Connectivity between lentic and lotic freshwater habitats identified as a conservation priority for coho salmon

2021 ◽  
Author(s):  
Suresh A. Sethi ◽  
Joshua Ashline ◽  
Bradley P. Harris ◽  
Jonathon Gerken ◽  
Felipe Restrepo
Keyword(s):  
Coho Salmon ◽  
Conservation Priority ◽  
Freshwater Habitats

scholarly journals Can the creation of new freshwater habitat demographically offset losses of Pacific salmon from chronic anthropogenic mortality?

2020 ◽  
Author(s):  
Pascale Gibeau ◽  
Michael J. Bradford ◽  
Wendy J. Palen
Keyword(s):  
Pacific Northwest ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Life Stages ◽  
Typical Size ◽  
Side Channels ◽  
Lower Productivity ◽  
Freshwater Habitats ◽  
The Creation ◽  
Habitat Compensation

AbstractOver 1 billion USD are devoted annually to rehabilitating freshwater habitats to improve survival for the recovery of endangered salmon populations. Mitigation often requires the creation of new habitat (e.g. habitat compensation) to offset population losses from human activities, however compensation schemes are rarely evaluated. Anadromous Pacific salmon are ecologically, culturally, and economically important in the US and Canada, and face numerous threats from climate change, over-harvesting, and degradation of freshwater habitats. Here we used a matrix population model of coho salmon (Oncorhynchus kisutch) to determine the amount of habitat compensation needed to offset mortality (2-20% per year) caused by a range of development activities. We simulated chronic mortality to three different life stages (egg, parr, smolt/adult), individually and in combination, to mimic impacts from development, and evaluated if the number of smolts produced from constructed side-channels demographically offset losses. We show that under ideal conditions, the typical size of a constructed side-channel in the Pacific Northwest (PNW) (3405 m2) is sufficient to compensate for only relatively low levels of chronic mortality to either the parr or smolt/adult stages (2-7% per year), but populations do not recover if mortality is >10% per year. When we assumed lower productivity (e.g.; 25th percentile), or imposed mortality at multiple life stages, we found that constructed channels would need to be larger (0.2-4.5 times) than if we assumed mean productivity or as compared to the typical size built in the PNW, respectively, to maintain population sizes.. We conclude that habitat compensation has the potential to mitigate chronic mortality to early life stages, but that current practices are likely not sufficient when we incorporate more realistic assumptions about productivity of constructed side-channels and cumulative effects of anthropogenic disturbances on multiple life stages.

Residence times of juvenile salmon and steelhead in off-channel tidal freshwater habitats, Columbia River, USA

2015 ◽  
Vol 72 (5) ◽  
pp. 684-696 ◽  
Author(s):  
Gary E. Johnson ◽  
Gene R. Ploskey ◽  
Nichole K. Sather ◽  
David J. Teel
Keyword(s):  
Life History ◽  
Fresh Water ◽  
Chinook Salmon ◽  
Coho Salmon ◽  
Columbia River ◽  
Tidal Freshwater ◽  
Life History Strategies ◽  
Residence Times ◽  
Juvenile Salmonids ◽  
Freshwater Habitats

We documented two life history strategies for juvenile salmonids as expressed in off-channel tidal freshwater habitats of the Columbia River: (i) active migrations by upper river Chinook salmon (Oncorhynchus tshawytscha) and steelhead (Oncorhynchus mykiss) during the primary spring and summer migration periods and (ii) overwinter rearing in tidal freshwater habitats by coho salmon (Oncorhynchus kisutch) and naturally produced Chinook salmon mostly from lower river sources. During spring–summer 2007–2008, acoustic-tagged fish originating above Bonneville Dam (rkm 234) had short residence times in off-channel areas (rkm 192–203): median 2.5 and 2.6 h for yearling (mean lengths 134 and 158 mm) and 3.0 and 3.4 h for subyearling (104 and 116 mm) Chinook salmon and 2.5 h for yearling steelhead (215 mm). The percentage of fish in off-channel areas out of the total in the main- and off-channels areas was highest for yearling Chinook salmon (8.1% and 9.3% for 2007 and 2008, respectively) and lowest for steelhead (4.0% for 2008) and subyearling Chinook salmon (3.6% and 6.1% for 2007 and 2008, respectively). In late January and early February 2010, 2011, and 2012, we captured and tagged yearling Chinook and coho salmon occupying off-channel tidal freshwater habitats. Median residence times in off-channel areas were 11.6–25.5 days for juvenile Chinook (106, 115, and 118 mm, respectively by year) and 11.2 days for coho salmon (116 mm). This study is the first to estimate residence times for juvenile salmonids specifically in off-channel areas of tidal fresh water and, most importantly, residence times for Chinook salmon expressing a life history of overwintering in tidal fresh water. The findings support restoration of shallow off-channel habitats in tidal freshwater portions of the Columbia River.

Reference points for coho salmon (Oncorhynchus kisutch) harvest rates and escapement goals based on freshwater production

2000 ◽  
Vol 57 (4) ◽  
pp. 677-686 ◽  
Author(s):  
Michael J Bradford ◽  
Ransom A Myers ◽  
James R Irvine
Keyword(s):  
Reference Point ◽  
Historical Data ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Reference Points ◽  
Data Sets ◽  
Ocean Productivity ◽  
Freshwater Habitats ◽  
Marine Survival ◽  
Stick Model

We describe a simple scheme for the management of coho salmon (Oncorhynchus kisutch) population aggregates that uses reference points derived from an empirical analysis of freshwater production data. We fit a rectilinear "hockey stick" model to 14 historical data sets of female spawner abundance and resulting smolt production and found that at low spawner abundance, the average productivity was about 85 smolts per female spawner. Variation in productivity among streams may be related to the quality of the stream habitat. We show how freshwater productivity can be combined with forecasts of marine survival to provide a limit reference point harvest rate. Our method will permit harvest rates to track changes in ocean productivity. We also used the historical data to estimate that, on average, a density of 19 female spawners·km-1 is required to fully seed freshwater habitats with juveniles. However, there was considerable variation among the streams that might limit the utility of this measure as a reference point. Uncertainty in the forecasts of marine survival and other parameters needs to be incorporated into our scheme before it can be considered a precautionary approach.

scholarly journals Can the creation of new freshwater habitat demographically offset losses of Pacific salmon from chronic anthropogenic mortality?

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0237052
Author(s):  
Pascale Gibeau ◽  
Michael J. Bradford ◽  
Wendy J. Palen
Keyword(s):  
Pacific Northwest ◽  
Coho Salmon ◽  
Pacific Salmon ◽  
Life Stage ◽  
Life Stages ◽  
Typical Size ◽  
Side Channels ◽  
Lower Productivity ◽  
Freshwater Habitats ◽  
The Creation

Over 1 billion USD are devoted annually to rehabilitating freshwater habitats to improve survival for the recovery of endangered salmon populations. Mitigation often requires the creation of new habitat (e.g. habitat offsetting) to compensate population losses from human activities, however offsetting schemes are rarely evaluated. Anadromous Pacific salmon are ecologically, culturally, and economically important in the US and Canada, and face numerous threats from degradation of freshwater habitats. Here we used a matrix population model of coho salmon (Oncorhynchus kisutch) to determine the amount of habitat offsetting needed to compensate mortality (2–20% per year) caused by a range of development activities. We simulated chronic mortality to three different life stages (egg, parr, smolt/adult), individually and simultaneously, to mimic impacts from development, and evaluated if the number of smolts produced from constructed side-channels demographically offset losses. We show that under ideal conditions, the typical size of a constructed side-channel in the Pacific Northwest (PNW) (3405 m2) is sufficient to compensate for only relatively low levels of chronic mortality to either the parr or smolt/adult stages (2–7% per year), but populations do not recover if mortality is >10% per year. When we assumed lower productivity (e.g.; 25th percentile), we found that constructed channels would need to be 2.5–4.5 fold larger as compared to the typical size built in the PNW, respectively, to maintain population sizes. Moreover, when we imposed mortality to parr and smolt/adult stages simultaneously, we found that constructed side-channels would need to be between 1.8- and 2.3- fold larger that if the extra chronic mortality was imposed to one life stage only. We conclude that habitat offsetting has the potential to mitigate chronic mortality to early life stages, but that realistic assumptions about productivity of constructed side-channels and cumulative effects of anthropogenic disturbances on multiple life stages need to be considered.

Multispecies and Watershed Approaches to Freshwater Fish Conservation

2019 ◽  
Keyword(s):  
Chum Salmon ◽  
Habitat Restoration ◽  
Coho Salmon ◽  
Limiting Factors ◽  
Watershed Scale ◽  
Ecological Processes ◽  
Pacific Lamprey ◽  
Freshwater Habitats ◽  
Restoration Strategies ◽  
Active Research

<em>Abstract</em>—Habitat restoration in streams is critical to recovery of imperiled fishes. In the Pacific Northwest of North America, stream habitat restoration has focused primarily on anadromous salmonids <em>Oncorhynchus </em>spp. listed under the Endangered Species Act. Substantial restoration efforts have focused on the Oregon Coast evolutionary significant unit of Coho Salmon <em>O. kisutch</em>. However, many of these efforts have been local in scale (i.e., particular reaches within relatively small streams, high up in watersheds) and do not address habitat-forming processes at the watershed scale. Other anadromous species such as Chum Salmon <em>O. keta </em>and Pacific Lamprey <em>Entosphenus tridentatus </em>that co-occur in these watersheds are rarely targeted in habitat restoration yet are thought to benefit from restoration efforts for Coho Salmon. However, Chum Salmon and Pacific Lamprey tend to occur lower in watersheds than Coho Salmon, inhabit freshwater for different periods of time, and are therefore challenged by different limiting factors. As a result, benefits from restoration efforts for Coho Salmon may not be fully realized by Chum Salmon and Pacific Lamprey. Mounting evidence suggests that process-based restoration may yield substantial biological dividends for anadromous fishes. Although process-based restoration is still an area of active research, it does possess a stronger and more holistic conceptual foundation than restoration strategies aimed at creating particular channel forms. Process-based restoration addresses the geological, physical, chemical, climatic, and ecological processes that interact to form habitat mosaics to which anadromous fishes have adapted. Understanding and working within these processes throughout entire watersheds and downstream into the estuary has the potential to benefit multiple anadromous fishes and substantially improve the ecological functions of watersheds. We explore the range of habitat relationships expressed among three imperiled anadromous fishes—Coho Salmon, Chum Salmon, and Pacific Lamprey—and present case studies to illustrate the importance of implementing process-based restoration to address limiting factors in their freshwater habitats. We conclude by suggesting three main strategies to address restoration challenges and limitations: forming multidisciplinary collaborations of restoration practitioners, investing in education and outreach to build larger and more diverse constituencies, and developing spatial and organizational tools to expand restoration efforts to the watershed scale.

Prey tell: what quillback rockfish early life history traits reveal about their survival in encounters with juvenile coho salmon

2020 ◽  
Vol 650 ◽  
pp. 7-18 ◽  
Author(s):  
HW Fennie ◽  
S Sponaugle ◽  
EA Daly ◽  
RD Brodeur
Keyword(s):  
Life History ◽  
Early Life ◽  
Life History Traits ◽  
Direct Evidence ◽  
Coho Salmon ◽  
Larval Fish ◽  
Early Life History ◽  
In The Wild ◽  
Otolith Microstructure Analysis ◽  
Pelagic Juvenile

Predation is a major source of mortality in the early life stages of fishes and a driving force in shaping fish populations. Theoretical, modeling, and laboratory studies have generated hypotheses that larval fish size, age, growth rate, and development rate affect their susceptibility to predation. Empirical data on predator selection in the wild are challenging to obtain, and most selective mortality studies must repeatedly sample populations of survivors to indirectly examine survivorship. While valuable on a population scale, these approaches can obscure selection by particular predators. In May 2018, along the coast of Washington, USA, we simultaneously collected juvenile quillback rockfish Sebastes maliger from both the environment and the stomachs of juvenile coho salmon Oncorhynchus kisutch. We used otolith microstructure analysis to examine whether juvenile coho salmon were age-, size-, and/or growth-selective predators of juvenile quillback rockfish. Our results indicate that juvenile rockfish consumed by salmon were significantly smaller, slower growing at capture, and younger than surviving (unconsumed) juvenile rockfish, providing direct evidence that juvenile coho salmon are selective predators on juvenile quillback rockfish. These differences in early life history traits between consumed and surviving rockfish are related to timing of parturition and the environmental conditions larval rockfish experienced, suggesting that maternal effects may substantially influence survival at this stage. Our results demonstrate that variability in timing of parturition and sea surface temperature leads to tradeoffs in early life history traits between growth in the larval stage and survival when encountering predators in the pelagic juvenile stage.

Changes in Immunological Parameters and Disease Resistance in Juvenile Coho Salmon (Oncorhynchus kisutch) in Response to Dehydroabietic Acid Exposure under Varying Thermal Conditions

2004 ◽  
Vol 39 (3) ◽  
pp. 175-182 ◽  
Author(s):  
Keith B. Tierney ◽  
Eric Stockner ◽  
Christopher J. Kennedy
Keyword(s):  
Coho Salmon ◽  
Thermal Conditions ◽  
Dehydroabietic Acid ◽  
Aeromonas Salmonicida ◽  
Acclimation Temperature ◽  
Dependent Manner ◽  
Immunological Parameters ◽  
Cold Temperatures ◽  
Temperature Shock ◽  
Exposure Temperature

Abstract This study explored the effects of a sublethal 96-h dehydroabietic acid (DHAA) exposure on aspects of the immune system of juvenile coho salmon under varying temperature conditions. Coho were exposed to DHAA concentrations below the determined LC50 value of 0.94 mg/L (95% confidence limits of 0.81 to 1.24 mg/L) for 96 h at either their acclimation temperature (8 or 18°C), or during an acute warm-shock (8 to 18°C) or cold-shock (18 to 8°C). Acclimation temperature alone significantly affected hematocrit (Hct), neutrophil respiratory burst activity (RBA) and leucocyte proportions. With temperature-shock, leucocrit (Lct), RBA and leucocyte proportions were altered. All parameters were affected by DHAA exposure, but not always in a dose-dependent manner. Across groups, DHAA caused Hct, lysozyme, thrombocyte, neutrophil and monocyte proportions to increase, and Lct, RBA and lymphocyte proportions to decrease. DHAA-temperature interactions resulted in the exacerbation of DHAA-induced effects. Exposure temperature had the most significant effect on the susceptibility of coho to Aeromonas salmonicida; fish were more susceptible at cold temperatures and when subjected to a temperature-shock compared to their respective controls. DHAA exposure modulated the response of temperature-shocked fish to this pathogen.

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