The sockeye salmon of the Naknek system have the 

 general freshwater life history common to most stocks 

 of the species. Adults return to fresh water in early 

 summer, ascend the system through rivers and lakes, 

 and spawn in gravel of streams or lake beaches. The 

 embryos overwinter in the gravel, and young salmon 

 emerge and enter the littoral areas of the lakes in 

 spring. The juvenile salmon soon move out into the 

 pelagic areas where they feed on zooplankton for 1 or 

 2 summers before going to the ocean as smolts in the 

 spring. In the Naknek system, smolts are yearlings 

 (age I); 2-year-olds (age II); or, rarely, 3-year-olds 

 (age III). Each lake in the Naknek system has its own 

 unique combination of physical features and assem- 

 blage of other species offish associated with the young 

 sockeye salmon. 



The National Marine Fisheries Service (formerly 

 the Bureau of Commercial Fisheries) has conducted 

 research on the Naknek system since about 1940, but 

 intensive work on juvenile sockeye salmon and as- 

 sociated species offish began in 1961. A principal ob- 

 jective of this research has been to define some of the 

 details of the life history of the juvenile sockeye salm- 

 on in the system. The results of the research on 

 juvenile sockeye salmon through 1962 were presented 

 in a report that summarized all available information 

 on the major sockeye salmon systems of southwestern 

 Alaska (Burgner et al., 1969). 



I continued the work on juvenile sockeye salmon 

 and associated species in the Naknek system, and in 

 this report I analyze the data collected from 1961 

 through 1964. First is a description of the general dis- 

 tribution and relative abundance of all species of fish 



in the system, based on sampling with several types of 

 gear. This is followed by a discussion of the abun- 

 dance of juvenile sockeye salmon and a few associated 

 species in the habitats where these fish are most 

 abundant — the pelagic areas. Next is the account of 

 the migrations of young-of-the-year (age 0) sockeye 

 salmon from lake to lake in two areas. Changes in 

 average lengths and length-frequency distributions are 

 then used to determine relative growth in the lakes of 

 the system. The significance of predators in control- 

 ling the numbers of juvenile sockeye salmon in the 

 Naknek system is considered next. Finally, all of the 

 available information is marshaled and summarized to 

 consider for the fishery manager what factors seem to 

 be limiting the production of sockeye salmon in the 

 Naknek system and what might be done to increase 

 production. 



THE STUDY AREA 



The freshwater environment of sockeye salmon in- 

 cludes the spawning grounds of streams or lake 

 beaches, followed briefly by the open waters of the 

 spawning streams or beaches, and then the littoral 

 areas of the lakes for a few days or weeks and the 

 pelagic areas of the lakes for several months, followed, 

 again briefly, by the outlet river as the juveniles go to 

 the ocean as smolts. 



The Naknek system (Fig. 1) consists of four major 

 connected lakes — Coville, Grosvenor, Naknek, and 

 Brooks — and the outlet stream, Naknek River, which 

 connects the lakes to the ocean. Naknek Lake con- 

 tains four distinct basins and a large shallow outlet 



HAMMERSLY 



V"lv. HARDSCRABBLE 

 CREEK ■ 



HEADWATER 

 CREEK 



Figure 1.— Naknek River system, Bristol Bay, Alaska, showing sampling units where juvenile sockeye salmon were studied from 



1961 to 1964. 



