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' , <br />Methods: Place traps in hatchery discharge pipes and attempt to attract <br />fish that were reared at Ouray and released into the Green River 3 to 5 years <br />previously. <br />H4: Colorado squawfish and razorback sucker can be artificially-imprinted to a <br />suitable synthetic substance. <br />Task: Test synthetic substances for imprinting effectiveness. <br />Methods: Obtain newly-fertilized eggs from a hatchery, mark them during <br />incubation and early larval development, rear to sub-adult size, and release <br />at a re-introduction site. Three groups would be marked: morpholine, phenethyl <br />alcohol and a control group that would be hatched in hatchery water. The <br />reintroduction site would be carefully chosen for its adequacy as a future <br />spawning and rearing area, and the fish would be attracted as spawning adults <br />by releasing imprinting chemicals (and control water) during tfie anticipated <br />spawning period. <br />Response of the imprinted fish to suitability of the attractant and various <br />habitats would be monitored by recaptures. <br />H5: Colorado squawfish and razorback suckers recognize odors from reproductive <br />byproducts and use them to locate specific sites for egg deposition. <br />Task: Determine if reproductive by-products can be used to attract fish in <br />lieu of using a synthetic chemical. <br />Methods: Obtain biological waste-products (egg cases, feces, etc) from <br />hatchery-reared fish, and place these in selected spawning locations. Monitor <br />the location by capturing fish during the spawning season. This could be done <br />in the presence or absence of other cues (HSOB or synthetic compounds) <br />depending on study design. <br />Morphology <br />It is important to determine temporal development of functional receptors <br />used in olfaction to determine the timing associated with imprinting. <br />Therefore it is necessary to determine the comparative functional morphology <br />of sensory organ development and their function. <br />Also there are accessory organs involved with reproduction in both species: <br />In the Colorado squawfish, breeding tubercles are hard, horny structures that <br />may have a tactile function in breeding, and razorback sucker tubercles are <br />soft and fleshy organs that may be involved with secretions of attractant <br />odors. <br />H6: Functional receptors used in olfaction develop at an early stage in <br />Colorado squawfish and razorback sucker <br />Task: Determine the development of olfactory sensory organs <br />8 <br />