Date of Award

5-1978

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Dr. John B. Owen

Abstract

This study was undertaken to investigate the population and abundance of year-classes of the buffalo fishes in Lake Sakakawea, North Dakota. Fish used in this study were obtained from Grasteit Dakota Fisheries, a commercial fishing operation headquartered in Newtown, North Dakota.

Only bigmouth buffalo (Ictiobus cyprinelius) and smallmouth buffalo (Ictiobus bubalus) were collected during this study; no black buffalo (Iciobus niger) were captured. The age and growth of these fish was found to be quite similar to that in other Missouri River mainstem reservoirs. The mean condition factor (K-TL) for the bigmouth was found to be 1.88 and for the smallmouth was found to be 1.83. These values are higher than any reported for other mainstem reservoirs, and were probably due to the preponderance of large fish in our populations. The length-weight regression was calculated to be Log W = -3.63 + 2.60 log L for the bigmouths and Log W = -5.94 + 3.42 log L for the smallmouths.

Lake Sakakawea reached full pool for the first time in 1967. Year-classes before this time are strong for both species of buffalo, making up over 73% of the smallmouths and over 69% of the bigmouths that were aged. After this full pool elevation was reached there was a dramatic decrease in year-class strength due to loss of optimal spawning areas. An exception was the 1969 year-class, which was of moderate strength, probably due to the fact that water levels were 0.8 feet above the full pool elevation.

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