little effort was made to avoid catching trout, 

 only 3.1 percent of the total catch by weight 

 were lake trout. A commercial operation could 

 expect to catch fewer trout. Forty-four drags 

 of the Kaho made in 35 fathoms or deeper had 

 commercially significant quantities of chubs. 

 The total catch of these 44 drags was 29,187 

 pounds, of which only 323 pounds or 1.1 percent 

 ■were lake trout. 



Lake trout taken by a trawl can usually be 

 returned alive to the water. Successful survival 

 depends upon the following factors: (1) amount 

 of crowding in the code end, (2) availability 

 of recovery tank with running water, (3) suitable 

 water temperatures on the lake surface and in 

 the recovery tank, (4) deflation of the swim 

 bladder if necessary, (5) sufficient time in the 

 recovery tank, and (6) protection from preda- 

 tion by sea gulls. Survival rates can be in- 

 creased in proportion to application of the 

 above factors. 



I doubt that trawling would conflict with 

 commercial and sport fishing for trout. In 

 addition to selective depth fishing, the trawler 

 can reduce the catches of snnall trout by 

 increasing the cod end mesh size and by avoid- 

 ing areas where trout are concentrated. 



A practical method to conserve small, 

 planted lake trout and at the same time effec- 

 tively harvest chubs and smelt would be to 

 regulate trawling in depths from 28 to 37 

 fathoms. Commercial trawl drags in these 

 depths should be preceded by short (10- to 15- 

 minute) exploratory drags to determine if 

 small trout are present. Commercial quantities 

 of smelt were found most frequently at depths 

 shallower than 28 fathoms, and commercially 

 significant amounts of chubs were located most 

 frequently in waters deeper than 37 fathoms. 



Whitefish 



Common whitefish were caught consistently 

 in commercially significant amounts ( 15 pounds 

 per one -half hour) only in Munis ing Bay. 

 Here catches of 60, 140, 150, 180, and 230 

 pounds were taken, but most of the fish were 

 small. Edsall (I960) reported that the whitefish 

 population in Munising Bay is unharvested and 

 slow growing. Only five other drags took 25 to 

 50 pounds. 



Catches of menominee whitefish were small; 

 the largest catch was 16 pounds, and the 

 average catch for effective effort was 5 pounds. 



Alewife 



Alewives were not found in commercially 

 significant amounts in Lake Superior. The best 

 catches of 110 and 200 pounds were landed 

 in Whitefish Bay during the first cruise. These 

 catches accounted for 42 percent of the total 

 alewife catch. The only other catches over 35 

 pounds were 60 pounds taken in 5 fathoms in 

 Marquette Bay during cruise 20 and 75 pounds 



Table 5. --Largest alewife catches taken by 

 otter trawl in Lake Superior by district 

 and year 



Year 



District 



II III 



IV V VI 



VII 



taken from 30 fathoms in Keweenaw Bay on 

 cruise 23. The largest alewife catches taken 

 in each district by year are given intable 5. 



Lake Herring 



Thus far, efforts to catch lake herring by 

 the Kaho with a bottom trawl in Lake Superior 

 have been unsuccessful. A heavy bottom con- 

 centration of this species has not been found. 

 Echo tracings indicated that lake herring may 

 connprise some midwater schools of fish not 

 taken by bottom trawls (fig. 11). 



Lake herring appeared in one-quater of the 

 trawl catches, but the average catch for ef- 

 fective effort was only 6 pounds and less than 

 1 percent of the total catch was composed of 

 this species. The best catch was only 45 pounds; 

 however, a 7-minute drag caught 22pounds--a 

 catch rate of 94 pounds per one -half hour. 

 Both catches were in late spring. 



Miscellaneous Species 



The trawl took small amounts of twelve 

 other species [burbot, sculpin (Cottidae), stick- 

 leback ( Pungitius pungitius ), trout -perch ( Per- 

 copsis omiscomaycus ). pigmy whitefish ( Pro- 

 sopiunn coulteri) , yellow perch ( Perca 

 flavescens ), spottail shiner ( Notropis hud- 

 sonius ), rainbow trout (Salmo gairdneri ), yel- 

 low pike or walleye ( Stizostedion vitreum 

 vitreum ), lake sturgeon (Acipenser fulvescens ), 

 brown trout ( Salmo trutta ), and redhorse Mox- 

 ostoma spp.).] None were caught frequently 

 enough or in sufficient quantities to be com- 

 mercially significant. The total poundage of the 

 12 species was only 2.0 percent of the total 

 catch, and none was more than 0.9 percent in- 

 dividually (see table 2). Of the miscellaneous 

 species, burbotwas caught most frequently- -70 

 times at an average catch for effective effort 

 of 8 pounds. Burbot was taken in greater 

 quantities west of the Keweenaw Peninsula. 

 Although only 21 percent of the fishing effort 

 was expended west of the Keweenaw Peninsula, 

 75 percent of the burbot catch was takenthere. 

 During cruise 29 at 35 fathoms, trawls took 

 only two adult sea lampries (Petromyzon 

 marinus )- -one in Whitefish Bay and the other 

 off Eagle Island. 



15 



