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Becker, George C. / Fishes of Wisconsin
(1983)

Cod family - gadidae,   pp. 745-751 ff. PDF (2.7 MB)


Page 748

748    Cod Family-Gadidae 
Range of the burbot 
0 Specimens examined 
A Wisconsin Fish Distribution Study (1974-75) 
o Literature and reports 
O Greene (1935) 
behind, swam in under her belly and placed his head un- 
der hers, so that her chin rested on his crown. In this po- 
sition the couple swam about at the bottom for some min- 
utes. The male suddenly rotated his body half a turn, 
pushing his belly against the vent of the female. In this 
mating act a cloud of eggs and sperm was released. After 
mating the male and female separated for a moment, the 
female performed a series of powerful tail beats which 
stirred up the sexual products and scattered the eggs. The 
eggs were carried about by the water movements caused 
by this activity, but they finally sank down to the bottom. 
This activity was repeated until the female was spent. 
  Cahn (1936) observed probable spawning by the 
burbot in Minnesota (p. 164): 
  On the night of February 12 the interesting phenome- 
non of breeding was observed .... At first a dark shadow 
was noted at the edge of the ice, something which ap- 
peared to be a large ball. Eventually this moved out into 
view and it was seen to be indeed a ball-a tangled, nearly 
globular mass of moving, writhing lawyers. The fish were 
all intertwined, slithering over one another constantly, 
slowly, weaving in and out of the living ball. About a dozen 
fish were involved. ... 
The mass of fish, about 76 cm (30 in) diam, was in 
water about 1.2 m (4 ft) deep. 
   In Lake Superior burbot (Bailey 1972), the esti- 
mated number of eggs in the ovaries of eight fe- 
males, 373-541 mm (14.7-21.3 in) long, ranged from 
268,832 to 1,154,014. In New York (Robins and Deu- 
bler 1955), a 643-mm, 2.8-kg (25.3-in, 6.1-1b) female 
held 1,362,000 eggs. The average diameter for the 
semipelagic eggs varies with the region, but gener- 
ally ranges from 1.25 to 1.9 mm. 
  The incubation period of burbot eggs is from 4 to 5 
weeks, at a water temperature of 4°C (39.2°F) (Breder 
and Rosen (1966). Fish (1932) provided sketches from 
the 3.5- to 19-mm stages, along with descriptions of 
these and the 30.5-mm stage. The median barbel is 
recognizable in the 10.9-mm stage. 
  Many newly hatched young burbot are found on 
the shallow, sandy bottoms of lakes (Eddy and Sur- 
ber 1947) and in trout streams which may act as nur- 


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