72 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Table 6. — Animals found on and near lake-trout spawning 

 area in Otsego Lake, Apr. 27-June 2, 1941 



Phylum and 

 order 



Coelenterata 



Platyhelminthes. 

 Arthropoda; 



Amphipoda. 



Neuroptera... 



Ephemerida. , 



Do- 



Do 



Do 



Do 



Odonata 



Do 



Do 



Do 



Do 



Do 



Do 



Plecoptera 



Coleoptera . . . 



Trichoptera- . 



Do 



Do 



Do 



Diptera 



Do 



MoUusca: 



Gastropoda... 

 Do- 



Pelecypoda.. 

 Chordata: 



Pisces 



Do 



Do 



Do 



Do- 



Do 



Do 



Do 



Do 



Do 



Do 



Do. 



Do 



Amphibia... 



Species 



Hydra sp 



Planaria sp- 



Hyalella sp 



Sialis sp - 



BlastuTUi sp -. 



Ephemerella sp 



Stenonema sp 



Hexagenia sp 



Ephemera sp 



Qomphus sp - 



Didymops transversa 



Epicordulia princeps 



Helocordulia tihleri. . 



Neurocordulia obsoleta^ .. 



Argia moesta 



Enallagma sp 



Neoperla sp 



Dineutes sp 



Stenophylaz scabripennis . 



Molanna sp 



Phryganea sp 



Qtossosomatinae ' 



Chironomus sp 



Tanytarsus sp 



Limnea sp 



Planorbis sp 



Unidentifiable. 



Coregonus dupeaforrrtis ^ . 

 Cristivomer n. namaycush. 



Notropis h. hudsonius 



Hyborhynchus notaius 



Esoi niger 



Angidlla hostoniensis 



Perca fjavescens 



Stizosledion v. vitreum 



Bolesoma nigrum olmstedi 

 Micropterus d. dolomieu.. 



Lepomis gibhosus 



AmhloplUes rupestris. 



Cottus cognatas 



Triturus viridescens.,. 



Common name 



Alderfly.. 

 Mayflay. 

 ....do--- 



do--. 



do... 



.do- 



Dragonfly 



do 



do 



. -do 



do 



Damsel fly 



do.. 



Stone fly 



Whirligig-beetle. 



Caddisfly 



do 



do 



do 



Midge.. 



do.. 



Pond snail . . 

 Wheel snail. 

 Clam 



Whiteflsh 



Lake trout 



Spot-tail shiner 



Blunt-nosed min- 

 now. 



Chain pickerel 



American eel 



Yellow perch 



Yellow pike-perch. 



Johnny darter 



Small-mouthed 



bass. 

 Pumpkinseed (sun- 

 flsh). 



Rock bass 



Slimy muddler 



Newt -.- 



Stage 



Larva. 

 Nymph. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Do. 



Larva. 

 Do. 

 Do. 

 Do. 

 Do. 

 Do. 



' Two or more species. 



be trout-egg eaters. On the Otsego Lake spawn- 

 ing area, an eel (Anguilla bostoniensis) and several 

 whitefish (Coregonus clupeajormis) were seen 

 industriously feeding among the stones where 

 the lake trout were spawning. In addition, a 

 slimy muddler {Coitus cognatus), which is known 

 to eat trout eggs, was captured in the immediate 

 vicinity. 



What is the effect of this predation? Greeley 

 (1932) concluded that practically all the eggs of 

 rainbow, brown, and brook trout eaten were 

 waste eggs not buried in the redd, and that the 

 effect of egg predators on reproduction was neg- 

 ligible. Hobbs (1937) thought that the number 

 of eggs eaten from the redds of rainbow and 

 brown trout and quinnat salmon was very small. 

 The spawning trout themselves are important 

 predators but they could scarcely be accused of 

 eating all their own spawn. 



It seems likely that predation would have no 



more effect on the eggs of lake trout than it has 

 on those of other trout. If the lake trout can 

 spawn on the type of bottom they seem to prefer, 

 the eggs and alevins are certainly well protected 

 until they emerge from the rubble. It was neces- 

 sary to dig deep into the rubble in the Otsego 

 Lake spawning area to capture either eggs or 

 alevins. 



Additional evidence is provided by the lack of 

 any lake-trout alevins in the stomachs of the 

 following fish captured in the immediate vicinity 

 of the lake-trout spawning area between April 

 27 and June 2, 1941: 



6 whitefish {Coregonus clupeaformis) 



I adult lake trout {Salvelinus { = Cristivomer] namay- 

 cush) 



II shiners {Notropis hudsonius) 



1 blunt-nosed minnow {Hyborhynchus notatus) 



1 chain pickerel {Esox niger) 



17 yellow perch {Perca flavescens) 



22 johnny darters {Boleosoma nigrum olmstedi) 



I smallmouth bass {Micropterus d. dolomieu) 

 4 common sunfish {Lepomis gibhosus) 



13 rock bass (Ambloplites rupestris) 



II slimy muddlers {Cottus cognatus) 



These fish were all captured during the pre- 

 sumably vulnerable time the alevins were absorb- 

 ing the yolk sac and leaving the spawning bed. 

 Such negative evidence is inconclusive but reassur- 

 ing. 



It is important to note that most trout-egg 

 predators have been indicted for their activities 

 during the time the eggs were being laid and not 

 after the eggs were hidden in the gravel. It is 

 concluded that lake-trout eggs and alevins suffer 

 little from predation after the spawning season, 

 and that during spawning the eggs that are eaten 

 are only those left exposed on the bottom. 



DEVELOPMENT OF EGGS AND ALEVINS 



Greeley (1936) collected eyed eggs and newly 

 hatched alevins on the Otsego Lake spawning 

 area on April 12, and more-advanced alevins on 

 May 9. I took newly eyed eggs on February 17, 

 1941, and later-eyed stages on March 31, 1941, by 

 chopping holes through the ice. (The lake trout 

 had been observed spawning December 5, 1940.) 

 Later, on April 27, with the surface water tempera- 

 ture 44° F., newly hatched sac fry were taken, and 

 on May 17, 1941, many more-advanced fry were 

 taken (temperature data in fig. 6). All the stages 

 were taken from the rubble on the spawning area. 



