Influence of Different Salinities on the Growth and Physiology of Alewives

Alewives are small fishes that are native to the Atlantic coast from North Carolina to Newfoundland. In their ancestral marine environments they are anadromous, meaning that they live most of their lives in the ocean but return to freshwater in the spring to reproduce. Their young then spend several months in freshwater before migrating out to sea to mature. Although alewives are considered a marine species, they have a remarkable ability to invade freshwater habitats and form permanent “landlocked” populations that are then able to complete their lifecycles entirely in freshwater. In the Great Lakes and the Finger Lakes region of New York, landlocked alewives support valuable sport fisheries by providing food for salmon and trout. In this study I examine the physiology and growth of freshwater and anadromous alewives under controlled conditions in the laboratory to better understand their ability to adapt to different salinities. The results suggest that although alewives can successfully invade freshwater habitats and form permanent landlocked populations, these environments may not provide optimal conditions for alewife growth and survival.