Fishery bulletin of the Fish and Wildlife Service - NOAA

WHITEFISH FISHERY OF LAKES HURON AND MICHIGAN 387
bined. The data do not, however, support the complaint that the deep-trap-net fishery
was extremely harmful to the pound-net fishery in 1931. It is true that the total production
in pound nets .was less in 1931 than in 1930, but the decline was the result of
reduced fishing intensity. The average catch of whitefish per lift of pound nets was
approximately 10 pounds greater in 1931 than in 1930.
Although the average lifts of whitefish in deep trap nets in 1931 were 2.3 times those
of pound nets, this advantage depended only on the greater depth of water in which
deep trap nets were fished. The effect of the depth of water on the size of the lift is
brought out by the comparison of the lifts of whitefish in shallow pound nets, deep
pound nets (more than 50 feet of water), and deep trap nets (table 51). There was little
difference between the size of the lifts of deep pound nets and deep trap nets, but both
took more than 8 times as many fish per lift as shallow pound nets (less than 50 feet
of water). It is obvious, therefore, that any indictment of the deep trap net in Door
County waters as a dangerously effective gear must apply also to deep pound nets. 44
TABLE 51.—Comparison of the catch of whitefish of shallow pound nets, of deep pound nets, and of deep trap
nets fished in Door County, Wisconsin waters, June 1981
Shallow „und net
Gear
Number of lifts
58
60
184
Total production
(pounds)
2,566
21,861
69,359
Catch per lift
(pounds)
Further conclusions based on observations of pound nets and deep trap nets in
Door County waters are summarized as follows:
(1) The sorting of fish was more difficult in deep trap nets than in pound nets.
However, less sorting was necessary with deep trap nets than with pound nets which
ordinarily had 2-inch mesh (stretched measure). Very few illegal whitefish (legal size
limit, 13 inches, total length, at the time of the investigation) were seen in deep trap
nets, the mesh of which ranged from З 1
/^ to 4^ inches. On several occasions small
fish were seen to escape through the meshes as deep trap nets were lifted.
(2) Very few gilled fish were observed in deep trap nets, and most of the fish
gilled were of legal size. A SV^-inch-mesh net allows the escape of whitefish of 13
to 13% inches, total length, and smaller; 4%-inch meshes release whitefish about 16
inches long, and smaller.
(3) The observations did not support the contention that illegal whitefish brought
to the surface in deep trap nets die. Small whitefish and herring were seen to pass
through the bottom of the trap nets when they reached the surface, apparently uninjured
and certainly not bloated.
REGULATIONS RECOMMENDED FOR THE DEEP TRAP NET IN
WISCONSIN WATERS
The investigating committee submitted the following recommendations for the
regulation of the deep trap net in Wisconsin waters (almost entirely direct quotation
from report) :
1. The size of the mesh in the lifting pot must be not less than 4% inches but the
side of the pot where fish are bagged may be of smaller mesh.
2. The length of the lead shall be not more than 50 rods.
3. A buoy must be attached to every anchor and each buoy must have a flag
attached to it, extending not less than 30 inches above the surface of the water.
4. The shortest distance between strings of trap nets or between trap nets and
pound nets shall be not less than one-half mile. A trap net as here defined refers
to any part of the net constructed of webbing and includes the pot, tunnel, heart, and
lead (not the anchors, ropes, buoys, and flags).
" Both gears can operate on the concentrations of whitefish at depths of 50 or 60 feet. Attempts of deep-trap-net fishermen to locate whitefish
in deeper water (ox. 100 feet) were unsuccessful.
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364.3
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