drainage, they are seldom if ever seen during the daylight hours. 

 HoTVBver, visits at night to areas apparently devoid of sea 

 lampreys during the day reveal many migrants clinging to rocks or 

 working their way upstream. In daylight hours, they are found 

 "vvedged among and under rocks, logs, brush tangles, or retired 

 imder overhanging banlcs or on the bottom of the deeper pools. 

 ■When prodded from these hiding places thej'" dash blindly aimy "vaith 

 little regard for the direction taken. In several instances, 

 disturbed specmens darted at right angles to the current mth 

 such force that they slithered several feet up onto a low, grassy 

 banlc or mud flat. Generally, after traveling but a short distance, 

 they sought to conceal themselves again by utilizing vjhatevcr cover 

 iras available. Vfcen disturbed at night by having an observer shine 

 an artificial light on them, the lampreys flee also Tdth apparent 

 lack of direction. I have been -unable to drive them ahead of me 

 at night vri.th a jacklight accompanied by splashing. Again they 

 tend to scui-rj'- in all directions, mostly doTimstream and often be- 

 tween the legs of the drivers. Their fellovr migrants, the suckers 

 ( Catostomus spp.)j behave differently. They move systematically 

 aivaj'' from such disturbances in more or less of a groTong school. 



Prior to any spa-vming activity, migrant sea lampreys taken in 

 streams are very tenacious of life, particularly in cool weather, 

 and lidll survive much longer v;-hen held out of imter than most other 

 fishes. Specimens retained in a miH: can vd.thout water for six 

 hoi\rs at about 3^ degrees F. on a spring night shovred no apparent 

 ill effects of their confinement vrhen placed in water again. The 

 pumping action of tlie gill pouches is very persistent, and vrlll 

 last as long as 1 l/2 hours in specimens that have been drawn 

 (gutted). 



Both negative phototropism and vitality change with the 

 advent of pealc spaivning activity. Migrants become more and m-ore 

 evident during daylight houi's, particularly at obstructions to 

 migration, and nest building and spa-wning activity becomes as 

 great in the light as during the hours of darkness. Among those 

 sea lampreys engaged in spawning, this is most probably due to 

 progressive loss of vision wliich accompanies the physical degener- 

 ation talcing place at this time. Wearing the completion of spawn- 

 ing, most individuals were judged to be blind or nearly so. The 

 tendency of migrating sea laj-npreys to be more in evidence in daj"-- 

 light during the latter half of the run may be due to this ocular 

 degeneration and/or to an ixrge to reach suitable grounds and com- 

 mence spawning. Both or either may offset to some degree the dis- 

 played response to light of earlier migrants. 



The great vitality noted in early migrants lil^evase disappears; 

 late migrants die on little handling or removal from the water. 



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