of the results of each drag. The catch records 

 have been coded and recorded on punchcards. 

 The following criteria were used for this 

 analysis of seasonal availability ofalewives: 



1. Drags that had a fishing depth range of 

 more than 4 fathoms were eliminated 

 because these were searching efforts and 

 cross contour drags. 



2. Drags that did not contain at least 500 

 pounds of alewives were elinninated, thus 

 sorting out effort that was likely directed 

 at other species. Early operations by 

 these trawlers were directed mainly at 

 catching chubs. 



3. Drags were sorted by month and year, 

 and each month was further subdivided 

 into three periods, i.e., the 1st to the 

 10th, the nth to the 20th, and the 21st 

 to the end of the month inclusive. 



4. Drags meeting the above criteria were 

 tabulated by 1/3-month periods, and a 

 mean fishing depth was calculated. 



5. The mean depths were graphed if at 

 least five drags made during the period 

 had a catch rate of at least 500 pounds 

 per hour. Many of the drags that fulfilled 

 criterion 2 were for more than 1 hour. 



Data from all three vessels were combined. 

 The results are presented in the alewife 

 discussion. 



A catch is considered here to be connmer- 

 cially significant when its exvessel value is 

 $7.50 or more per one-half hour. Under cur- 

 rent conditions a significant catch would be 

 500 pounds of alewives per one-half hour, 

 based on a value that lies between prices paid 

 by manufacturers of pet food and prices paid 

 by fish meal producers. Because chubs are 

 comnnonly used for pet food and most catches 

 have some chubs large enough for human 

 consumption, 250 pounds per one-half hour 

 was considered a commercially significant 

 catch of chubs. Seventy- five pounds of yellow 

 perch in a |-hour drag is significant. 



FISHING EFFORT 



Fronn 1962 to 19^5, 14 exploratory cruises 

 were entirely or partially devoted to fishing 

 explorations in southern Lake Michigan. These 

 cruises totaled 193 operating days and aver- 

 aged 14 days per cruise. During the survey, 

 798 trawl drags were completed in 388 hours 

 (table 1). Exploratory fishing cruises are 

 nunnbered consecutively regardless of opera- 

 tion; therefore, cruise numbers in this paper 

 are not consecutive. 



In 1962 three entire cruises were spent in 

 southern Lake Michigan. Owing to gear limita- 

 tions, fishing was restricted to depths between 

 8 and 45 fathoms. Most of the drags were 



between 10 and 40 fathoms. Cruise I was a 

 Kaho shakedown cruise in which two trial 

 drags were made off Saugatuck in February 

 and eight drags off Saugatuck and two drags 

 off Ludington in March. The main portion of 

 cruise 1 was made in April and covered the 

 east shore from Benton Harbor, Mich., to 

 Ludington and the west shore from Milwaukee, 

 Wis., to Manitowoc. Cruise 3 was divided in 

 three phases--(l) June, (II) July, and (III) 

 August. Southern Lake Michigan was explored 

 during each phase. Cruise 6 was nnade in 

 November and December, and trawls were 

 dragged at stations on both sides of the 

 lake. During 1962 the Kaho fished in south- 

 ern Lake Michigan at least 1 day a month 

 for 8 months. 



The fishing effort in southern Lake Michigan 

 during 1963 was about half that of the previous 

 year. Depth coverage was from 5 to 88 fathoms, 

 and the scope of operations were extended to 

 Green Bay and northern Lake Michigan. Of 

 five cruises in Lake Michigan in 1963, four 

 explored the southern portion of the lake. 

 Cruise 9 included operations off Manitowoc, 

 Ludington, Port Washington, Wis., and White 

 Lake, Mich. On cruise 13 three cross-lake 

 transects were made in southern Lake Michi- 

 gan as follows: Manitowoc to Ludington; Ra- 

 cine, Wis., to Saugatuck; and Waukegan, HI., 

 to Benton Harbor. During cruise 14 a cross- 

 lake transect was made from Ludington to 

 Manitowoc. Five drags made off Saugatuck in 

 Decennber are a part of cruise 15, In 1963 

 the Kaho was active in southern Lake Michi- 

 gan during 5 months. 



In 1964 the fishing effort in southern Lake 

 Michigan was about the same as in 1962. 

 Drags were made at depths of 5 to 80 fathoms. 

 The remainder of cruise 15 included a series 

 of drags off Saugatuck in late January and 

 early February and a transect between Sauga- 

 tuck and Racine in March. Cruise 16 consisted 

 of two cross-lake transects, Manitowoc to 

 Ludington and Waukegan to Benton Harbor. 

 Cruises 17 and 21 each consisted of three 

 cross-lake transects as follows: Manitowoc 

 to Ludington, Port Washington to White Lake, 

 and Waukegan to Benton Harbor. On cruise 19, 

 random stations were fished on both sides of 

 southern Lake Michigan and one transect was 

 made from Manitowoc to Ludington. In 1964 

 the Kaho fished in southern Lake Michigan 

 for 7 months. 



Operations in Lake Michigan during 1965 

 were concerned primarily with explorations 

 in Green Bay and northern Lake Michigan; 

 however, three transects were made between 

 Manitowoc and Ludington during cruises 24 

 (April), 28 (August), and 30 (December). A 

 depth series was also made off Port Wash- 

 ington during cruise 24. 



Owing to rough bottonn conditions close to 

 shore in southern Lake Michigan, very few 



