Laserfiche WebLink
<br />168 mm TL) released into the Gila River Arizona were heavily preyed on by <br />flathead catfish (Pylodictis olivaris) and channel catfish (Ictaluras <br />punctatus), thereby revealing such predation as an important limiting <br />factor for those species in the Gila River system. <br /> Whether for reintroduction, augmentation, or experimental purposes, an <br /> important consideration of any future stocking program will be the need to <br /> maximize the survival of stocked fish. On the basis of using largemouth <br /> bass as potential predators, Osmundson (1987) recommended rearing squaw- <br /> fish to a length of 200-250 mm before stocking as a means to insure great- <br /> er survival of stocked fish. Similarly, Marsh and Brooks (1989) recom- <br /> mended rearing razorbacks to lengths of 300 mm or greater as one means of <br />' reducing predation intensity. Osmundson's (1987) study of growth and <br /> survival of Colorado squawfish stocked in gravel-pit ponds near Grand <br /> Junction, Colorado, demonstrated that growth rate of squawfish in a pond <br /> environment (warm water; abundant forage fish) can be more than twice that <br /> of fish in either river or hatchery environments. Rearing squawfish in <br /> ponds that contain self-sustaining forage fish may be significantly more <br /> cost effective than traditional, labor-intensive, raceway or pond fish <br /> culture, which rely on the use of artificial feeds. However, results of <br /> Osmundson's pond studies indicated that growth of Colorado squawfish is <br /> variable, depending largely on season of stocking and availability of <br /> appropriate-size foods, and that survival varies greatly among ponds and <br /> years and can be very low. However, other than predation, the causes of <br /> squawfish mortality in ponds were not made clear and need to be identi- <br />fied. <br />2