This paper presents a study of ciscoes of Irondequoit Bay, New York, and deals with their migration, age and time of spawning, associated species at the time of spawning, predators, and conservation. This study is based on the age determinations of 505 specimens, on the calculations of the length at the end of various years of life of 500 of these ciscoes, and on the examination of the ovaries of 104 fish.