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14 I I I I I I I I I I I I I I I I I I I culturing practices and feed available (see guidelines mentioned in Nutrition and Feeding section), intensively cultured pikeminnow averaged about 4 inches after one year (@ 0.009 inches growth per. day). Pikeminnow reared at FRH had an average specific growth ratel of about 1, and an overall feed conversion2 of about 2. To put this into perspective, trout have a specific growth rate of2-3 and feed conversion of 1.2-1.5. This means trout grow two to three times faster than pikeminnow. Carrying Capacity (Density and Loading) In 1991, a seven-month study was conducted to determine density, loading thresholds, and optimum ranges for intensively cultured pikeminnow at 68-700 F. Results from this study, along with data from the previous years. of pikeminnow culturing, are presented only as recommendations. The optimum range for densities is 1-5 pounds per cubic foot. With densities below 1 pound per cubic foot, feeding response was reduced and slower growth occurred. It was observed that even with young fry, if the densities were too low, the fish were very spooky and did not feed as well. Growth fell off rapidly once the maximum point of 5 pounds per cubic foot was exceeded. The desired range for loading is 0.5-4 pounds per gallon per minute. Growth decreased and water quality lowered once 4 pounds per gallon per minute was exceeded. Growth rates were highest when both density and loading were kept in their optimum ranges. HANDLING The most critical aspect of intensive pikeminnow culture is increasing survival of the small, delicate sac fry and fry. Pikeminnow are very vulnerable to any handling during the first few months. Extra care should be taken to avoid possible mechanical damage to small fish when handling and cleaning. Equipment and culturing techniques must be adjusted to accommodate the delicate fry. Approximately 30 percent of the fish reared at the FRH had some type of deformity (fin and spinal damage, eyes missing, etc). It is believed that some of the deformities could be genetic defects, but most likely the majority of the damage was associated with improper handling of young fry. It is recommended that handling be kept to a minimum until pikeminnow reach 2 inches in length. From 2 inches on, pikeminnow were found to be very hardy and withstood handling extremely well (no significant mortality). WEIGHING, ENUMERATING AND MEASURING FISH Length and weight data were collected montWy to determine the condition of the fish and proper feed usage. A random sample of 100 fish from each tank were individually measured and weighed. To reduce handling stress, these fish were anesthetized with 50-100 parts per million of Tricane Methanesulfonate (MS-222) during measuring and weighing (68-700 F). To decrease the time fish were anesthetized, only 10-15 fish were done at a time. This way fish were back in fresh lSpecific Growth Rate = lnWp - lnWr, where WF == Final weight, and WI = Initial weight # days 2p eed Conversion = weight food fed divided by weight gained .