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<br />~ 1)b P.4LIL u". f1:PPSON AND WILLIAT•t 5. PLATYS
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<br />Perch flat~e.rcenJ, squawfish, longnose sucker,
<br />Cat~rtonra,r catn.rtonrtr.r. mountain Whitefish,
<br />Coregonn.r tcillial))colli, rainbow trout, cut-
<br />throat trout, black crappie, Pon7oxiJ rtigronzacu-
<br />latnJ, brown bullhead, lctalnruJ nebuloarrJ,
<br />largemouth bass, lllicro pteruJ JalmoideJ, and
<br />tench, Tinca Zr7ICa. As judged from gill-net
<br />catches (Table 1) yellow perch, longnose
<br />suckers, and squawfish were the commonest
<br />species present. This lake supplies sport fishing
<br />primarily for rainbow and cutthroat trout. Fish-
<br />tng for perch and warm-water species is less
<br />popular. A small winter fishery for whitefish
<br />occurs intermittently.
<br />In Cocolalla Lake the nets took Columbia
<br />River chub, h1 ylocheilur raurinrr.r, pumpkinseed
<br />sunfish, LepomiJ gibboJUJ, and Columbia large-
<br />scaled sucker, CatoJtor77rrJ r7lacrOClJerltlJ, in ad-
<br />dition to the ten species named above. Here,
<br />yellow perch, suckers, sunfish, and squawfish
<br />were the commonest species in the net catches.
<br />Fishing activity was qu;te similar to that at
<br />Hayden Lake, anglers primarily seeking trout.
<br />Cocolalla Lake was treated with rotenone and
<br />restocked with cutthroat trout in 195'.
<br />Net catches from Pend Oreille Lake in-
<br />cluded lake whitefish,CoregonnJ clupeafor)ni.r,
<br />kokanee, and Dolly, Varden trout in addition
<br />to the species found in Cocolalla Lake. Perch,
<br />kokanee, Columbia River chub, squawfish,
<br />suckers, and lake whitefish are believed to be
<br />the commonest species. Kokanee are pelagic
<br />and were therefore infrequently taken in gill
<br />nets, which were usually set inshore. This }ake
<br />is famous for its catches of record-size rainbow
<br />trout and abundant kokanee, but anglers also
<br />commonly take cutthroat and Dolly Varden
<br />trout, whitefish, perch, crappie, and bass.
<br />Records of gill-net sets In northern Idaho
<br />lakes indicate squawfish are demersal and fairly
<br />well distributed to depths`as great as 60 feet,
<br />occupying roughly the same habitat as trout.
<br />This concurs with the findings of Forester and
<br />Ricker (1941) who collected squawfish from
<br />Cultus Lake. They had most success when gill
<br />nets were set near shore during the spawning
<br />period and, following spawning, poor catches
<br />of squawfish were made until mld-September,
<br />after which they were most easily taken off-
<br />shore.
<br />FOOD HABITS AND ]NTERSPECIFIC COMPETITION
<br />Stomachs were removed from fish taken by
<br />gill netting, by dynamiting, and from the
<br />catches of sport fishermen. Food items in the
<br />stomachs were identified .and measured volu-
<br />metrically by water displacement. In a11, the
<br />contents of 205 stomachs from 9 species of
<br />fish were examined from Pend Oreille Lake,
<br />TABLE 1.-Selecti:~ity` of gill nets of Jereral mesh rizer for, rquawjrJh and auociated 3pecieJ in Xayden,
<br />Cocolalla, and Pend Oreille Laker, Idaho. ]953 to 1958
<br />{Experimental nets have nylon webbing; others are linen or cotton; mesh measurements are stretch
<br />measure; (-) indicates species not taken}
<br />
<br />Gear .................
<br />
<br />-
<br />Lake ................. -
<br />Experimental
<br />gill net°
<br />
<br />Ha Coco- Pend
<br />den I laila IOredl
<br />I 3-inth
<br />I gilt net
<br />i
<br />Hay- Coco- Pend
<br />t den ~ -alia Oreiile~
<br />,
<br />3}/~•inch
<br />gill net
<br />~- - -
<br />Hay- Coco- Pend
<br />' den I Iafta Oreill
<br />I 4-inch
<br />gill net~
<br />
<br />II Ha Coco- Pend I
<br />i den lalla OreiI1H
<br />I
<br />I 5-inch
<br />l gill net
<br />LLL---
<br />~ Hay Coco-) Fend
<br />1 den lalla JOreiik
<br />I
<br />
<br />Net-days'..._.......
<br />Mean number days
<br />betaveen lifts........
<br />7
<br />
<br />3
<br />~ 2~
<br />
<br />]
<br />~ 116 i
<br />~
<br />1.8
<br />~ 12
<br />1
<br />12.0 _
<br />~ 81
<br />
<br />1.1 __
<br />27 I
<br />I
<br />1.3
<br />~ LZ
<br />
<br />2.0
<br />81
<br />
<br />i.l
<br />24
<br />
<br />1.3 __
<br />~ 615
<br />
<br />'2.5 __
<br />273
<br />
<br />1.4
<br />3b
<br />
<br />1.3
<br />~ 229
<br />~
<br />2.5
<br />SI
<br />
<br />i.i _
<br />~ 20
<br />
<br />1.3
<br /> ~
<br />Yellow perch...... ... 4.00 (4.80 3.93 l i 0.75 0.16 0.04 ~ I 0.58 10.01 0.00 ~i 0 0.00 -0.00 ~ 0.00 0.00 0.00
<br />squawfish ............. 0.86 9.20 1.04 ~ ~ 8.58 0.88 0.11 4.50
<br />~ 0,12 0.00 If 1.65 0.44 0.00 0.27 0.00 0.00
<br />Suckers ..... . ... ..... 2.57 + 2.110 0.76 0.42 1.72 0.11 1.17 0.37 0,04 ! 0.27 0.12 0.00 0.00 0.00 O.tg1
<br />Mountain whitefish.... 4.71 0.00 0.32 I ! 0.0r1 0.56 0.00 0.00 0.00 0.00 I
<br />0.00 0.00 0.00 ~ 0.00 0.00 0.00
<br />Rainbow trout......... 1.86 1.20 tl.D9 ~ 0.00 0.22 0.00 0.00 0.14 0.00 II
<br />0.04 1 0.14 0.00 ~ 0.00 0.00 0.00
<br />Cutthroat trout ... 0 00 0.00 0.03 ~ 0.0(1
<br />~ 0.00 0.0r1 ~ 0.00 0.01 0.00 7
<br />!!!7 0.0(I 0.00 0.00 10.01 0.00 0,t1(1
<br />Black cLappie.. 0.00 0.00 0.10 •
<br />l 0.00 0.00 0.22 4It I 0.00 0.(10 0.00 0.02 0.02 0.00 0.00 0.00 0.00
<br />Brown bullhead...
<br />L
<br />h b 000 4.00 O.Ot ; 0.00 0.26 0.00 ~ 0.00 0.02 0.00 0.00 0.03 0.00
<br />~ 0.00 0.00 0.00
<br />argemout
<br />ase ....
<br />Tench .... . . ......... 0.00
<br />0.0(1 0.00
<br />0.00 0.00 ~
<br />0.03 ,, 0.00
<br />i 0.00 0.00
<br />0.00 0.00
<br />I
<br />0.00 i 0.00
<br />o,00 0.00
<br />0.00 0.00
<br />0.00 0.00
<br />0.04 0.01
<br />0.00 0.00
<br />0.00 0.00
<br />0.19 0.00
<br />0.00 0.00
<br />0.15
<br />Columbia River chub... - 2.00 1.37 ~ ; - 0.00 0.00 - 0.00 0.00 - 0.00 0.00 - 0.00 0.00
<br />Pumpkinseed sunfish... - 1.60 0.07
<br />~ ~ - 0.40 0.00 + 0.00 0.00 - 0.00 0.00 ~ ~ - 0.00 0.00
<br />Bedside shiner.........
<br />L
<br />k
<br />hi
<br />fi
<br />h - 0.00 0.00
<br />I ' -
<br />I 0.00 0.00 _
<br />I 0.00 0.00 - 0.00 0.00 - 0.00 0.00
<br />e w
<br />te
<br />.........
<br />a
<br />s - - 0.43 - - 1.19 - 0,62
<br />~ - 0.03 - - 0.00
<br />Kokanee ..... . ........ - - 0.08 ! ' - - 0.00 - - 0.00 - -
<br />~ 0.00 - - 0.00
<br />Dolly Varden trout..... - - 0.09 f ! - - 0.00 I I - - 0.00 I - - 0.00 I - - 0.00
<br />' The catch index used is the aceraRe number of fish taken in 100 lineal feet of gill het per 24-hour period.
<br />Experimental net has 6 x 25-foot sections of 13,-. 2?~-. 3-, and 4-inch mesh (stretch measure).
<br />'Net-day is 100 lineal feet of gill net far a 24-hour pesiod.
<br />~ .~ -
<br />~~ :,.
<br />~~ -
<br />148 stomachs
<br />Lake, and I00
<br />Cocolalla Lake.
<br />Table 2.
<br />It mill be nh
<br />food of squanf
<br />than 58 perccn•
<br />in Hayden Lak~
<br />Lake, and kokar,
<br />bow trout, a h i
<br />also fed on fish
<br />was identified
<br />(12 to 56 percc
<br />fed mostly on c
<br />trout fed almost
<br />rain whitefish on
<br />fish, taken onlti•
<br />fed on insects,
<br />Dolly Varden tr.
<br />bullheads on f1sh.
<br />worms, and scud
<br />sects, crayfish, h
<br />and Columbia R i
<br />and plant materi.t
<br />TABLE 3. Food ~.
<br />northern Idaho .'
<br />Item
<br />squawfish T__
<br />stomachs toot.:
<br />Total volume
<br />Fish .........._
<br />Insects ..
<br />Crayfish ...__
<br />Scuds ..::..
<br />Mollusks
<br />Plant material
<br />Rainbow trout
<br />Stomachs cunt
<br />Total volumr t
<br />Fish ......,.._., ..
<br />Insects _.
<br />Plant material
<br />Dolly Varden trout
<br />Stomachs coma-
<br />Total volume
<br />Fish ........_...
<br />I RSeCtS ........ ... ..
<br />Earthworms
<br />Scuds .._....__
<br />Fish eggs ..
<br />Cutthroat trout
<br />Stomachs conta~:
<br />Total volume
<br />Fish ..................
<br />Insects ...__.___
<br />Earthworms
<br />Flant material
<br />' Food of squawfish
<br />
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