an area of short, gravel riffles alternating with deep^ sandy 

 or silted pools. Continuing do'vmstreaniy hard bottom types dis- 

 appear rapidly and most of this lower zone of the river has a 

 bottom of fine sands v/ith occasional patches of g^-avel or exposed 

 clay substrate (Ficu.re 23, Zone 1)„ Sea la:nprey sparniing occurred 

 ■path equal intensity in tlae middle and lower thirds of the river", 

 in the former it was dispersed throug^iout the zonei in the latter^, . 

 it was concentrated in a short distance immediately below the 

 zonal boundary (Ocqueoc Falls ) . 



During 19U7 and 19U8, an intensive survey was r^ade of the 

 Ocqueoc River for areas occupied by larval lampreys. Thirty-seven 

 collecting stations encompassing all types of habitats were 

 visited one or more times each. Ammocoetes were found in bottom 

 m.aterials from the beach line at the mouth of the estuary upstream 

 throughout the lower tiTo-thirds of the watershed. They did not 

 occur above the hi^est point of spaivning., 16.5 stream miles from 

 the mouth of the river (Figure 28, Station 21),, 



Larval lampreys were found in greatest abundance -where soft 

 bottom types occurred. Here they can evidently make their burrows 

 most easily and find the greatest abundance of the micro-orgarasms 

 upon friiich they feed. The greatest concentrations of all age 

 groups were present where at least four, or more, inches of black 

 muck or silt, with some small adm±xture of sand, had been deposited 

 by the current. These sites frequently contained much undecompcsed 

 organic detritus (t^vigs, leaves, etc). Such deposits were normal- 

 ly situated in backwaters, eddies, sloughs^, or along the inside 

 of bends in the river where sluggish currents or slack wa.ter ex- 

 isted (Figures 51^ 52), Larvae were abundant in beds in these 

 locations, from the waters edge to depths of 3 l/2 feet (limit of 

 visibility in collecting with shocker) , 



Three areas occupied by numerous larvae, ivithin the 2-mile 

 reach below the Ocqueoc Falls "where the heaviest sea lamprey 

 spaivning occurs, may be cited as examples ^ One ■was a slough„ 

 formed in a quiet side channel around a small island in the river^ 

 In the months of July and August, a 226-square-foot area of this 

 bed ■vvas fo'und to contain 630 ammocoetes older than young-of-the- 

 year or about 3 individuals per square footc Young-of-the-year 

 larvae ivere present at the rate of 6 to 1? indi-vlduals per square 

 foot, averaging close to lii per square foot,, 



Another area -was a backwater along the bank of a swift flee- 

 ing portion of the river (Figure ^1). A 90— square-foot area of 

 this bed was shocked on two succeeding dates in "the month of 

 October, 19U7, A total of 107 larvae older than yoTjmg-of-the-year 

 were removed. No effort was made to collect the yoxmger specimens 

 but their concentration was estimated to average at least 10 indi- 

 •^riduals per square foot. 



111 



