Value of estuaries to rainbow smelt in New Hampshire
Populations of rainbow smelt, a species important in ice fishing, have declined in New Hampshire and are listed as a Species of Concern by state and federal agencies. Estuaries are presumed to serve as important ecosystems for rainbow smelt because smelt travel between fresh and saltwater habitats, but the role of estuaries play in smelt populations is not well understood. Through experimental larval release, acoustic telemetry, and otolith microchemistry, a team of researchers led by Nathan Furey at the University of New Hampshire will explore how rainbow smelt use estuaries throughout their life cycle. Future managers of the stock will be able to use this research to better protect and enhance populations of rainbow smelt and revive a threatened ice fishery.
Rainbow smelt (Osmerus mordax) are an important diadromous fish that contribute to popular recreational ice fisheries in New Hampshire, Maine, and Massachusetts. Unfortunately, migratory populations of rainbow smelt have declined considerably in recent decades and are now listed by NH and federally as a species of concern. Human activities in the estuaries and their tributaries have been implicated in the decline of smelt. Rainbow smelt are presumed to use estuaries extensively throughout their life history, but current knowledge on the subject is largely based on anecdotes and short seasonal surveys, providing barriers to effective conservation and management. A better understanding of estuarine use, including identifying important habitats, quantifying duration of residency, and characterizing connectivity among freshwater, estuarine, and marine systems, would optimize current management efforts, including stock enhancement and habitat restoration projects.
With this project, we will define the value of estuarine habitats within Great Bay, New Hampshire to rainbow smelt throughout their life cycle by integrating complementary field and laboratory approaches. First, we will experimentally release larvae among systems with and without dams and quantify dispersal rates and changes in condition (RNA:DNA ratios). Condition of naturally produced larvae will also be compared among sites. Second, we will use acoustic telemetry to characterize seasonal movements of adult rainbow smelt throughout the system. Finally, we will use otolith microchemistry to quantify duration of rainbow smelt residency in freshwater, estuarine, and marine waters across the entire life cycle. Field work will be conducted in collaboration with New Hampshire Fish and Game and volunteer citizen scientists organized by NH Sea Grant and Extension. Collectively, these efforts will provide a comprehensive description of estuarine use by rainbow smelt throughout the life cycle, and help managers identify optimal stocking sites for future stock enhancement efforts and help prioritize restoration sites for aiding natural productivity.