Borgmann, U., and D.M. Whittle. 4994. Particle-size-conversion efficiency, invertebrate production, and potential fish production in Lake Ontario. Can. J. Fish. Aquat. Sci. 51: 693-780.The relationships between body sime and p,pf-DDE and total PCB concentration in zooplankton, rnysids, amp h ipods, slimy scu [pin (Cottus cognatus), rainbow smelt (Osmerus mordax), alewife (Alosa pseudoharengus), and lake trout (Sa%vebinus namaycush) in bake Ontario were determined for samples collected from 5989 ts 1992. Amphipods, and to a lesser extent sculpins, had higher DDE and PCB concentrations than predicted from the contaminant concentration -body size relationship for the pelagic species. PCB, but not DDE, concentrations in zooplankton were also abnormally high. For the pelagic species, excluding PCB concentrations in zooplankton, the log contaminant concentration -log body sime relationship had a slope of 0.23 (95% confidence limits = k8.014). Combined with revised estimates of the efficiency of contaminant retention from one body size to anbtker (EL 0.85-8.10), the revised estimate of particle-size-conversion efficiency (E) for Lake Ontario falls between 0.27 and 0.35. Recent estimates of inve~ebrate (zooplankton, mysid, and amphipod) annual production average 18 dm' (dry weight) with upper and lower limit estimates of 14-27 d m 2 . Using E to extrapolate from invertebrate to fish production results in estimates of mean potential fish production in Lake Ontario of 1-7 kdha (wet weight), as csmpared with previously published estimates of 6 and 14 kglha. Nous avsns calcule, pour des kchantilions prelevks de 1989 21 1992, Bes relations entre la taille csrporelle et la concentration de p,pf-DDE et des BPC totaux dans le nooplanctsn, les rnysidac6s, les amp hi psdes, les c haboisseaux (Cottus cognatus), If6perlon (Osmerus mordax), le gaspareau (A%osa pseudoharewgus), et le touladi (Salvelinus namaycush) du lac Ontario. Les amphipodes, et les chaboisseaux dans une moindre mesure, prksentaient des concentrations de DDE et de BPC plus eleves que pr6vu dPaprPs la relation concentration de contaminants -tailie corporelie pour les espPces pdagiques. Les concentra-tions de BPC, mais non de DDE, dans B e zooplancton 6taient aussi anormalemewt klevbes. Pour les esp$ces pelagiques, si I'on exclut les concentrations de BPC dans le zooplancton, la relation log de la concentration de contaminants -Isg de la taille corporelle prksentait une pente de 0,23 (seuil de confiance de 95 % = +_8,014). Si on la combine 21 des estimations rbvisees de I'efficience de la retention des contaminants d'une taille corporetle . 3 I'autre (E' = 0,05-8,10), Ifestimation reviske de I'efficience (E) de la conversion particule-taille pour E e lac Ontario tombe entre 0,27 et 8/35. Les estimations recentes de la production annuelie les invert6brks (zooplancton, mysidacks et am-lphipodes), est en moyenne de 18 d m 2 (poids sec), avec des limites superieure et infkrieure estimees 3 54 et 27 gj/m2. Le recsurs 2 e pour extrapoler de la production dfinvert6br6s 2 l...