The Systematics of the Prickly Sculpin, Cottus asper Richardson, 
a Polytypic Species 
Part II. Studies on the Life History, with Especial Reference to Migration 1 
Richard J. Krejsa 2 
ABSTRACT : The occurrence of a downstream spring migration of weakly-prickled 
Cottus asper in coastal streams is confirmed and documented. Successful intertidal 
spawning and incubation is followed by a pelagic larval stage of about one month. 
Metamorphosis occurs and the pre juveniles settle to the bottom to feed in the 
estuarine portion of the river. An upstream migration of adults precedes that of 
the young-of-the-year in late summer. During the non-migratory phase, prickly 
sculpins are located in the low gradient, low velocity portions of coastal streams. 
Densely-prickled Cottus asper living in distant inland waters, where access to the 
sea is almost impossible, undertake only local migratory movements. Densely- 
prickled forms living in some inland lakes and streams relatively close to the sea, 
where access to the sea is open and relatively easy, do not migrate seaward but 
undertake only local movements to spawn in fresh water. The present study dis- 
cusses differences in migratory behavior between "coastal” and "inland” prickly 
sculpins. 
The existence of a seaward spawning migra- 
tion of prickly sculpins in coastal streams has 
been suggested, or implied, for at least 30 years 
(Taft, 1934; Pritchard, 1936; Sumner, 1953; 
Shapovalov and Taft, 1954; Hunter, 1959; and 
McAllister and Lindsey, 1959). Although some 
of these authors have observed the presence of 
reproductively mature Cottus asper in the inter- 
tidal areas of coastal streams, none has demon- 
strated that intertidal spawning actually occurs. 
Populations of C. asper occurring in lakes 
and streams far enough inland to preclude the 
possibility of an annual seaward spawning mi- 
gration are presumed to spawn in fresh water. 
The approximate or exact spawning sites of 
some of these populations have now been deter- 
mined from the presence of larvae (Nicola Lake, 
British Columbia), and egg clusters or gravid 
females (Pothole Lake, near Merritt, British 
1 With data taken from a thesis submitted in par- 
tial fulfillment of the requirements for the degree of 
Doctor of Philosophy at the University of British 
Columbia. Manuscript received March 23, 1966. 
2 Institute of Fisheries, University of British Colum- 
bia, Vancouver, Canada. Present address: Department 
of Anatomy, College of Physicians and Surgeons, 
Columbia University, New York, N.Y. 
Columbia). Other localities are close enough to 
the sea to imply the existence of a short seaward 
migration on the part of the C. asper popula- 
tions living therein, but access to the sea is pre- 
vented by natural or man-made barriers, e.g., at 
Buttle Lake and Horne Lake, on Vancouver 
Island, British Columbia. Spawning of prickly 
sculpins in these areas is necessarily restricted 
to fresh water. 
Still other localities, frequented by migratory 
salmonids, are close enough to the sea to permit 
a seaward migration on the part of C. asper 
living there, but it does not occur. For example, 
these spawning sites of the following prickly 
sculpin populations in the lower Fraser Valley 
in British Columbia are known from capture of 
gravid fish and/or egg masses: South Alouette 
River; Kenworthy Creek and Chilqua Slough 
(both are inlet streams to Hatzic Lake) ; Squa- 
kum Lake (Lake Erroch) ; and Cultus Lake. In 
addition, spawning fish have been captured in 
inlet streams of Skidegate Lake, in the Queen 
Charlotte Islands, along with migratory juvenile 
salmonids. The outlet of Skidegate Lake is only 
about 13 miles from the sea. A newly hatched 
larva of C. asper (?) has been taken in a 
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