NIELSEK, L. A. 1980. Ek'fect of walleye (Stizostedion vitrcwm vifreum) predation on juvenile mortality and recruitment of yellow perch ( P P~C C P & V~S C C V Z S ) in Oneida Lake, New York. Can. J. F15h. Aquat. Sci. 37: 11-19.The abundance of 12 year-classes of yellow perch (Perca fluvescens) in Oneida Lake, New York, was estimated at anterkals between ages 0 and IY from catch and area swept by trawls.Rankings of abundarnce of year-classeh changed between the ends of the first and third growing seasong, wggestlng that ultimate year-class strength was influenced strongly by mortality of age 1 and I I fish. Predat~on by walleyes wa5 probably the principal cause of mortality of age 1 and II perch. Although frequency of occurrence of age I and I1 perch in stomachs of walleyes was Icaw, w w a l limb of evidence suggested that density of juvenile perck also was low and that walleyes conwrned a large proportion of each perch cohort. Rates of mortality were modified by perch length, perck dens~ty, and density of age O perch. all of which relate to intensity of walleye predation. NIELSEN, C. A. 1980. ERwt of walleye (Srizostediotr vitreum vitrmm) predation on juvenile mortality and recruiera~ent of yellow perch ( P w x fivescrm) in Oneida Lake, New York. Can. J. Fish. Aquat. Sci. 37: 11-19. 1,'alsondancc de 12 classes d'hge, cntre les Ages 0 et B I , de perchaudes (l'~~rcufiuvrscensj du lac Oneida, New York, a 136 estimee ii intervalles h mCme les priscs et dams la region balayke par les chaluts. L.es rangs ci'abondance changent entre la tin de la prernikre saison tie croissance et la iin de ia trc~isikme, ce qui donne i penser que !'abomdance ultime deb classcs d'dge est fortement irmfluenc& par la rnortalitk cia poissms d9iige I et 81. Ida principale cause de mortalite des perchaudes ci'9ge 1 et EI est probaldement la prCdation par le dore jaune. Hien que les pcrchaudes d'iige I et I 1 ne Badssent pas trop communes clans les estunlacs de dares, on a plusieurs indices 2 i'ef'et que la densite cks jeunes ixrchaudeo etait faible et que les dark jaunes avalaientune forte proportion cfe chaquc cohorte de pershaudcs. La longueur et la densite des perchaudes, aimi clue la densit6 des perchaudes cl'2ge 0, toutes liees h 19intensiti de la yrkdation par les aiores, affsctent B e taux dc rrmortalitd.

Proven strategies that reduce alcohol consumption and make the environment safer for excessive drinkers should be further implemented in AI/AN communities.

The magnitude of fish consumption by brown trout (Salmo trutta) was assessed by experimentally stocking large (> 280 mm) and small (< 280 mm) brown trout in separate sections of a Virginia stream. Large brown trout ate five species of fish consistently during the May–November, 1979, experimental period; by November, every trout stomach examined contained fish remains. Small trout rarely ate fish. Effects of fish consumption were apparent in trout growth and in abundance of prey species. Large trout grew 9.4% in length and 21.3% in weight, whereas small trout grew 4.5% in length and 4.7% in weight. Abundance of the major prey species, torrent sucker (Moxostoma rhothoecum), decreased between April and October in the stream section containing large trout, but remained constant in a comparable reference section; estimates of total consumption of torrent suckers by brown trout accounted for a large portion of the decrease in abundance. Predation on torrent suckers was selective for smaller individuals. The field experiment indicates that stocking large-sized brown trout may enhance growth and survival of brown trout, but that standing crops of nongame species are likely to decline.Key words: brown trout, nongame fishes, predation, stocking strategy, stream ecology

Fish in the Kanawha River were collected with a 0.5-m plankton net in main-channel borders and in open areas of backwaters and with a I-mZ enclosed dropbox in shallow backwater habitats. Larval emerald shiners, Notropis atherinoides, were twice as dense, and gizzard shad, Dorosoma repedianum, 2.5 times as dense in main-channel borders as in backwaters; larval Lepomis spp. were 20 times as dense in backwaters as in main-channel borders. Smaller Lepomis larvae used openwater backwater areas primarily; larger larvae migrated to vegetated backwater habitats later in the summer. Backwaters appear crucial for the maintenance of nest-building fish species in temperate rivers, just as floodplains are necessary for the maintenance of high species diversity in tropical rivers.

No abstract