326 
station, pool numbers, and the distances 
of stations from Dubuque. 
The survey covered 306 miles of the 
Mississippi below the mouth of the Mis- 
souri River and 383 miles above this point. 
The lower section extended from the 
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CARUTHERSVILLE STA. TENNESSEE 
Fig. 1.—The Mississippi River between 
Caruthersville, Missouri, and Dubuque, Iowa; 
shown is the location of field sampling sta- 
tions used during the fisheries survey of 1944 
and 1946. The river distance between Caruth- 
ersville and Dubuque is 689 miles. 
Intinois NATURAL History SuRVEY BULLETIN 
Vol. 26, Art. 4 
mouth of the Missouri River to Caruth- 
ersville and is referred to in this paper as 
the MR-C section. The upper section 
extended from Dubuque to the mouth of 
the Missouri River and is designated as 
the D-MR section. 
In both years of the survey, a key sta- 
tion was established for checking seasonal 
differences in catches. In 1944, Grafton 
was the key station and, in 1946, Andalu- 
sia. Three sampling periods were spent 
at each of these stations. 
In the fall of 1944, trammel net ex- 
periments were conducted at Quincy and 
at Grafton, Illinois. The data from these 
experiments are treated separately in this 
paper. 
When, in this paper, reference is made 
to mesh size of nets and seines, the size of 
the mesh in inches is indicated; for ex- 
ample, a l-inch-mesh wing net refers to 
a wing net having mesh of 1-inch square 
measure. Square measure mesh size is 
used throughout this publication. The ap- 
proximate stretch measure of the webbing 
can be calculated by multiplying the 
square measure by two. 
The following fishing devices, some of 
which could not in 1944 or 1946 be used 
legally by commercial fishermen, were 
tested by the survey party: 
Trammel nets, length of each 80, 100, 
or 150 yards (mesh of inner net 11/4, 134, 
2, or 3 inches), depth 5 or 6 feet 
Seines, length of each 100, 150, or 200 
yards (mesh 1 inch), depth 10 feet 
Hoop nets (mesh 1 inch, hoop diam- 
eters 314 or 4 feet; mesh 214 inches, hoop 
diameters 4 or 414 feet; mesh 3 inches, 
hoop diameters 4 or 414 feet) 
Wing nets with and without leads 
(mesh 1 inch, hoop diameters 214 to 414% 
feet; mesh 114 inches, hoop diameter 3 
feet; mesh 214 inches, hoop diameters 31% 
and 41% feet) 
Trap nets (mesh 11, inches) 
Basket traps (opening 114 inches) 
Trot lines 
The number of each of the various 
kinds of fish caught and the total lengths 
of the individuals and their weights, as 
well as the dates and hours of setting and 
- 
3 
raising gear, were recorded separately for x 
each type of fishing device (except trot 
lines) and each mesh size of net (except <i 
trammel net) and seine used. The data — 
