7625

• UCREFRP Catalog Number: 7625
• Author: Stone, R. C., L. Fields and K. Miller.
• Title: Lake Powell Post Impoundment Investigations.
• USFW Year: 1964.
• USFW - Doc Type: Progress Report No. 2,
• Copyright Material: NO

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and 1.2 percent of mmbers in the '':u:::bi;:ed g:'oup. Annelids ',ier.'2 fC'J;,c. c~::y

in one sto~ach of the 2]1-324mm le~IGth 5rou9 i~ the lQ~er reservoir. !~se~t

OCC',lrre::ce} as expected} '..13.5 8.L., 3.6} a::.J 0 percer~t it: the :J-23Cn:c, ~jl-32:.;.::::a.

a.-,j 325 a::.d longer groups. Percen:. of r:.i..l::toers was 9.1, 2.1} and 0, re:::.oecti'lel:i.

However, the insects were foued only from individuals from the upper reservoir.

Rain"::Jo'o'! Trol.l'c,

The stonachs from 21 rainbo'..J trout up to 325mm total length and from 55

trout 326mm to 461mm total length were examined (Table 8). Analysiswcc;:,

also r::.ade of the total s-:o;::achs as :;. g:::'OU}?

Both animal and plar.t matter ',lere taken by the 76 rainbo'.J trout s:.udied

('l'able 8). Ardmal matter, fish and zooplankton, l7lade up 49.3 of the total

occurrences and 90.4 perce::.';; of the total food volur:1e. Zooplankton, both

in occurrence and volume, was the predominate food item and made up ~o.8

perce:1t of occurrences a;'cd 80.9 perce:1t of volume. The ge:J.era of z')o'p2.~u:~:t(:r;

most pre'lalent in the sto:::ach CO:1tem,s were daphnia and diapt,or:n.1s. DC2:::i ::'-lJ

ceriodaphania} ar..d cyclops occurred also. Zooplankton accouated for 9:'.6

percent by volume and 43.5 percent by occurrence in the fish under 325~:1J

'dnile contributing 73.7 percer.t and 40 percent) resp,:cti velj', in tr-,e :'isn

over 326r.-.rn.

Phytcplankto:1 occurrcr,ces were second to zooplankton 1:1 t:-.':: c:'::'e~ '.. r;)~~L

groups. It amount.ed to 37.1 percer.t of total occurrences :lEd 3.3 :;:;e:.cc'::nt

of the total food volume i:1 the COt:10 ined sample.

Occurrences of phytoplu!1ktcn a:~lounted to 41.3 percent of the CCC'.1r-

rer:ccs ~nd 3. 7 perce~lt. of t.he vclui.1~ :n the s;n,'_':.llcr j:'i:ir: a:'1(l 35.. J :J:..:~cc:::

a:1d 3.1 perce:1t, re~pectively, in the larger group. Fourteen of th~ fiftee:1

total f~sh food items, rai~bow trout and green sunfish, appeared in t~~

larger group of ralnoows. Fish m~Q0 up 14.2 percen~ of the aninal ~OGj

volu:ne of the larger group.