Survival of Migrating Atlantic Salmon Smolts through the Penobscot River, Maine: a Prerestoration Assessment

Holbrook, Christopher M.; Kinnison, Michael T.; Zydlewski, Joseph D.

doi:10.1080/00028487.2011.618356

Cited by 43 publications

(72 citation statements)

References 33 publications

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“…No mortality was observed in any of those fish. Previous studies observed elevated mortality immediately following release (up to 50% in wild smolts but generally less than 5% in hatchery-reared fish) associated with the handling, transport, and release of acoustically tagged smolts in the Penobscot River (Holbrook et al 2011). All smolts used for analyses in the present study were released a minimum of 50 km above the head of tide (rkm 45), so we assumed that residual effects of tagging were minimal during estuary passage.…”

Section: Methodsmentioning

confidence: 99%

“…The removal of Great Works and Veazie dams will likely increase smolt survival in the Penobscot River estuary by reducing dam-related mortality in the estuary (Figure 5), even though these dams resulted in little acute mortality during freshwater smolt migration (Holbrook et al 2011;Stich et al 2014). Indeed, the indirect, dam-related estuary mortality resulting from each of these structures (about 6%; Figure 5) was greater than the direct mortality incurred during passage (0-1%) of the facilities (Holbrook et al 2011;Stich et al 2014).…”

Section: Conservation and Management Implicationsmentioning

confidence: 99%

“…The acoustic tagging methods we used are described in detail by Holbrook et al (2011) and Stich et al (2014). Identical procedures were used in all years of the present study (2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013).…”

Section: Methodsmentioning

confidence: 99%

“…Based on differential survival through the freshwater migration routes in the lower river (Holbrook et al 2011;Stich et al 2014), we hypothesized that differential use of the Stillwater Branch or main stem might result in differences in estuary arrival date, movement rates, or dam-related estuary TABLE 1. Release sites, river kilometer of release sites (rkm), rearing history (Origin), and number of fish used in the study (n; numbers in parentheses indicate the total number of fish originally released in each group) for Atlantic Salmon smolts acoustically tagged and released throughout the Penobscot River and its estuary in 2005-2013; twp.…”

Section: Methodsmentioning

confidence: 99%

“…higher survival for smolts moving through the Stillwater Branch compared with the main-stem route in this area (Holbrook et al 2011;Stich et al 2014). Finally, smolts traveling either route would then pass the Veazie Dam, at the head of tide, until 2013, when that dam was removed.…”

mentioning

confidence: 99%

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Linking Behavior, Physiology, and Survival of Atlantic Salmon Smolts During Estuary Migration

et al. 2015

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Decreased marine survival is identified as a component driver of continued declines of Atlantic Salmon Salmo salar. However, estimates of marine mortality often incorporate loss incurred during estuary migration that may be mechanistically distinct from factors affecting marine mortality. We examined movements and survival of 941 smolts (141 wild and 800 hatchery‐reared fish) released in freshwater during passage through the Penobscot River estuary, Maine, from 2005 to 2013. We related trends in estuary arrival date, movement rate, and survival to fish characteristics, migratory history, and environmental conditions in the estuary. Fish that experienced the warmest thermal history arrived in the estuary 8 d earlier than those experiencing the coolest thermal history during development. Estuary arrival date was 10 d later for fish experiencing high flow than for fish experiencing low flow. Fish released furthest upstream arrived in the estuary 3 d later than those stocked further downstream but moved 0.5 km/h faster through the estuary. Temporally, movement rate and survival in the estuary both peaked in mid‐May. Spatially, movement rate and survival both decreased from freshwater to the ocean. Wild smolts arrived in the estuary later than hatchery fish, but we observed no change in movement rate or survival attributable to rearing history. Fish with the highest gill Na+, K+‐ATPase activity incurred 25% lower mortality through the estuary than fish with the lowest gill Na+, K+‐ATPase activity. Smolt survival decreased (by up to 40%) with the increasing number of dams passed (ranging from two to nine) during freshwater migration. These results underscore the importance of physiological preparedness on performance and the delayed, indirect effects of dams on survival of Atlantic Salmon smolts during estuary migration, ultimately affecting marine survival estimates. Received October 25, 2014; accepted January 8, 2015

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Section: Methodsmentioning

confidence: 99%

Section: Conservation and Management Implicationsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Linking Behavior, Physiology, and Survival of Atlantic Salmon Smolts During Estuary Migration

et al. 2015

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Surgical Implantation of Acoustic Tags in American Shad to Resolve Riverine and Marine Restoration Challenges

Gahagan¹,

Bailey

2020

Mar Coast Fish

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A variety of data needs challenge the successful restoration and management of alosine populations, including information on the migration, mortality, behavior, demographic rates, and distribution of fish, both in riverine and marine environments. Radiotelemetry with gastric-implanted transmitters has typically been used to answer some of these questions; however, observing alosines over extended periods and in the marine environment has remained beyond the limitations of this technology and implantation technique. To address these issues, we conducted an acoustic telemetry study on American Shad Alosa sapidissima by using surgical implantation methods. We tagged fish during 2015 (n = 46) and 2016 (n = 52) in the Charles River, Massachusetts, an urbanized watershed where American Shad were believed to be extirpated prior to restoration efforts beginning in 2006. Surgical implantation produced rates of in-river mortality (40% overall) and posttagging fallback (39% overall) that were comparable to those from traditionally used gastric implantation methods. Data from American Shad that were retained for statistical analyses (n = 59) demonstrated that Watertown Dam (at river kilometer 14.3) impeded upstream migration and that New Boston Dam and Locks (at the mouth of the river) delayed postspawn emigration from the river. In total, 49 American Shad were detected outside of the Charles River. The distribution and low number of total detections, despite a large number of nearshore arrays, suggest that American Shad occupy waters farther offshore during their marine phase. American Shad were detected as overwintering on the Scotian Shelf (n = 5) and the Mid-Atlantic Bight (n = 1). In 2017, 10 of the individuals that were tagged in 2016 returned to spawn, providing the first reported data on total migration timing and migratory behavior free of handling effects. Surgical implantation of acoustic telemetry tags is an effective method that can provide necessary and previously unattainable data on a species of conservation need. Modern restoration efforts begin with a basic understanding of the biology and ecology of populations as a whole. These fundamental building blocks are difficult to obtain when dealing with highly migratory populations in which individuals move across varied habitats and multiple management regimes. Anadromous fish populations are notable both for their highly variable migratory patterns and for the large reduction in their population sizes over the last 200 years (Limburg and Waldman 2009; Hall et al. 2012). Management and restoration of

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Managing for Atlantic Salmon Smolt Run Timing Variability in a Changing Climate

Frechette

Hawkes

Kocik

2023

N American J Fish Manag

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The Gulf of Maine Distinct Population Segment of Atlantic Salmon Salmo salar is listed under the U.S. Endangered Species Act, with dams cited as a key threat to the species. Safe, timely, and efficient passage of emigrating smolts is critical for advancing recovery goals. However, climate change and the earlier (and more variable) onset of smolt migration have challenged the effectiveness of measures designed to protect smolts. Therefore, we used data from four long-term smolt trapping sites in Maine to characterize run duration, identify a standardized smolt run, and develop a predictive model for the initiation of smolt emigration for natural-and hatchery-origin smolts. We combined these data into a basinwide deterministic model that projects the movement of smolts from their point of origin to estuary entry, which we used to (1) evaluate duration and temperature triggers for supplemental spill periods used at hydroelectric dams to protect smolts and (2) investigate how knowledge of smolt emigration dynamics can guide protective measures in rivers where management actions are being developed. Timing of run initiation varied by over 14 d; however, mean air temperature for the first quarter of the year explained over 60% of the variance in the onset of emigration. Initiation temperature was linked with higher-elevation rearing areas where smolts originated and not with downstream dams where temperature was monitored. The shape of the smolt wave varied considerably; thus, our standardized smolt wave captured average dynamics but not the specific shape. Overall, 14-d spill windows are too short. To account for the variable timing and shape of the run, a 54-72-d protection window would be necessary to protect the earliest and latest emigrants in the absence of physical structures (e.g., turbine screens) and preserve the adaptive variation required for populations to respond to climate-driven changes in temperature and hydrology.Populations of Atlantic Salmon Salmo salar in Maine are listed under the U.S. Endangered Species Act, and the impacts of dams on these fish pose a threat to the species' recovery (National Research Council 2004;Fay et al. 2006; USFWS and NMFS 2018). Although both upstream and downstream passage at dams is essential, losses during the downstream migration of smolts in the springtime are particularly problematic. Estimates of smolt emigration from the Penobscot River-the largest watershed in Maine-from 1970 to 2012 indicated that of 19.7 million smolts stocked, only 7.7 million (39%) entered the ocean, and survival (63-95%) was most variable at dams (Stevens et al. 2019).

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Survival of Migrating Atlantic Salmon Smolts through the Penobscot River, Maine: a Prerestoration Assessment

Cited by 43 publications

References 33 publications

Linking Behavior, Physiology, and Survival of Atlantic Salmon Smolts During Estuary Migration

Linking Behavior, Physiology, and Survival of Atlantic Salmon Smolts During Estuary Migration

Surgical Implantation of Acoustic Tags in American Shad to Resolve Riverine and Marine Restoration Challenges

Managing for Atlantic Salmon Smolt Run Timing Variability in a Changing Climate

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