All of the stragglers which composed the end of the Carp 

 Creek run in 19h7 displayed some evident loss of vision. In 

 several of the migrants taken during tl'ie month of July, the eyes 

 \vere already millcy-Tviiite and opaque and those specimens did nob 

 respond to visual sticiuli. This ims likemse true of the late 

 migrants captured in Ocqueoc Lal-ce during July of the same season. 



A general increase in migratory activity during daylight 

 hours as the spa'vvning season progresses has been described pre- 

 viously. The increase in activity during the daytime is much 

 more pronounced on the spa^-vning grounds during the sane period 

 and is climaxed -with equaJL spaivning activity occurring at all 

 hours of the day and night. It appears that loss of vision 

 parallels ripening of tlie gonads, that it progresses in severity 

 as spatming time approaches, and that it culminates in total 

 blindness by the time an individual is spent. Other evidence 

 indicates that loss of vi,sion occurs more rapidly among late 

 migrants than among early ones. 



(2) Loss of epidermis 



In all dying and freshly dead sea lampreys it was observed 

 that large, irregular patches of outer skin had been lost. ViTith 

 the layer that had been sloughed-off , went its mucous coating 

 and the pigmentation of the variety of spawning colorations 

 •viiiich occurred. The deeper layers of the integument which vrere 

 exposed ivere a dull^, blue-black in color ivith a vague overprint- 

 ing of the characteristic black mottling. Those areas upon 

 Ti/hich the outermost layers still remained coiild easily be de- 

 nied of their covering by a firm stripping action with the hand. 



Skin loss was first noticeable in mid-breeding season among 

 live adults which were nearing the completion of sparming. As 

 the spaiwiing period progressed, increasing numbers of individuals 

 ivere found on the nests -viiiich displayed some loss of body cover- 

 ing. At the close of the season, all adults observed at the 

 peak of their spawning activity, or later, had suffered a similar 

 loss. Among li'/e indi\d,duals, the most noticeable loss cf 5.reas 

 of the skin was found among spent males. These males character- 

 istically cling to^ or remain in the bottom of, the nest for a ' 

 variable period foll.owing the completion of spavming. On observa- 

 tion, it seems hardly possible that these males, ^•a.th their life- 

 less behavi.or-;; with white, opaque eyes and ivith scaly, broken 

 skin, could still be alive or could live to spa'vvn again. 



Much of this loss of body covering may be attributed to abra- 

 sion against hard bottom materials during the violent exertions 

 of nest building and spawning. Among the females, further scar- 

 ring and abrasion of the head region occurs from the male grasp- 

 ing her in that region Td.th his mouth during each spaivning act. 



- 119 - 



