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reach. These curves should not be used for site-specific instream flow <br />assessments, because results. obtained from these curves may be subject <br />to challenge during adjudication or other defenses of the streamflow <br />recommendation. However, the curves can provide useful information for <br />reconnaissance level investigations and early planning studies. <br />All curves, regardless of their IFG rating, are subject to periodic <br />review and revision as more data become available. The user would be <br />well advised to update his own collection as new curves are produced. <br />Field practitioners are encouraged to collect their own field data, and <br />produce their own curves whenever feasible. IFG-will attempt to keep <br />abreast of new data produced and will continually upgrade the species <br />curves. <br />DATA ACQUISITION TECHNIQUESFOR DEVELOPP~ENT <br />OF PROBABILITY CRITERIA <br />For some species, existing data will be of poor quality, incom- <br />plete, or in the wrong format for frequency analysis. Sometimes it will <br />be nonexistent. If for any of these reasons, biological criteria devel- <br />opment requires the collection of field data, the several options listed <br />below may be used. <br />OPTION 1 - INDIVIDUAL CAPTURE <br />This method is best applied to those species and life stages that <br />tend to be solitary and sedentary. Electrofishing, spot concussion and <br />(for some species) drifted gill nets, and SCUBA, snorkel, or surface <br />observation are the most amenable field techniques for use with this <br />method. <br />If electrofishing is used, care must be taken to spot-sample loca- <br />tions. Continuous application of the electric field may drive fish <br />away from their original locations prior to capture, which will lead <br />to false data. Stunned fish should be removed to a live car so that <br />multiple sets of measurements are not .made for the same fish (which <br />under stress may select a different type of habitat). <br />At each location where the species of interest is observed or <br />captured, a small maker buoy is dropped for later reference. These <br />buoys may be inexpensively constructed (20~) from concrete, nylon twine, <br />and blocks of wood. They may be color-coded to represent different <br />species, or different life stages. Plate I shows the construction of a <br />marker buoy. <br />21 <br />