaivning grounds of the Naknek and 

 Karluk systems 



Area of Area 



potential required 



System and type of spawning per Redd 



spawning ground ground female sites 



Hectares M.  Number 



Naknek system 



Terminal streams 124 9 4 1 302,000 



Small lateral streams__. 12 3 2 6 47.000 



I.arge lateral streams. . - 62 7 7 6 83.000 



Rivers between lakes__- 7 2 "8 8 8.000 



Outlet river 147,3 8 184,000 



Lake beaches . (-) 



Total 354-4 -_^^ 624 , 000 



Karluk system 



Terminal streams 1 67 2 8.000 



Lateral streams 6 71 2 34.000 



Lake beaches 125 2 6,000 



Outlet river 25 28 2 126,000 



Tot al 34 91 ._^ 174,000 



' Dfies not take into consideration successive waves of spawners. 



- An estimate of 20.000 redd sites is based on number of fish seen 



using the beaches of Grosvenor Lake. Other beach spawning areas 



e.xist. 



Table 14. — Estimated majiminn populations ol adult sockeye 

 salmon in strea^ns and lake beaches of Wood system in any 

 year between 19UG and 1962 



lation in streams in the Wood system is 2,414,000 

 sockeye salmon. 



The maximum numbers of sockeye salmon ob- 

 served on each spawning ground in 1946-62 were 

 summed by lake for stream spawning and for 

 beach spawning. Since only about 43 percent of 

 the fish that enter the system (estimated by 

 counts from towers) are seen during spawning 

 surveys, the summed maxima have been in- 

 creased to produce the estimate of the maximum 

 populations for streams and for lake beaches 

 (table 14). 



Maximum populations and the estimated po- 

 tential capacity of the spawning grounds in 

 streams are thought to be in reasonable agree- 

 ment, because use of the spawning grounds is 

 highly variable and some of the larger streams 



424 



U.S. FISH AND WILDLIFE SERVICE 



