WHITEFISH FISHERY OF LAKES HURON AND MICHIGAN 



353 



Table 27. — Number of legal and illegal whitefish per lift of pound nets and deep trap nets in the Green Bay 

 area (ports of Marinette, Escanaba, and Fairport), 1931-1932 



[Number of lifts in parentheses. Asterisks indicate concentrations] 



NORTHEASTERN LAKE MICHIGAN 

 I MANISTIQUE, EPOUFETTE, AND NAUBINWAY I 



The data on the bathymetric distribution of the whitefish are more complete for 

 northeastern Lake Michigan than for any other region. Not only was the number of 

 lifts of pound nets and deep trap nets observed large (350) but these lifts were well 

 distributed as to depth of water. Only the deep water (depths greater than 110 feet) 

 was poorly represented, largely because few nets were set there owing to the compara- 

 tive scarcity of whitefish. 



Distribution of legal-sized whitefish. — Peak concentrations of legal whitefish in 

 June occurred at 61-70 feet and 81-90 feet (table 28 and fig. 22). The average num- 

 ber of fish per lift in "deep water" (more than 110 feet) exceeded slightly the average 

 in 101-110 feet but the deeper water was represented by only two lifts. There were 

 again two peaks in July, but in this month they occurred in water 20 feet deeper (81-90 

 and 101-110 feet I. This offshore movement was reflected also in the reduced catches 

 of nets in all waters shallower than 71 feet. The depths of greatest concentration of 

 legal whitefish were the same in August as in July although the small decrease in the 

 average number of fish from nets set in 71-80 feet together with the increase in the 

 catch per net from all deeper waters may be taken as an indication of possible further 

 offshore movement. In September the average number of legal whitefish per lift was 

 below the August average at all depths less than 91 feet. The single peak occurred in 

 the 101-110 foot interval. (Nothing is known concerning the abundance of whitefish 

 at depths greater than 110 feet in September.) The improved catches in the shallower 

 water (less than 71 feet) in October offer evidence of a return onshore movement. In 

 this same month the condition of two concentration zones reappeared although it was 

 by no means pronounced. 



The seasons' averages show a consistent increase in the number of legal fish per 

 lift from shallow water (less than 41 feet) to the 81-90 foot interval, followed by a 

 sharp decline at 91-100 feet and a rise to a second peak at 101-110 feet. The average 

 of 7 lifts from the deepest water was about half that of lifts from the 101-110 foot 

 interval. 



Distribution of illegal-sized whitefish. — The data on the depth distribution of illegal 

 whitefish resembled in general those for legal fish. Both groups were characterized by 



