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.j . During lY/tl, t~'enty adult humpback chubs were placed at W1~iOW Beach National Fish Hatchery, for propagation purposes. The fish were collected from the Little Colorado River, in the vicinity of its mouth,: flown to the south rim of the Grand Canyon, and transported to Willow Beach. All fish arrived in good condition and were in the hatchery raceways within five hours of lift-off from the Little Colorado River. . During 1978, 555 humpback chubs were collected. Of these fish, 21.5% (196) were juveniles, and 78.5% (359) were adults. Distribution of this species within the mainstream Colorado River was extended to river mile 194, based on a report from a commercial rive~ runner. General distribution with- in th~.EYM~m .L~f l~_c_ts- thELs:i,z~g_~ _~JS!b.~ w:t1:_~_~~Ig.f:!_L.?Aul tl;LP_I;:~t~rrj.n~ t...?..I:.- pver two meters in d~th. Juvenile fish occu~L~~.~U-R~~~r_l~~th~n t~. meters in dep~ Both siz~~}'~tlP3~~~.':l~~_~JIY__~0l:!E~.iJLIl1QgeI:ClJ_~"._~.q".,:>19~__ current ever silt-Osand hot'tom in the Little Colorado River. .._~....~...~..,--~......."-"""---.~--- -,,- ~,...,~ '~-, . - --.'-, ..'. - - . '.-... -. ,.....---.--- ...._--,.,....._--,,_......~,~-~~.~- - - -. ..-"""---- J "it- ~- . \ . Y'-- I I ; sp. as well as food from cotr~ercial river parties. i ~le stomachs of three Schooling was observed both in adult and juvenile humpback chubs, as was feeding behavior. Schooling fish were observed feeding both on the bottom substrate and the surface film. Adult chubs were observed to take Cladophora young-of-the-year humpback chubs were fou.'Jd by direct examination to contain dipteran Families of Chironomidae, Ceratopogonidae and Dolichopodidae. ~-- Reproduction appeared to have occurred in early June based on the small size of the fish collected by seining (x T. L. = 19 mm). It is suspected that spawning commences in early spring (March) and continues through early su~~er, as observed. _"_,_~r--'-_____ Estimated numbers of humpback chubs, based on seining collections, tanged from 122 fish/hectare in May up to 1527 fish/hectare in June. Tagging operations were .also implemented in July of 1978 using' 3/8" x 1/8" fingerling tags. To date~/16rhumpback chubs have been tagged and none have been recaptured. .....-.-,...,.---.-.<,-.--..#, .. Major problems faced by this population of humpback chubs are human impact, water fluctuations, and a newly discovered infestation of the anchorworm parasite Learnea sp. During October. 54% of the chubs collected were infested. '----- ". ~