Laserfiche WebLink
<br />. , <br /> <br />be utilized as a base of operations. <br /> <br />A series of exclosures will be constructed at randomly-chosen <br />locations in backwater in the Ouray area. These would be designed <br />to exclude or admit fishes. Benthos and plankton will be monitored <br />by core an net sampling for about 100 days, i.e., during the period <br />when Colorado squawfish are present. Sampling frequency will be a <br />function of water temperature, and samples will range form one per <br />week to three per day. <br /> <br />Data collected will allow the computation of invertebrate densities, <br />changes in cOlllllunity structure, and production estimates for the <br />dominant invertebrate species in the system. Preliminary studies <br />will be conducted to generate growth rates for invertebrates and <br />additional growth information will be made form size-class <br />distributions. <br /> <br />Fish collections will also be made a bi-weekly intervals to document <br />the use of the area by various species. Fish biomass wi 11 be <br />estimated by determining the relative numbers and weights by <br />species. <br /> <br />Rationale <br />Interactions between introduced an native fishes have been <br />implicated in the decline of the Colorado River endangered fishes. <br />However, competition is difficult to prove in natural environments, <br />and especially in large rivers like the Green River. In-depth <br />studies of competition could be very expensive and result in little <br />insight. This project will approach the topic of fish competition <br />in Colorado squawfish nursery habitats by using a stepwise <br />procedure. First, we would determine if fish predation in <br />backwaters has an impact on the structure and function of benthic <br />and planktonic cOlllllunities. If not, we would anticipate that <br />resource sharing between fishes is not limiting. However, if a <br />significant shif~ in food organisms occurs, this would demonstrate <br />that the food base is impacted, thus implying resource competition. <br /> <br />This study is needed to help determine the significance of species <br />interactions so that intelligent management strategies, including <br />flow manipulation, can be devised. <br /> <br />Deliverables <br />An final report for the project will be submitted by the end of the <br />fiscal year. . <br /> <br />1993 BudQet <br />-Labor $4,000 <br /> <br />-Total <br /> <br />j4.000 <br /> <br />Flaming Gorge Studies <br /> <br />30 <br />