Disentangling bottom-up and top-down effects on survival during early ocean residence in a population of Chinook salmon (Oncorhynchus tshawytscha)

2013 ◽  
Vol 70 (4) ◽  
pp. 617-629 ◽  
Author(s):  
Jessica A. Miller ◽  
David J. Teel ◽  
Antonio Baptista ◽  
Cheryl A. Morgan
Keyword(s):  
Chinook Salmon ◽  
Coastal Waters ◽  
Oncorhynchus Tshawytscha ◽  
River Estuary ◽  
Condition Index ◽  
River Plume ◽  
Future Research ◽  
Top Down ◽  
Bottom Up ◽  
Biological Condition

We evaluated the relative importance of “bottom-up” (production-limited) and “top-down” (predator-mediated) processes during early marine residence in a population of Chinook salmon (Oncorhynchus tshawytscha) from the upper Columbia River, USA. We examined length, mass, and condition index of age-0 juveniles collected in the ocean during June and September across 11 years in relation to conditions in the river, estuary, and coastal ocean and to future adult returns. Characteristics of juveniles in September, but not June, were related to adult returns. During years when coastal waters were relatively cool and productive, juveniles captured in September displayed relatively low condition and reduced otolith growth compared with years when coastal waters were relatively warm and unproductive; this contrast indicates that top-down effects such as selective mortality or competition are important during early marine residence. Key physical (river plume volume during emigration) and biological (condition) variables and their interaction accounted for >95% of the variation in adult returns. Future research should focus on evaluating predators and competitors and understanding how river plume structure influences survival.

The influence of the Columbia River plume on the survival of steelhead (Oncorhynchus mykiss) and Chinook salmon (Oncorhynchus tshawytscha): a numerical exploration

2010 ◽  
Vol 67 (10) ◽  
pp. 1671-1684 ◽  
Author(s):  
Michela Burla ◽  
António M. Baptista ◽  
Edmundo Casillas ◽  
John G.  Williams ◽  
Douglas M.  Marsh
Keyword(s):  
Oncorhynchus Mykiss ◽  
Chinook Salmon ◽  
Large Scale ◽  
Oncorhynchus Tshawytscha ◽  
Numerical Models ◽  
River Estuary ◽  
Columbia River ◽  
River Plume ◽  
Columbia River Estuary ◽  
Columbia River Plume

Are smolt-to-adult return rates (SARs) for wild steelhead (i.e., sea-run rainbow trout, Oncorhynchus mykiss ) and wild Snake River spring–summer Chinook salmon ( Oncorhynchus tshawytscha ) related to changes in the Columbia River plume at the time that juvenile migrants enter the ocean? We used three-dimensional (3D) numerical models of the baroclinic circulation in the Columbia River estuary–plume–shelf system to simulate within-season variation in plume size and location, comparing the results with SARs for each day that juvenile salmon entered the ocean for 1999–2003. We found that steelhead benefited from the plume environment at a narrow window of time around their ocean entry. However, when large-scale ocean conditions turned unfavorable, the contribution of local plume conditions to the overall variability in steelhead survival became not significant. A similar evaluation revealed that the plume did not affect survival of Chinook salmon, at least at the fine scale of variability considered. The differential response between the two species is consistent with observed and previously reported behavioral characteristics they exhibit. We speculate that steelhead mainly use the plume to move quickly away from coastal habitats and the predation pressures associated with this environment, for a more direct migration than Chinook salmon to ocean habitats in the Gulf of Alaska.

Food and Habitat Utilization by Juvenile Salmonids in the Campbell River Estuary

1987 ◽  
Vol 44 (6) ◽  
pp. 1233-1246 ◽  
Author(s):  
J. Stevenson Macdonald ◽  
I. K. Birtwell ◽  
G. M. Kruzynski
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Saline Water ◽  
Salt Water ◽  
River Estuary ◽  
Stomach Contents ◽  
Water Velocity ◽  
Interspecific Differences ◽  
Marine Influence ◽  
Outer Estuary

Salmonid behaviour and abundance in several microhabitats within the Campbell River estuary was observed monthly, from May to July, by divers using snorkels and face masks. Concurrent vertical profiles of physical and biological parameters at each microhabitat were taken to characterize habitats frequented by the fish. Data were collected at high and low tide to record behavioural reactions to changes in water velocity, salinity, and temperature associated with tidal height and salt wedge intrusion. Samples of plankton collected at each microhabitat were compared with stomach contents of salmonids caught nearby to determine if interspecific differences in diet could be correlated with differences in the habitats they occupied. Fish occurred in loose assemblages, aligned with the current, feeding near estuarine banks. As water velocities increased with the ebbing tide, the fish concentrated in a shear region near the mouth of a slough and behind large rocks and submerged vegetation. At both high and low tide, larger coho (Oncorhynchus kisutch) and chinook salmon (Oncorhynchus tshawytscha) (usually hatchery reared) were in deeper, frequently more saline water and further from shore than the smaller conspecifics. Hatchery chinook, however, were also seen in sloughs where water velocity was low. Marine influence as reflected in plankton composition and salmonid diet was greater in the outer estuary and in the deep salt water that intrudes the inner regions of the estuary. Differences in the habitats occupied by the fish were reflected in differences in their diets.

Juvenile Chinook salmon, Oncorhynchus tshawytscha, use of the Elwha river estuary prior to dam removal

2013 ◽  
Vol 97 (6) ◽  
pp. 731-740 ◽  
Author(s):  
Thomas P. Quinn ◽  
J. Anne Shaffer ◽  
Justin Brown ◽  
Nicole Harris ◽  
Chris Byrnes ◽  
...  
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
River Estuary ◽  
Dam Removal ◽  
Elwha River ◽  
Juvenile Chinook Salmon ◽  
Juvenile Chinook

Differential Use of the Campbell River Estuary, British Columbia by Wild and Hatchery-Reared Juvenile Chinook Salmon (Oncorhynchus tshawytscha)

1986 ◽  
Vol 43 (7) ◽  
pp. 1386-1397 ◽  
Author(s):  
C. D. Levings ◽  
C. D. McAllister ◽  
B. D. Chang
Keyword(s):  
Transition Zone ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
River Estuary ◽  
Transition Zones ◽  
Juvenile Chinook Salmon ◽  
Hatchery Fish ◽  
Mean Size ◽  
Juvenile Chinook ◽  
Marine Zone

From March 1982 to December 1983, juvenile chinook salmon (Oncorhynchus tshawytscha) were sampled by beach-seine in the Campbell River estuary and adjacent waters of Discovery Passage in order to examine estuarine use by wild and hatchery stocks. Wild juvenile chinook entered the estuary as migrant fry and were present in the estuarine zone mainly in late April to June, in the transition zone in mid-May to July, and in the marine zone in July. Hatchery fish were released from early May to early July. Maximum catches of wild stocks were similar in the estuarine and transition zones, while the maximum catches of most hatchery stocks were higher in the transition zone. For both wild and hatchery chinook, catches in the marine zone were much lower than in the estuarine and transition zones. Wild fry resided in the estuary for 40–60 d, while most hatchery fish used the estuary for about one-half this period. Wild stocks showed a relatively constant rate of increase in mean size from May to September. Higher rates of increase in the mean size of hatchery fish were shown by groups with earlier release dates and smaller mean sizes. Residency time and growth rates for wild fish were comparable with those observed in an estuary without hatchery fish. Potential for interaction between wild and hatchery stocks was greatest in the transition zone, where hatchery fish were most abundant and because hatchery releases occurred when catches of wild fish were highest in this foreshore area.

Tidal movements and residency of subyearling Chinook salmon (Oncorhynchus tshawytscha) in an Oregon salt marsh channel

2010 ◽  
Vol 67 (3) ◽  
pp. 524-533 ◽  
Author(s):  
David K. Hering ◽  
Daniel L. Bottom ◽  
Earl F. Prentice ◽  
Kim K. Jones ◽  
Ian A. Fleming
Keyword(s):  
Salt Marsh ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
River Estuary ◽  
Fork Length ◽  
Full Duplex ◽  
Salmon River ◽  
Salt Marsh Habitat ◽  
Tidal Cycles ◽  
Insight Into

A novel application of full-duplex passive integrated transponder (PIT) tag technology was used to investigate movements of individual subyearling Chinook salmon ( Oncorhynchus tshawytscha ; fork length ≥ 60 mm) into and out of tidally flooded salt marsh habitat in the Salmon River estuary, Oregon, USA. PIT interrogation was effective, with mean tag detection ≥ 92%. Salmon movement peaked late during both flood and ebb tide periods, indicating that salmon did not drift passively. Most movements were in the direction of tidal currents, but 20% of individuals entered the channel against the ebbing tide. Individuals occupied the intertidal channel for a median 4.9 h and as long as 8.9 h per tidal cycle, and few were detected moving when water depth was <0.4 m. Some individuals used the channel on multiple successive tidal cycles, and others entered intermittently over periods of up to 109 days. Using an individual-based approach, we characterized diversity of juvenile Chinook salmon behavior within a marsh channel, providing insight into the value of such habitats for conservation and restoration of salmon populations.

scholarly journals It’s Not Easy Being Agile: Unpacking Paradoxes in Agile Environments

2020 ◽  
Author(s):  
Bettina Horlach ◽  
Andreas Drechsler
Keyword(s):  
Big Bang ◽  
Future Research ◽  
Change Processes ◽  
Critical Perspective ◽  
Top Down ◽  
Bottom Up ◽  
Organizational Settings ◽  
Organizational Inertia ◽  
Learning And Change ◽  
Agile Teams

Abstract In this paper, we outline inherent tensions in Agile environments, which lead to paradoxes that Agile teams and organizations have to navigate. By taking a critical perspective on Agile frameworks and Agile organizational settings the authors are familiar with, we contribute an initial problematization of paradoxes for the Agile context. For instance, Agile teams face the continuous paradox of ‘doing Agile’ (= following an established Agile way of working) versus ‘being Agile’ (= changing an established Agile way of working). One of the paradoxes that organizations face is whether to start their Agile journey with a directed top-down (and therefore quite un-Agile) ‘big bang’ or to allow an emergent bottom-up transformation (which may be more in-line with the Agile spirit but perhaps not be able to overcome organizational inertia). Future research can draw on our initial problematization as a foundation for subsequent in-depth investigations of these Agile paradoxes. Agile teams and organizations can draw on our initial problematization of Agile paradoxes to inform their learning and change processes.

A Field Experiment to Test the Importance of Estuaries for Chinook Salmon (Oncorhynchus tshawytscha) Survival: Short-Term Results

1988 ◽  
Vol 45 (8) ◽  
pp. 1366-1377 ◽  
Author(s):  
J. Stevenson Macdonald ◽  
Colin D. Levings ◽  
Carey D. McAllister ◽  
U. H. M. Fagerlund ◽  
J. R. McBride
Keyword(s):  
Transition Zone ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
River Estuary ◽  
Dispersal Pattern ◽  
Estuarine Site ◽  
Fish Predators ◽  
Marine Site ◽  
River Estuarine ◽  
Seawater Challenge

In late April of 1983, 1984, and 1985, 140 000 marked chinook salmon (Oncorhynchus tshawytscha) smolts (2–4 g) were transported by helicopter from Quinsam Hatchery to four release sites near Campbell River, B.C. (river, estuarine, transition, and marine), in an experiment to test the importance of estuarine residency to chinook survival. At the marine site, fish were released directly into seawater. These fish had high cortisol levels and larger interrenal nuclear diameters than those at the estuarine site, indicating a transitory stress response to seawater exposure. Nevertheless, there was little direct mortality due to stress or osmoregulatory shock at any of the release sites. Marine-released fish were exposed to more bird and fish predators. Mortality of caged chinook was higher at the marine location than at all other sites despite seawater challenge tests indicating that the chinook were smolted and "ready for sea." Beach seine data obtained biweekly for 4 mo after the releases showed that fish released directly into marine waters rarely dispersed to the Campbell River estuary. Fish released immediately adjacent to the mouth of the estuary (transition zone) had the widest immediate dispersal pattern, with many of them returning to the estuary. Estuarine zone fish displayed the most restricted distribution. Fish released to the river and estuary remained in the sampling area for a longer period (34–47 d) than those released in the marine or transition zone (20–23 d).

Towards lean transformation: the analysis of lean implementation frameworks

2015 ◽  
Vol 26 (7) ◽  
pp. 1031-1052 ◽  
Author(s):  
TickFei Chay ◽  
YuChun Xu ◽  
Ashutosh Tiwari ◽  
FooSoon Chay
Keyword(s):  
Shop Floor ◽  
Future Research ◽  
Top Down ◽  
Implementation Framework ◽  
Bottom Up ◽  
Lean Implementation ◽  
Content Type ◽  
Lean Transformation ◽  
Supervisory Staff ◽  
Internal Stakeholders

Purpose – Failure in engaging shop floor employees (including supervisory staff) in lean, lacking of supervisory skills in leading workers and lacking of lean technical knowhow among the shop floor employees are some of the major obstacles in lean transformation. One of the reasons of inefficient lean transformation is the shortages in frameworks or plans in implementing lean. The purpose of this paper is to investigate the shortfalls in the current lean implementation frameworks. Design/methodology/approach – The frameworks were analysed according to the following criteria: first, “What” is the approach of lean implementation, i.e. top-down or bottom-up; second, “How” to implement lean (description of steps or sequences of lean implementation along the lean journey); third, “Why” – the reason of adoption of the proposed lean tools, techniques or practices (thereafter TTPs) in each phase of lean implementation; and fourth, “Who” are the targeted internal stakeholders to use or apply the lean TTPs that were proposed in the frameworks. Findings – Most of the current available lean frameworks were prone to top-down approach but not bottom-up. Improvement initiatives from the shop floor employees were often overlooked by researchers. In proposing their frameworks, most of the researchers have neglected the importance of “Why” aspect in the adoption of TTPs or the framework itself without giving the “reason” for each of the elements in lean implementation. Besides the aspects of “What” and “How”, the mentioned “Why” aspect is important in contributing to capability building among the shop floor employees in carrying out improvement, problem-solving or waste elimination activities. The aspect of “Who should carry out which lean TTP” was somewhat not emphasised by most of the lean researchers. In addition, the current frameworks were prone to “one-best-way” approach with lacking of contingency sense, which is one of the common criticisms against Lean Production System. Originality/value – This paper provides a critical view on the shortfalls of current lean implementation frameworks, and proposes an insight of new criteria for future research in analysing and proposing new lean implementation framework towards lean transformation.

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