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<br />( <br /> <br />( <br /> <br /><- <br /> <br />Task 4. Determine the food habits of native and nonnative fishes in backwaters <br />and secondary channels and evaluate for dietary overlap. <br /> <br />o <br />o <br />,-) <br />,,0::.. <br />.... <br />" <br /> <br />A. Methods <br />1. Collect fish by seine and preserve <br />2. Record habitat type <br />3. Record standard length and examine stomach contents of specimens <br />of all native and dominate nonnative fish species <br />4. Summarize findings according to habitat type, species, and <br />size <br /> <br />B. <br /> <br />Schedule, <br />Jan.Feb: <br />May- Jun : <br />Aug-Oct: <br /> <br />" <br /> <br />1992-1996 (three years: high, low, 3000-5000 <br /> <br />fish sampling and sample processing <br />II II II II <br /> <br />cfs flows) <br /> <br />" <br /> <br />" <br /> <br />" <br /> <br />Task 5. <br /> <br />Compare growth and survival of y-o-y and juvenile <br />native fishes in backwater habitats with and without <br />predators and/or competitors. <br /> <br />A. Methods <br />1. Select experimental backwaters according to size, degree of <br />protection from flood flows, and suitability for temporary barrier <br />construction. <br />2. Erect temporary barriers at selected backwaters and from 1-2 <br />backwaters each remove all nonnative predators and all nonnative <br />predators and competitors <br />3. Select control (unaltered) backwaters for comparison <br />4. After barrier erection and fish removal, sample biweekly (or more <br />often?) and record length/weight data and preserve subsample from each <br />backwater . <br />S. By snorkeling, observe native and nonnative species interactions <br />in backwaters with adequate visibility to determine presence of <br />interspecific aggression <br /> <br />B. Schedule, 1993-1996 (two years, non-high flow) <br /> <br />Jul: <br />Aug-Oct: <br /> <br />select backwaters, barrier erection <br />biweekly sample fish in backwaters <br /> <br />Task 6. <br /> <br />Identify the presence/absence and the <br />characterization of habitats providing refuge for native fish species. <br /> <br />A. <br /> <br />Methods <br />1. Synthesize the results and interpretations of completed Tasks 1-5 <br />2. Identify habitats, including type and ecological characterization, <br />where collection and growth and survival of y-o-y and juvenile native <br />fishes is greatest and least for nonnatives <br />3. Relate habitats identified in 2. to recent flow history <br />4. Identify flows that maximize the presence of native fish habitats <br />which exclude nonnative fish <br /> <br />B. <br /> <br />Schedule, 1996-1997 <br />Ongoing <br /> <br />A2a <br />