Date of Award:

1975

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Natural Resources

Department name when degree awarded

Wildlife Resources

Advisor/Chair:

C. B. Stalnaker

Abstract

The upper optimum temperature for embryonic development of mountain whitefish is 6 C, and for the post yolk sac stage is 9 to 12 C. The need to know effects on all stages in the life cycle in cases of thermal pollution is demonstrated. Abnormalities caused by thermal pollution in hatched larvae were agape jaws, coloboma or fissure of the eye, monophthalmia or the presence of only one eye, monomicrophthalmia or the presence of one small eye and one case of twinning. High mortalities of eggs occurred at 9 C and higher.

Study of the energy expenditure, by the dry weight method showed an energy deficit at 6 and 9 Cat the time of hatching. The larvae are then fully capable of offsetting these deficits by feeding. The oxygen consumption method showed an energy deficit during hatching at 6 C, but failed to show any at 9 C. The efficiency of yolk conversion generally decreased as development progressed. No group effect in active metabolism was observed in the underyearlings.

The electrochemical method of measuring oxygen consumption of embryos gave a cumulative value which was 6.8% higher than values obtained using the manometric method. This increase is attributed to the increase in activity of embryos caused by the nature of the experimental set up.

Active metabolism and scope for activity were high at 9 and 12 C compared to 6 and 15 C. Standard metabolism steeply increased at 1:5 C. There was very little scope for activity at 15 C.

The embryonic development was similar to that of other whitefishes. The mountain whitefish requires more thermal units to reach corresponding stages than does the lake whitefish, after the stage when the blastodisc is prominantly raised up on the yolk.

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