Visual observations were made during daylight and 

 darkness while walking along Grosvenor Lake from 

 Hardscrabble Creek to Grosvenor River and along 

 Grosvenor River on the shore or in shallow water. 

 Hand-held lights were used at night. 



Most of the sockeye salmon fry captured in the fyke 

 nets (Table 20) or seen migrating were moving down- 

 stream on the east shore of Grosvenor River at night. 

 A few fry were seen moving upstream near shore from 

 Grosvenor River to Grosvenor Lake from May to 

 June; the only other indication of an upstream move- 

 ment from Grosvenor River was the capture of a few 

 fry in fyke nets open downstream (Table 20). Fyke 

 nets fished in shallow water near the lower end of 

 Grosvenor River on 11, 16, 17, and 19 May indicated 

 that recently emerged fry were moving downstream, 

 but the origin of these fry is uncertain. Presumably 

 they were a mixture of fry originating in Grosvenor 

 River and Hardscrabble Creek. 



Migrating fry were also sampled intermittently with 

 fyke nets in Hardscrabble Creek between 11 May and 

 25 June. During this time the water level and velocity 

 changed so that the rate of catch of fry in Hardscrab- 

 ble Creek is the result of straining greatly different 

 proportions of the total flow and, presumably, of the 

 nightly migration. Therefore, only one general conclu- 

 sion can be made about the migration — some sockeye 

 salmon fry were moving downstream in Hardscrabble 

 Creek between 11 May and 25 June. 



Visual observations along the edge of Hardscrabble 

 Creek at night below the fyke net collecting site 

 showed that the fry usually swam downstream. Some 

 fry stayed in shallow water in the delta of the stream 

 and could be seen along the lake shore and on into 

 Grosvenor River. It appeared that at least some fry 



from Hardscrabble Creek never entered the pelagic 

 area of Grosvenor Lake but stayed in water from 

 Hardscrabble Creek well downstream in Grosvenor 

 River. Hardscrabble Creek water was not mixed with 

 water from Grosvenor Lake until about 180 m below 

 the lake. The two waters were initially quite 

 distinct — the water of Hardscrabble Creek was murky 

 from erosion products and glacial melt and the water 

 of Grosvenor Lake was clear. Further evidence that at 

 least some fry moved directly from Hardscrabble 

 Creek to Grosvenor River was found by comparing 

 fry from Hardscrabble Creek and from the head of 

 Grosvenor River. Samples collected on the same or 

 adjacent nights in the two areas were nearly identical 

 in regard to length frequencies and the proportion of 

 fry containing visible yolk. If the fry leaving Gros- 

 venor Lake had been in the lake very long, they would 

 have absorbed more yolk and increased in length. 



I concluded that Uiuk Arm is the basin of first resi- 

 dence of practically all sockeye salmon fry originating 

 in Grosvenor River and of an unknown portion of 

 those originating in Hardscrabble Creek. Iliuk Arm 

 also receives some fry from streams tributary to the 

 Savonoski River above Grosvenor River. 



SIZE, LENGTH FREQUENCY, 

 AND GROWTH 



Intimately associated with the abundance of ani- 

 mals are the growth and size of individuals. In the 

 present study, the sizes of individual fish in the 

 catches were measured so that the effects of biological 

 and physical factors on size could be determined and 

 groups of fish could be identified. Although both 

 length and weight were measured, only the length 



Table 20. --Numbers of recently emerged sockeye salmon fry captured in fyke nets set on the east 

 and west shores of Grosvenor River near Grosvenor Lake in May and June 1962 to determine whether 

 fry were migrating upstream or downstream. 



Date 



Downstream migrants 



East shore West shore 



Hours 

 fished 



Fry caught 

 per hour 



Hours 

 fished 



Fry caught 

 per hour 



Upstream migrants 



East shore West shore 



Hours 

 fished 



Fry caught 

 per hour 



Hours 

 fished 



Fry caught 

 per hour 



May 17 

 May 18 

 May 19 

 May 20 

 May 21 

 May 22 

 May 23 

 May 24 

 May 25 

 June 10 

 June 11 

 June 16 

 June 17 

 June 19 

 June 25 



1.0 



0.5 

 2.5 

 4.8 

 1.7 

 4.2 

 7.5 

 3.5 



21.0 

 7.5 

 1.8 

 2.8 



11.4 



12.1 



51.0 



44.0 



190.0 



1-05.0 



95.3 



94.2 



12.7 



194.5 



36.8 



40.1 



70.6 



70.7 



1.6 



1.7 

 1.0 



1.7 

 4.2 



8.2 

 20.0 



2.2 

 158.3 



5.5 

 0.5 

 2.0 

 2.8 



0.4 

 0.0 

 2.0 

 1.1 



32 



