Aspects of the life histories of Anadromous Alewife, Alosa pseudoharengus (Wilson), and the Blueback herring, A. estivalis (Mitchell) in the southwest Margaree River and Lake Ainslie, NovaScotia, 1978-1979

The spawning migrations of the anadromous alewife, Alosa pseudoharengus (Wilson) and blueback herring, A. aestivalis (Mitchell) were studied in the Southwest Margaree River and Lake Ainslie, N. S. during the summers of 1978 and 1979. Changes in species composition, sex ratios, and age structure during the run were monitored and preferred spawning areas in Lake Ainslie ascertained from larval collections. The incidence of repeat spawning, age and adult growth patterns in both species were deduced from examination of scales. The distribution, abundance, and growth of Alosa larvae and juveniles were determined by extensive larval tows and beach seine collections. The reliability of selected meristic and morphometric characteristics for distin- guishing alewife and blueback herring is assessed and a comparison of the results obtained from two common methods of backcalculating adult growth is provided. Water quality and Morphoedaphic Index values for Lake Ainslie are also reported. The abundance and distributions of other species of fish encountered are given.