The seasonal and diurnal movements of sockeye, pink and coho salmon
fry are described. For sockeye, at least, the time of the seasonal migration
froa the spawning area is related to the temperature "budget" during their
period of development in the gravel. Their seasonal migration occurs earlier
following an incubatory period in which above average temperature prevailed
and later following relatively low temperatures. Emergence from the gravel
appears to occur normally only after a certain stage of development is reached.
The diurnal movements of all three species are precisely regulated
by their response to light. The strong negative phototaxis exhibited by the
fry at this time restricts their movement solely to the hours of darkness.
The downstream movement of sockeye and coho and also apparently of pink fry
is initiated within a three hour period following darkness. The presence of
artificial light almost completely prevents this movement either throughout
the night or until such time as the light is removed. The data indicate that
a period of night blindness occurs which is common to the three species and
that their downstream movement is initially a result of a displacement by the
current. Once entered into the stream the migration continues until evacuation
of the stream is complete or until daylight approaches. The response of sockeye
fry to current during this continued movement appears predominantly positive in
fast currents and negative in relatively slew currents. The migration is
considered to result from both a displacement by the current and a movement
directed on the part of the fry. / Science, Faculty of / Zoology, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/41663 |
| Date | January 1956 |
| Creators | McDonald, John George |
| Publisher | University of British Columbia |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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