District III - (MS-4) Michigan waters from 



outlet of Beaver Lake 

 to Salmon-Trout Point. 



District IV - (MS-3) Michigan waters from 



Salmon-Trout Point to 

 the Elm River, 



District V - {MS-2) Michigan waters from 



the Elm River to the 

 Montreal River. 



District VI - (Wise.) Wisconsin waters. 



District VII - (M-1) Minnesota waters from 



Duluth to the Encamp- 

 ment River. 



Trawlable grounds were located in all seven 

 districts (fig. 4). All districts were not visited 

 during each cruise (table 1), nor was any 

 district completely covered during the investi- 

 gation. Thus, it is possible that additional 

 trawlable grounds will be located in the future. 



Exploratory fishing cruises are numbered 

 consecutively regardless of area of operation. 

 Thus, in this paper ontrawling in Lake Superior 

 cruise numbers are not consecutive. 



Cruises were planned to explore progres- 

 sively westward along the south shore. The 

 first cruise (cruise 14) was a brief trip to the 

 extreme eastern portion of the lake in the fall 



of 1963 to obtain preliminary data regarding 

 fish distribution and bottom conditions needed 

 for survey planning purposes. Cruise 18 was 

 devoted to initial explorations along the central 

 portion of the south shore and Keweenaw Bay. 

 On cruises 20 and 23, seasonal assessments 

 were made in areas previously visited. Cruise 

 25 was concerned primarily with the seasonal 

 assessments from Munising to Manitou island 

 and the potential of fish production in District 

 IV, but was extended to include initial explora. 

 tions west of the Keweenaw Peninsula to Duluth. 

 During cruise 29, seasonal explorations were 

 made along the entire south shore in all 

 seven districts. 



Three hundred and forty exploratory trawl 

 drags, which amounted to 157 hours of fishing 

 time, were made in Lake Superior during this 

 study. The effort by district was unequal owing 

 to extent of trawlable grounds, more favorable 

 locationforproductionstudies, and sequence of 

 initial explorations. The effort (number of drags 

 in each district) was distributed as follows: 



District I- 39 drags District V - 27 drags 



District II- 14 drags District VI - 34 drags 



District III - 49 drags District VII- 10 drags 

 District IV - 167 drags 



LEGEND 



3 » 



o 



CHUBS 



OTHER SPECIES 



FISHING EFFORT 

 5-HOUR CATCH RATE 



I 



30 35 



DEPTH (FATH.) 



< 



O 



Figure 5. — Fishing effort, total pounds landed, and catch rate by depth for 340 trawl drags In Lake Superior Note that 

 fishing effort was fairly well distributed by depth; however, catch rate and total pounds landed were higher in water 

 deeper than 30 fathoms and reached a peak at 45 fathoms because chubs were concentrated at these depths. On this 

 figure the 1/2-hour catch rate has been multiplied by 10 to comply with the scale. 



