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Becker, George C. / Fishes of Wisconsin

Stickleback family - gasterosteidae,   pp. 775-786 PDF (5.3 MB)

Page 777

Brook Stickleback  777 
Brook Stickleback 
Culaea inconstans (Kirtland). Culaea-coined from the 
     former generic   name    Eucalia; inconstans- 
     changeable, variable. 
Other common names: fivespined stickleback, vari- 
     able stickleback, freshwater stickleback, com- 
     mon stickleback, pinfish, sixspined stickleback, 
     black stickleback. 
Adult 68 mm, Slough Cr. (Marinette Co.), 21 June 1966 
Body deep, compressed laterally. Length 38-61 mm 
(1.5-2.4 in). TL = 1.15 SL. Depth into TL 4.7-5.4. 
Head length into TL 3.4-4.3. Mouth small, oblique, 
and dorsal, with lips swollen. Lower jaw projecting 
beyond upper jaw; minute, needlelike teeth in sev- 
eral irregular rows on upper and lower jaws. Dorsal 
spines 4-6, separate, and each with its own mem- 
brane, followed by dorsal fin with 9-11 rays. Anal fin 
with 1 spine and 9-10 rays; pelvic fin with 1 heavy 
spine and 1 ray (pelvic skeleton absent in some pop- 
ulations--see J. S. Nelson 1969 and 1977). Pectoral fin 
9-11 soft rays; caudal fin rounded to truncate. Body 
scaleless, but with 30-36 small, bony plates along the 
lateral line (see J. S. Nelson 1969); lateral line com- 
plete. Digestive tract about 0.5 TL. Chromosomes 2n 
- 46 (Chen and Reisman 1970). 
  General color olive green on back and sides, with 
white spots of varying sizes and shapes, or with light 
vertical, wavy lines; belly and ventral region of head 
of lighter greenish color to whitish. All fins lightly to 
darkly pigmented. 
  Breeding male with body and fins jet black, some- 
times tinged with copper. 
The brook stickleback was known for many years by 
the generic name Eucalia. It was shown by Whitley 
(1950) that Eucalia Jordan, 1878, in the Gasterosteidae 
is preoccupied by Eucalia C. Felder, 1861, in Lepidop- 
tera (Nymphalidae). Bailey and Allum (1962) saw no 
alternative to the adoption of Culaea Whitley, 1950, as 
the generic name for the brook stickleback. 
  In examining populations of the brook stickleback 
throughout its range, J. S. Nelson (1969) found a 
clinal variation in dorsal and pelvic spine lengths, 
with the longest spines occurring in the Wisconsin to 
Ohio area. He suggested that the long spines of the 
Midwest forms act as protection against predators in 
an area where predators have a large selection of 
prey species. In the West, however, where the prey- 
predator ratio is less, natural selection favors short- 
spined individuals with streamlined bodies and light 
pelvic skeletons which are better able to escape into 
dense vegetation. In southern Manitoba, Moodie 
(1977) noted the small body size of a population of 
brook sticklebacks which are exposed to predatory 
The brook stickleback occurs in all three drainage 
basins in Wisconsin. It is widely distributed in most 
small river basins, particularly in headwater reaches; 
it occurs in shoal waters of Lakes Superior and Michi- 
gan, and in inland lakes, especially northward. 
  Where the brook stickleback is found, it is often a 
common species. It is rare in Lake Winnebago (Prie- 
gel 1967a) and occasional in Lakes Superior and 
Michigan. Its position in state waters appears to be 
  In Wisconsin, the brook stickleback was encoun- 
tered most frequently in clear to slightly turbid water 
at depths up to 1.5 m, over substrates of sand (24% 
frequency), gravel (21%), silt (16%), mud (11%), rubble 
(9%), boulders (9%), clay (5%), detritus (4%), and 
bedrock (2%). It occurred in spring holes, boggy lakes, 
and occasionally in well-protected bays of large lakes. 
This species preferred moderate currents in streams 
of the following widths: 1.0-3.0 m (36%), 3.1-6.0 m 
(36%), 6.1-12.0 m (11%), 12.1-24.0 m (8%), 24.1- 
50.0 m (7%), and more than 50 m (2%). It occurs in 
the Great Lakes in shallows down to 31 m (Hubbs 
and Lagler 1964), and in Lake Huron at all depths to 
55 m (Scott and Crossman 1973). It is usually found 
in the colder waters, and invariably is associated with 
a moderate to dense vegetation cover. In southwest- 
ern Wisconsin, it is frequently encountered in highly 
turbid waters, suggesting the development of silt- 
tolerant populations. 
In Wisconsin, spawning may begin as early as April, 
and is known to occur from May to mid-June. Jacobs 
(1948) stated that the water must attain a minimum 
temperature of 8°C (46°F) before the brook stickle- 
back begins to spawn. However, nests have been 
found normally at 15-19'C (59'-66°F) (Winn 1960); 

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