Observational or direct evidences to support these statements 

 are of tivo types: Those derived from observations on the spasm- 

 ing gi'ounds and those obtained in connection with the operation 

 of sea lanprey ireirs and traps. D-uring the 19h7 and 19hQ seasons, 

 sea lamprey spawning activity was studied in detail in the Ocoueoc 

 River watershed. During and after the peak of spai^ming activity, 

 spent and dead or djd-ng adtGLts could always be found on those 

 spavming grounds where thorough examination was possible. Admit- 

 tedly, spent and dead sea lampreys were never verj' nuch in evi- 

 dence to the casual observer but a careful search under brush 

 tangles, in sloughs, baclavaters, and in the deeper silted pools 

 revealed manj"" that would ordinarily escape notice. Details of 

 one daj''s observations will illustrate this. On June 2k, 19l|7, a 

 0.6-mile stretch of the Ocqueoc River was carefully censused for 

 spavjning and dead sea lampreys. Of 19li individuals seen, 1^5 vrere 

 occupied ivith spawning activity. The remainder, 39 (20.1 percent), 

 were dead or very nearly so, and were picked up in quiet water or 

 in locations ivhere their bodies vrould catch imder or against logs, 

 brush, and stones. Furthermore, an investigation of the deeper, 

 silted pools revealed many dead lampreys in advanced stages of 

 decay ivhich, because of f^agpientation, could not be counted. The 

 remains of most dead sea. lampreys present in the vratershed lay 

 at the bottom of these deeper pools. The depth of the pools 

 (many to 10 feet or more), the tea-colored water of the river, 

 and -the rapid decay and silting-over of the bodies all combined 

 to conceal the many dead individuals deposited there by the river 

 current . 



In pools, particularly below much-used spaivning riffles, 

 dredging activities produced numerous i^ite, tape-like structujresj 

 on comparison these proved to be sea lamprey notochords. These 

 notochordal "tapes" were all that remained of decayed sea lam- 

 preys. These persistent structures were also fcand caught against 

 brush and other snags in other parts of the stream. 



A contributing factor to the paucity of observable dead in 

 the shallower waters is the activities of the gulls and other 

 scavengers as described in a previous section of this study. 



This direct evidence that some or most sea lampreys die fol- 

 loTrving spaiivning, does not refute the contention that perhaps 

 some individuals recover to spaivn in another season. 'lowever, 

 the operation of the Ocqueoc River weir in 19h$ 'vAiich has been 

 reported upon by Shetter (19U3) offers excellent testimony that 

 very few if any recover from the spairTning act. Tiils point has 

 not been elaborated by Shetter. A weir and trap was operated L'l 

 the Ocqueoc River from April 22 to July 1$, 19U5. The river over- 

 topped the weir on April 2^^-28 and again, diu:'ing the peak of mj.- 

 gration, on May 28-June 6. Although l4.,608 sea lampreys were 

 trapped, an escapement of perhaps I|.0 percent, of the run occ-iorred. 

 Those that passed the iveir were observed spawning subsequently 



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