. Fish populations of the wild & scenic Missouri River, Montana . Fishing surveys; Wild and scenic rivers; Fishes; Fishes. were to monitor the migration to determine timing of the run, relative abundance of paddlefish involved in the run, and extent of their upstream movements. The migration was monitored by sampling with boom suspended electro- fishing apparatus. Survey counts were made by tabulating all paddlefish observed by the boat operator and dip netter during the electrofishing operation (Figures 12 and 13). Since the effective field of the boom shocker did not cover the entire wid
. Fish populations of the wild & scenic Missouri River, Montana . Fishing surveys; Wild and scenic rivers; Fishes; Fishes. were to monitor the migration to determine timing of the run, relative abundance of paddlefish involved in the run, and extent of their upstream movements. The migration was monitored by sampling with boom suspended electro- fishing apparatus. Survey counts were made by tabulating all paddlefish observed by the boat operator and dip netter during the electrofishing operation (Figures 12 and 13). Since the effective field of the boom shocker did not cover the entire width of the river, the survey counts are a sample of the spawning run, not a complete census. A direct current of 6 to 8 amps and 120 volts pulsed at 120 to 160 pulses per second with a pulse width of 40 to 50 percent was sufficient to make the survey counts. The effective field of the boom shocker at this setting was 15 to 20 meters. More than a thousand paddlefish were counted in three years with the electrical field at this setting, and no paddlefish mortality was observed. Paddlefish were considerably less vulnerable to electrofishing mortality at these settings than other game fish species such as sauger, walleye, mountain whitefish, and trout. Only two known paddle- fish electrofishing mortalities occurred during the entire three years, and these occurred at the inception of the study when the current was allowed to exceed 10 amps and 200 volts. The electrofishing census technique was a Mery safe and effective method for monitoring the paddlefish migration in the Missouri Figure 12. Photograph of a paddlefish ahead of the boat. in the field of the positive electrodes 59. 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 Berg, Rodney K; Montana. Dept. of Fish, Wildlife, and Parks. [Helena] : Montana
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Keywords: ., book, bookcentury1900, bookcollectionamericana, booksubjectfishes
