WHITEFISH FISHERY OF LAKES HURON AND MICHIGAN 



331 



In size and construction the pound net and deep trap net resemble each other so 

 closely that the latter gear was known in some localities as the "submarine pound net" 

 (p. 300) . If the two gears are fished in the same depth of water neither has an impor- 

 tant advantage over the other. 25 However, pound nets which are held in place by 

 stakes driven into the bottom of the lake, and have cribs or pots extending from the 

 bottom to above the surface, ordinarily cannot be fished successfully at depths greater 

 than 80 feet. Most pound nets are operated in much shallower water. Deep trap nets, 

 on the other hand, have covered cribs and are held in position by means of lines attached 

 to anchors and by buoys. Consequently, they can be employed at all depths frequented 

 by whitefish. The use of stakes also limits pound nets to areas with a soft bottom into 

 which stakes can be driven. Deep trap nets do not suffer from this limitation. 



A further advantage of the deep trap net lies in its greater mobility. Pound nets 

 are fished in the same locality throughout the season (and usually year after year) but 

 deep trap nets can be moved much more easily and consequently can be fished in the 

 exact locations at which whitefish are found to be concentrated. 



The vertical distribution of the whitefish will be treated in part III. It may be 

 stated at this time, however, that usually whitefish are readily available to pound nets 



o 



5 



o 



0. 



7 S - 



Figure 12. — Comparison of the monthly production of whitefish in the Michigan waters of Lake Huron in 1929 and 1931, to bring out the effects 

 of the deep-trap-net fishery on the seasonal distribution of the catch. Gill nets, long dashes; deep trap nets, short dashes; pound nets, short and 

 long dashes; total production, solid line. 



M Field observations in northern Lake Michigan indicated that pound nets may take slightly more fish than deep trap nets fished at the same 

 depth. This relationship is not surprising since the pound net is a "lighter" net (that is, the open top permits the free penetration of light) and 

 would, therefore, be entered by fish more readily than the "darker" deep trap net. Also see table 51, appendix C. 



