Migration Timing, Size, and Salinity Tolerance of Sea-Type Sockeye Salmon (Oncorhynchus nerka) in an Alaska Estuary

1989 ◽  
Vol 46 (4) ◽  
pp. 633-637 ◽  
Author(s):  
Jonathan Heifetz ◽  
Scott W. Johnson ◽  
K V. Koski ◽  
Michael L. Murphy
Keyword(s):  
Salinity Tolerance ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
River Estuary ◽  
Fork Length ◽  
Habitat Types ◽  
Southeast Alaska ◽  
Fish Size ◽  
Migration Timing

Migration timing, size, and salinity tolerance were determined for sea-type sockeye salmon (Oncorhynchus nerka), which migrate to sea as underyearlings (age-0), in the Situk River estuary, Southeast Alaska. Ten sites in three habitat types were seined monthly from Sate April through August, 1987, and age-0 sockeye from the estuary were tested for salinity tolerance. Age-0 sockeye were most abundant (up to 13∙m−2) from late April through June, and by late July, most sockeye had left the estuary. Mean fork length (FL) was 31 mm in April and increased 0.4 mm∙d−1 to 70 mm in late July when most (72%) remaining sockeye had grown to about the same size as age-1 smolts (69–95 mm) emigrating in May and June. Mean FL of age-0 sockeye in the estuary in July was 23 mm greater than in freshwater areas of the river. Salinity tolerance was directly related to fish size, and a size of at least 50 mm was required for 100% survival in seawater. Because salinity in the estuary ranged 0–30‰, sockeye of all sizes could survive in the estuary. Thus, in 3–4 mo, sea-type sockeye attained a size large enough to adapt to seawater and migrate to sea.

Does mortality select size or growth potential in young sockeye salmon (Oncorhynchus nerka)? A simulation based on otolith - fish size relationships

1998 ◽  
Vol 55 (7) ◽  
pp. 1674-1681 ◽  
Author(s):  
M G Meekan ◽  
DAJ Ryan ◽  
J J Dodson ◽  
S P Good
Keyword(s):  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Fork Length ◽  
Field Studies ◽  
Growth Potential ◽  
Selective Mortality ◽  
Fish Size ◽  
Conflicting Evidence ◽  
Selection For ◽  
Otolith Size

There is conflicting evidence on the role of size-selective mortality in the demography of populations of young sockeye salmon (Oncorhynchus nerka). A previous field study suggested that increases in mean fork length and otolith size at emergence observed in a cohort of salmon between fry and smolt stages were due to size-selective mortality, such that fry with small fork lengths underwent higher mortality than larger individuals. However, a subsequent study used a simulation to show that such increases could not have been achieved by size-selective mortality without levels of survivorship of the cohort far lower than those that had been observed in the field. To account for field observations, the simulation study proposed that individuals with high metabolic rates had better survivorship, a process that was termed "selection for growth potential." Here, we use a simulation approach to show that size-selective mortality may result in shifts in mean fork length and otolith size at emergence comparable with those observed in the field at total mortalities within the range of estimates of natural values. The contrasting outcomes of earlier simulation work and the present study are probably due to the assumption by the former that otolith and fish size in young salmon were weakly correlated and the use of an inappropriate model of size-selective mortality. We conclude that size-selective mortality can explain the results of previous field studies and that little empirical evidence exists to support the hypothesis of selection for growth potential in cohorts of young salmon.

A widespread decrease in productivity of sockeye salmon (Oncorhynchus nerka) populations in western North America

2012 ◽  
Vol 69 (8) ◽  
pp. 1255-1260 ◽  
Author(s):  
Randall M. Peterman ◽  
Brigitte Dorner
Keyword(s):  
Sockeye Salmon ◽  
Spatial Scales ◽  
Oncorhynchus Nerka ◽  
Geographic Area ◽  
Fraser River ◽  
Western North America ◽  
Southeast Alaska ◽  
The Past ◽  
Large Geographic Area ◽  
Marine Areas

We used data on 64 stocks of sockeye salmon ( Oncorhynchus nerka ) from British Columbia (B.C.), Washington, and Alaska to determine whether recent decreases in abundance and productivity observed for Fraser River, B.C., sockeye have occurred more widely. We found that decreasing time trends in productivity have occurred across a large geographic area ranging from Washington, B.C., southeast Alaska, and up through the Yakutat peninsula, Alaska, but not in central and western Alaska. Furthermore, a pattern of predominantly shared trends across southern stocks and opposite trends between them and stocks from western Alaska was present in the past (1950–1985), but correlations have intensified since then. The spatial extent of declining productivity of sockeye salmon has important implications for management as well as research into potential causes of the declines. Further research should focus on mechanisms that operate at large, multiregional spatial scales, and (or) in marine areas where numerous correlated sockeye stocks overlap.

Movements of Sockeye Salmon (Oncorhynchus nerka) in the Skeena River Estuary as Revealed by Ultrasonic Tracking

1975 ◽  
Vol 32 (2) ◽  
pp. 233-242 ◽  
Author(s):  
C. Groot ◽  
K. Simpson ◽  
I. Todd ◽  
P. D. Murray ◽  
G. A. Buxton
Keyword(s):  
Tidal Cycle ◽  
Sockeye Salmon ◽  
Salt Water ◽  
Oncorhynchus Nerka ◽  
River Estuary ◽  
River Mouth ◽  
Tidal Flows ◽  
Skeena River ◽  
Ultrasonic Tracking ◽  
Passive Movements

Movements of adult sockeye salmon (Oncorhynchus nerka) entering the Skeena River were examined in 1969 and 1970 by ultrasonic tracking methods. Fifteen of 18 sockeye released in the lower river seemed to move passively in and out with flood and ebb streams. Two fish moved upstream independent of tides and one salmon swam against ebb and flood currents. Ground speeds in both years of operation were 1.6 km/h during rising and 2.1 km/h during falling tides, causing the fish to be transported downstream by about 3 km per tidal cycle. Three salmon released outside the river mouth in salt water also seemed to ride the tidal flows passively. Ground speeds during ebb (3.6 km/h) were again greater than during flood (2.0 km/h), indicating a net offshore movement. We conclude that these passive movements are not an artifact but that sockeye salmon normally slow down or pause upon reaching the "home river" and drift for a period in tidal currents in the estuary and river mouth before migrating upstream.

Swimming Thrust of Sockeye Salmon (Oncorhynchus nerka) in Relation to Selectivity of Gillnets

1969 ◽  
Vol 26 (5) ◽  
pp. 1383-1385 ◽  
Author(s):  
R. H. Lander
Keyword(s):  
Significant Relationship ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Fork Length

A significant relationship between girth at the mesh mark and fork length indicates that long sockeye salmon (Oncorhynchus nerka) have more swimming thrust than short ones. This tends to confirm a speculation of Regier and Robson (J. Fish. Res. Bd. Canada 23: 423–454, 1966). Preliminary conjecture relates the observation to the theory of mesh selectivity.

Growth Rate of Young Sockeye Salmon, Oncorhynchus nerka, in Relation to Fish Size and Ration Level

1975 ◽  
Vol 32 (11) ◽  
pp. 2103-2110 ◽  
Author(s):  
J. R. Brett ◽  
J. E. Shelbourn
Keyword(s):  
Growth Rate ◽  
Specific Growth Rate ◽  
Sockeye Salmon ◽  
Specific Growth ◽  
Oncorhynchus Nerka ◽  
Limiting Factor ◽  
Fish Size ◽  
Ration Level ◽  
The Family ◽  
Constant Growth

The specific growth rate of young sockeye salmon (Oncorhynchus nerka) was studied for a period of 7 mo to determine the effect of body weight when on restricted and unrestricted rations. It was hypothesized that a restricted ration would result in a fixed growth rate until size became a limiting factor reducing food demand below the prescribed level and thereby reducing growth rate. The results support the hypothesis, with the possible exception that growth rate may increase slightly during the period of fixed ration. On excess ration the specific growth rate fell from 3.6% weight per day (2.4 g mean weight) to 1.0% weight per day (37 g mean weight); intermediate constant growth rates accompanied the periods of fixed ration, inflecting to lower rates subsequently. The general equation log G = a + b log W (where G = specific growth rate, and W = weight in grams) was found to apply to a number of salmonids. The slope value of b = −0.4 ±.04 appears to characterize the family, with the intercept a taking on different values according to the varying capacity for rapid growth.

scholarly journals Habitat Utilization by Juvenile Pacific Salmon (Onchorynchus) in the Glacial Taku River, Southeast Alaska

1989 ◽  
Vol 46 (10) ◽  
pp. 1677-1685 ◽  
Author(s):  
Michael L. Murphy ◽  
Jonathan Heifetz ◽  
John F. Thedinga ◽  
Scott W. Johnson ◽  
K V. Koski
Keyword(s):  
Pacific Salmon ◽  
Habitat Type ◽  
Fork Length ◽  
Habitat Utilization ◽  
Habitat Types ◽  
Southeast Alaska ◽  
Beaver Ponds ◽  
Spawning Areas ◽  
Poor Access ◽  
Juvenile Pacific Salmon

Habitat utilization was determined in summer 1986 by sampling 54 sites of nine habitat types: main channels, backwaters, braids, channel edges, and sloughs in the river; and beaver ponds, terrace tributaries, tributary mouths, and upland sloughs on the valley floor. Physical characteristics were measured at all sites, and all habitats except main channels (current too swift for rearing salmon) were seined to determine fish density. Sockeye (Oncorhynchus nerka) averaged 23 fish/100 m2, nearly twice the density of coho (O. kisutch) and four times that of chinook (O. tshawytscha), 14 and 6 fish/100 m2, respectively. Sockeye were age 0, 27–84 mm fork length (FL), and most abundant in upland sloughs, beaver ponds, and tributary mouths. Coho were ages 0 and 1, 33–132 mm FL, and most abundant in beaver ponds and upland sloughs. Chinook were age 0, 40–93 mm FL, and more abundant than the other species in habitats with faster currents (1–20 cm/s), particularly channel edges. Each species was absent from about one-quarter of the seining sites of each habitat type. Thus, the lower Taku River provides important summer habitat for juvenile salmon, but many suitable areas were unoccupied, possibly because of their distance from spawning areas and poor access for colonizing fish.

Host–Parasite Relationships Between Sockeye Salmon, Oncorhynchus nerka, and Salmincola californiensis (Copepoda: Lernaeopodidae)

1977 ◽  
Vol 34 (2) ◽  
pp. 191-202 ◽  
Author(s):  
Z. Kabata ◽  
B. Cousens
Keyword(s):  
Sockeye Salmon ◽  
Body Wall ◽  
Oncorhynchus Nerka ◽  
Mechanical Damage ◽  
Fork Length ◽  
Parasitic Copepod ◽  
Size Groups ◽  
Branchial Cavity ◽  
Host Parasite ◽  
First Time

The distribution of the parasitic copepod, Salmincola californiensis, on two size-groups (fry, fork length 3.2–5.8 cm; juveniles, fork length 10.2–27.0) of the sockeye salmon, Oncorhynchus nerka, is described. The existence of preferred sites for both groups is established. The distribution on the smaller fish differs from that on the larger in that on the former the copepods are most abundant in the region of pectoral and pelvic fins, whereas on the latter they are by far most common in the branchial cavity. Macroscopic and microscopic mechanical damage to the fish tissues, resulting from the presence and activity of the copepod, comprises injuries to gills, skin, muscle, and even bone. The "burrowing phenomenon" (failure on the part of the copepod to cease excavation of a completed cavity of implantation, resulting in perforation of body wall and penetration of the viscera) is reported upon for the first time.

Selective tidal stream transport of adult sockeye salmon (Oncorhynchus nerka) in the Fraser River Estuary

1995 ◽  
Vol 52 (1) ◽  
pp. 1-12 ◽  
Author(s):  
David A. Levy ◽  
Allen D. Cadenhead
Keyword(s):  
Water Column ◽  
Sockeye Salmon ◽  
Flow Direction ◽  
Oncorhynchus Nerka ◽  
River Estuary ◽  
Acoustic Doppler Current Profiler ◽  
Fish Abundance ◽  
Monitoring Site ◽  
Fraser River ◽  
Local Flow

Mobile acoustic surveys of 24-h duration were undertaken at Steveston Bend between 1991 and 1993, close to the time of maximum adult Early Stuart sockeye salmon (Oncorhynchus nerka) abundance in the Fraser River estuary. During each survey, extreme variations in the abundance and directional orientation of fish targets appeared to be related to local flow direction and velocities. Acoustic Doppler Current Profiler (ADCP) measurements of water currents adjacent to the fish monitoring site showed that the water column stratified into two vertical layers under certain tidal conditions, with an upper outflowing layer over a lower inflowing layer. Under strong flood or ebb conditions, most of the water column was, respectively, inflowing or outflowing. Fish abundance in the water column appeared to be related primarily to tidal current variations. Maximum fish abundance and upstream orientation occurred during flood tidal periods with upstream current flows. We conclude that migrations of Early Stuart sockeye salmon are synchronized with the tidal cycle for energetically efficient net upstream displacement through the Fraser River estuary.

Evidence for Size-Selective Mortality of Juvenile Sockeye Salmon (Oncorhynchus nerka) in Babine Lake, British Columbia

1987 ◽  
Vol 44 (4) ◽  
pp. 712-721 ◽  
Author(s):  
Cameron J. West ◽  
P. A. Larkin
Keyword(s):  
British Columbia ◽  
Sockeye Salmon ◽  
Oncorhynchus Nerka ◽  
Length Distribution ◽  
Fork Length ◽  
Late Summer ◽  
Selective Mortality ◽  
Daily Growth ◽  
Back Calculation ◽  
Spawning Tributaries

Otolith – body length relations and back-calculation procedures were used to test the hypothesis that mortality of juvenile sockeye salmon (Oncorhynchus nerka) in Babine Lake, British Columbia, is size selective. Samples of the 1978 brood of sockeye were collected as fry from spawning tributaries as juveniles in the main basin, and as smolts at the outlet. Total otolith length was chosen as the most useful otolith dimension for back-calculation of fork length at emergence. Sockeye from the various tributaries show different fork length – otolith length relationships necessitating a weighting procedure for comparisons involving samples of mixed stocks from the lake. Instantaneous daily growth rate and In fork length during the early lake-rearing period were significantly correlated. Smaller juveniles grew more slowly than larger individuals in mid-july, and a hierarchy of sizes was maintained. The distributions of total otolith length at emergence for fry, surviving juveniles, and smolts indicate selective mortality of fish with smaller otoliths, hence of small size at emergence. Survivals from the lower and upper halves of the initial total otolith length distribution were 8.9 and 63.6%, respectively. Comparable estimates for back-calculated fork lengths at emergence were 27.2 and 43.4%. Size-selective mortality is most intense in the late summer and early autumn, and may be associated with predation and parasitism.

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