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Becker, George C. / Fishes of Wisconsin

Bullhead catfish family - ictaluridae,   pp. 693-732 PDF (19.6 MB)

Page 728

728   Bullhead Catfish Family-Ictaluridae 
Flathead Catfish 
Pylodictis olivaris (Rafinesque). Pylodictis-mud fish; 
     olivaris-olive colored. 
Other common names: flathead, Mississippi bull- 
     head, Mississippi cat, Hoosier, goujon, shovel- 
     nose cat, shovelhead cat, mudcat, yellow cat, 
     Johnny cat, Morgan cat, flatbelly Appaluchion, 
     pied cat, Opelousas cat, granny cat. 
(Forbes and Richardson 1920:180) 
Body elongate, head and body depressed dorsoven- 
trally. Length 508-762 mm (20-30 in). TL = 1.15 SL 
in adults; 1.21 SL in young-of-year. Depth into TL 5.3- 
7.6. Head broadly flattened; head length into TL 3.4- 
3.8. Snout pointed in lateral view; barbels arising from 
collar surrounding posterior nostrils and tips of bar- 
bels scarcely reaching back of eye. Mouth short but 
wide, horizontal. Lower jaw protruding beyond up- 
per jaw; long barbel (almost reaching edge of oper- 
cular flap) attached to upper jaw at each corner of 
mouth; 4 barbels (outer 2 about V2 length of maxillary 
barbels, inner 2 decidedly shorter) attached on chin. 
Numerous small, sharp teeth in broad bands on up- 
per and lower jaws; tooth patch on upper jaw with 
elongate lateral backward extensions. Dorsal fin ori- 
gin barely in advance of midpoint between pectoral 
and pelvic fins; dorsal fin spine about 1/2 fin height; 
dorsal fin rays usually 6; dorsal adipose fin long (al- 
most as long as depressed dorsal fin), separated from 
caudal fin and forming a free, flaplike lobe. Anal fin 
rays 14-16; pelvic fin rays 9; pectoral fin spine /2 to 
2/3 fin length, saw-edged both anteriorly and posteri- 
orly; caudal fin straight and slightly notched posteri- 
orly, not forked. Scaleless. Lateral line complete. 
Digestive tract about 1.0 into TL. Chromosomes 2n 
= 56 (LeGrande 1978). 
  Color variable with size and habitat. Dorsal region 
of head, back, and sides light brown to yellow, mot- 
tled with dark brown or black (mottling tending to 
disappear in adults from turbid water); ventral re- 
gion of head and belly yellowish to cream colored. 
Caudal fin darkly pigmented, except upper lobe, 
which has a distinct white patch along dorsal border 
(white patch disappears with age); other fins pig- 
mented like adjacent parts of body All barbels slightly 
to darkly pigmented. Young more contrastingly col- 
ored than adults. 
  Sexual dimorphism: In males, a single urogenital 
opening behind anus; in females, two openings uri- 
nary and genital; these openings more pronounced 
in adults than in young, especially during spawning 
season (Moen 1959). 
  Hybrids: Experimental flathead catfish x channel 
catfish, flathead catfish x yellow bullhead, flathead 
catfish x blue catfish, flathead catfish x white cat- 
fish (Sneed 1964, Dupree et al. 1966). 
In Wisconsin, the flathead catfish occurs in the Mis- 
sissippi River and Lake Michigan drainage basins. In 
the Mississippi basin, it is known from the St. Croix, 
Red Cedar, Chippewa, La Crosse, Wisconsin, Peca- 
tonica, and Sugar river systems. It reaches the north- 
ern limit of its distribution in the St. Croix River. Ac- 
cording to Cahn (1927), the flathead catfish was taken 
from the Mississippi River overflows and introduced 
into Oconomowoc and Nagawicka lakes. The intro- 
duced fish did not spawn and are undoubtedly extir- 
pated. In the Lake Michigan basin, this species oc- 
curs in the lower Wolf and upper Fox rivers and in 
their lakes. Greene (1935) did not report this species 
from the Lake Michigan drainage, and the possibility 
exists that he overlooked it in his survey. It probably 
entered the Lake Michigan drainage via the Fox-Wis- 
consin crossover connection or the canal at Portage. 
  In Wisconsin, the flathead catfish is rare to com- 
mon in the Mississippi River and in the lower por- 
tions of its major tributaries. Priegel (1967a) listed it 
as common in Lake Winnebago. It is uncommon to 
common in sectors of the lower Wolf River and the 
upper Fox River. 
  In comparing his results on the Mississippi River 
with the earlier findings of Barnickol and Starrett 
(1951), Schoumacher (1968) concluded that flathead 
catfish are being exploited quite heavily by commer- 
cial fishermen. Many fishermen feel that fewer fish, 
especially large fish, are being taken now as com- 
pared with past years. 
  Little is known about the biology and the popula- 
tion structure of the flathead catfish in Wisconsin. To 
ensure sustained fishing and a viable population, a 
long-term, active research program is advised. 
  Young flathead catfish are often found among rocks 
on riffles, occupying the same habitat as the riffle- 
dwelling madtoms. Adults occur in deep pools cre- 

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