Table 1. — Sockeye salmon in daily escapements and num- 

 ber and percent tagged, Naknek River, June $4 to July SI, 

 1962 



1 Escapement estimates provided by Alaska Department of Fish and 

 Game. Margin of error determined from previous studies is 3 percent of 

 estimated total run. 



J Colors used were blue (B), green (G),red (R), white (W),and yellow (Y). 

 The first letter of a color combination designates the left side tag color. 



3 Percent of daily escapement tagged was not completed for the first 2 days. 

 The earliest fish to arrive commonly held up between the tagging and tower 

 sites below the rapids for a day or two until the schools build up in size. 



* Tagging ended on this date. 



of the catch and the magnitude of the daily 

 escapement. If the escapement and seine catch 

 were small, every fish was sampled; if they were 

 large, every second, third, or fourth fish was 

 sampled. A total of 3,094 fish, or about 45 per- 

 cent of the total number tagged, were sampled. 



Samples were also taken from individual 

 spawning grounds during the period of spawning 

 activity and from the weirs on Brooks River and 

 American and Hardscrabble Creeks almost daily. 

 In addition, fish obtained during beach seining 

 for tag recovery records were sampled for age, size, 

 and sex. Survey crews covering the smaller 

 tributary streams for tags sampled the spawners 

 in these areas. 



Tagged fish were seen near the outlets of all 

 lakes and on some spawning grounds. Observers 

 in towers located on each bank of the river at the 

 outlet of Grosvenor and Coville Lakes (fig. 2) 

 recorded the number of fish and the color combina- 

 tion of all tags seen entering these lakes. At 

 Brooks Lake observers recorded tagged fish as they 

 passed through counting gates of the Brooks River 



weir (fig. 2). On certain spawning grounds it was 

 necessary to rely largely on observations of tagged 

 fish, because sometimes the fish could not be 

 recaptured. This was particularly true for salmon 

 spawning on Grosvenor Lake beaches and deep 

 swift portions of Grosvenor River and Naknek 

 Lake outlet areas. Here observers counted tagged 

 fish from towers located on boats. 



Actual recaptures of tagged fish were obtained 

 from several sources. On Brooks River and 

 American and Hardscrabble Creeks (fig. 2) , tagged 

 fish were obtained at weir traps. Tributary and 

 interconnecting streams that were not checked 

 by means of weirs were surveyed for tagged fish 

 on foot or by boat several times during the spawn- 

 ing period. In some of the larger and deeper 

 streams, tagged fish were recaptured by beach 

 seining or by spearing with the use of skin diving 

 and scuba diving techniques. 



Total spawning ground recoveries amounted to 

 1,202 fish, or about 18 percent of those tagged 

 (table 2). An additional 82 tagged fish were 

 sighted, but the color combinations could not be 

 positively identified. 



Scales taken from sockeye salmon at the time 

 of spawning have margins that are absorbed to 

 such an extent that only fresh-water age is dis- 

 cernible on a projector. It was necessary to resort 

 to length-frequency distributions of 2- and 3-ocean 

 sockeye salmon derived from fish sampled at the 

 tagging site (1,428 males and 1,621 females) for 

 the assignment of ocean age to each fish sampled 

 on the spawning ground. Approximately 98 per- 

 cent of the fish in the 1962 escapement spent 2 or 3 

 years in the ocean. For assignment of ocean age, 

 the dividing line used between fish of 2-ocean and 

 3-ocean age was 540 mm. for females and 553 mm. 

 for males. Fish shorter than those lengths were 

 considered as 2-ocean, and those longer as 3-ocean. 

 I found no discrepancies between ages assigned to 

 tagged salmon sampled twice — in the trunk stream 

 and on the spawning grounds. 



Fish were measured to the nearest millimeter 

 from the center of the eye to the fork of the tail. 



The sex of each fish was determined from exter- 

 nal characteristics. 



METHODS OF ANALYSIS 

 Seasonal Timing of Spawning Populations 



The extent of segregation of individual spawning 

 populations by time of occurrence in the run may 



SALMON SPAWNING POPULATIONS IN NAKNEK RIVER 

 774-711 O — 66 12 



465 



