Differences in life history patterns of American shad, Alosa sapidissima, populations between ancestral, Atlantic coast, and non-native, Pacific coast rivers of North America

Canadian Journal of Fisheries and Aquatic Sciences
By: , and 

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Abstract

Organisms naturalized outside their native range can reveal new life history patterns in new environments. Here, we compare life history patterns of American shad, Alosa sapidissima, from five rivers along the U.S. Pacific coast (introduced range) with contemporary data from the Atlantic coast source populations. The Pacific coast fish grew slower, matured at a younger age, and were less often iteroparous than conspecifics from the Hudson River and Susquehanna River sources. Differences among the Pacific coast populations indicated that some combination of phenotypic plasticity and genetic adaptation has occurred since the transplants in the 1870s. Microchemical analysis of otoliths from returning adults demonstrated an immature, extended freshwater life history form, locally known as “mini-shad”. These fish remain in the river for at least 1 year or enter salt water briefly and then return to fresh water for several months prior to subsequent seaward migration and return as adults. This and other forms of variation (extent of estuary use and size at sea water entry) expand the understanding of Alosine migration and life history diversity.
Publication type Article
Publication Subtype Journal Article
Title Differences in life history patterns of American shad, Alosa sapidissima, populations between ancestral, Atlantic coast, and non-native, Pacific coast rivers of North America
Series title Canadian Journal of Fisheries and Aquatic Sciences
DOI 10.1139/cjfas-2023-0286
Volume 81
Issue 7
Year Published 2024
Language English
Publisher Canadian Science Publishing
Contributing office(s) Western Fisheries Research Center
Description 17 p.
First page 862
Last page 878
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