A Study of the Orientation and Migration of American Shad in Long Island Sound and the Connecticut River Estuary
migration, American shad, shad, Long Island Sound, sound, Connecticut River, estuary, anadromous fish, mechanisms, Alosa sapidissima, behavior, homing, tagging
From introduction: The 1972 sonic tracking program continued the investigation of the orientation mechanisms employed by American shad (Alosa sapidissima) native to the Connecticut River, as they approached the river from Long Island Sound. The sonic tracking date from 43 normal shad tracked in 1970 and 1971 indicated that tracked shad favoured a westerly displacement in Long Island Sounds (see 1970, 1971 reports). As all of these fish were tagged and released west of the Connecticut River, we postulated that these fish had overshot their home river. To successfully home, these fish must modify their behavior to proceed east toward the Connecticut River. We further concluded that some environmental clue was responsible for the uni-directional displacement and its absence or the presence of some other clue was responsible for the reversal in direction. To test the hypothesis that some environmental clue was responsible for uni-directional displacement and eventual homing, three classes of sensory impaired fish were tracked in 1972. These included blind fish, olfactory occluded fish, and blind and olfactory occluded fish. In addition, a dart tagging program was carried out using the same three classes of sensory impaired fish and unimpaired fish. The role of these sensory mechanisms in open water orientation and homing is presented in the following report in three sections, each dealing with a specific impairment.