. The Canadian field-naturalist. Natural history. 2002 Fisher, , Olson, and Krentz: Flathead Chubs in Upper Missouri 31 25 20 52 ^ 39 >» <i) 3 3 5- 26 o 3 0) 3 C o o 13 70 56 42 28 14 32 24 E o iJ 3 16 8. 8 12 16 20 24 8 12 16 20 24 Total length (cm) Total length (cm) Figure 2. Length-frequency histograms of Flathead Chub captured from sandbar habitats in the Missouri River. North Dakota during four sample periods in 1997 and 1999. The frequencies represent the total catch from six seine hauls per sample period. not spawn until the following season. Of male Flathead Chubs captured
. The Canadian field-naturalist. Natural history. 2002 Fisher, , Olson, and Krentz: Flathead Chubs in Upper Missouri 31 25 20 52 ^ 39 >» <i) 3 3 5- 26 o 3 0) 3 C o o 13 70 56 42 28 14 32 24 E o iJ 3 16 8. 8 12 16 20 24 8 12 16 20 24 Total length (cm) Total length (cm) Figure 2. Length-frequency histograms of Flathead Chub captured from sandbar habitats in the Missouri River. North Dakota during four sample periods in 1997 and 1999. The frequencies represent the total catch from six seine hauls per sample period. not spawn until the following season. Of male Flathead Chubs captured in April, 66% had devel- oped testes at 75-mm TL. At 110-mm TL, 100% of male Flathead Chubs had reached sexual maturity. The smallest Flathead Chub that contained devel- oped ovaries in April was 85-mm TL. Only 21% of the chubs that appeared to be female and were less than 125-mm TL contained mature eggs. By 155- mm TL, 80% of the female Flathead Chubs were mature, but not until 170-mm TL was 100% female sexual maturity noted. Olund and Cross (1961) suggested that sexual maturity was attained by both sexes at about 85-mm standard length in Alberta, and Brown (1971) noted well-developed gonads in Flathead Chubs approxi- mately 82-mm TL in Montana. Conversely, Gould (1985) found that the minimum total length for male and female maturation in the Musselshell Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ottawa Field-Naturalists' Club. Ottawa, Ottawa Field-Naturalists' Club
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