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<br />2.) To comparatively describe the early morphological ontogeny of <br />selected important fishes (e.g., native and non-native cyprinids and <br />catostomids), including morphology and development of sense organs <br />and locomotor structures. <br /> <br />3.) To evaluate responses of selected important fishes to manipulate <br />physical conditions and assess the role of sensory and locomotor <br />systems in various early behaviors such as feeding, predator <br />avoidance, and swimming performance. <br /> <br />4.) To evaluate effects of variable environmental factors (streamflow, <br />water temperature, food supply) on growth and survival of Colorado <br />squawfish in laboratory and field studies. <br /> <br />End product - - Annual progress reports for each study will be provided at <br />end of fiscal year. <br /> <br />IV. Study Araa: <br />Lower Y&mpa River, Colorado, and Green River, Utah. <br /> <br />v. Study Hathods/Approach: <br /> <br />Objective 1 -- Use of otoliths from larvae in fishery-science studies is <br />a relatively a recent innovation that has provided a wealth of new <br />information to biologists. Ability to accurately age larvae can provide <br />data on hatching dates, spawning intensity and duration, age-specific <br />growth and mortality, and effects of environmental factors, such as <br />changes in water temperature on growth of larvae. discrete cohorts of <br />larvae within a reproductive year could potentially be identified with <br />accurate otolith-aging techniques. With subsequent sampling, effects of <br />various environmental factors on growth, survival, and recruitment of <br />larvae in those cohorts could be identified. Most of this sampling is <br />already proposed. in the systematic data collection and research studies to <br />evaluate reproduction and recruitment of fishes in the Green River. Thus, <br />studies that may result from validation of otolith techniques will not <br />require excessive additional sampling, and could potentially incorporate <br />specimens collected from previous studies. Validation studies are labor <br />intensive and time consuming, but are critical if otoliths are to be used. <br />The most desirable method is sequential sacrifice of Icnown-age specimens. <br />These can be attained frOll\ hatchery stocks at Dexter National Fish <br />Hatchery. FrOll\ these specimens, time of otolith formation relative to <br />hatching, timing of ring deposition, and relation of ring number and age <br />can be assessed. Because conditions in the wild change from year-to-year, <br />and within a spawning season, effects of environmental factors such as <br />changes in water temperature (and food availability) would also need to be <br />assessed. Otolith validation would employ standard microscopic and would <br />be to determine whether this technique could be applied to specimens <br />captured in the wild. For more details see pages 27-29, 40-41 in K. R. <br />Bestgen's graduate-research proposal. <br /> <br />Objective 2 Early morphological and especially physiological <br />development of fishes int eh Colorado river Basin have been little <br />studied. Observed behavioral and lifestyle attributes in fishes affect <br />reproductive success, habitat selection, growth, and survival, and are <br />linked with changes in physiology and morphology. A literature review <br />will be conducted to determine av,l.ilable techniques, information on other <br />fishes, and current Icnowledge of early development and behavior of species <br />of concern. Eggs of selected species will be obtained from existing <br />hatchery or laboratory stocks. Larvae will be reared in the laboratory <br />and observations of general development and behavior will be conducted. <br />Detailed microscopic examinations using scanning-electron microscopy (SEM) <br /> <br />C25 <br />