Response of juvenile Chinook salmon to managed flow: lessons learned from a population at the southern extent of their range in North America

2014 ◽  
Vol 21 (2) ◽  
pp. 155-168 ◽  
Author(s):  
S. C. Zeug ◽  
K. Sellheim ◽  
C. Watry ◽  
J. D. Wikert ◽  
J. Merz
Keyword(s):  
North America ◽  
Chinook Salmon ◽  
Lessons Learned ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

Fine-scale taxonomic and temporal variability in the energy density of invertebrate prey of juvenile Chinook salmon Oncorhynchus tshawytscha

2020 ◽  
Vol 655 ◽  
pp. 185-198
Author(s):  
J Weil ◽  
WDP Duguid ◽  
F Juanes
Keyword(s):  
Energy Density ◽  
Chinook Salmon ◽  
Temporal Variability ◽  
Energy Content ◽  
Single Point ◽  
Single Species ◽  
Fine Scale ◽  
Temporal Differences ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

Variation in the energy content of prey can drive the diet choice, growth and ultimate survival of consumers. In Pacific salmon species, obtaining sufficient energy for rapid growth during early marine residence is hypothesized to reduce the risk of size-selective mortality. In order to determine the energetic benefit of feeding choices for individuals, accurate estimates of energy density (ED) across prey groups are required. Frequently, a single species is assumed to be representative of a larger taxonomic group or related species. Further, single-point estimates are often assumed to be representative of a group across seasons, despite temporal variability. To test the validity of these practices, we sampled zooplankton prey of juvenile Chinook salmon to investigate fine-scale taxonomic and temporal differences in ED. Using a recently developed model to estimate the ED of organisms using percent ash-free dry weight, we compared energy content of several groups that are typically grouped together in growth studies. Decapod megalopae were more energy rich than zoeae and showed family-level variability in ED. Amphipods showed significant species-level variability in ED. Temporal differences were observed, but patterns were not consistent among groups. Bioenergetic model simulations showed that growth rate of juvenile Chinook salmon was almost identical when prey ED values were calculated on a fine scale or on a taxon-averaged coarse scale. However, single-species representative calculations of prey ED yielded highly variable output in growth depending on the representative species used. These results suggest that the latter approach may yield significantly biased results.

scholarly journals Empirically Estimating Carrying Capacity for Juvenile Chinook Salmon

2021 ◽  
Vol 102 (2) ◽  
Author(s):  
Kevin E. See ◽  
Michael W. Ackerman ◽  
Richard A. Carmichael ◽  
Sarah L. Hoffmann ◽  
Chris Beasley
Keyword(s):  
Chinook Salmon ◽  
Carrying Capacity ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

scholarly journals Managed Wetlands Can Benefit Juvenile Chinook Salmon in a Tidal Marsh

2021 ◽  
Author(s):  
Nicole M. Aha ◽  
Peter B. Moyle ◽  
Nann A. Fangue ◽  
Andrew L. Rypel ◽  
John R. Durand
Keyword(s):  
San Francisco ◽  
Growth Rates ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Nursery Habitat ◽  
San Francisco Estuary ◽  
Rice Fields ◽  
Fish Growth ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

AbstractLoss of estuarine and coastal habitats worldwide has reduced nursery habitat and function for diverse fishes, including juvenile Chinook salmon (Oncorhynchus tshawytscha). Underutilized off-channel habitats such as flooded rice fields and managed ponds present opportunities for improving rearing conditions and increasing habitat diversity along migratory corridors. While experiments in rice fields have shown enhanced growth rates of juvenile fishes, managed ponds are less studied. To evaluate the potential of these ponds as a nursery habitat, juvenile Chinook salmon (~ 2.8 g, 63 mm FL) were reared in cages in four contrasting locations within Suisun Marsh, a large wetland in the San Francisco Estuary. The locations included a natural tidal slough, a leveed tidal slough, and the inlet and outlet of a tidally muted managed pond established for waterfowl hunting. Fish growth rates differed significantly among locations, with the fastest growth occurring near the outlet in the managed pond. High zooplankton biomass at the managed pond outlet was the best correlate of salmon growth. Water temperatures in the managed pond were also cooler and less variable compared to sloughs, reducing thermal stress. The stress of low dissolved oxygen concentrations within the managed pond was likely mediated by high concentrations of zooplankton and favorable temperatures. Our findings suggest that muted tidal habitats in the San Francisco Estuary and elsewhere could be managed to promote growth and survival of juvenile salmon and other native fishes.

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