196 research outputs found

    First Record of Freckled Madtom (Noturus nocturnus) in Iowa

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    This is the first record of freckled madtom in Iowa and is one of the northern most records. On 30 August 1984, five freckled madtoms were collected from the English River, Washington County. The specimens ranged from 46 to 95mm in total length and mean weight of 3.3g. Estimate of standing stock was 0.807 Kg/ha with a density of 44 fish/ha

    Food Habits of Largemouth Bass (Micropterus salmoides) at Big Creek Lake

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    Food habits of largemouth bass (Micropterus salmoides) were studied at Big Creek Lake, from 1974-76, to determine the utilization of various prey species, temporal food habits, size at which bass became piscivorous, and size of fish-food items in relation to size of bass. Stomach contents from 259 bass were examined and 75 were empty. Entomostraca and insects were important food items of young bass but a transition stage was noted at about 125 mm TL when fish became the prominent food item. Crayfish were important food items early in the spring. Bass fed mostly on 0-age Centrarchids, and particularly bluegill and Notropis sp. Fish provided 29 to 86% of the biomass consumed and 2 to 70% by number. Larger bass (300+ mm) tended to utilize larger but fewer fish-food items while smaller bass (200-299 mm) consumed smaller fish more frequently

    Characteristics of Channel Catfish Populations in Streams and Rivers of Iowa with Varying Habitats

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    From 1983 co 1985, more than 1,000 channel catfish (Icatalurus punctatus) were sampled with rotenone from 50 streams and rivers in Iowa to assess differences in population densities, standing stocks, viral statistics, age and growth, and habitat use Catfish densities ranged from 5 fish/ha in sites on the South Skunk and Upper Iowa Rivers to more than 4,400 fish/ha at a site on the Thompson Fork of the Grand River. Standing stocks ranged from a low of 0.1 kg/ha on a site on the South Skunk River to a high of 467 kg/ha on the East Fork of the Des Moines River. In general, catfish in rivers grew at a slower rate than lake populations (taking about four years to reach 305 mm), but total annual morality was relatively low compared to one published lake population, usually between 20 and 35% for fish age III and older. Larger catfish were usually found in streams of larger watersheds, but headwater streams were important nursery areas for fish less than age III. Mean standing stocks of channel catfish were similar between landforms (P\u3e0.05), but both relative weight (W,) of channel catfish and PSD was higher (

    Standing Stocks of Fish in Some Iowa Streams, with a Comparison of Channelized and Natural Stream Reaches in the Southern Iowa Drift Plain

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    Comparisons were made of fish populations inhabiting 11 channelized and natural stream reaches in the Southern Iowa Drift Plain and two drainage ditches in the Des Moines Lobe. Fish were sampled with rotenone, identified, enumerated, and weighed. Total densities of fish ranged from 483/ha at Cylinder Creek to 51,941/ha at Walnut Creek. Total standing stocks of fish ranged from 14 kg/ha at a channelized site on the Chariton River to 1,344 kg/ha at an unchannelized site on the same river. Number of fish species ranged from six sampled at Silver Creek to 16 sampled at Jack Creek. Channelized sites contained fewer fish and substantially lower standing stocks of fish than natural reaches; however the number of species sampled was often similar. The abundance of sport fish was significantly higher in the natural stream reaches, particularly channel catfish (lctalurus punctatus), flathead catfish (Pylodictis olivaris), bullhead (I. melas and natalis), and carp (Cyprinus carpio). The Index of Biotic Integrity average was higher at the natural stream reaches (x = 36) than channelized sites (x = 29. 7). The major differences in fish populations were due to habitat quality and diversity found in the natural sites as compared to the homogeneous habitat of channelized reaches. Iowa streams have insufficient protection from the inroads of man

    Some Genetic Characteristics of Three Walleye Stocks in Iowa and the Impact of Fry Stockings in the Cedar River

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    Fry stockings of walleye Stizostedion v. vitreum into the Cedar River, Iowa began in the early 1950\u27s, and two studies of the success of these plants gave conflicting results. The objectives of my study were to identify some genetic characteristics in three stocks of walleye and to utilize these characteristics to assess the genetic impact of fry stockings in the Cedar River. Electrophoretic analysis of malate dehydrogenase (MDH) and isocitrate dehydrogenase (IDH) was completed for walleye stocks from the Mississippi and Cedar Rivers, and Big Spirit Lake, Iowa. Phenotypic frequencies of Mdh - B2 and Mdh - B3 were as follows: Mississippi River walleye, 83 and 17%, respectively; Cedar River walleye, 71 and 29%, respectively; and Spirit Lake walleye, 19 and 81%, respectively. Chi-Square testing of these frequencies demonstrated that Spirit Lake fish differed significantly from Mississippi (P\u3c0.001) and Cedar River fish (P\u3c0.05), but there was no difference in frequencies between the two river walleye populations. Phenotypic frequencies of Idh - B1 and B2 were 54 and 46% for Mississippi River fish; 65 and 35%, respectively, for Spirit Lake fish; and, 65 and 35 % for Cedar River walleye, respectively. Chi-square testing indicated that these frequencies were similar (P\u3e0.05). My study indicated that there are some genetic differences between walleye stocks in the two Iowa rivers and Big Spirit Lake. It is probable that the native Cedar River and Mississippi River stocks are genetically similar, particularly since the former is a tributary to the latter. Also, fry stockings of Big Spirit Lake walleye, and their progeny, have contributed only about 19% to the Cedar River population. Fry stockings are less successful than was once thought, and a more refined stocking program is needed

    Seasonal movement of burbot in relation to temperature and discharge in the Kootenai

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    abstract.-Movements of 11 sonic tagged burbot Lota lota were examined in the Kootenai River, Idaho, USA and Kootenay River and Kootenay Lake, British Columbia, Canada through up to three spawning seasons. Our objectives were to determine seasonal movements, differences in behavior of individual burbot, and the role of temperature and discharge on prespawn movement. Burbot demonstrated multiple movement patterns: 3 burbot were very mobile, 3 appeared to be intermediate in activity, and 5 were sedentary in summer, while 2 of the 11 entered Kootenay Lake and returned to the river. Most burbot began in autumn what may have been prespawn migrations when river temperatures fell to a range of 3.0-4.9°C. Six burbot entered the Goat River during the spawning season, of which five showed a multiple-year pattern of fidelity, and four returned to an apparent home pool and then exhibited sedentary behavior until the following winter. Three of the 11 burbot demonstrated an apparent nonspawning or rest year, but this was thought to be habitat-related. Logistic regression analysis of three of the six fish entering the Goat River suggested their migration to be best correlated to decreasing temperature and discharge. If the logistic model were representative of the population, then predicted migrations of burbot to the Goat River during winter would have followed a consistent pattern in November preLibby Dam, while postLibby Dam showed migrations to be unpredictable. Results of this study suggest that burbot had multiple life history patterns and several spawning locations and that rehabilitation measures should promote cooler winter water temperatures less than 5°C and discharges less than 300 m 3 /s
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