Date of Award

Fall 2023

Project Type

Thesis

Program or Major

Biological Sciences

Degree Name

Master of Science

First Advisor

Nathan B Furey

Second Advisor

David Berlinsky

Third Advisor

Alyson Eberhardt

Abstract

Anadromous rainbow smelt in the northeastern USA have experienced range contraction over the past few decades, and are now restricted to waters in Massachusetts and northwards. In their current range, populations appear to be in decline, including in New Hampshire; in Great Bay, New Hampshire, conservation methods such as habitat restoration and stocking efforts have been suggested to improve populations, with projects underway to implement these methods. To optimize these conservation efforts, specific knowledge regarding rainbow smelt habitat use in estuaries is needed, including the specific habitats used as well as timing and duration of use. In March 2021, we used acoustic telemetry to monitor seasonal movements of adult rainbow smelt in Great Bay, New Hampshire, USA. We tagged 44 smelt (mean FL = 164 mm) with Innovasea V5 (180 kHz) tags at upriver spawning sites in three tributaries of Great Bay. An array of 22 180 kHz VR2W receivers were deployed throughout Great Bay to detect movements of tagged fish from March-October 2021. Analyses of these movements suggest that rainbow smelt can use multiple rivers during the spawning season, potentially moving with the tide to facilitate habitat transitions. Additionally, we used Cormack-Jolly-Seber (CJS) mark-recapture models to estimate survival from release in the spawning rivers to the Piscataqua River (which leads to the Gulf of Maine) and estimated emigration survival to be 74% (95% Confidence Interval = 0.62-0.91). Among these survivors, individuals resided in the system for an average of 38.9 +/- 1.2 days prior to emigration, with most rainbow smelt remaining in the estuary for a few weeks after spawning. This project also provides a preliminary analysis of water chemistry in Great Bay to support ongoing and future studies of rainbow smelt migration patterns using otolith microchemistry, a technique that provides lifelong, information on broad-scale migratory patterns across the salinity gradient that is complementary to the seasonal, fine-scale acoustic telemetry data described in this thesis. Overall, this project shows that estuary systems such as Great Bay provide more to adult rainbow smelt than just spawning habitat; adult rainbow smelt rely on a variety of riverine and estuarine habitats, utilizing the estuary as important habitat post-spawning.

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