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2-2 . Chapter 2 Twenty-day trips were conducted to assess composition and distribution of fish, monitor habitat availability and use, determine important biotic interactions between humpback chub and other fish species, and capture humpback chub for implanting radio transmitters. These trips included two field crews. Crew one consisted of six BIW biologists and one Aquatic Coordination Team (ACT) biologist sampling in Region I. Crew two consisted of four BIW biologists and one ACT biologist sampling in Region IT. The two crews jointly sampled Region ill during the last 5 days of the trip, so that each of the three study regions was sampled with equal effort of about 10 crew-days. Twelve-day trips were conducted primarily to recontact previously radio-tagged adult humpback chub and to monitor their movement and habitat use in Region I. These trips involved one field crew with six BIW and two ACT biologists. Fish were usually equipped with radio transmitters during 20- day trips, and they were tracked and monitored during 12-day trips from October 1990 through November 1992. Sixteen-day trips were conducted from January through November 1993 after radiotelemetry was discontinued in Region I and implemented in Region II. The 16-day schedule allowed crews to allocate more time to tracking fish in Region IT, while maintaining sampling frequency and intensity throughout the study area. The number of crews on 16-day trips alternated between one crew (February, April, June, August, October) and two crews (January, March, May, July, September, November) with numbers of personnel as described for 12-day and 20-day trips, respectively. Reports Trip reports were completed and submitted within 10 days of the completion of each of the 36 field trips, and annual reports were completed at the end of 1990, 1991, and 1992. These reports were submitted to Reclamation and GCES, and distributed to cooperating agencies and interested individuals. A list of reports and publications ,f"'C)..,,,~ Final Report produced from this investigation is included as Appendix A of this Final Report. This Final Report was written by the BIW Grand Canyon Staff and reviewed by GCES, Reclamation, the Senior Scientist, several independent reviewers, and the National Research COWlCil of the National Academy of Sciences. SAMPLING DESIGN A stratified sampling design was implemented to distribute sampling effort in time and space (Schreck and Moyle 1990). The four study regions (O-III) were longitudinally divided into 11 geomorphic reaches previously described by Schmidt and Graff (1988, 1990), each with distinct channel and shoreline characteristics (See Chapter 1 - INTRODUCTION, Table 1-3). The 11 geomorphic reaches were subdivided into 34 sample strata that ranged from 3.2 to 19.5 kIn (2.0 to 12.1 mi) in length (Table 2-1). These strata were the primary spatial sampling units and were considered representative of the geomorphic reaches in which they occurred (Fig. 2-2). Eight to 16 strata were randomly selected for sampling during each monthly trip. Selected strata were not eliminated from consideration for selection on subsequent trips, i.e.,sample with replacement. The five major tributary inflows in Region IT (Bright Angel Creek, 6'J"'!9h/ t a J I I I I I J j _ - Upper Granite - Gorge creek Fig.. 2-2. Spatial stratified sampling design for Region II; a through m are sampling strata within geomorphic reaches, Upper Granite Gorge, Aisles, Middle Granite Gorge, and Muav Gorge.