Restoration potential for reproduction by Striped Bass (Morone saxatilis) in the Saint John River, New Brunswick
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Date
2019
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University of New Brunswick
Abstract
In 2012 the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) listed the Striped Bass (Morone saxatilis) of the Saint John River, New Brunswick, as endangered as part of the Bay of Fundy designatable unit. This listing was due to an apparent rapid collapse and subsequent absence of presumed native origin Striped Bass, juvenile recruitment, and spawning by the species following the completion of the large Mactaquac Dam in 1968. Expert reports hypothesized that alteration in the river flow and temperature regime imposed upon the Saint John River downstream from the Mactaquac Dam were responsible for the disappearance, however, no recovery efforts or exploratory studies were conducted, and the native Striped Bass population was deemed extinct. This dissertation explored the collapse of the Saint John River Striped Bass starting with a complete historic perspective of the species in the Saint John River and concluded with a possible means to recover the population that was once believed to be lost.
Within the chapters of this thesis I first summarize the history of Striped Bass in the Saint John River and explore why the current understanding of the species status needs to be updated. I locate and sample juvenile Striped Bass within the Saint John River for the first time since 1979, prove their native ancestry, and monitor their year class success. Native adult Striped Bass matching juvenile ancestry are tagged and tracked to determine the timing and location of their upstream spawning migration and the migrations of non-native adult Striped Bass within the Saint John River are also explored. I summarize information on Striped Bass winter ecology in Canada, then locate and describe four key winter habitats used by Striped Bass in the Saint John River. Finally, I draw a possible connection between the regulated discharges at the Mactaquac Generating Station to the success of Striped Bass juvenile recruitment observed in the Saint John River over six consecutive years of sampling.
My general conclusion is that spawning by native Striped Bass in the Saint John River downstream of the Mactaquac Dam has been severely impacted, though not eliminated, by the regulated discharges resulting for power production. These discharge regimes have resulted in infrequently successful year classes, poor recruitment and possible spawning failures; however, spawning by surviving native origin Striped Bass may be recovered through the management of spring discharges. Managing for extended periods of moderate, sustained flow of sufficient volume and duration to keep Striped Bass eggs in suspension during the incubation period may restore successful Striped Bass spawning and juvenile recruitment in the Saint John River, New Brunswick.