344 
‘so 
(s,)? (se)? 
n; Ne 
\ 
X, and Xx, are the mean total lengths 
of the fish; n, and n, represent the num- 
bers of individuals, all sizes, of the species 
taken in the gear; and s, and s, represent 
the standard deviation. The degrees of 
freedom were determined by using the 
geometric mean: 
es 
V nm; * Ne 
d.f. = —1 
From actual net data, table 13, an ex- 
ample is given below table 6 to test if a 
significant difference exists between the 
size of carp taken in l-inch-mesh wing 
nets and the size of those taken in the 114- 
inch-mesh wing nets. 
The t-test below table 6 shows that, at 
the 0.05 level and with 561 degrees of 
freedom, there is a significant difference 
in size between the carp taken in the 114- 
inch-mesh wing nets and those taken in 
the l-inch-mesh wing nets. The 1%- 
inch-mesh wing nets, on the basis of this 
test, catch carp which are significantly 
larger than those taken in the 1-inch-mesh 
wing nets. 
Ittinois Natura History Survey BULLETIN 
Vol. 26, Art. 4 
Catches With Basket Traps.—Not 
a great deal of fishing was done with bas- 
ket traps during the survey; however, 74 
sets were made in the spring and early 
summer months of 1944. In these sets, 
the catch was dominated by catfish, table 
7. Of a total of 73 fish taken with basket 
traps, 80.8 per cent were catfish. Chan- 
nel catfish made up 54.2 per cent of the 
number and 59.8 per cent of the weight 
of the catfish catch. 
The shortnose gar, the only other fish 
taken in numbers with basket traps, 
amounted to 15.1 per cent of the number 
of fish taken with these traps. No sport 
fish was taken in the basket traps set by 
the survey party. However, the writers 
have observed a few crappies taken in 
baited basket traps set in one of the bot- 
tomland lakes of the Illinois River. 
A comparison of the catches of 1-inch- 
mesh wing nets with catches of basket 
traps may be made by referring to tables 
8 and 9. Fishing was done at the same 
stations. The channel catfish was the only 
species of fish taken in greater numbers 
per net-day in basket traps than in 1-inch- 
mesh wing nets; the difference was not 
significant. The catch of flathead catfish 
was much greater in l-inch-mesh wing 
nets than in basket traps. The difference 
Table 9.—Size ranges and means of the total lengths of fish taken in basket traps and in 
l-inch-mesh wing nets without leads in fisheries survey of the Mississippi River between Cape 
Girardeau and Louisiana, Missouri, 1944. 
BasKET TRAPS 
Kinp oF Fisu 0A oe Ss a 
~ n R S 
a oO Sle al te = 
SsH|28| oS] Se 
see[Go| $e) es 
BS x 
Reazc sng] as 
TG Ta oe ae Ree — 2) — — 
Bigmouth buffalo.| — Oo} — — 
Smallmouth buf- 
BN i ot onkea ss — 0} — — 
Freshwater drum.|) — 1} — _- 
Channel catfish...| 50.0) 32) 14.16} 5.1-19.4 
Flathead catfish..| 22.2) 9) 14.83) 8.1-21.6 
Bluegill.......5..) — oj} — _ 
White crappie..... — | 0) — — 
Black crappie....) — 0) —_— — 
| 
— 
* Denotes a significant difference, in sizes 
level for degrees of freedom indicated. 
° 
Standard 
ee 
1-IncH-Mesu Winc Nets 
WirHout Leaps 
eg i¢ | zz 
SA |4 | 52 Fs $ 
S)o 6 ai Zhe = uySlas 
sleceisgiez| &. |B8|23) s 
SO.8H10.8) -o| mg joslga| § 
Blsee|§a| Ss] ge l|eslag = 
AlMERiz<d S45) 6S |nalag! © 
— | 631; — a= —|—|; — 
= 7 gees Se _: eee 
pre ‘aaa gare A eee 
— | — |377| — — —|—}|; — 
64, 53.4) 58) 15.0 | 2.8-24.5/4.10]} 42) 1.001 
88) 39.0] 254) 17.23) 9.4-29.0/4.50) 47) 1.813 
ran tig at 77 ole Sakai bya Poy 
—_ 366, — — —|i—| — 
— | 365} — — —|—|} — 
fish taken, between basket traps and l-inch-mesh wing nets at 0.05 
