at Station 5A. Passage upstream, beyond this point, is denied 

 the sea lamprey by an area Tihere the river disappears \mder~ 

 ground. Here it percolates through the sub-surface limestone 

 formations for several hundred yards, reforming at the surface 

 by the union of numerous^ small, sprinf~like feeders. Downstream 

 from the graveled area at ^A, the river ]ias a sand, cr sand and 

 clay bottom not utilized for spasming. 



Bottom types in Zone 2 -were predominantly rock, rubble, and 

 gravel and this combination occurred more or less unifonnly 

 throughout the zone varying only, from place to place, in their 

 relative proportions to each other. Sea lamprey spaiwiing activity 

 ivas more or less uniformly distributed throughout this zone 

 (Table 5, Figure 28, and Appendix G, Table 2). Within it, spaiwi- . 

 ing activity did not take place in the sandy-bottomed area ex- 

 tending from one-half mile below Station 2F to Station 2G nor did 

 it occur in those areas, occasionally intermediate between riffles, 

 •vvhich were characterized by bottom types of bou2ders and large 

 rubble imbedded in silt and/or clay. The farthest point upstream 

 utilized by the sea lampreys for spawning occurred at the head 

 of this zone at Station 21. This locality is 16.5 stream-miles 

 from the mouth of the river. 



No spawning occurred in either year in Zone 3» The stream 

 bed in this zone is predominantly covered mth muck or silt. 



Changes in the geographical pattern of spawning activity 

 during the spawning season were consistent for both years. Spscwn- 

 ing occurred initially in the area immediately below Ocqueoc Falls 

 (Zone 1, Stations IL to IM) and reached its peak there earlier 

 than anywhere else in the river. Six to ten days after the begin- 

 ning of spawning in the aforementioned area, spa-roing activity 

 spread rapidly in a progressive fashion down-river as far as 

 Ocqueoc Lake (Stations IL to IC). Peak spawrjjn.g activity in each 

 area, progressing downstream, vras proportionately later than that 

 peal^ which occurred just below the falls. 



In Zone 2, spaivning activity commenced uniformly over the 

 entire zone $ to 12 days later than in the area immediately below 

 Ocqueoc Falls, although water temperatures were consistently 

 higher than in Zone 1, I attribute this to generally less suit- 

 able spawning facilities "vrfaich resulted in a delay on the part 

 of the migrants entering this zone in selecting an acceptable 

 place for nest construction. This delay lasted until an increas- 

 ing urge to spaiim forced them to accept what ivere e\rLdently Su'b-=- 

 optijnum nest-b-ui.lding conditions. As it wj.ll ba shown in a la-ter 

 disc\is3icn, the shallow, rock- and rubble--strewn riffles char- 

 acteristic of Zone 2, offer acceptable, although not eminently 

 suitable, sea lamprey nest-building sites. 



- 93 



