Fishery bulletin of the Fish and Wildlife Service - NOAA

332 FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE
TABLE 12.—Monthly production of whitefish in 'Lake Huron, 1929 and 1931, in gill nets, deep trap nets,
pound nets, and all gears combined
Gear
1919
Gill net
Deep trap net-
All gears
19S1
Gill net
Deep trap net.
All gears
Jan.
/ 180
\ (0.0)
I 180
\ (0.0)
/ 390
\ (0.1)
/ 390
\ (0.0)
Feb.
580
(O.I)
580
(0.0)
317
(0.1)
2
1 (0.0)
319
(0.0)
March
2,465
(0.5)
2,468
(0.2)
4,663
(0.7)
55
(0.0)
4,785
(0.1)
April
52,029
(10.6)
f 1,239
\ (1.4)
/ 1,278
\ «U)
57,764
• (4.0)
82,423
(13.3)
í 19,220
1 (0.9)
3,340
(0.4)
116,754
(2.8)
[Percentages are in parentheses]
Production of whitensh in pounds in month
May
04,066
(19.2)
1,774
(2.0)
19,582
(2.4)
117,463
(8.1)
124,071
(20.0)
115,241
(5.6)
41,882
(4.6)
289,342
(7.0)
June
79,724
(16.3)
10,867
(12.5)
101,424
(12.3)
193,906
(13.3)
112,776
(18.2)
334,943
(16.1)
269,224
(29.5)
808,065
(19.5)
July
82,332/
(16.8)
20,535
(23.6)
165,066
(20.0)
276,917
(19.0)
113,365
(18.3)
528,609
(25.4)
169,001
(18.5)
961,095
(23.2)
Aug.
88,890
(18.2)
15,068
(17.3)
33,145
(4.0)
137,161
(9.4)
107,329
(17.3)
498,984
(24.0)
53,513
(5.9)
709,469
(17.2)
Sept.
58,534
(12.0)
9,809
HI.«
163,763
(19.9)
233,074
(16.0)
36,492
(5.9)
391,921
(18.8)
65,801
(7.2)
591,894
(14.3)
Oct.
21,744
(4.4)
24,061
(27.6)
244,055
(29.6)
302,087
(20.7)
7,752
(1.2)
172,701
(8.3)
184,552
(20.3)
441,501
(10.7)
Nov.
8,848
(1.8)
3,768
(4.3)
91,878
(11.2)
130,694
(9.0)
' 9,001
(1.5)
15,757
(0.8)
121,774
(13.4)
186,997
(4.5)
Dec.
569
(0.1)
3,505
(0.4)
4,074
(0.3)
20,936
(3.4)
2,220
(0.1)
1,796
(0.2)
29,161
(0.7)
Total
489,961
(100.0)
87,121
(100.0)
623,696
(100.0)
1,456,068
(100.0)
619,515
(100.0)
2,079,590
(100.0)
910,940
(100.0)
4,139,772
(100.0)
only during limited periods, one in late spring and early summer and another in midautumn.
Many fishermen discontinue pound-net operations at other seasons. It is
true also that even in periods of active operation the greatest concentrations of whitefish
may be at depths beyond the reach of pound nets.
The offshore movement that leads to a concentration in relatively deep,water in
the summer and early autumn exposes the whitefish to the inroads of the deep trap net
at the time it is most vulnerable. Formerly, the only toll on the whitefish in its summer
concentration was that levied by gill nets, and in the modern fishery of Lake Huron this
type of gear has not proved generally effective for the large-scale catching of whitefish.
The gill net is so ineffective for the capture of whitefish under modern conditions that
gill-net fisheries are supported by this species alone only in very limited areas or over
extremely short periods of time (chiefly during the spawning season). 26 The largemesh
gill-net fishery is now conducted ordinarily for the capture of both trout and
whitefish or of trout alone, but very seldom exclusively for the taking of whitefish. 27
The comparative ineffectiveness of gill nets made the time of summer concentration of
the whitefish a "semi-closed" season during which the species was in large measure
immune to capture. The introduction of the deep trap net made this same period the
season of maximum production.
The effect of the deep-trap-net fishery on the monthly distribution of the whitefish
catch and the high production this gear made possible in the summer months may be
illustrated by the data of table 12 and figure 12. The gill-net season extended through
the months, May-August, in both 1929 and 1931. (September was a fairly good month
in 1929.) No distinct peaks occurred in either year. The pound-net catch, on the
contrary, was divided into two distinct seasons, each with a sharp peak. The earlyseason
maximum occurred in July in 1929 and in June in 1931. Both of the autumn
maxima were in October. The 1931 data which show the more pronounced summer
depression provide the better description of the monthly distribution of pound-net production
because the 1929 early-summer peak was later and the September catch was
relatively higher than usual. The data for both years, however, have a distinct latesummer
minimum—August in 1929 and August-September in 1931.
The curve of total catch in 1929 has a minimum in August corresponding to the
August depression in the pound-net data. A similar minimum would have existed in
* When gill nets «ere fished on the spawning grounds the catches «ere sometimes enormous—thousands of pounds m a single lift.
» ТЫ» statement holds true even In Lake Michigan where the gill net is normally the dominant gear for the production of whitefish.