CRUISE 18 



(MAY M- JUNE 7) 



CRUISE 20 



(AUGUST 10-161 



CRUISE 23 



(NOVEMBER (0-19) 



LEGEND 



,T, , ,T 



I:' - I CHUBS 

 ^^M LAKE TROUT 



CRUISE 25 



(MAY 15-Z5) 



CRUISE 29 



(SEPTEMBER 19-24) 



Figure 8. — Bathymetric distribution of chubs and lake trout In District IV by cruise. Distribution Is based on catch rate 

 per 1/2-hour effort at each depth range. Fishing at 35 fathoms (dotted line) or deeper would produce the highest catch 

 rate of chubs and take few trout. 



and between Oak Island and the mainland. Very 

 favorable trawling bottom was found from north 

 of Sand Island continuously to Superior at depths 

 of 4 to 50 fathoms. Snags were encountered 

 only at 25 fathoms off the Brule River and in 

 shallow water off Superior where clay banks 

 make trawling difficult. 



Chubs were 87 percent of the total catch in 

 District VI and were taken in all but five drags. 

 The most productive grounds were located 

 along the 35 -fathom contour running from 

 directly north of Sand Island to 3 miles past 

 the Eagle Island shoals. Four drags here had 

 catch rates of 656 pounds of chubs and 17 pounds 

 of lake trout. In the same area, but along the 

 30 -fathom contour, four drags had catch rates 

 of only 278 pounds of chubs and 40 pounds of 

 lake trout. The best individual catches in the 

 above area by cruise were 1,500 pounds during 

 cruise 25 and 525 pounds during cruise 29. 

 During cruise 29, smaller but significant chub 

 catches were taken along the 30- and 35 -fathom 

 contours at stations from Eagle Island to 

 Duluth and from the Montreal River to Made- 

 line Island. All drags deeper than 33 

 fathoms had a catch rate of 263 pounds 

 of chubs. 



Lake trout were caught in 23 of the 34 drags 

 in this district and composed 4 percent of the 

 total catch. Heavy concentrations, however, 

 were located only in 28 to 33 fathoms from 

 Sand Island to Eagle Island shoals and in 22 

 fathoms south of Madeline Island. Five drags 

 in these two areas and at the depths indicated 

 took 75 percent of the lake trout catch in the 

 district. West of Cornucopia, only 9 pounds of 

 lake trout were caught in 13 drags. 



During cruise 29, in the Apostle Islands 

 area one 15 -minute drag took 50 pounds of 

 smelt, and another similar drag caught 175 

 pounds of suckers. 



District vn - Minnesota Waters from 

 Duluth to the Encampment River 



This district is trawlable from 2 fathoms off 

 Duluth eastward to 40 fathoms. Towards the 

 north shore, however, the bottom becomes 

 rougher and suitable trawling grounds are 

 scarce. 



Although only 10 drags were made in the 

 district, maximum catches of chubs, smelt, 

 and suckers were 350, 225, and 124 pounds, 

 respectively. A total of 10 pounds of lake 

 trout were taken in three drags. On cruise 

 29, over 200 young -of-the -year yellow pike 

 or walleye ( Stizostedion vitreum vitreum) 

 were caught in 4 fathoms off Duluth. 



DISCUSSION BY SPECIES 



The following discussion describes fishing 

 results, by species, for each of the important 

 commercial species taken during this study. 

 The discussion order is based on total landings 

 for the six curises. Two species of suckers 

 [longnose ( Catostomus catostomus ) and white 

 (C. commersoni)] are discussed together as 

 are two species of whitefish [common ( Core- 

 gonus clupeaformis) and menominee ( Proso- 

 pium cylindraceum) ]. Burbot is considered as 

 a miscellaneous species even though it ex- 

 ceeded lake herring (497 pounds to 446 pounds) 

 in total landings. In Lake Superior burbot has 

 never been an important commercial species 

 whereas lake herring has long dominated the 

 commercial landings. 



Chubs 



Chubs were caught most frequently in com- 

 mercially significamt quantities during the 



U 



