Cisco Coregonus artedi was once an important native fish in Lake Ontario; however, after multiple population crashes, the cisco stock has yet to recover to historic abundances. Rehabilitation of cisco in Lake Ontario is a fish community management objective, but the extent to which recent non-native species and pelagic food web changes have influenced cisco is not well understood. We described cisco diets in contemporary Lake Ontario following the addition and spread of non-native zooplankton species. We collected 618 cisco and processed 178 for full diet analysis in eastern Lake Ontario using mid-water trawls and bottom-set gill nets from 2016 to 2020. We found that Lake Ontario cisco were mostly zooplanktivorous, and non-native zooplankton dominated their diet during July and September. Cisco smaller than 300 mm had a more diverse diet including both native and non-native zooplankton, while cisco larger than 300 mm fed almost exclusively on non-native predatory cladocerans Bythotrephes longimanus and Cercopagis pengoi (98.9% consumed prey dry mass). We also found fish eggs, presumed to be of coregonine origin in 75% of non-empty December-collected cisco diets, suggesting eggs subsidize cisco diets when available. Juvenile round goby Neogobius melanostomus, alewife Alosa pseudoharengus and rainbow smelt Osmerus mordax were found in 2% of all analyzed non-empty stomachs. Lake Ontario cisco diet appears to be more similar to zooplanktivorous Lake Superior cisco than Lake Michigan where piscivory is prevalent. Lake Ontario cisco diets reflected zooplankton community changes indicating that non-native predatory cladocerans are now an important energy source supporting this native species.

思科Coregonus artedi曾是安大略湖重要的原生鱼类；然而，在多次人口崩溃之后，思科的库存尚未恢复到历史丰度。安大略湖中思科的恢复是鱼类群落管理的目标，但最近的非本地物种和远洋食物网变化对思科的影响程度尚不清楚。我们描述了随着非本地浮游动物物种的加入和传播，当代安大略湖中的思科饮食。2016 年至 2020 年，我们在安大略湖东部使用中层拖网和底置刺网收集了 618 条 cisco 并处理了 178 条进行全面饮食分析。我们发现安大略湖 cisco 主要以浮游动物为食，非本地浮游动物在其饮食中占主导地位七月和九月。Bythotrephes longimanus和Cercopagis pengoi（98.9% 消耗了猎物的干重）。我们还在 75% 的非空 12 月收集的 cisco 饮食中发现了鱼卵，推测其源自 cogonine，这表明鸡蛋在可用时可以补贴 cisco 饮食。在所有被分析的非空胃中发现了 2% 的幼年圆形虾虎鱼Neogobius melanostomus、alewife Alosa pseudoharengus和 Rainbow smelt Osmerus mordax。安大略湖 cisco 饮食似乎更类似于浮游动物的苏必利尔湖 cisco，而不是鱼类盛行的密歇根湖。安大略湖 cisco 饮食反映了浮游动物群落的变化，表明非本地掠食性枝角类动物现在是支持这种本地物种的重要能源。