7166 - Laserfiche WebLink

Home Browse Search

pattern developed between these two measurements among the six fish tested. This precluded the use of a common conversion factor. A Chi-square analysis of the calculated ratio from live.fish vs. preserved fish was performed. This analysis indicated a statistically significant difference (P=0.001, 15 df) between the ratio of the live fish vs. the ratio of the preserved fish. 2. Measurements taken by CRFP personnel have differed up to five units from person to person and from those measurements taken by G. R. Smith, Because four different people have taken measurements, reliability of these ratios is questionable. 3. Gila spp. measured by FWS personnel having ratios in the midrange of G. elegans were later identified as being G. cypha by G. R. Smith and R. R. Miller. Further refinement of this method is needed for field use. An Attempt to resolve some of the problems was made in 1981. Gila spp. 2 (adult and juvenile) collected in 1981 were photographed on a large cm grid board. This should aid in identifying those fish, since morpho- logic counts and measurements can be made from the photographs. Photo- graphs will be measured independently by several workers and results of these analyses will be compared and reported on at a latter date. No single criterion is available that can appropriately identify the fish in the laboratory or afield. The need to take morphomeristic measurements (possibly as many as 20) is impractical afield because it is time consuming and cumbersome and could lead to the death of the fish. Additionally, it is difficult to transport the necessary equip- ment to remote areas where Gila spp. commonly occur. Most morphomeristic measurements (gillraker and vertebrae counts) taken from Gila spp. require the fish to be sacrificed. Also, standard systematic techniques require a large number of specimens. However, legal constraints for sacrificing a large number of endangered fishes preclude extensive collection and preservation to verify their identification. All preserved specimens of Gila spp. collected from the Green and Yampa rivers were recalled to the Vernal station. An effort was made to identify these specimens using taxonomic keys, professional judgement and by corroborating with known authorities. A number of meristic characters identified earlier (see methods) were utilized to segregate Gila spp. Nineteen specimens subjected to this taxonomic analysis were identified as follows: G. robusta (4), G. cypha (5), G: elegans (1). - - In addition, three specimens appeared to be G. cypha influenced with G. robusta characteristics, two specimens appeared to be G. robusta influenced with G. cypha characteristics, one specimen appeared to be G. cypha influenced with G. elegans characteristics, and three were classified unknown. 71