118 U.S. BUREAU OP FISHERIES 



1. The amount of destruction of baby lake trout (average weight 

 about 12 ounces) by chub nets cannot be reduced by changing the 

 mesh in these nets to a size that would still be suitable for the pur- 

 pose of taking chubs. The adoption of any one of the three sizes of 

 mesh (2}^, 2%, and 2% inches) now legally employed in the different 

 States fronting Lake Michigan will not alter the destructiveness of 

 chub nets to small lake trout. 



2. Chubs show a sensitive reaction to the size of mesh in gill nets 

 in the number of fish taken per net. On the average, the number of 

 chubs taken in the 2J^-inch mesh gill nets is reduced by 38 percent 

 with an increase in mesh to 2% inches and by 62 percent with an 

 increase in mesh to 2% inches, or in terms of weight in pounds the per- 

 centages of reduction are respectively 36 and 61 percent. With an 

 increase in size of mesh from 2% to 2% inches there is a corresponding 

 decrease of 39 percent in both the number and weight of chubs. 



3. Baby lake trout were found to be about 2.7 times as abundant 

 in the Michigan waters of Lake Michigan as in the Wisconsin waters 

 of this lake. In Michigan the sale of all baby lake trout is prohibited; 

 in Wisconsin the sale of those taken in gill nets is permitted and, as 

 a consequence of this, a large market has been developed for these 

 immature fish. It is believed that this practice of selling these baby 

 trout in Wisconsin is primarily responsible for the difl^erence in its 

 abundance in the two States. It has been recommended, therefore, 

 that suitable legislation to prohibit or at least to curb the sale and 

 transportation of these immature fish be enacted in those States that 

 have no such restrictions at the present time. 



4. Chubs were found to be about 2.7 times as abundant in the 

 Michigan waters of Lake Michigan as in the Wisconsin and Ilhnois 

 waters of this lake. It is believed that this difference in abundance 

 is caused primarily by the difference in the size of mesh employed for 

 chubs in the three States. Illinois permits a 2K-inch mesh, Wiscon- 

 sin a 2%-inch mesh, and Michigan a 2%- to 2%-incli mesh. It is com- 

 mon knowledge among the fishermen that the chubs are steadily 

 decreasing in abundance in Lake Michigan especially along the Wis- 

 consin shore. It is absolutely essential, therefore, that fishing inten- 

 sity be decreased if the chub fisheries are to be saved. One of the 

 most practical ways to do this is to increase the size of mesh in chub 

 nets to a minimum of 2% inches. Such a minimum in size of mesh 

 would, according to our data, reduce the catch of chubs about 39 per- 

 cent in Wisconsin where most of the small mesh chub nets are fished. 

 If such reduction in catch is not sufficient to enable the chubs to 

 maintain the desirable level of abundance further restrictions, such 

 as a closed season, will be necessary. An increase in the size of mesh 

 would also give additional protection to the smaller chubs, would 

 increase the average size of chub produced for the market, which 

 increased size would in turn raise the price per pound paid the 

 fishermen. 



DEEP TRAP NETS OF LAKES HURON AND MICHIGAN 



The deep trap-net investigation, begun in 1931 (see report for 1931), 

 was resumed on May 7, 1932, and completed on October 20, 1932, 

 The State of Michigan again cooperated with the Bureau by furnish- 

 ing 3 field assistants and 2 automobiles for transportation. Deep 

 trap and pound-net lifts were studied at Harbor Beach, Bay Port, 



