When possible, drags were made along depth 

 contours at 5-fathom intervals, i.e., 5, 10, 



15 and 50 fathoms, and at the 60- and 70- 



fathonn contours. Bottonn irregularities and 

 water currents often caused the actual fishing 



depths to sonnetimes vary by several fathonns. 

 To simplify discussion, I have rounded off the 

 fishing depths to the nearest 5- or 10-fathom 

 midpoint as follows: 



Depth Designated 



In this study, evaluations of fishing results 

 are based on two methods of calculations: 



(1) catch rate, which is pounds per unit effort 

 for all drags in a particular evaluation, and 



(2) average catch for effective fishing effort, 

 which is pounds per unit effort for only those 

 drags that contained the particular species 

 being evaluated. Hile (1962) has discussed 

 effective fishing effort. All analyses of catch 

 rate and average catch for effective fishing 

 effort are based on 1 /2-hour fishing time. 

 Total fishing time was divided into 1 /2-hour 

 periods, thus drags that snagged are included 

 in the evaluations. Analysis on a l/2-hour 

 basis is judged to be realistic for it appears 

 that most commercial trawl drags in Lake 

 Superior would be limited to about one-half 

 to 1 hour because of bottom conditions and the 

 need to save incidentally caught lake trout. 



A catch is considered here to be commer- 

 cially significant when its ex-vessel value is 

 $7.50 per l/2-hour drag. For the four species 

 that are considered to be available for com- 

 mercial bottom trawling the individual com- 

 mercially significant l/2-hour catches would 

 be as follows: chubs - 250 pounds, snnelt - 150 



pounds, suckers - 200 pounds, and common 

 whitefish - 15 pounds. 



FISHING EFFORT 



During the study period, the R/V Kaho 

 completed six exploratory cruises in Lake 

 Superior (table 1). Snnith, Buettner, and Hile 

 (1961) have defined fishery statistical districts, 

 which are used to report annual commercial 

 production for the Great Lakes. The informa- 

 tion connpiled during this study is described 

 and analyzed in reference to these districts. 

 Only the south shore was explored, and trawls 

 were dragged in seven statistical districts. 

 To simplify discussions the seven districts 

 are renumbered consecutively fronn east to 

 west. The district boundaries are outlined in 

 figure 4 and defined simply below: 



District I - (MS-6)i/Michigan waters from 



Sault Ste. Marie to the 

 Crisp Point Light. 



District II - (MS-5) Michigan waters fronn 



Crisp Point Light to the 

 outlet of Beaver Lake. 



■"^Designations In parentheses are those used by Smith 

 et al. (1961). 



Table 1 — R/V Kaho fishing effort in Lake Superior by cruise, 1963-65 



Cruise 

 No. 



Districts 

 fished 



Dates 



Days^ 



Drags 



Trawl damage 



Minor 



Major 



Time 

 fished 



1/2 -hr. 

 periods 



Number Number Number Number Minutes Number 



Nov. 16-20, 1963 

 May 26 -June 8, 196-4 

 Aug. 7-22, 1964- 

 Nov. 8-Dec. 8, 1964 

 May 15 -June 11, 1965 

 Sept. 9 -Oct. 6, 1965 



Total 



122 



340 



39 



17 



9,404 



313.4 



^ Travel and storm-bound days excluded. 



