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conclusion of biologists involved- in this recovery effort. <br />Depletion of predators, while most practical, may not be <br />acceptable to AGFU or the fishing public. Sport harvest figures <br />for catfish from riverine portions of the Gila River drainage are <br />unavailable but probably small due to inaccessibility of much of <br />the study area. Removal or depletion of predators by piscicides <br />or mechanical means from discrete (1-2 km) or larger (e.g. the <br />ca. 90 km of the Salt River in the Salt River Canyon from Apache <br />Falls downstream to the diversion structure above Roosevelt Lake) <br />could be accomplished without permanently impacting sportfish <br />populations. In turn, reduced predator levels would allow <br />stocked razorback suckers an opportunity to acclimate to stream <br />conditions without immediate threat of predation by introduced <br />fishes. <br />Size of razorback sucker stocked is of great concern in <br />light of existing predator populations. Fry, nearly 873'0 of <br />razorbacks stocked in 1985, are susceptible to essentially all <br />sizes of predators. Predation studies of Gila River stockings <br />illustrate the susceptibility of fingerling suckers (ca. 75- <br />150 mm TL) to the often voracious appetites of catfish. Stocking <br />a larger size would presumably reduce the threat of predation but <br />would also result in fewer fish stocked -- bigger fish require <br />more space, a limited resource at DNFH. This trade-off could be <br />partially offset by continuing to rear razorback sucker at PSH <br />and using various ponds on FWS lands (refuges) for stocking and <br />grow out. Size of stocked razorback sucker should be no less <br />than 25U mm TL (requiring an additional year~of hatchery rearing <br />-9- <br />