Critical Size and Maximum Yield for Chinook Salmon (Oncorhynchus tshawytscha)

1960 ◽  
Vol 17 (2) ◽  
pp. 199-210 ◽  
Author(s):  
Robert R. Parker
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Critical Size ◽  
Maximum Yield ◽  
Minimum Size ◽  
Relative Growth Rates ◽  
Size Regulation ◽  
Direct Injury ◽  
Feasible Alternative ◽  
Temporal Restriction

Instantaneous natural mortality rate is estimated from tagging and recovery data and compared with instantaneous relative growth rates for each life history type of chinook salmon. It is demonstrated that critical size is not attained prior to maturity, hence, juveniles should be protected from fishing if maximum yield in pounds is desired. Yield cannot be increased by a minimum size regulation, for losses due both to direct injury and hyperactivity reduce critical size to levels not ordinarily encountered by existing fisheries. A further complication arises in that size is not a reliable indicator of maturity. The most feasible alternative to a minimum size regulation appears to be spatial and temporal restriction of the fishery to known concentrations of maturing fish, together with the encouragement of non-size-selective gear.

Dependence of Exploitation Rates for Maximum Yield and Stock Collapse on Age and Sex Structure of Chinook Salmon (Oncorhynchus tshawytscha) Stocks

1986 ◽  
Vol 43 (9) ◽  
pp. 1746-1759 ◽  
Author(s):  
David G. Hankin ◽  
M. C. Healey
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Maximum Yield ◽  
Complex Nature ◽  
Sex Structure ◽  
Early Maturing ◽  
Stock Recruitment ◽  
Mixed Stock ◽  
Age And Sex ◽  
Stock Collapse

In this paper we investigate the equilibrium behavior of an age- and sex-structured version of the Ricker stock–recruitment model specifically tailored to the complex nature of chinook salmon (Oncorhynchus tshawytscha) biology and fisheries. Conclusions from our analysis include the following. (1) Exploitation rates for maximum yield (umsy) and stock collapse (umax) depend strongly on a stock's maturity schedule, being lowest for a late-maturing stock and greatest for an early maturing stock. (2) Values of exploitation rates for umax overlap considerably with those for umsy, emphasizing the probability of stock collapse in fully exploited mixed stock fisheries. (3) Values of umsy and umax are independent of the value of the Ricker β parameter but depend directly on the Ricker α parameter, indicating that management research should focus on obtaining better estimates of α, contrary to recent suggestions in the literature. (4) Because they mature at older ages, female chinook suffer greater cumulative fishery removal rates than males and decline in abundance more rapidly as exploitation increases. Consequently, the use of sex-independent maturity schedules can give misleading estimates for umsy and umax. (5) Maximum changes in mean age of stocks that can be attributed to fishing up effects ranged from 0.32 to 0.81 yr. Many stocks appear already to have declined in mean age by this amount, further emphasizing the probability of impending collapse of some stocks.

Differences in the onset of salinity tolerance between juvenile chinook salmon from two coastal Oregon river systems

1995 ◽  
Vol 52 (3) ◽  
pp. 623-630 ◽  
Author(s):  
Karen Young Kreeger
Keyword(s):  
Salinity Tolerance ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Sodium Concentration ◽  
Minimum Size ◽  
Plasma Sodium ◽  
Juvenile Chinook Salmon ◽  
First Feeding ◽  
Juvenile Chinook ◽  
Interpopulational Differences

Trask River juvenile chinook salmon (Oncorhynchus tshawytscha) rear in an estuarine environment, whereas Rogue River juveniles rear in a riverine environment, suggesting these populations differ in the ontogeny of smolting physiology. To study differences in the onset of salinity tolerance between these populations, I reared individuals from the Trask and Rogue rivers (Oregon) in a common environment and monitored changes in their physiology throughout their first 5–6 months. Trask fish were able to tolerate oceanic salinities at a smaller size and younger age than Rogue juveniles. Fifty days post-first feeding and at < 2 g 65% of Trask juveniles survived in 32 ppt compared with 40% of Rogue juveniles. Trask juveniles also maintained their water balance in 32 ppt seawater relative to freshwater at 50 days post-first feeding compared with 80 days for Rogue juveniles. Plasma sodium concentration indicated that both populations did not competently osmoregulate until approximately 108 days post-first feeding. Although the minimum size and age of salinity tolerance depended on which indicator of tolerance was chosen for study, physiological parameters suggested interpopulational differences in the timing of the onset of salinity tolerance.

Systematic hexamitid (Protozoa: Diplomonadida) Infection in seawater pen-reared Chinook salmon Oncorhynchus tshawytscha

1992 ◽  
Vol 14 ◽  
pp. 81-89 ◽  
Author(s):  
ML Kent ◽  
J Ellis ◽  
JW Fournie ◽  
SC Dawe ◽  
JW Bagshaw ◽  
...  
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha

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.

Analysis of straying variation in Alaskan hatchery chinook salmon (Oncorhynchus tshawytscha) following transplantation

1999 ◽  
Vol 56 (4) ◽  
pp. 578-589 ◽  
Author(s):  
Jeffrey J Hard ◽  
William R Heard
Keyword(s):  
British Columbia ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Release Site ◽  
Substantial Variation

In 1976 chinook salmon (Oncorhynchus tshawytscha) gametes from the Chickamin and Unuk rivers in southeastern Alaska were transplanted 250 km to establish hatchery runs at Little Port Walter (LPW), Baranof Island. From 1977 to 1989, 1 862 058 marked smolts from 12 broods were released from LPW. Homing and straying were estimated from adult recoveries at 25 locations in Alaska and British Columbia between 1981 and 1989. Of 22 198 LPW fish recovered over this period, 21 934 (98.8%) were collected at LPW. Of 264 fish recovered elsewhere, 38.3% were within 7 km of LPW; 64.4% were within 25 km of LPW. No LPW fish were recovered from the ancestral rivers, but nine fish were recovered from rivers supporting wild chinook salmon. Straying declined with distance from the release site but varied between hatcheries and streams. Straying declined with increasing age and run size. Straying was similar between the populations but varied among broods, and analysis of straying in experimental groups provided evidence for a heritable component. Males strayed more often than females. Population, gender, run size, and recovery age interacted to produce substantial variation in straying, indicating that run composition can produce complex straying responses.

Route selection in a large river during the homing migration of Chinook salmon (Oncorhynchus tshawytscha)

2006 ◽  
Vol 63 (8) ◽  
pp. 1752-1762 ◽  
Author(s):  
Matthew L Keefer ◽  
Christopher C Caudill ◽  
Christopher A Peery ◽  
Theodore C Bjornn
Keyword(s):  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Columbia River ◽  
Large River ◽  
Migration Route ◽  
Route Selection ◽  
Behavioral Differences ◽  
Long Distance ◽  
Selection Decisions ◽  
Efficient Route

Upstream-migrating adult salmon must make a series of correct navigation and route-selection decisions to successfully locate natal streams. In this field study, we examined factors influencing migration route selections early in the migration of 4361 radio-tagged adult Chinook salmon (Oncorhynchus tshawytscha) as they moved upstream past dams in the large (~1 km wide) Columbia River. Substantial behavioral differences were observed among 11 conspecific populations, despite largely concurrent migrations. At dams, Chinook salmon generally preferred ladder passage routes adjacent to the shoreline where their natal tributaries entered, and the degree of preference increased as salmon proximity to natal tributaries increased. Columbia River discharge also influenced route choices, explaining some route selection variability. We suggest that salmon detect lateral gradients in orientation cues across the Columbia River channel that are entrained within tributary plumes and that these gradients in cues can persist downstream for tens to hundreds of kilometres. Detection of tributary plumes in large river systems, using olfactory or other navigation cues, may facilitate efficient route selection and optimize energy conservation by long-distance migrants.

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