Putrefaction was pronounced during the second and third days after poisoning, and 

 It seems likely that there may have been weight shrinkage as great as 5 or 10 per cent 

 due to bacterial action. No corrections have been attempted for such losses. Large 

 representative samples were preserved for the Survey collections and for subsequent 

 examination. Scales from several klnda were taken for age determination. 



As many of the fry of the year as could be gathered up were preserved. These 

 amounted to about one pound. All other fish were burled as fast as the observations 

 on them were completed. 



The four most abundant species (by weight) In Fork Lake were the black bullhead, 

 redmouth buffalo, carp and golden shiner. Only 32 of the 3,520 black bullheads were 

 large enough to be caught and dressed. Redmouth buffalo almost never take the hook. 

 Carp bite more readily but few people are Interested In fishing for them. The golden 

 shiner Is a large minnow but 18 not considered edible nor sought for by anglera. The 

 nimibers and weights of fish of legal size of those kinds which take the hook readily 

 are given In table 6. These edible hook-and-llne fish weighed 36,7 pounds, less than 

 5 per cent of the total weight of all fish, 



TABLE e.—^OOK-rAND-LINE FISH OF EDIBLE SIZES 



* Arbitrary sizes chosen as the minimum for table use, 



LIMNOLOGICAL OBSERVATIONS 



At the time of the fish census the lake had a surface temperature between 80 and 

 90 degrees F. The water was thermally stratified and had a temperature approximately 

 70 degrees F. near the bottom. Later (August 10), during a period of very wann weather, 

 temperatures and dissolved oxygen concentrations near the center of the lake were found 

 as shown In table 7, 



TABLE 7.— TEMPERATURES AND DISSOLVED OXYGEN 

 CONCENTRATIONS, AUGUST 10, 1938 



While the deeper samples showed depletion of oxygen, there was still sufficient 

 for most of the kinds of fish found in Illinois lakes. Although the lake Is protected 



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