lining cells into the Ixmen of the dicestive tract ivas observed. 

 Those facts suggest tl^at the general regression of all tissue 

 la7ers present in the intestines of se^rually naturing sea lanprejs 

 results frojn an active autolysis, i.e., a resorption and diges- 

 tion of these tissues. It seeir.s entirely feasible that such re- 

 sorbed cellular material could be utilized by the sea lanprey; 

 subsequent to the time that it ceases feeding it nust migrate 

 often long distances upstream, aiid collaterally must complete 

 the fon.iation of its sexual products, and finally must construct 

 its nest and spaTvn, 



It is "ivitidn the realm of possibility that a regeneration 

 of tissues might take place in the intestine of a spar^ned-out 

 adult. However, this is deemed hi:_:hly unlikely. The functional 

 characteristics and the digestive capabilities of this organ 

 have been so severely reduced th^t such a regeneration could 

 hardly occur. 



(U) Discoloration of flesh 



The flesh of sexually-iimature, adult lampreys taken in the 

 Great Lalces was found to be unif onrily white and of an appearance 

 not unlike that of many other fishes. In virtually all migrating 

 sea lampreys, certain localized areas of the flesh display varying 

 amounts of a bluish discoloration. This discoloration occurred 

 primarily in a band immediately beneath the integument, along the 

 dorsal septum, and around the median skeletogenous elements (noto- 

 chord, etc). Furthermore, in the most mature specir.ens, a light 

 bluish tint was im.parted to all portions of the flesh, 



Presumatly this discoloration is the result of the deposi- 

 tion of catabolic wastes in the flesh consequent to the decline 

 in the functional capabilities of the digestive tract and associated 

 organs of elimination, 



VII, Some economic characteristics of spa?ming runs 



This discussion is not concerned T/ith the matter of control 

 of lamprey populations in the upper Great Lalces, but rather with 

 the potential commeicial utilization of sea lampreys taken either 

 by control devices or hy a possible commercial trapping enterprise. 

 This matter has been given some attention Tdth the object of deter- 

 milling compensatory uses for this predator in the event that the 

 control of its nxmbers is deemed either physically or financially 

 impractical. 



The m.ajor uses to Tri;ich sea lampreys, trapped on their spairvn- 

 ing runs, might be put are as follows: (1) Food — for human con- 

 sumption or as animal farm (mdnk, fox ranches, etc.), or fish hat- 

 chery rations; (2) reduction for oil, fertilizer, meal or derived 

 by-products; (3) reduction for medicinal products; and (Ij.) sale 

 as biological specimens. 



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