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.

Importance of Smolt Size and Early Ocean Growth to Interannual Variability in Marine Survival of Coho Salmon (Oncorhynchus kisutch)

1990 ◽  
Vol 47 (11) ◽  
pp. 2181-2194 ◽  
Author(s):  
L. Blair Holtby ◽  
Bruce C. Andersen ◽  
Ronald K. Kadowaki
Keyword(s):  
Interannual Variability ◽  
Coho Salmon ◽  
Age Groups ◽  
Oncorhynchus Kisutch ◽  
Northwest Coast ◽  
Size Distributions ◽  
Strongly Correlated ◽  
Large Size ◽  
Ocean Conditions ◽  
Marine Survival

The importance of smolt size and early ocean growth to the marine survival of coho salmon was examined over a 17-yr period at Carnation Creek, British Columbia. Comparisons of overall marine survival were made both between-years, using two smolt age-groups of different mean sizes, and within-years using observed smolt size distributions and smolt size distributions back-calculated from the scales of returning adults. Large size did not confer a consistent survival advantage but large smolts did survive better in years when marine survival was relatively poor. Marine survivals were strongly correlated with early ocean growth as estimated by the spacing of the first five ocean circuli on the scales of returning adults. Marine survival and early ocean growth were positively correlated with ocean conditions indicative of strong upwelling along the northwest coast of Vancouver Island. Neither smolt survival nor early ocean growth were correlated with regional coho smolt production. Our observations suggest that interannual variability in smolt survival was being driven by ocean conditions that determined smolt growth rates which subsequently affected the susceptibility of smolts to a size-selective predator.

Environmental factors influencing freshwater survival and smolt production in Pacific Northwest coho salmon (Oncorhynchus kisutch)

2004 ◽  
Vol 61 (3) ◽  
pp. 360-373 ◽  
Author(s):  
P W Lawson ◽  
E A Logerwell ◽  
N J Mantua ◽  
R C Francis ◽  
V N Agostini
Keyword(s):  
Pacific Northwest ◽  
Air Temperature ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Stream Flows ◽  
Factors Influencing ◽  
Life Phase ◽  
Air Temperatures ◽  
Queets River ◽  
Marine Survival

Climate variability is well known to affect the marine survival of coho salmon (Oncorhynchus kisutch) in Oregon and Washington. Marine factors have been used to explain up to 83% of the variability in Oregon coastal natural coho salmon recruitment, yet about half the variability in coho salmon recruitment comes from the freshwater life phase of the life cycle. This seeming paradox could be resolved if freshwater variability were linked to climate and climate factors influencing marine survival were correlated with those affecting freshwater survival. Effects of climate on broad-scale fluctuations in freshwater survival or production are not well known. We examined the influence of seasonal stream flows and air temperature on freshwater survival and production of two stock units: Oregon coastal natural coho salmon and Queets River coho salmon from the Washington Coast. Annual air temperatures and second winter flows correlated strongly with smolt production from both stock units. Additional correlates for the Oregon Coast stocks were the date of first fall freshets and flow during smolt outmigration. Air temperature is correlated with sea surface temperature and timing of the spring transition so that good freshwater conditions are typically associated with good marine conditions.

A Bayesian life-cycle model to estimate escapement at maximum sustained yield in salmon based on limited information

2019 ◽  
Vol 76 (2) ◽  
pp. 299-307
Author(s):  
Jan Ohlberger ◽  
Samuel J. Brenkman ◽  
Patrick Crain ◽  
George R. Pess ◽  
Jeffrey J. Duda ◽  
...  
Keyword(s):  
Life Cycle ◽  
Time Series Data ◽  
Coho Salmon ◽  
Reference Points ◽  
Series Data ◽  
Limited Information ◽  
Maximum Sustained Yield ◽  
Sustained Yield ◽  
Life Cycle Models ◽  
Marine Survival

Life-cycle models combine several strengths for estimating population parameters and biological reference points of harvested species and are particularly useful for those exhibiting distinct habitat shifts and experiencing contrasting environments. Unfortunately, time series data are often limited to counts of adult abundance and harvest. By incorporating data from other populations and by dynamically linking the life-history stages, Bayesian life-cycle models can be used to estimate stage-specific productivities and capacities as well as abundance of breeders that produce maximum sustained yield (MSY). Using coho salmon (Oncorhynchus kisutch) as our case study, we show that incorporating information on marine survival variability from nearby populations can improve model estimates and affect management parameters such as escapement at MSY. We further show that the expected long-term average yield of a fishery managed for a spawner escapement target that produces MSY strongly depends on the average marine survival. Our results illustrate the usefulness of incorporating information from other sources and highlight the importance of accounting for variation in marine survival when making inferences about the management of Pacific salmon.

Influences of Upwelling, Ocean Temperature, and Smolt Abundance on Marine Survival of Coho Salmon (Oncorhynchus kisutch) in the Oregon Production Area

1986 ◽  
Vol 43 (3) ◽  
pp. 527-535 ◽  
Author(s):  
Thomas E. Nickelson
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
High Survival ◽  
Ocean Temperature ◽  
Related Factors ◽  
Public And Private ◽  
Adult Relationships ◽  
Significant Relationships ◽  
Production Area ◽  
Marine Survival

The relationships between the marine survival of hatchery and wild coho salmon (Oncorhynchus kisutch) in the Oregon Production Area and ocean upwelling, ocean temperature, and smolt abundance were investigated. Hatchery coho appear to be more sensitive than wild coho to changes in upwelling-related factors although this difference may be due to errors in the estimates of wild smolts and adults that were used in the analysis. Two levels of upwelling (strong and weak), which are associated with a twofold difference in survival of hatchery coho smolts, were identified. Significant relationships were identified between survival of hatchery smolts and survival of wild smolts that migrated in strong upwelling years and sea-surface temperature during that year. Similar relationships were not as apparent for smolts migrating in weak upwelling years as they were for smolts migrating in strong upwelling years. Each major component of coho production (wild, public hatchery, and private hatchery), when treated separately, as well as public and private hatchery coho combined, exhibited linear smolt-to-adult relationships. Only hatchery plus wild coho that migrated in weak upwelling years and hatchery plus wild coho in all years combined exhibited nonlinear smolt-to-adult relationships. I concluded that these nonlinear relationships were caused by a shift in the stock composition of the Oregon Production Area coho population from predominantly high-survival, wild fish when smolt numbers were low to predominantly low-survival, hatchery fish when smolt numbers were high.

Survival, Ocean Growth, and Ocean Distribution of Differentially Timed Releases of Hatchery Coho Salmon (Oncorhynchus kisutch)

1989 ◽  
Vol 46 (7) ◽  
pp. 1216-1226 ◽  
Author(s):  
Stephen B. Mathews ◽  
Yukimasa Ishida
Keyword(s):  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Adult Survivors ◽  
Small Fish ◽  
Large Fish ◽  
Release Date ◽  
Marine Life ◽  
Coos Bay ◽  
The Mean ◽  
Marine Survival

Estimates of growth rates in early ocean life and length frequency distributions at time of release for adult survivors were inferred from scale measurements for lots of coho salmon (Oncorhynchus kisutch) released at several dates from a Columbia River hatchery (Big Creek) and a southern Oregon hatchery (Coos Bay). Analysis of these measurements failed to support either of two literature-suggested hypotheses for the variability of marine survival of hatchery coho by date of release: (1) intraseasonal variability of food supply during early marine life; and (2) intraseasonally improving ability of smaller individuals within release lots to convert to salt water. Marine survival improved substantially with date of release at both hatcheries. However, fish released earliest, which survived relatively poorly, grew as fast in early marine life as fish released later, which survived better. Thus, poor survival of the early released fish did not appear related to lack of food at early ocean life. For the Big Creek hatchery, no significant differences were seen between the mean lengths at date of release and the mean release-date lengths of adult survivors back calculated from their scales, for lots released on May 5, June 3, and July 2. Apparently, small and large fish of each lot survived with equal probability. For the Coos Bay hatchery, the mean release-date lengths of adult survivors were significantly larger than the mean lengths of all fish released, for each of six lots released between early June and late July. Thus, large fish apparently survived better than small ones within each of these six lots. But there was no seasonal trend in survivability of small fish relative to large ones, contrary to hypothesis (2)

Bias in hatchery-origin coho salmon survival estimates due to underestimated prerelease mortality

2021 ◽  
pp. 1-4
Author(s):  
James R. Irvine
Keyword(s):  
British Columbia ◽  
Experimental Evidence ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Data Sets ◽  
Wild Salmon ◽  
Natural Origin ◽  
Additional Work ◽  
Seaward Migration ◽  
Over Time

The widely accepted belief that hatchery-origin salmon survive less well than natural-origin or wild salmon can be, at least in part, an artifact of the way hatchery salmon survival is estimated. Hatchery salmon are often marked several months before release, while natural salmon are marked during their seaward migration. Underestimated prerelease mortalities result in biased low survival estimates. In British Columbia, although hatchery rearing practices have been modified to reduce unrecorded mortalities, experimental evidence indicates that coho salmon (Oncorhynchus kisutch) smolt survivals continue to be underestimated by ∼13%. Better reporting and incorporation of survival bias in data sets and analyses as well as additional work to evaluate bias for other regions and species over time is needed.

Landscape characteristics and coho salmon (Oncorhynchus kisutch) distributions: explaining abundance versus occupancy

2012 ◽  
Vol 69 (3) ◽  
pp. 457-468 ◽  
Author(s):  
E.A. Steel ◽  
D.W. Jensen ◽  
K.M. Burnett ◽  
K. Christiansen ◽  
J.C. Firman ◽  
...  
Keyword(s):  
Coho Salmon ◽  
Full Range ◽  
Model Performance ◽  
Oncorhynchus Kisutch ◽  
Monitoring Data ◽  
Published Data ◽  
Data Sets ◽  
Data Set ◽  
Landscape Characteristics ◽  
Oregon Plan

Distribution of fishes, both occupancy and abundance, is often correlated with landscape-scale characteristics (e.g., geology, climate, and human disturbance). Understanding these relationships is essential for effective conservation of depressed populations. We used landscape characteristics to explain the distribution of coho salmon ( Oncorhynchus kisutch ) in the Oregon Plan data set, one of the first long-term, probabilistic salmon monitoring data sets covering the full range of potential habitats. First we compared data structure and model performance between the Oregon Plan data set and two published data sets on coho salmon distribution. Most of the variation in spawner abundance occurred between reaches but much also occurred between years, limiting potential model performance. Similar suites of landscape predictors are correlated with coho salmon distribution across regions and data sets. We then modeled coho salmon spawner distribution using the Oregon Plan data set and determined that landscape characteristics could not explain presence vs. absence of spawners but that the percentage of agriculture, winter temperature range, and the intrinsic potential of the stream could explain some variation in abundance (weighted average R2 = 0.30) where spawners were present. We conclude that the previous use of nonrandom monitoring data sets may have obscured understanding of species distribution, and we suggest minor modifications to large-scale monitoring programs.

Stress Responses to Transportation and Fitness for Marine Survival in Coho Salmon (Oncorhynchus kisutch) Smolts

1980 ◽  
Vol 37 (5) ◽  
pp. 765-769 ◽  
Author(s):  
J. L. Specker ◽  
C. B. Schreck
Keyword(s):  
Kidney Disease ◽  
Atpase Activity ◽  
Stress Responses ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Control Fish ◽  
Performance Capacity ◽  
Bacterial Kidney Disease ◽  
Marine Survival

Smolting coho salmon (Oncorhynchus kisutch) were transported experimentally at low and high densities (12 and 120 g/L) for short and long periods (4 and 12 h). Because smolts can be transplanted directly to seawater, half of the fish in each treatment were transported to tanks containing seawater and half to tanks containing freshwater. Plasma corticosteroids and glucose were elevated at unloading in all groups, and corticosteroids were still above the resting level 24 h later. Potential smoltification indicators such as plasma thyroxin concentration and gill (Na+/K+)–ATPase activity were not affected by transportation. Increased corticosteroids were correlated to increased mortality in transported salmon compared to acclimated control fish when subjected to a bioassay of stress — severe confinement. The various transport regimens did not cause increased expression of latent bacterial kidney disease. In a further experiment, smolting coho salmon were released into a stream after transport for different durations. The number of fish migrating on the 1st d appeared to be inversely related to the degree of "stress" en route, but the movements of all groups were similar thereafter. We concluded that transportation caused stress in the fish regardless of hauling regimen; that increased corticosteroids may have potential as indicators of reduced performance capacity; that the greatest stress occurred during loading and the first few hours en route; and that transported smolting coho salmon seem to be equally fit for entry into freshwater or seawater.Key words: coho salmon, stress, transportation, seawater entry, corticosteroids

Multivariate regression relationships between ocean conditions and early marine survival of coho salmon (Oncorhynchus kisutch)

1999 ◽  
Vol 56 (12) ◽  
pp. 2374-2384 ◽  
Author(s):  
Kristen E Ryding ◽  
John R Skalski
Keyword(s):  
Multivariate Regression ◽  
Coastal Upwelling ◽  
Coho Salmon ◽  
Oncorhynchus Kisutch ◽  
Washington State ◽  
Sea Surface ◽  
Spring Transition ◽  
Recorded Data ◽  
Marine Survival ◽  
Curvilinear Relationships

Washington State hatcheries have released coded wire tagged coho salmon (Oncorhynchus kisutch) since the early 1970s and have recorded data on the number and ages of adult returns. From these data, we isolated marine survival from release to age 2 using a multinomial model incorporating the multivariate structure of the age-at-return data. Only hatcheries on or near the coast were used in the analysis in order to isolate marine effects. Using models to explore linear and curvilinear relationships, early marine survival was regressed against environmental covariates of sea surface temperature (SST), coastal upwelling, and the date of spring transitions. With hatcheries serving as replicates, curvilinear relationships were found between survival and both June SST and the date of spring transition. Maximum survival occurred for a June SST of 13.45°C and for a spring transition date around April 2. The regression results support the idea of optimal environmental conditions for coho salmon survival and may help fisheries managers better understand the dynamics of early marine survival of salmonids.

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