Like the Carp Creek vreir, the Ocqueoc structure was contin- 

 ually checked for points of escapement. In view of this procedure 

 and the small size of the two specimens recovered in the watershed, 

 I conclude that those that negotiated the weir did so by working 

 through the steel grates. A check of the spacing between bars of 

 the grates, -vvhich was made late in the season, indicated that 

 several bars had become spread so that the intervening space was 

 as much as 5/8 inch. It seems certain, then, that the smaller 

 migrants can work their way through vertical bars spaced at 5/8 of 

 an inch. 



(3) Methods , places and times of sampling , and 

 collection of other data in 19h7 and 19U8 



Sea lampreys in the Ocqueoc watershed tended to concentrate 

 at two points during their upstream migration. The first concen- 

 tration place was in Ocqueoc Lake, 2 l/U miles above the mouth of 

 the river. This was accidentally discovered on May 29, 19h7 , "vvhen 

 netting operations were begun to determine if any predation upon 

 resident game fish occurred while the sea lampreys were passing 

 through the lake. On that date an 18.2-inch male sea lamprey in 

 an advanced state of sexual maturity was taken in the 1 l/2-inch 

 stretch mesh of an experimental gill net set in the north end of 

 the lake. Thereafter, gill nets set in the northern half of the 

 lake always yielded one or more sea lampreys in the 1 l/2-inch mesh 

 portion of the nets. The greatest catch was on June 19 when 16 sea 

 lampreys were taken in a 125-foot, 1 1/2 -inch stretch measure gill 

 net; this was a 20-hour set. Concentration in Ocqueoc Lake was 

 evidently due to the inability of the run moving into the lalce to 

 find immediately the inlet of the Ocqueoc River. Ocqueoc Lake is 

 long, narrow and irregular in outline; its outlet where the sea 

 lampreys migrate into the lake is at the extreme northern end of 

 the lake and its inlet enters the southernmost extension. Captures 

 in the gill nets were made at all depths from 2 to 18 feet. Further- 

 more, specimens taken ■vrere traveling in all possible directions 

 ■srtiich would seem to indicate that they were searching more or less 

 aimlessly for the inlet stream. On several occasions during the 

 second week in June, sea lampreys were seen from the bank moving 

 along the shoals in a direction opposite to that which would lead 

 them to the inlet of the river. 



Altogether, 69 sea lampreys in advanced stages of sexual matu- 

 rity were collected by this method. They varied in total length 

 from lij..3 to 20.5 inches and presiimably indicate the size range 

 most efficiently trapped by this method. Actually, the sea lamprey 

 does not become "gilled" in the net but is trapped by its oivn 

 natural reactions. Swimming noinally with their buccal funnel 



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